Ion chromatography for dairy product analysis: a technical and regulatory review

Abstract

Ion chromatography (IC) is a well-established analytical technique for quantifying ionic species in complex food matrices, offering high sensitivity, selectivity, and multi-analyte detection capability. This review provides a critical and comprehensive overview of IC applications in dairy product quality control and regulatory compliance, focusing on the determination of electrolytes (Na⁺, K⁺, Ca²⁺, Mg²⁺), inorganic anions (Cl⁻, NO₃⁻, SO₄²⁻, PO₄³⁻), organic metabolites (citrate, lactate), carbohydrates, amino acids, and contaminants. A systematic literature search was conducted in Scopus and Google Scholar (2000–2026) using keyword combinations related to ion chromatography and dairy products. From 287 initial records, 98 peer-reviewed articles met the inclusion criteria after full-text assessment. Manual screening of reference lists yielded 110 references, demonstrating that IC contributes significantly to adulteration detection, nutritional monitoring, quality assessment of processing steps (pasteurization, maturation), and compliance with international standards. Major identified gaps include (i) the absence of standardized IC methods for amino acid and peptide profiling in dairy matrices; (ii) the limited application of IC coupled to high-resolution mass spectrometry for non-target screening of emerging contaminants; and (iii) insufficient comparative studies between IC and alternative techniques (IC-mass spectrometry or ICP-based methods) across different dairy products. Emerging trends are discussed, including advanced sample preparation (online dialysis), miniaturization (capillary IC), automation, chemometrics and machine learning for fraud detection, and sustainability-driven approaches (green chemistry, reagent-free IC systems). This review aims to contribute to researchers, industry professionals, and regulatory authorities by identifying priority areas for future IC methodological development.

Keywords:
Ionic speciation; Food adulteration; Quality assurance; Analytical validation; Dairy safety; Chromatographic methods

Highlights

Ion chromatography (IC) enables accurate ion profiling in dairy matrices

IC supports quality control, safety assessment, and the detection of adulteration in dairy matrices

IC improves speed, sensitivity, and regulatory compliance in chemical analyses of dairy matrices

1 Introduction

Ion chromatography (IC) is a well-established technique in food science for quantifying cations and anions in complex matrices, offering high sensitivity, selectivity, minimal sample preparation, multianalyte analysis in a single run, low detection limits (ppb range), reduced solvent consumption, and alignment with green chemistry practices, making it the preferred method for food safety, quality control, and regulatory compliance (Bruggink & Jensen, 2021; Fritz & Gjerde, 2009; Leng et al., 2025; Muntean, 2022).

In food analysis, IC is widely applied to determine inorganic nutrients (calcium, sodium, potassium, magnesium, chloride, and phosphate) and monitor contaminants (nitrate, nitrite, perchlorate, and sulfite). Advances in stationary phases, automation, and coupled techniques (IC‒MS, IC‒ICP‒MS) have increased productivity and robustness, enabling rapid, reliable analyses in complex matrices with minimal pretreatment (Fritz & Gjerde, 2009; Muntean, 2022).

Dairy products particularly benefit from IC analysis. Studies have demonstrated its application in quantifying free inorganic ions (sodium, potassium, ammonium, calcium, magnesium, chloride, phosphate, and sulfate) in milk and cheese (Hu & Rohrer, 2020; Wei et al., 2017). Wei et al. (2017) developed a column-switching method for the simultaneous determination of L-carnitine, choline, and cations in infant formulas (94–105% recoveries; mg/L detection limits). IC also detects undesirable ions from agricultural inputs or processing, nitrate, nitrite, chlorate, perchlorate, and bromate (Michalski, 2016; Muntean, 2022; Suess, 2021).

Previous reviews focused on ion chromatography in the context of food analysis (Muntean, 2022) or its technical fundamentals (Nesterenko et al., 2023; Weiss, 2016). Regarding IC and dairy matrices, Poitevin (2016) reviewed the detection of minerals and trace elements in infant formula, while Michalski & Pecyna-Utylska (2021) were responsible for the sample preparation. We are not aware of any other literature review on ion chromatography for dairy products addressing a comprehensively and critically integrated review embracing: (i) the theoretical foundations of IC tailored to complex dairy matrices; (ii) a compilation of IC applications for different analyte classes (minerals, carbohydrates, organic acids, amino acids, choline, and contaminants); (iii) the alignment with regulatory standards (AOAC, ISO, IDF) that certify official IC methods; and (iv) the perspectives of the IC uses emphasizing sustainability and green chemistry. Given this gap, this review provides an updated framework that connects theory, practice, and regulation involved in the quality control and safety of dairy products. Therefore, this review promotes the integration of three dimensions of IC for dairy product analysis: theoretical foundations of IC, ordered presentation of IC analytical parameters (LOD, LOQ, recovery, and RSD), and regulatory standards (AOAC, ISO, and IDF), combined with a discussion on automation, chemometrics, and green chemistry.

This review addresses the crucial role of ion chromatography in quantifying ionic components in dairy products given the complexity of food samples. Our main objectives include providing guidance on applications, considering technological advances and existing practices, addressing sample preparation, column selection, analytical configurations, reagents, and appropriate detection, in addition to contributing to quality control, regulatory compliance, and quality standards in the dairy industry.

2 Methodology

This narrative review was conducted by searching the Scopus and Google Scholar databases using combinations of the following keywords: ‘ion chromatography’, ‘chromatographic applications’, ‘ion chromatography in dairy products’, ‘dairy quality and safety’, ‘chromatographic methods’ and ‘sample preparation for chromatography’. The specific search strings used were (“ion chromatography” OR “chromatographic applications”) AND (“dairy” OR “cheese” OR “yogurt” OR “milk”), and (“ion chromatography” AND “dairy quality” AND “safety”).

The search was conducted between 2000 and 2026 and covered all publications available up to the manuscript preparation date, including both initial studies and recent advances on IC and dairy matrices, as shown in Figure 1. Only peer-reviewed articles, systematic reviews, and standardized analytical methods published in English were considered. The reference lists of selected articles were also manually screened to identify additional relevant studies (a snowballing method).

Figure 1
Methodological evolution of chromatography over time, highlighting the main technological advances in ion chromatography since its creation in 1975 to the present.

The following inclusion criteria were applied to the search: (a) studies addressing ion chromatography applications in dairy quality control; (b) development or validation of methods for ionic species in dairy matrices; and (c) original experimental data.

In turn, the exclusion criteria were applied: (a) articles not directly related to applications in the dairy sector or lacking practical relevance for quality monitoring, (b) conference abstracts, and (c) book chapters without peer review.

Selection process and article numbers: The initial search yielded 287 articles after duplicate removal. After screening by title and abstract, 163 articles were excluded, leaving 124 for full-text review. After the full-text assessment, 98 articles met the inclusion criteria. An additional 12 articles were identified through manual screening of reference lists, bringing the total to 110.

The selected studies were organized into five thematic categories: (1) theoretical and analytical foundations of ion chromatography; (2) sample preparation techniques for dairy matrices; (3) role of ion chromatography in monitoring dairy composition and safety; (4) practical applications in dairy products (minerals, carbohydrates, organic acids, amino acids, and contaminants); and (5) regulatory standards, methodological limitations, and future perspectives.

This structure provides an integrated overview of current practices and emerging trends in ion chromatography to ensure dairy product quality and safety. Figure 2 summarizes the article selection procedure.

Figure 2
Flowchart of the article selection for the review. The search, conducted between 2000 and 2026, used the Scopus and Google Scholar databases. After duplicate removal, the titles and abstracts of 287 records were screened, resulting in 124 articles for full-text assessment. After the full texts were read, 98 articles met the inclusion criteria. An additional 12 articles were identified through manual screening of reference lists (snowball sampling), yielding a total of 110 articles included in the review.

3 Theoretical aspects of ion chromatography

Throughout this review, the abbreviation IC refers to ion chromatography, an analytical method that separates ions based on their interactions with an ion-exchange stationary phase. Ion-exchange chromatography is the most common IC separation mechanism. Techniques such as high-performance anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD) are specific IC configurations optimized for carbohydrates. IC‒MS and IC‒ICP‒MS refer to IC coupled with mass spectrometry, either by electrospray ionization (ESI‒MS) or inductively coupled plasma (ICP‒MS).

3.1 Separation mechanisms

Chromatography separates molecules based on their differential interactions with the mobile and stationary phases. Ion chromatography (IC) uses three mechanisms, depending on the analyte properties and analytical objectives (Weiss, 2016). As with conventional ion exchange methods, several hybrid approaches and coupled detectors have expanded the analytical scope of ion chromatography (Table 1).

Table 1
Main techniques applied to ion chromatography.

