Simultaneous Determination of Na, K and Ca in Biodiesel by Flame Atomic
               Emission Spectrometry

Raposo, Juliana D.; Costa, Letícia M.; Barbeira, Paulo Jorge S.

doi:10.5935/0103-5053.20140231

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Journal of the Brazilian Chemical Society

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Articles • J. Braz. Chem. Soc. 26 (1) • Jan 2015 • https://doi.org/10.5935/0103-5053.20140231 copy

Simultaneous Determination of Na, K and Ca in Biodiesel by Flame Atomic Emission Spectrometry

Authorship SCIMAGO INSTITUTIONS RANKINGS

This work aimed to develop a methodology for simultaneous determination of Na, K and Ca in biodiesel samples by flame atomic emission spectrometry, using a continuous electromagnetic radiation detector. Two procedures were employed for biodiesel sample preparation: direct dilution with kerosene and sample emulsification with HNO₃, n-butanol and Triton X-100. The proposed methodology presented good linearity, relative standard deviations less than 5% and limits of quantification of 0.05 and 0.02 mg kg^–1 for Na and K, respectively, using emulsification and solvent dilution. For Ca, the limit of quantification was 0.2 and 1.0 mg kg^–1, applying direct dilution and emulsion, respectively. The emulsification procedure showed no matrix influence when recovery tests were performed (89-108%). Reference methodology (ABNT NBR 15553) was used to check the accuracy, presented consistent results at 95% confidence level, being suitable for biodiesel samples in a routine analysis.

atomic emission spectrometry; biodiesel; direct dilution; emulsion; sodium; potassium; calcium

Analyte	Method	WLR / (mg kg^-1)	R	LOD (n = 10) / (mg kg^-1)	LOQ (n = 10) / (mg kg^-1)	RSD (n = 5) / %
Na	FAES-CDK	0.05 to 2.00	0.9992	0.01	0.05	0.73- 5.4
	FAES-CDE	0.05 to 2.00	0.9998	0.01	0.05	0.95-5.1
	ABNT NBR 15553	0.1 to 2.00	0.9995	0.04	0.1	1.7-5.1
K	FAES-CDK	0.02 to 2.00	0.9997	0.005	0.02	2.4-5.2
	FAES-CDE	0.02 to 2.00	0.9998	0.005	0.02	1.0-4.8
	ABNT NBR 15553	0.1 to 2.00	0.9990	0.05	0.1	3.2-3.9
Ca	FAES-CDK	0.2 to 2.00	0.9998	0.08	0.2	0.86-3.6
	FAES-CDE	1.0 to 10.00	0.9998	0.3	1.0	2.6
	ABNT NBR 15553	0.05 to 2.00	0.9993	0.006	0.05	1.9-7.3

Sample	Na / (mg kg^-1)			K / (mg kg^-1)			Ca / (mg kg^-1)
Sample	ABNT NBR15553	FAES-CDK	FAES-CDE	ABNT NBR15553	FAES-CDK	FAES-CDE	ABNT NBR15553	FAES-CDK	FAES-CDE
SB-01	< 1.0^a a Considering the dilution of the samples.	0.77 ± 0.05	0.78 ± 0.03	< 1.0^a a Considering the dilution of the samples.	0.19 ± 0.008	0.22 ± 0.01	0.58 ± 0.05	< 2.0^a a Considering the dilution of the samples.	< 10^a a Considering the dilution of the samples.
SB-02	2.53 ± 0.06	2.5 ± 0.2	2.5 ± 0.1	< 1.0^a a Considering the dilution of the samples.	< 0.2^a a Considering the dilution of the samples.	< 0.2^a a Considering the dilution of the samples.	2.7 ± 0.1	2.6 ± 0.1	< 10^a a Considering the dilution of the samples.
SB-03	12.9 ± 0.4	13.0 ± 0.9	13.3 ± 0.6	2.04 ± 0.08	2.02 ± 0.09	2.0 ± 0.1	0.68 ± 0.03	< 2.0^a a Considering the dilution of the samples.	< 10^a a Considering the dilution of the samples.
CA-01	3.8 ± 0.2	3.69 ± 0.07	3.66 ± 0.07	< 1.0^a a Considering the dilution of the samples.	0.32 ± 0.02	0.36 ± 0.02	1.34 ± 0.03	< 2.0^a a Considering the dilution of the samples.	< 10^a a Considering the dilution of the samples.
SF-01	13.9 ± 0.3	15.9 ± 0.5	15.7 ± 0.3	< 1.0^a a Considering the dilution of the samples.	0.37 ± 0.02	0.38 ± 0.01	1.71 ± 0.05	< 2.0	< 10^a a Considering the dilution of the samples.
SF