Separation techniques	Principle	Advantages	Disadvantages	References
Ion-exchange chromatography (IEX)	A technique based on the affinity of ions for the stationary and mobile phases. Sample components are separated as they pass through the chromatography column, depending on their interactions with functional groups present in the stationary phase and the ionic species.	Applicable to a wide variety of analytes — such as metal ions, anions, cations, and charged molecules — with applications in the analysis of water, proteins, nucleic acids, and inorganic ions.	The stability of these interactions depends on temperature, pH, and the nature and balance of electrical charges among the ions present, making it somewhat difficult to separate components with very similar sizes and charges.	(Fanali et al., 2023; Muntean, 2022; Weiss, 2016)
Ion-exclusion chromatography (IEC)	A technique for separating charged molecules based primarily on molecular size and shape, regardless of charge (involving Donnan exclusion, surface steric exclusion, and sorption processes).	Simplified sample preparation results in less denaturation or chemical alteration compared to other techniques, which is particularly beneficial for sensitive biomolecules. Hence, the technique is used to separate polysaccharides, nucleic acids, proteins, amino acids, and weak bases.		(Fanali et al., 2023; Weiss, 2016)
Ion-pair chromatography (CIFM)	A technique that allows ions in the mobile phase to interact with an ion-pairing agent, facilitating the separation of ionic and polar compounds.	Enables the separation of ionic and polar compounds that are undetectable by other techniques by adjusting mobile-phase polarity and adding various ion-pairing agents. Thus, analytes with and without ionic charge can be separated simultaneously, such as certain anions and cations, sulfur compounds, amines, and transition metal complexes.	Mobile phase preparation can be more complex due to the need to add ion-pairing agents. Furthermore, there is a risk of contamination of the stationary phase by these agents, requiring ongoing preventive maintenance and potentially leading to a loss of column efficiency over time.	(Muntean, 2022; Weiss, 2016)
Reversed-Phase Liquid Chromatography (RPLC)	A technique that enables the separation of highly polar and ionic analytes based on their hydrophobic interactions with the stationary phase.	Allows for the determination of various compounds, including organic acids, bases, salts, and other ionic compounds, provided they are sufficiently hydrophobic or can be derivatized.	Requires special handling to accommodate highly polar compounds, requiring mobile phase modifiers and posing a potential risk of column contamination.	(Weiss, 2016)
Chelation Ion Chromatography (CIC)	A technique that identifies analytes by forming stable complexes using chelating agents to separate specific metal ions from a sample.	Offers high selectivity for specific metal ions and enables the separation of inorganic ions, particularly cations. Its compatibility with various detector types is also a key factor, such as mass spectrometry and atomic absorption spectrometry.	Chelating agents and specialized columns can make the method costly. Controlling the complete chelation process for all analytes is complex. This complexity imposes limits on selectivity, particularly in samples containing multiple metals that form complexes with the same chelating agents.	(Fanali et al., 2023)
Multidimensional ion chromatography	A technique that allows for the analysis of ions in complex samples, such as biological or environmental ones. This advanced technique employs multiple separation stages using sequential columns, enabling more efficient isolation and separation of ions, including those with very similar properties that might not be resolved in a single separation step.	It improves component resolution and separation, accommodating sample complexity. The inclusion of one or more separation stages enables more detailed component characterization, thereby facilitating the identification of individual analytes.	The methodology entails a longer analysis time than one-dimensional separation, resulting in greater complexity in data acquisition and interpretation. It also requires alignment between system configuration and operation across different pieces of equipment.	(Weiss, 2016)
Ion chromatography with atomic spectrometry (such as atomic absorption, atomic emission, and mass spectrometry)	Technique based on coupling an atomic absorption spectrometer with an ion chromatograph via a capillary connecting the separation column outlet to the instrument’s nebulizer.	Provides high sensitivity and precision in the detection and quantification of various specific elements and compounds. It also offers high specificity for identification, minimizing interferences and enabling the distinction between elements with similar masses.	The equipment entails considerable cost and operational complexity, with long analysis times. Additionally, the presence of co-eluents in the matrix or introduced during sample preparation can affect sensitivity and specificity.	(Michalski, 2016; Weiss, 2016)
Ion chromatography with ultraviolet (UV) spectroscopic detection	Technique that utilizes ultraviolet light absorption to identify and quantify specific substances.	Detection of inorganic ions (such as alkali and transition metals) and non-metallic ions (such as phosphate and nitrate), as well as charged organic molecules (such as amino acids, peptides, and small organic molecules with ionic functional groups)	Direct detection is quite uncommon for inorganic ions, requiring pre- or post-column derivatization. Significant background interferences and exclusion effects, which often hinder fluorescence detection, have limited its utility in ion chromatography.	(Fanali et al., 2023; Michalski, 2016)

3.2 Columns

Chromatographic columns form the backbone of ion chromatography, critically defining separation efficiency, selectivity, and robustness. characteristics: (1) they are typically manufactured from inert materials (PEEK or stainless steel) to withstand pressures up to 400 bar, 50–250 mm in length, 2.0–4.6 mm in internal diameter (Muntean, 2022); (2) their stationary phase of silica or polymeric resin spheres are grafted with ionic functional groups of quaternary ammonium for anion exchange and sulfonate or carboxylate for cation exchange; (3) the anion exchange resins have porous polymeric beads (high capacity, pH resistance) and latex-based particles (sharper peaks via shorter diffusion paths); (4) the cation exchange resins have strongly acidic (sulfonate, fully ionized across a wide pH range) or weakly acidic (carboxylate, pH-dependent ionization requiring precise control); (5) the resin particle size affects column performance: microporous particles (3–10 µm) balance efficiency and backpressure; sub-2 µm and core-shell designs increase resolution at higher pressure; and monolithic columns offer high permeability for fast bioanalytical applications (Fanali et al., 2023; Muntean, 2022); (6) the density and distribution of resins influence column capacity, selectivity, and kinetic performance; and (7) the proper column conditioning, regeneration, and maintenance prevent fouling and ensure reproducible performance, requiring alignment of column selection with method requirements, sample throughput, and sustainability considerations (Fritz & Gjerde, 2009).

3.3 Detectors

IC detectors convert eluted ions into measurable signals, providing qualitative and quantitative compositional data. The detectors provide (1) conductivity detection, which is a prototypical approach, exploits the direct relationship between ionic concentration and electrical conductivity; post-column eluent quenching converts highly conductive eluents into weakly conductive species (water, weak acids), reducing background noise and enabling detection at low levels (µg/L) essential for trace analyses (Fritz & Gjerde, 2009; Muntean, 2022); (2) UV–Vis detection that quantifies light absorption by chromophoric species (e.g., nitrite, nitrate) or analytes derivatized with color-forming reagents, offering fast, economical measurements but limited selectivity for absorbing compounds (Fritz & Gjerde, 2009; Muntean, 2022); (3) fluorescence detection that achieves parts-per-trillion sensitivity for intrinsically fluorescent compounds or those made fluorescent by post-column derivatization, making it valuable for organic acids and polyphenols at trace concentrations in complex food matrices (Nesterenko et al., 2023); (4) electrochemical detection that encompasses potentiometric methods (ion-selective electrodes measuring potential difference) and amperometric methods (current from redox reactions), with pulsed electrochemical detection expanding applicability through periodic electrode cleaning (Fritz & Gjerde, 2009; Muntean, 2022); (5) refractive index detection, which is a universal detector for non-volatile, non-chromophore solutes but requires strict temperature and flow control due to baseline instability (Fritz & Gjerde, 2009; Muntean, 2022); and (6) evaporative light scattering that detects non-volatile compounds (carbohydrates, lipids, polymers) by nebulizing the eluent, evaporating the solvent, and measuring light scattered by residual particles — invaluable when analytes lack UV absorbance or conductivity (Fritz & Gjerde, 2009). Coupled techniques represent the cutting edge; e.g., IC–ESI–MS and IC–HESI–MS enable structural elucidation of polar metabolites and peptides at nanomolar concentrations, while IC–ICP–MS provides robust speciation of trace elements (As, Cr, Hg, Se) at parts-per-trillion levels. These combinations offer unparalleled specificity but require rigorous mobile-phase compatibility and entail high operational costs, limiting routine use to specialized laboratories (Nesterenko et al., 2023).

3.4 Suppression system

Suppression systems are essential for detecting low-concentration analytes by reducing mobile-phase background conductivity. The high electrolyte concentrations required for effective elution generate baseline noise that can mask analyte signals. Chemical and electronic strategies are the two main suppression systems. In chemical suppression, the column effluent passes through an ion-exchange suppressor, where regenerant protons convert carbonate or hydroxide eluents into weakly conductive species (water or carbonic acid), minimizing noise and achieving µg/L detection limits with excellent reproducibility (Fritz & Gjerde, 2009; Muntean, 2022). In electronic suppression, a controlled direct-current field is applied across a suppressor cell to drive ionic conversion without chemical regenerants, stabilizing the baseline near zero conductivity while eliminating reagent handling and waste. Modern electronic systems provide comparable performance with longer lifespans and lower operating costs, though they require precise electrical control and can be sensitive to pressure fluctuations (Weiss, 2016). Selection of the system depends on workflow: high-throughput laboratories benefit from automated, low-maintenance electronic operation, whereas labs handling complex, variable samples may favor the robustness and contamination tolerance of chemical suppressors. Regardless of system type, regular performance monitoring is essential.

3.5 Sample preparation

Detailed sample preparation is fundamental to accuracy, precision, and system longevity, particularly for complex matrices such as food, environmental water, and biological fluids, which may contain particles, proteins, lipids, and macromolecules that can clog columns, suppressors, and detectors. Customized approaches are employed to remove interferents and concentrate analytes while preserving species integrity (Table 2). Regardless of method, rigorous attention to routine consistency, reagent purity, pH adjustment, and run time is crucial for intra- and interlaboratory comparability; in addition, standard operating procedures, proficiency testing, and full method validation are required to ensure reliable, reproducible data.

Table 2
The advantages and disadvantages of supplementary sample preparation steps.

Treatment	Principle	Advantages	Disadvantages	References
Sample dilution	A key procedure for adjusting analyte concentrations to fall within the chromatographic system’s optimal detection range, ensuring accurate and reproducible results.	By adjusting analyte concentrations and reducing interferences, sample dilution facilitates the acquisition of reliable, high-quality results.	Reducing the concentration of certain analytes can affect the system’s detection limit, resulting in a loss of sensitivity. Therefore, preparing the dilution requires care and precision to ensure it is appropriate and that results are reproducible.	(Muntean, 2022; Seubert et al., 2021; Weiss, 2016)
Dialysis	A technique used to purify, concentrate, or desalt complex samples, based on the selective diffusion of low-molecular-weight molecules through a semipermeable membrane. In this process, sample ions diffuse into an eluent solution, seeking equilibrium with the eluent. This technique is suitable for samples with high organic matter content, such as dairy products, which could otherwise contaminate equipment and columns.	A relatively simple and efficient procedure that minimizes the denaturation or degradation of sensitive biomolecules. For dairy products, in-line dialysis stands out for its efficiency in separating organic contaminants and microorganisms.	A time-consuming process, especially for samples requiring extensive impurity removal; it poses challenges for purifying low-molecular-weight analytes, which diffuse easily through the membrane.	(Muntean, 2022; Seubert et al., 2021; Weiss, 2016)
Sample filtration	A procedure that ensures the removal of particles and impurities that could compromise the analysis and the equipment. Filter types range from syringe filters with specific pore sizes (0.22 to 0.45 μm) to ultrafiltration membranes, depending on analytical requirements.	Filtration is considered a simple, cost-effective process that ensures the integrity of the chromatographic system by retaining particulate matter and impurities, thereby preventing flow obstructions. Thus, it helps extend the lifespan of the column and accessories while reducing noise and interference in chromatograms.	There is a risk of retaining analytes of interest that are similar in size to the particles being removed. In samples with complex matrices, filtration may be insufficient, requiring additional sample preparation methods.	(Muntean, 2022; Seubert et al., 2021; Weiss, 2016)
Deproteinization	A procedure used to remove proteins and other macromolecules by precipitating agents and centrifugation, purifying the matrix and making it suitable for chromatographic analysis. Various precipitating agents exist, such as organic solvents and protein precipitation reagents.	Reduces the risk of contamination and column clogging, extending its lifespan. Thereby, it helps preserve the integrity of accessories and reduces noise and interference in chromatograms.	The use of solvents, precipitation reagents, or ultrafiltration membranes increases the cost, complexity, and duration of this step. Additionally, the co-precipitation of analytes with proteins can lead to underestimated values.	(Nesterenko et al., 2023; Nielsen, 2017; Weiss, 2016)
Clarification via the Carrez method	Clarification involves the sequential addition of Carrez I (potassium ferrocyanide) and Carrez II (zinc sulfate) reagents to precipitate and remove proteins, polysaccharides, and colloidal particles from the sample. Next, the sample is centrifuged, and the supernatant is collected and filtered to remove unwanted residues.	The procedure does not require complex equipment and improves chromatogram resolution, thereby increasing precision and reproducibility.	Co-precipitation of analytes can lead to an underestimation of results. Furthermore, Carrez reagents can interact with the analytes of interest, the mobile phase, and the stationary phase, impacting the chromatographic analysis.	(Nielsen, 2017; Seubert et al., 2021; Weiss, 2016)
Solid-Phase Extraction ( Christiansen et al., 2020 )	SPE involves separating the components of a liquid sample using a solid adsorbent, yielding a purified, concentrated sample suitable for chromatographic analysis. Analytes are adsorbed onto the solid phase, while impurities are eluted. Subsequently, the analytes are removed from the solid phase using a suitable solvent.	The extraction allows for analyte concentration and the removal of interfering substances that could compromise chromatographic analysis. Hence, it reduces interference affecting the stationary phase and system components, leading to better resolution, improved detection limits, and increased durability of the chromatographic system.	The procedure can increase the cost and time required for sample preparation. During extraction, there is a risk of analyte loss during adsorption and elution. Proper selection of the solid phase is critical and depends on the type of analyte being extracted. Furthermore, the solvent used for analyte elution must be compatible with the mobile phase.	(Knoll et al., 2020; Seubert et al., 2021; Weiss, 2016)
QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe)	A liquid‒liquid extraction technique involving “salting-out”, followed by dispersive solid-phase extraction (d-SPE) cleanup. Essentially, it involves extracting analytes with organic solvents, partitioning to remove interferences and concentrate the target analytes, and then purifying to enhance selectivity.	This extraction method applies to a wide range of matrices and is effective at removing organic and inorganic interferences. Compared to other extraction techniques, it offers faster sample preparation and efficient cleanup, resulting in greater precision and sensitivity in analyte detection.	The choice of solvent and sorbents must ensure compatibility with the mobile phase, particularly for ion chromatography, which may require additional sample preparation steps. Inappropriate selection of sorbents and improper handling of volatile analytes can result in losses during extraction and cleanup.	(Knoll et al., 2020; Muhammad et al., 2018)

3.6 Advantages and limitations of ion chromatography

Ion chromatography (IC) incorporates green analytical chemistry principles through its predominantly aqueous eluents, minimizing the use of organic solvents and hazardous waste while enabling the simultaneous determination of multiple ionic species in a single analysis. Its high sensitivity and selectivity make it indispensable for water quality monitoring, environmental surveys, pharmaceutical impurity profiling, and clinical electrolyte assays. Advances in automation and miniaturization have produced compact benchtop systems with integrated components offering high throughput and low reagent consumption, aligning with sustainability goals (Nesterenko et al., 2023).

However, IC faces challenges with highly complex matrices: components such as organic matter, proteins, or colloids can cause column fouling, increased backpressure, and peak deterioration, requiring preventive maintenance that increases costs and downtime. Specialized columns and reagents can also make routine IC methods more expensive than single-analyte alternatives. Furthermore, coupling with mass spectrometry imposes restrictions on the mobile phase (volatile electrolytes for electrospray) and demands advanced training, confining such systems primarily to research and regulatory laboratories with adequate infrastructure (Nesterenko et al., 2023).

Despite these limitations, continuous innovations in column materials (monolithic, core-shell particles), suppression technology (combining electronic convenience with chemical robustness), and detector platforms (miniaturized amperometric arrays, photonic crystal sensors) promise to expand the reach of ICs, reduce analysis times, increase robustness, and simplify multiplex analyses, consolidating its role as a versatile, high-performance technique capable of meeting evolving analytical demands.

4 Importance of ion chromatography in food quality and safety

Ion chromatography (IC) plays a central role in ensuring the authenticity, quality, and safety of food, allowing the detection of characteristic ionic analytes that reveal adulterations, such as dilution, undeclared additives, or substitution with cheaper ingredients, thus protecting the integrity of the supply chain (Muntean, 2022; Robson et al., 2021).

Monitoring the process with IC enables the identification and quantification of specific ions to control nutritional losses during steps such as pasteurization or maturation, ensuring compliance with quality standards and optimizing the quality of the final product (AlYammahi et al., 2023; Kilic-Akyilmaz et al., 2022).

This technique is also routinely applied to detect inorganic contaminants, including heavy metals (Hg, Pb, and Cd), toxic species (CrO₄²⁻, As, ClO₄⁻, BrO₃⁻, and SO₃²⁻), and nitrite/nitrate from fertilizers or additives, which pose serious health risks at high levels. In addition, ion chromatography enables monitoring of essential elements, such as iodine (excessive intake of which can lead to thyroid disorders), and the determination of residual lactose in “lactose-free” products to prevent adverse reactions in consumers with lactose intolerance (Muntean, 2022; Nesterenko et al., 2023).

Ion chromatography ultimately ensures compliance with regulatory limits for nutrients and contaminants, verifies label information, and upholds legal standards, promoting transparency and trust in the food chain while guaranteeing the quality and safety of marketed products (Muntean, 2022; Nesterenko et al., 2023).

5 Applications of ion chromatography in dairy products

5.1 Minerals

Ion chromatography (IC) allows the simultaneous determination of cations and anions with high sensitivity and minimal reagent consumption (De la Guardia & Garrigues, 2015). The mineral composition of milk, influenced by genetic, environmental, and nutritional factors, includes macroelements (calcium, phosphorus, magnesium, sodium, potassium, and chloride) and essential trace elements (iron, zinc, copper, manganese, selenium, and iodine) necessary for metabolic functions and the physicochemical stability of casein proteins and micelles (Foroutan et al., 2019; Gaucheron, 2011; Muntean, 2022). Table 3 summarizes the applications of ion chromatography in the analysis of minerals in dairy matrices.

Table 3
Applications of ion chromatography for mineral determination in dairy products.

Analyte	Matrix	Colun	Linearity	LOD	LOQ	Recovery	Accuracy (RSD%)	Detection Method	Sample Preparation	Time (min)	Reference
Bicarbonate, chloride, hydrogen phosphate, nitrate	Milk	Shodex IC I-524A	n.i.	n.i.	n.i.	n.i.	n.i.	Conductivity	Dilution, solid-phase extraction	20	(Shodex, 2023)
Bromide, chloride, citrate, phosphate, isocitrate, sulfate	Milk whey	IonPac AS11-HC + AG11-HC	5 mg/L (Br–) 2–75 mg/L (Cl–) 5–60 mg/L (SO42–) 10–180 mg/L (PO43–) 10–120 mg/L (citrate) 10–120 mg/L (isocitrate)	0.40 mg/L(Br–), 0.10 mg/L(Cl–), 0.17 mg/L(SO42–), 0.84 mg/L(PO43–), 2.9 mg/L(citrate), 3.3 mg/L(isocitrate)	1.3 mg/L(Br–), 0.3 mg/L(Cl–), 0.6 mg/L(SO42–), 0.84 mg/L(PO43–), 9.5 mg/L(citrate), 10.9 mg/L (isocitrate)	≥ 96.7%	0.15–0.26%	Suppressed conductivity	Clarification (Carrez method), centrifugation (4000 rpm/30 min)	15	(Cataldi et al., 2003)
Calcium	Milk, milk whey	Metrosep C2	1 – 10 mg/L	n.i.	n.i.	n.i.	n.i.	Conductivity	Extraction with hydrochloric acid (1 M) at pH 3.0, centrifugation (4500 g/15 min)	20	(Rahimi-Yazdi et al., 2010)
Calcium, magnesium, potassium, sodium	Milk, dairy products	IonPac CG15 + IonPac CS15	-	0.5 mg/kg (Na+, K+, Ca2+, Mg2+)	1.6 mg/kg(Na+, K+, Ca2+, Mg2+)	97 – 100%	n.i.	Suppressed conductivity	Extraction in hydrochloric acid (1 M) at pH 4.6, centrifugation (300 g/15 min)	45	(Gaucheron & Le Graet, 2000)
	Milk powder	Metrosep C 4 - 150/4.0	2 mg/kg(Na+, K+, Ca2+, Mg2+)	2 mg/kg (Na+, K+, Ca2+, Mg2+)	n.i.	n.i.	n.i.	Suppressed conductivity	Extraction in nitric acid (2.5 mM), online dialysis	18	(Suess, 2021)
	Milk	Metrosep C 4 - 250/4.0	0.5 mg/L(Na+, K+, Ca2+) 0.1 mg/L(Mg2+)	0.5 mg/L (Na+, K+, Ca2+) 0.1 mg/L(Mg2+)	n.i.	n.i.	n.i.		Online dialysis
	Whey powder	Metrosep C6	n.i.	n.i.	n.i.	97 – 99%	n.i.	Conductivity	Extraction in eluent (50 °C)	18	(Metrohm, 2018)
Calcium, magnesium, potassium, sodium, lithium	Milk whey	IonPac CS12A + CG12A	5 mg/L (Li+) 1–150 mg/L (Na+) 1–50 mg/L (K+,Mg2+, Ca2+)	10 µg/L(Li+), 70 µg/L(Na+), 50 µg/L(K+), 40 µg/L(Mg2+), 60 µg/L(Ca2+)	33 µg/L(Li+), 230 µg/L(Na+), 165 µg/L(K+), 130 µg/L(Mg2+), 200 µg/L(Ca2+)	≥ 96.7%	0.15–0.26%	Suppressed conductivity	Clarification (Carrez method), centrifugation (5000 rpm/60 min)	14	(Cataldi et al., 2003)
Calcium, sodium, potassium, magnesium	Milk, milk powder	IonPac NG1 + SCS + SGS	1–100 mg/L (Na+, K+, Mg2+), 2–200 mg/L (Ca2+)	0.05 mg/L(Na+), 0.15 mg/L(K+), 0.3 mg/L(Mg2+), 0.25 mg/L(Ca2+)	0.18 mg/L(Na+), 0.50 mg/L(K+), 0.99mg/L(Mg2+), 0.85 mg/L(Ca2+)	94 –105%	≤ 2%	Conductivity	Extraction with acetonitrile, centrifugation (10000 rpm/10 min)	20	(Wei et al., 2017)
Chloride, citrate, phosphate, fluoride, nitrite, nitrate, bromide, sulfate	Milk powder	Metrosep A Supp 5 250/4.0	0.05 – 25 mg/L (Cl–, NO2–, NO3–, PO43–, SO42–, citrate)	0.05 mg/L(Cl–, NO2–, NO3–, PO43–, SO42–, citrate)	n.i.	n.i.	n.i.	Conductivity	Online dialysis	16	(Suess, 2021)
	Milk	Metrosep A Supp 5 100/4.0	0.5–7 mg/L (F–, NO2–, NO3–, Br–, SO42–), 5–40 mg/L (Cl–, PO43–)	0.5 mg/L (F–, NO2–, NO3–, Br–, SO42–), 5 mg/L (Cl–, PO43–)	n.i.	n.i.	n.i.
	Infant formula	Metrosep A Supp 5 150/4.0	1–50 mg/L (Cl–, SO42–), 0.002–0.1 mg/L (Br–)	1 mg/L (Cl–, SO42–), 0.002 mg/L(Br–)	n.i.	n.i.	n.i.		Microwave digestion	18
Iodine (iodide, iodate, organoiodine)	Milk	IonPac AG19 + AS19	0–16 µg/L	-	n.i.	n.i.	n.i.	Inductively coupled plasma atomic emission spectrometry	Microwave extraction with tetramethylammonium hydroxide, centrifugation (3000 g/20 min)	n.i.	(van der Reijden et al., 2019)
Iodide	Milk powder	Metrosep A Supp 5 150/4.0	100–300 µg/L	100 µg/L	300 µg/L	n.i.	n.i.	Suppressed conductivity	Low-flow online dialysis	35	(Suess, 2021)
	Milk	Metrosep A Supp 17	2–50 µg/L	2 µg/L	7 µg/L	n.i.	n.i.	Pulsed amperometric
	Dairy products	IonPac AS11	0.025–10 mg/L	0.01 mg/L	0.025 mg/L	82–115%	<0.6% for retention time and <6% for peak area	Pulsed amperometric	Extraction with acetic acid (3%), solid-phase extraction	n.i.	(Dionex, 2003)
	Milk powder, infant formula	IonPac AG-16 + AS-16	0.04–0.2 mg/kg	2.48 mg/kg	8 mg/kg	96–104%	3–5%	UV‒Vis (225 nm)	Ultrafiltration (10000 Daltons), centrifugation (4500 rpm/60–90 min), solid-phase extraction	16	(Niemann & Anderson, 2008)
Iodide, thiocyanate, perchlorate	Milk	Metrosep A Supp 17	10–800 μg/L (I–, [SCN] –, ClO4–)	3.3 μg/L(I–, [SCN] –, ClO4–)	10 μg/L(I–, [SCN] –, ClO4–)	111%(I–), 103% ([SCN] –), 96% (ClO4–)	n.i.	Suppressed conductivity	Clarification (Carrez method), online dialysis	28	(Suess, 2021)
Selenium (IV), selenomethionine, selenocysteine	Milk	PRP X-100	0.02–2.00 mg/L	0.006 mg/L	0.02 mg/L	91 ± 5%	n.i.	Inductively coupled plasma‒mass spectrometry	Extraction with nitric acid (65%) and hydrogen peroxide (35%), size-exclusion column, ultracentrifugation (290,000 g/20 min), proteolytic digestion (lipase + pronase + Tris buffer pH 7.5)	42	(Bierla et al., 2008)

• LOD: limit of detection; LOQ: limit of quantification; RSD: relative standard deviation; n.i.: not informed in the original article; (-): not applicable.

The complex milk matrix, which is rich in proteins and lipids, requires rigorous sample preparation (such as protein precipitation, Carrez clarification, in-line dialysis, or filtration) to minimize interference (Rahimi-Yazdi et al., 2010; Wei et al., 2017). Classical IC methods with unsuppressed conductometric detection have been adapted to quantify total and ionized calcium in milk and whey by converting calcium salts to free Ca²⁺, thereby ensuring accuracy and reproducibility.

For infant formulas, Wei et al. (2017) developed a method that couples a polymeric reverse-phase precolumn to a cation-exchange column, allowing simultaneous determination of L-carnitine, choline, Na⁺, K⁺, Mg²⁺, and Ca²⁺ with recoveries of 94–105%. Iodine speciation via IC‒ICP‒MS revealed iodide as the predominant bioavailable form in milk (van der Reijden et al., 2019).

Standardized sample preparation techniques and high-performance ion-exchange resins, combined with online eluent generation, have increased analytical productivity and reduced solvent use, establishing IC as an indispensable tool for quality control, food safety, and nutritional formulation research in dairy products (Cataldi et al., 2003; Metrohm, 2018; Suess, 2021).

Although IC is widely applied for simultaneous determination of cations (Na⁺, K⁺, Ca²⁺, and Mg²⁺) and anions (Cl⁻, PO₄³⁻, and citrate) in dairy products, ICP‒OES and ICP-MS offer lower detection limits (parts per trillion) for trace elements (e.g., Fe, Cu, and Se). The advantage of IC lies in its ability to perform simultaneous cation/anion determination in a single injection and in its lack of aggressive acid digestion, reducing preparation time and contamination risk. However, for routine trace element analysis, ICP‒MS is often preferable, whereas IC is more suitable when ionic speciation (e.g., free vs. bound phosphate) is relevant (Cataldi et al., 2003).

5.2 Carbohydrates

Ion chromatography (IC) is a widely used analytical tool for the determination of carbohydrates (lactose, galactose, glucose, fructose, sucrose, and maltose) and dairy products, supporting quality control, fermentation monitoring, and nutritional assessments. Pulsed amperometric detection is frequently employed because of its high specificity and low detection limits (Nesterenko et al., 2023).

Quantifying residual lactose in “lactose-free” products is critical for ensuring consumer safety. IC methods with pulsed amperometric detection offer robust performance and sensitivity below 10 mg/L, surpassing conventional enzymatic assays in terms of selectivity (Monti et al., 2017; Muntean, 2022; Panseri et al., 2021). N-acetylneuraminic acid (sialic acid) is a bioactive monosaccharide in human and bovine milk associated with immunological and cognitive benefits that has been quantified by pulsed amperometry ion chromatography at different stages of lactation, providing key data for the development of enriched infant formulas (Alahmad et al., 2021; Chenying et al., 2022).

Fructo-oligosaccharides (FOS), galacto-oligosaccharides (GOS), and oligosaccharides from human milk exert prebiotic effects, promoting beneficial effects on the gut microbiota. Anion-exchange IC with pulsed amperometric detection efficiently quantifies GOS and FOS in infant formulas, even in matrices with high levels of free lactose. For qualitative structural characterization without derivatization, IC coupled with mass spectrometry offers superior resolution and specificity (Lin et al., 2018; Zhang et al., 2021). Table 4 details the IC methods for dairy carbohydrate analysis, including detection methods, limits of detection, and sample preparation.

Table 4
Applications of ion chromatography for carbohydrate determination in dairy products.

Analyte	Matrix	Colun	Linearity	LOD	LOQ	Recovery	Accuracy (RSD%)	Detection Method	Sample Preparation	Time (min)	Reference
Arabinose, galactose, glucose, sucrose, fructose, lactose, maltose	Dairy products	CarboPac PA1 Guard + CarboPac PA1	35 mg/L (arabinose) 0.52–260 mg/L (galactose, glicose, frutose) 0.8–400 mg/L (sucrose, lactose, maltose)	35 mg/L(arabinose), 0.52 mg/L(galactose, glucose, fructose), 0.8 mg/L(sucrose, lactose, maltose)	- (arabinose), 1.7 mg/L(galactose, glucose, fructose), 2.6 mg/L(sucrose, lactose, maltose)	n.i.	< 1.98%	Pulsed amperometry	Extraction with methanol/ethanol/PIPES buffer solution, clarification (Carrez method), centrifugation (5000 g/10 min), in-line dialysis	52	(Hu & Rohrer, 2020)
Arabinose, galactose, lactose, fructose, sucrose, maltose, fucose, trehalose, melibiose, lactulose, isomaltulose	Infant formula, dairy products	Metrosep Carb 2 - 250/4.0	0.1–100 mg/L	0.0005 mg/L	0.0015 mg/L	n.i	< 6.5%	Pulsed amperometry with a sweep	Extraction with methanol/ethanol solution, clarification (Carrez method), in-line dialysis	60	(Suess, 2021)
Fructose, glucose	Infant formula	Metrosep Carb 2	2–250 mg/L (glicose) 20–1000 mg/L (frutose)	250 mg/L(glucose), 1000 mg/L(fructose)	750 mg/L(glucose), 3000 mg/L(fructose)	n.i	n.i	Pulsed amperometry with flexible potential	Hydrolysis (sucrase and α-glucanase), clarification (Carrez method), solid phase extraction	60
Fructose	Infant formula, milk powder	Hamilton RCX-30	0.8–16 mg/L	16 mg/L	48 mg/L	n.i	n.i	Pulsed amperometry	Hydrolysis (sucrase, inulinase), extraction with acetic acid	60
Galactose, glucose, lactose, lactulose, fructose, sucrose, maltose	Milk	Metrosep Carb 2 - 150/4.0 + Metrosep Carb 2 - 250/4.0	0.25–60 mg/L	60 mg/L	180 mg/Li	n.i	n.i	Pulsed amperometry	In-line dialysis	40
Galactose, glucose, lactose, fructose,	Lactic drink, fermented milk	Sugar SH-G + SH1011	n.i	n.i	n.i	n.i	n.i	Refractive Index	Precipitation with sulfosalicylic acid (5%), centrifugation (2500 rpm/10 min), in-line dialysis	10	(Muntean, 2022)
Inositol	Milk powder	Metrosep Carb 2 - 150/4.0	0.025–10.0 mg/L inositol	10 mg/L	30 mg/L	n.i	n.i	Pulsed amperometry	Extraction with hydrochloric acid (1 M), centrifugation (5000 g/10 min), in-line dialysis	25	(Suess, 2021)
Lactose	Infant formula and milk (low lactose, lactose-free)	Metrosep Carb 2 - 150/4.0	0.05–80 mg/L3	80 mg/L	240 mg/L	n.i	n.i	Pulsed amperometry	Clarification (Carrez method), in-line dialysis	30
		Metrosep Carb 2 - 250/4.0						Pulsed amperometry with a sweep
Lactose, lactulose, glucose, galactose	Dairy products	CarboPac PA20 + CarboPac PA20 BioLC	1–10 mg/kg (lactose), 10–30 mg/kg (lactulose, glucose, galactose)	1 mg/kg (lactose), 10 mg/kg (lactulose, glucose, galactose)	3 mg/kg (lactose), 30 mg/kg (lactulose, glucose, galactose)	92–94%	n.i	Suppressed conductivity with electrospray mass spectrometry	Extraction in an ultrasonic bath in propanol, centrifugation (2500 g/10 min)	25	(Panseri et al., 2021)
Lactose, galactose, glucose	Cheese	CarboPac PA20 Guard + CarboPac PA20	0.25–0.41 mg/L (lactose), 0.14–0.27 mg/L (galactose), 0.16–0.26 mg/L (glucose)	0.25 mg/L (lactose), 0.14 mg/L (galactose), 0.16 mg/L (glucose)	0.41 mg/L (lactose), 0.27 mg/L (galactose), 0.26 mg/L (glucose)	93–98%	< 2.79%	Pulsed amperometry	Extraction in heated ultrapure water, ultrasonication by a probe, centrifugation (6000 g/10 min), clarification (Carrez method), solid phase extraction	60	(Monti et al., 2017)
Residual lactose	Dairy products (lactose-free)	Metrosep Carb 2 - 150/4.0	n.i	100 mg/L	n.i	n.i	n.i	Pulsed amperometry	In-line dialysis	30	(Metrohm, 2022b)
Residual lactose, lactulose, allolactose, epilactose	Dairy products (lactose-free)	CarboPac PA210 Guard + CarboPac PA210	0.05–5 mg/L	0.004 mg/L (lactose), 0.003 mg/L (lactulose, allolactose, epilactose)	0.016mg/L (lactose), 0.01 mg/L (allolactose, epilactose), 0.009 mg/L (lactulose)	85–110%	< 0.92%	Pulsed amperometry with mass spectrometry	Clarification (Carrez method), centrifugation (3000 rpm/10 min), solid phase extraction	15	(Aggrawal & Rohrer, 2018)
				0.007 mg/L (lactose), 0.011 mg/L (lactulose), 0.008 mg/L (allolactose), 0.009 mg/L (epilactose)	0.037 mg/L (lactose), 0.037 mg/L (lactulose), 0.025 mg/L (allolactose), 0.03 mg/L(epilactose)		< 1.20%	Pulsed amperometry
Residual lactose, lactulose		Carbo Pac PA20 Guard + Carbo Pac PA20	0.25–100 mg/L (lactose) 0.5–100 mg/L (lactulose)	0.12 mg/L (lactose), 0.23 mg/L (lactulose)	0.36 mg/L (lactose), 0.69 mg/L (lactulose)	85–100%	< 5.0%			30	(Perati et al., 2016)
Residual lactose, galactose, fructose, sucrose, lactulose	Dairy products (low lactose)	CarboPac PA20-Fast Guard + CarboPac PA20-Fast	0.1–20 mg/L	0.03 mg/L	0.1 mg/L	98%	< 3.5%	Pulsed amperometry	Clarification (Carrez method), centrifugation (3000 rpm/10 min)	15	(Thienel & Jensen, 2018)
Raffinose	Milk, dairy products	Metrosep Carb 2 - 150/4.0	0.5–25 mg/L	25 mg/L	75 mg/L	n.i	n.i	Pulsed amperometry	Extraction in ultrapure water (45-50 °C), centrifugation (3000 rpm/10 min), extraction with acetonitrile	n.i	(Suess, 2021)
Sialic acid	Infant formula, human milk	Carbo Pac PA20 Guard + Carbo Pac PA20	0.1–10 mg/L	10 μg/L	30 μg/L	87.6–102%	< 2.65%	Pulsed amperometry	Extraction with trichloroacetic acid (20%), centrifugation (3000 rpm/30 min), hydrolysis with hydrochloric acid (0.1%)	25	(Ru et al., 2021)
Sorbitol, xilitol, manitol, glicose, frutose, maltitol, lactulose, lactose, sacarose, maltose	Milk (lactose free)	Metrosep Carb 2 - 250/4.0	0.1–100 mg/L	100 mg/L	300 mg/L	n.i	n.i	Pulsed amperometry	In-line dialysis	n.i	(Suess, 2021)
Total fructooligosaccharides, kestose, nystose, kestopentaose	Infant formula, raw material for FOS	Metrosep Carb 2 - 250/4.0	n.i	n.i	n.i	n.i	n.i	Pulsed amperometry with mass spectrometry	Extraction with phosphate buffer (80 °C/30 min), hydrolysis (β-galactosidase), centrifugation (6000 g/10 min)	n.i
Total galacto-oligosaccharides (GOS)	Goat milk powder	Metrosep Carb 2 - 250/4.0	4.46–133.84 mg/L total GOS	133.84 mg/L (total GOS)	390 mg/L(total GOS)	95–107%	< 3.6%	Pulsed amperometry	Hydrolysis (β-galactosidase), centrifugation (6000 g/10 min), extraction with acetonitrile	18
		Hamilton RCX-30 - 250/4.6
	Raw material for GOS	Metrosep Carb 2 - 250/4.0	2–32 mg/L glucose, galactose, lactose	0.1 mg/L (galactose), 0.2 mg/L (glucose, lactose)	0.3 mg/L (galactose), 0.6 mg/L (glucose, lactose)	95	< 5.0%	Pulsed amperometry with a sweep	Hydrolysis (β-galactosidase), centrifugation (6000 g/10 min), in-line dialysis at low flow	18

• LOD: limit of detection; LOQ: limit of quantification; RSD: relative standard deviation; n.i.: not informed in the original article; (-): not applicable.

HPAEC-PAD is the reference method for quantifying lactose, lactulose, and galactooligosaccharides in dairy products due to its high sensitivity (µg/L detection limits) and its lack of derivatization requirements. In comparison, HPLC-RI, although more accessible, has limited sensitivity (mg/L) and poor resolution for structurally similar carbohydrates. Enzymatic methods (e.g., lactose/galactose kits) are fast and low-cost but cannot simultaneously quantify multiple carbohydrates or distinguish lactose from lactulose. Thus, HPAEC-PAD is preferred for lactose-free product certification, whereas enzymatic methods are suitable only for initial screening (Monti et al., 2017).

5.3 Organic acids

Organic acids in milk and dairy products, such as lactic, malic, citric, formic, and succinic acids, are crucial for sensory attributes (flavor, aroma), cheese ripening, nutritional value, and food safety (Toldrá & Nollet, 2021). Produced naturally by the lactic microbiota during fermentation or added as preservatives, excessive levels can exceed regulatory limits and compromise product quality (Costa & Conte‐Junior, 2015).

Ion chromatography (IC) is the preferred method for quantifying these compounds and typically uses anion-exchange columns with suppressed conductivity detection, which provides low background noise and sensitivity in the µg/L range (Nesterenko et al., 2023). IC experimentation also allows the simultaneous analysis of inorganic anions (Cl⁻, NO₃⁻) and organic acids in a single run, optimizing productivity and simplifying sample preparation to a single aqueous extraction (Falchi et al., 2023).

Behbahani et al. (2023) employed IC with conductometric detection to monitor lactic, propionic, and acetic acids in bioprotective yogurt cultures and demonstrated synergistic fungistatic effects associated with desirable sensory development. Falchi et al. (2023) developed a rapid method to quantify chloride and lactic acid in cheeses, with high recoveries and without derivatization. Xiong et al. (2014) applied IC‒MS to yogurts and quantified 16 organic acids with optimized quantification limits and high reproducibility.

IC offers selectivity and analytical robustness for monitoring organic acids in dairy products, making it indispensable for quality assurance, food safety, and technological innovation in the sector. Table 5 summarizes the IC methods used in the quantification of organic acids in milk and dairy products.

Table 5
Applications of ion chromatography for organic acid determination in dairy products.

Analyte	Matrix	Colun	Linearity	LOD	LOQ	Recovery	Accuracy (RSD%)	Detection Method	Sample Preparation	Time (min)	Reference
α-Ketoglutaric acid, citric acid, lactic acid, malic acid, pyroglutamic acid, pyruvic acid, orthophosphoric acid, succinic acid, trans-aconitic acid	Lactic drink	-	0.312–40 mg/L (citric acid, malic acid) 0.039–5 mg/L (lactic acid, pyruvic acid) 0.156–20 mg/L (pyroglutamic acid)0. 078–10 mg/L (alpha-ketoglutaric acid, orthophosphoric acid, succinic acid, trans-aconitic acid)	0.01 mg/L(α-ketoglutaric acid, lactic acid, malic acid, pyruvic acid), 0.1 mg/L(citric acid), 0.05 mg/L (pyroglutamic acid), 0.22 mg/L (orthophosphoric acid), 0.02 mg/L(succinic acid), 0.04 mg/L (trans-aconitic acid)	0.03 mg/L(α-ketoglutaric acid, lactic acid, malic acid, pyruvic acid), 0.3 mg/L(citric acid), 0.15 mg/L (pyroglutamic acid), 0.65 mg/L (orthophosphoric acid), 0.06 mg/L(succinic acid), 0.12 mg/L(trans-aconitic acid)	80–109%	< 8.0%	Conductivity with atmospheric pressure ionization mass spectrometry	Extraction with acetonitrile saturated with hexane, centrifugation (5000 rpm/10 min)	32	(Xiong et al., 2014)
Acetic acid, lactic acid, malic acid	Milk	Hamilton PRP-X300	5–40 mg/L	n.i	n.i	n.i	n.i	Suppressed conductivity	In-line dialysis	n.i	(Suess, 2021)
Acetic acid, lactic acid, propionic acid	Lactic acid bacteria culture	n.i	0.5–25 mg/L	n.i	n.i	n.i	n.i	Suppressed conductivity	Extraction in ultrapure water (65 °C)	40	(Behbahani et al., 2023)
Lactic acid	Cheese	IonPac AG20 + IonPac AS20	0.60–250 mg/L	0.18 mg/L	0.6 mg/L	85–109%	5.9%	Suppressed conductivity	Extraction in ultrapure water (45-50 °C), centrifugation (1903 g/10 min)	15	(Falchi et al., 2023)
	Whey powder	Metrosep C6	Metrosep C6	1902 mg/kg	n.i	98%	n.i		Extraction in eluent (50 °C)	33	(Metrohm, 2018)
	Lactic acid drink, fermented milk	Shodex Sugar SH-G + Shodex Sugar SH1011	Shodex Sugar SH-G + Shodex Sugar SH1011	n.i	n.i	n.i	n.i	Refractive index, UV‒Vis (210 nm)	Precipitation with sulfosalicylic acid (5%), centrifugation (2500 rpm/10 min), in-line dialysis	10	(Muntean, 2022)

• LOD: limit of detection; LOQ: limit of quantification; RSD: relative standard deviation; n.i.: not informed in the original article; (-): not applicable.

Suppressed conductivity IC is particularly advantageous for non-chromophoric organic acids (e.g., lactic, propionic, and acetic acids), as it requires no pre- or post-column derivatization. In contrast, HPLC-UV requires low wavelengths (e.g., 210 nm), thereby increasing susceptibility to matrix interference. LC‒MS offers higher specificity and the ability to identify low concentrations, but its high cost and complexity limit its routine use. Conductivity IC represents an ideal balance of cost, robustness, and analytical capacity for monitoring organic acids in fermented dairy products (Costa & Conte‐Junior, 2015; Xiong et al., 2014).

5.4 Amino acids, peptides, and ammonium

Amino acids are fundamental protein building blocks that influence functional properties (Maillard reactions, gel formation, and antioxidant activity) and sensory attributes (flavor, aroma, and texture). Post-column ninhydrin derivatization with ion chromatography (IC) and photometric detection effectively quantifies free amino acids in dairy products. Hogenboom et al. (2017) applied IC-ninhydrin to profile amino acids in Grana Padano cheese, elucidating maturation and authenticity, and extended the method to milk, yogurt, infant formulas, and whey with high reproducibility.

Charged peptides can be separated by cation or anion-exchange ICs, although the efficiency is lower than that of reversed-phase chromatography for high-molecular-weight species (Sforza et al., 2011). UV‒Vis detectors provide protein profiles, whereas MS can be used to identify specific proteins. IC‒MS has shown potential for allergen analysis and the detection of post-translational modifications, but dairy applications remain scarce (Fanali et al., 2023).

Ammonium (NH₄⁺) originates from the enzymatic deamidation of amino acids and urea degradation during thermal processing and cheese maturation (Gaucheron & Le Graet, 2000). Cation-exchange IC with conductometric detection is the standard method for its quantification in milk, whey, and caseinates, offering accurate measurements with minimal matrix interference (Michalski & Pecyna-Utylska, 2021).

Biogenic amines (histamines, tyramine, and cadaverine) result from the microbial decarboxylation of amino acids in mature cheeses. IC with suppressed conductometric detection has been used to quantify these amines with minimal sample preparation, although the resolution is lower than that of LC‒MS methods, limiting comprehensive profiling (Rivoira et al., 2019). Table 6 summarizes the applications of IC for quantifying amino acids, ammonium, and amines in dairy products.

Table 6
Applications of ion chromatography for the determination of amino acids, ammonium, and amines in dairy products.

Analyte	Matrix	Colun	Linearity	LOD	LOQ	Recovery	Accuracy (RSD%)	Detection Method	Sample Preparation	Time (min)	Reference
Ammonium	Sodium caseinate, skim milk, cheese	IonPac CG15 + IonPac CS15	0.5–40 mg/kg	0.5 mg/kg	1.5 mg/kg	97–100%	5.0%	Suppressed Conductivity	Extraction with hydrochloric acid pH 4.6 (1 M), centrifugation (300 g/10 min)	45	(Gaucheron & Le Graet, 2000)
	Yogurt					99–100%			Centrifugation (300 g/10 min)
	Milk powder, milk	Metrosep C4	2–14 mg/L	2 mg/L	n.i	n.i	n.i		Extraction with nitric acid (2.5 mM), in-line dialysis	12	(Suess, 2021)
	Milk		0.005–0.1 mg/L	0.005 mg/L	n.i	n.i	n.i		In-line dialysis
	Whey	IonPac CS12A + CG12A	5–100 mg/L	70 µg/L	200 µg/L	96.7%	0.15–0.26%		Clarification (Carrez method), centrifugation (5000 rpm/60 min)	16	(Cataldi et al., 2003)
Biogenic amines	Cheese	IonPac CG17 + IonPac CS17	0.01–1 mg/L (trimethylamine), 0.05–10 mg/L (putrescine, cadaverine, spermidine), 0.01–10 mg/L (histamine, agmatine, 2-phenylethylamine), 5–100 mg/L (spermine), 0.025–10 mg/L (tryptamine), 0.01–25 mg/L (tyramine)	32 μg/L (trimethylamine), 42 μg/L (putrescine), 46 μg/L (cadaverine), 24 μg/L (histamine), 13 μg/L (2-phenylethylamine), 5400 μg/L (spermine), 800 μg/L (spermidine), 35 μg/L (tryptamine), 34 μg/L (agmatine), 12 μg/L (tyramine)	107 μg/L (trimethylamine), 140 μg/L (putrescine), 153 μg/L (cadaverine), 80 μg/L (histamine), 43 μg/L (2-phenylethylamine), 18000 μg/L (spermine), 2700 μg/L (spermidine), 117 μg/L (tryptamine), 113 μg/L (agmatine), 40 μg/L (tyramine)	n.i	< 10.9%	Conductivity with Electrospray Mass Spectrometry	Homogenization by probe ultrasound	45	(Ščavničar et al., 2018)
	Cheese	IonPac CS18 + IonPac CS18	2.97–4.33 mg/L (ethanolamine), 0.32–0.44 mg/L (ethylamine), 1.85–2.64 mg/L (putrescine), 0,75–3.25 mg/L (cadaverine), 1.66–9.51 mg/L (histamine), 2.09–3.24 mg/L (spermidine), 1.17–3.07 mg/L (spermine)	91 μg/L (ethanolamine), 9 μg/L (ethylamine), 109 μg/L (putrescine), 60 μg/L (cadaverine), 32 μg/L (histamine), 27 μg/L (spermidine), 10 μg/L (spermine)	278 μg/L (ethanolamine), 28 μg/L (ethylamine), 330 μg/L (putrescine), 183 μg/L (cadaverine), 106 μg/L (histamine), 82 μg/L (spermidine), 33 μg/L (spermine)	n.i	n.i	Pulsed amperometry	Extraction with methanesulfonic acid (20 mM), homogenization by sonication, centrifugation (4500 g/10 min)	48	(Rivoira et al., 2019)
Free amino acids	Cheese	Hipersil ODS	5500–8000 mg/100 g	50 mg/100 g	n.i	n.i	5.6%	Fluorescence	Extraction with sodium citrate (0.2 N), probe ultrasound homogenization, deproteinization with sulfosalicylic acid pH 1.7 (7.5%), buffering with lithium citrate pH 2.2 (0.2 N)	120	(Hogenboom et al., 2017)

• LOD: limit of detection; LOQ: limit of quantification; RSD: relative standard deviation; n.i.: not informed in the original article; (-): not applicable.

Post-column ninhydrin derivatization IC is a consolidated, interlaboratory-validated method for the analysis of free amino acids in cheese and other dairy products (Hogenboom et al., 2017). However, UHPLC-FLD with pre-column derivatization offers higher sensitivity (detection limits of nmol/L) and shorter analysis times. The main advantage of IC is the absence of pre-column derivatization, which reduces the preparation time and eliminates variability in derivatization efficiency. For ammonium, conductivity IC is the method of choice, as enzymatic methods are susceptible to interference from the dairy matrix (Hogenboom et al., 2017).

5.5 Choline (vitamin B8)

Vitamin B8, or choline, which is present in high concentrations in cow milk, is essential for maintaining cell membrane, liver, and muscle functions and contributes to healthy brain development (Shetty et al., 2020).

Wei et al. (2017) proposed a method that allowed the simultaneous determination of L-carnitine, choline, and mineral ions in infant formulas, powdered milk, and milk. Dionex (2002) and Suess (2021) applied microwave digestion to analyze choline in infant formulas and powdered milk. Table 7 summarizes the applications of ion chromatography in the analysis of choline in dairy products.

Table 7
Applications of ion chromatography for choline determination in dairy products.

Analyte	Matrix	Colun	Linearity	LOD	LOQ	Recovery	Accuracy (RSD%)	Detection Method	Sample Preparation	Time (min)	Reference
Choline	Infant formula	Metrosep C Supp 1	0.06–75.0 mg/L	n.i	n.i	115%	n.i	Suppressed conductivity	Microwave digestion, acidic extraction with hydrochloric acid (1.5 M at 70 °C)	32	(Suess, 2021)
		Metrosep C 6	0.5–50 mg/L	n.i	n.i	n.i	1.6%			15
	Milk powder, infant formula	IonPac CG12A	10–200 mg/L	3 mg/L	n.i	95%	n.i			25	(Dionex, 2002)
Choline, L-carnitine	Milk, milk powder, infant formula	IonPac NG1 + SCS + SGS	1–100 mg/L (choline)	0.1 mg/L (choline)	0.35 mg/L (choline)	94–95%	1.2%	Conductivity	Extraction with acetonitrile, centrifugation (10000 rpm/10 min)	20	(Wei et al., 2017)

• LOD: limit of detection; LOQ: limit of quantification; RSD: relative standard deviation; n.i.: not informed in the original article; (-): not applicable.

Suppressed-conductivity IC (Association of Official Analytical Collaboration International, 2012) is robust, requires no derivatization, and is moderately priced, making it ideal for routine analysis. In contrast, HPLC‒MS/MS offers lower detection limits (ng/mL) and multivitamin analysis but requires greater investment and greater technical expertise. Enzymatic methods are fast and inexpensive but less specific, unable to distinguish different forms of choline in milk (Association of Official Analytical Collaboration International, 2012).

5.6 Contaminants

Monitoring contaminants in dairy products can be achieved using ion chromatography (IC), which complies with international regulations and supports food safety (Poitevin, 2016).

IC quantifies nitrite and nitrate from additives and agricultural residues with suppressed conductometric detection, which requires pretreatment with acetic acid and NaOH to remove proteins and lipids (Chamandust et al., 2016; Wang et al., 2018). Biogenic amines (histamines and tyramine) are formed by microbial decarboxylation during cheese maturation and can be simultaneously quantified by IC with suppressed conductivity, with pulsed amperometric detection increasing specificity (Linares et al., 2011; Nesterenko et al., 2023). Arsenic reflects soil and water contamination and is determined by IC‒MS after acid digestion, allowing essential speciation for chronic risk assessment (Nesterenko et al., 2023; Permigiani et al., 2024). IC quantifies total chromium with post-column derivatization, whereas after alkaline extraction, Cr⁶⁺, which is highly toxic and carcinogenic, requires IC-MS (Hernandez et al., 2017; Mohana Rangan et al., 2021; Muntean, 2022). Perchlorate originates from fertilizers and industrial pollution and inhibits iodine uptake by the thyroid; it can be quantified by IC with suppressed conductivity and IC‒MS at trace levels (Dyke et al., 2006; Nesterenko et al., 2023; Nobile et al., 2022). Phosphates used as stabilizers (orthophosphate, pyrophosphate, triphosphate, tripolyphosphate, and hexametaphosphate) are simultaneously analyzed by IC on anion-exchange columns after deproteinization and defatting (Xie et al., 2020). Thiocyanate activates the lactoperoxidase system and can generate toxic cyanide; Jiang et al. (2021) developed a protocol with an aqueous biphasic system (acetonitrile/ammonium sulfate) followed by IC for rapid and sensitive determination in raw milk. Table 8 presents the IC methods used to determine contaminants in dairy products.

Table 8
Applications of ion chromatography for contaminant determination in dairy products.

Analyte	Matrix	Colun	Linearity	LOD	LOQ	Recovery	Accuracy (RSD%)	Detection Method	Sample Preparation	Time (min)	Reference
Total arsenic	Infant formula	PRP-X100	1–200 mg/kg	1 mg/kg	3 mg/kg	97–124%	n.i	Conductivity with inductively coupled plasma‒mass spectrometry	Lipid extraction with hexane and acetone (4+1, v/v), freeze-drying, nitric acid extraction (65%), microwave digestion	10	(Vela & Heitkemper, 2004)
Total arsenic, arsenic (III), arsenic (V)	Milk		0.5–120 µg/L (total arsenic, arsenic III, arsenic V)	0.2 µg/L (total arsenic), 0.6 µg/L (arsenic III), 0.7 µg/L (arsenic V)	0.8 µg/L (total arsenic), 1.9 µg/L (arsenic III), 2.5 µg/L (arsenic V)	88.3–93.7%	0.47–4.1%.		Freeze-drying, mobile phase	9	(Permigiani et al., 2024)
Total chromium, chromium (VI)	Dairy products	IonPac CG5A + IonPac CS5A	0.050–5 µg/kg	0.5 µg/kg	1.6 µg/kg	88%	3.1–4.6%.	Conductivity with inductively coupled plasma‒mass spectrometry	Extraction with ammonium hydroxide (67%) in an ultrasonic bath, centrifugation (10000rpm/15 min)	5	(Hernandez et al., 2017)
Melamine	Powdered milk	Metrosep C4	0.02–1 mg/L	0.13 mg/L	0.4 mg/L	100.4%	n.i	UV‒Vis (240 nm)	Extraction with hydrochloric acid (8.75 mM), centrifugation, and in-line dialysis	20	(Suess, 2021)
	Infant formula		1–150 mg/L
Nitrate, nitrite	Cheese	IonPac AG9-HC + IonPac AS9-HC	4.5–225 mg/kg (nitrite) 9.6–375 mg/kg (nitrate)	1.5 mg/kg (nitrite), 3.2 mg/kg (nitrate)	4.5 mg/kg (nitrite), 9.6 mg/kg (nitrate)	98.7–98.3%	n.i	Suppressed conductivity	Centrifugation (1500 g/10 min)	30	(Iammarino et al., 2013)
Nitrate, nitrite	Milk, powdered milk	IonPac AS14A	0.2–4 mg/L (nitrite), 0.5–10 mg/L (nitrate)	0.07 mg/L(nitrite), 0.33 mg/L(nitrate)	n.i	85.3–113.7%	1.4–9.3%.	Suppressed conductivity	Precipitation with acetic acid (3%) in an ultrasonic bath, centrifugation (7000rpm/10 min)	18	(Yeh et al., 2013)
Nitrate, nitrite	Milk		0.25–5 mg/L (nitrite), 1.25–25 mg/L (nitrate)	0.07 mg/L(nitrite, nitrate)	0.25 (nitrite), 1.25 (nitrate)	70.8–102%	3.0%	Suppressed conductivity	Centrifugation (10000rpm/5 min)	16	(Chamandust et al., 2016)
Nitrate, nitrite	Powder milk, infant formula	Metrosep A Supp 10 Guard HC + Metrosep A Supp 5	0.005–0.1 mg/L (NO2-) 0.05–.,0 mg/L (NO3-)	n.i	n.i	n.i	n.i	Suppressed conductivity	Extraction with acetic acid (3%)/acetonitrile, extraction on a reversed-phase column	n.i	(Suess, 2021)
		Metrosep A Supp 16 Guard + Metrosep A Supp 17		n.i	n.i	n.i	n.i			n.i
	Milk, powder milk	Metrosep A Supp 7	0.02–5 mg/L	n.i	n.i	n.i	n.i	UV‒Vis (225 nm)	Extraction in ultrapure water (40 °C), in-line dialysis	n.i
Orthophosphate, pyrophosphate, trimetaphosphate, tripolyphosphate, hexametaphosphate	Milk, yogurt	IonPac AG11 + IonPac AS11-HC	0.4–200 mg/L (orthophosphate, pyrophosphate, trimetaphosphate, tripolyphosphate) 2–1000 mg/L (hexametaphosphate	0.1 mg/L(orthophosphate, pyrophosphate, trimetaphosphate, tripolyphosphate) 0.6 mg/L(hexametaphosphate)	n.i	83.0–117.8%	0.9–9.0%	Suppressed conductivity	Extraction with trifluoroacetic acid (2%)/hexane, centrifugation (12000rpm/10 min), solid-phase extraction	28	(Xie et al., 2020)
Perchlorate	Milk	IonPac AG-16 + IonPac AS-16	3–50 µg/L	0.07 µg/L	n.i	98.2–104%	3.0–6.0%	Conductivity with electrospray mass spectrometry	Centrifugation (12000rpm/10 min), solid-phase extraction	12	(Dyke et al., 2006)
	Human milk		0.015–20 μg/L	n.i	0.015 μg/L	n.i	n.i			n.i	(Kirk et al., 2013)
	Milk	IonPac AG19 + IonPac AS19	1–6.95 μg/L	0.03 µg/L	6.95 µg/L	92%	n.i	Conductivity with electrospray mass spectrometry	Extraction with a formic acid/methanol solution (3%)/centrifugation (2500 g/10 min)	22	(Nobile et al., 2022)
Thiocyanate	Powder milk, infant formula	IonPac AG-16 + IonPac AS-16	0.2–4.1 μg/kg	-	1 mg/kg (powder milk), 0.2 mg/kg (infant formula)	96–104%	3–5%	UV‒Vis (210-225 nm)	Ultrafiltration, solid phase extraction	16	(Niemann & Anderson, 2008)
	Milk	Metrosep A Supp5	0.05–15 mg/L	0.2 µg/L	0.6 µg/L	81–119%	1.6%	Conductivity with Fourier transform infrared spectrometry (FTIR)	Hydrolysis with trichloroacetic acid (50%) and hydrogen peroxide (1%), centrifugation (5000 rpm/10 min), extraction in a two-phase aqueous system (acetonitrile/ammonium sulfate)	50	(Jiang et al., 2021)

• LOD: limit of detection; LOQ: limit of quantification; RSD: relative standard deviation; n.i.: not informed in the original article; (-): not applicable.

For inorganic contaminants (nitrate, nitrite, perchlorate, and chromate), a suppressed-conductivity IC is often the official method (AOAC or ISO) because of simultaneous multi-anion separation. In contrast, spectrophotometric methods (e.g., the Griess reaction for nitrite) are single-analyte specific and more prone to matrix color interference. For the speciation of toxic elements (arsenic, chromium, and selenium), IC‒ICP‒MS is the most powerful technique, combining ionic separation with ultrasensitive detection. However, its high acquisition and maintenance costs limit its use in reference laboratories. For routine nitrate/nitrite analysis in dairy products, conductivity IC remains the most cost-effective and reliable technique (Iammarino et al., 2013).

6 Application of ion chromatography in the assessment of the quality and compliance of dairy products

Ion chromatography (IC) stands out as a precise and reliable analytical technique accepted by regulatory agencies as an official method for quantifying ionic compounds in food, allowing the development of analytical approaches that ensure compliance with regional and international regulations (Metrohm, 2022a; Muntean, 2022). Its integration into dairy quality control (Table 9) represents a significant advance, particularly in ensuring regulatory compliance and promoting continuous improvement in food quality and safety.

Table 9
Standards and regulations for analytical methods and ion chromatography for dairy products.

Analytes	Matrix	Standard	Reference
Propionic acid	Cheese	ISO/TS 19046-2, IDF/RM 233-2:2017	(International Organization for Standardization, 2017)
Choline (Vitamin)	Infant formula, nutritional supplements for adults	AOAC Official Method 2012.20	(Association of Official Analytical Collaboration International, 2012)
Fructans	Cheese spread	AOAC Official Method 997.08-1999 (2003)	(Association of Official Analytical Collaboration International, 2003)
Fructans, glucose, fructose	Infant formula, nutritional supplements for adults	AOAC Official Method 2016.14-2016	(Association of Official Analytical Collaboration International, 2016)
		ISO 22579:2020, IDF 241:2020	(International Organization for Standardization, 2020)
Iodides	Pasteurized milk, skim milk powder	AOAC Official Method 992.22-2007	(Association of Official Analytical Collaboration International, 2007)
Lactose	Lactose-free dairy products and low-lactose dairy products	AOAC SMPR 2018.009	(Association of Official Analytical Collaboration International, 2018)
Myo-inositol	Infant and pediatric formula, nutritional supplements for adults	AOAC Official Method 2011.18-2011	(Association of Official Analytical Collaboration International, 2011)
		ISO 20637:2015	(International Organization for Standardization, 2015)
Trans-galactooligosaccharides	Yogurts and fermented dairy products	AOAC Official Method 2001.02-2004	(Association of Official Analytical Collaboration International, 2004)

The integration of ion chromatography (IC) into dairy quality control enables the detailed determination of ionic composition, which is vital for regulatory compliance and food safety.

Figure 3 shows three ion-exchange chromatograms of dairy matrices, illustrating how the resin, elution conditions, and detection methods influence analytical performance (Iammarino et al., 2011; Nair & Corredig, 2021; Thienel & Jensen, 2018). In Figure 3A, a weak ion-exchange column with conductivity detection was used to detect benzoic acid in cheese with ppm-level sensitivity. As shown in Figure 3B, HPAEC-PAD resolves lactose and lactulose in lactose-free milk and cream cheese. Figure 3C shows the cation-exchange profile of skim milk, with peaks for β-casein, αs-casein, and κ-casein; UV/conductivity detection captures changes in protein distribution due to the addition of formulation or caseinate.

Figure 3
Composite ion exchange chromatograms of dairy products: (A) Weak anion exchange/conductivity chromatogram highlighting benzoic acid in a non-compliant cheese sample. (B) High-performance anion exchange (HPAEC-PAD) separation of lactose and lactulose in lactose-free milk and cream cheese. (C) Cation-exchange chromatograms of skim milk concentrates, comparing the elutions of β-casein, αs-casein, and κ-casein under control, concentrate, and sodium caseinate-supplemented conditions.

While Figures 2A/2C use continuous gradients for high resolution, Figure 3B optimizes stepwise elution for productivity. Matrix effects are evident: cheeses with high fat/salt content (3A) require rigorous cleaning; aqueous lactose-free formulations (3B) allow for simpler conditions. The results suggest future optimizations: longer anionic columns to refine sugar peaks, coupling with mass spectrometry for rapid protein profiling, and adapting preparation protocols to each submatrix. The choice of column, elution, and detector must be balanced with the analytical objective, whether it is to detect preservatives, certify “lactose-free,” identify adulteration, or characterize protein fractions.

7 Future perspectives and recent developments

Ion chromatography has evolved significantly since its beginning in 1975, and future trends point toward greater automation, miniaturization, and integration with high-resolution techniques (Figure 3).

7.1 Two-dimensional ion chromatography (2D-IC)

2D-IC uses valve switching to move fractions from the first column to a second column with a distinct separation mechanism. This approach significantly increases resolution for complex matrices, such as whey protein hydrolysates, enabling separation of peptides with very similar charges (Liu et al., 2015; Yang et al., 2023). Applications in dairy products remain scarce, representing a research opportunity.

7.2 IC coupled to high-resolution mass spectrometry (HRMS)

IC-HRMS coupling enables non-targeted identification of emerging contaminants in milk and dairy products, including polar pesticide residues, disinfection by-products (chlorate, perchlorate, bromate), and natural toxins. Unlike IC‒ICP‒MS, which focuses on elemental speciation, IC‒HRMS provides structural information, allowing the identification of unknown compounds without analytical standards (Bigard et al., 2023; Bruggink & Jensen, 2021; Liu et al., 2015).

7.3 Miniaturization and capillary IC

Capillary columns (0.1–0.5 mm inner diameter) reduce eluent consumption by up to 100-fold compared with conventional analytical columns (4 mm inner diameter). This miniaturization aligns with green chemistry principles and facilitates coupling with mass spectrometers, as low flow rates (1–10 µL/min) are compatible with electrospray ionization sources (Liu et al., 2015; Muntean, 2022).

7.4 Automated online sample preparation

Inline dialysis systems and online solid-phase extraction (online SPE) are already commercially available and significantly reduce the analysis time and errors associated with manual preparation. For dairy products, integrating online deproteinization steps is a technical challenge (Liu et al., 2015) that must be addressed in the coming years.

7.5 Chemometrics and machine learning

The application of chemometric tools (PCA, PLS) and machine learning algorithms can optimize chromatographic conditions (gradient, eluent concentration, column temperature) (Alves et al., 2025) and aid in interpreting complex ionic profiles for the detection of adulteration in cheeses and protected designation of origin (PDO) milks. This approach, which is still emerging for IC in dairy products (Vatavali et al., 2020), represents one of the most promising frontiers in the field.

7.6 Sustainability and green chemistry

Future methodologies should prioritize non-toxic eluents, electrolytic eluent generation (RFIC), and waste reduction. IC is already ahead of other chromatographic techniques in this regard, but further improvements in column material biodegradability and eluent recycling are expected in the coming decade (Fanali et al., 2023; Muntean, 2022; Weiss, 2016).

8 Sustainable strategies and waste minimization

The concept of green analytical chemistry has driven the development of methods that minimize waste, reduce the use of toxic reagents, optimize costs, accelerate analyses, and enable simultaneous multi-analyte detection (D’Amore et al., 2021; Michalski & Pecyna-Utylska, 2021).

Ion chromatography (IC) aligns with the principles of sustainable analysis. Technological advances, including optimized elution gradients, next-generation suppressors, and miniaturization, allow low-impact eluents, reduced sample volumes, and elimination of organic solvents in most applications (Michalski & Pecyna-Utylska, 2021). Reagent-free IC (RF-IC) generates eluents in situ via membrane electrolysis, eliminating manual preparation, ensuring precise concentrations, improving reproducibility, and reducing costs (Fanali et al., 2023; Weiss, 2016).

Compared with classical methods (titrimetric, colorimetric, gravimetric, and electrochemical) and chromatographic techniques, IC demonstrates superior compliance with the 12 Principles of Green Chemistry. Unlike HPLC (methanol/acetonitrile/water mixtures) and GC (inert gases with derivatizing agents), IC employs aqueous saline eluents, reflecting its distinct physicochemical mechanisms (Fanali et al., 2023; McNair et al., 2019; Michalski & Pecyna-Utylska, 2021; Snyder et al., 2009). However, the limitations of IC include careful sample preparation, consumable costs (columns, PEEK components), and preventive maintenance requirements for high-pressure systems (Michalski & Pecyna-Utylska, 2021) (Table 10).

Table 10
The main reagents used in the chromatographic methods.

Methods	Reagents
Ion chromatography	Aqueous solutions with low concentrations of acids, alkalis, or salts such as HNO3, methanesulfonic acid, phthalic acid, p-hydroxybenzoic acid, KOH, NaOH, NaHCO3, and Na2CO3. In some cases, lithium chloride and sulfuric acid.
Liquid chromatography	Acetonitrile, methanol, hexane, tetrahydrofuran, phosphate buffers, and acid buffers (acetic acid and ammonia).
Gas chromatography	Gases include helium, hydrogen, nitrogen, oxygen, methane, and argon.

• Source: (McNair et al., 2019; Muntean, 2022; Snyder et al., 2009; Weiss, 2016).

9 Conclusions

Ion chromatography is a well-established, reliable, and versatile analytical technique for quality control of dairy products. This review demonstrates that IC is routinely applied for the determination of minerals, carbohydrates, organic acids, amino acids, choline, and contaminants, with methods validated according to international standards (AOAC, ISO, IDF). The main gaps identified in the literature include (i) the absence of standardized IC protocols for amino acid and peptide profiling in dairy matrices; (ii) the limited application of IC-HRMS for non-target screening of emerging contaminants; and (iii) insufficient comparative studies assessing IC versus alternative techniques (ICP‒MS, LC‒MS) across different dairy products. The contribution of this review lies in its integrated approach, which connects theoretical fundamentals, practical applications, and regulatory requirements. The arrangement of analytical parameters (LOD, LOQ, recovery, and RSD) in comparative tables allows the selection of the most appropriate method for each application. The discussion of future trends, including miniaturization, automation, chemometrics, and green chemistry, provides a roadmap for methodological innovation, positioning IC as a key tool for ensuring the safety, authenticity, and regulatory compliance of dairy products.

Acknowledgements

The authors also acknowledge the support of the Federal Institute of Education, Science, and Technology of Southeast Minas Gerais - Rio Pomba Campus, which enabled Jhonatan Faria da Costa to complete this work.

Data Availability Statement

Research data is available in the body of the article.

Cite as:

Costa, J. F., Moraes, M. N., Correa, K. P., Fontes, E. A. F., Ribeiro, O. A. S., Mesquita, B. M. A. C., Oliveira, E. B., & Coimbra, J. S. R. (2026). Ion chromatography for dairy product analysis: a technical and regulatory review. Brazilian Journal of Food Technology, 29, e2026025. https://doi.org/10.1590/1981-6723.0252026

Funding:

Conselho Nacional de Desenvolvimento Científico e Tecnológico (313641/2021-8), Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (Financial code – 001) and Fundação de Amparo à Pesquisa do Estado de Minas Gerais.

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*

Corresponding Author: Jane Sélia dos Reis Coimbra, Universidade Federal de Viçosa, Departamento de Tecnologia de Alimentos, Avenida Peter Henry Rolfs, s/n, CEP: 36570-900, Viçosa/MG - Brasil, e-mail: [e-mail]

Conflict of interests

The authors report no potential conflicts of interest.

Section Editor:

Marta H. Taniwaki.

Publication Dates

• Publication in this collection
  21 Sept 2026
• Date of issue
  2026

History

• Received
  07 Apr 2026
• Accepted
  20 July 2026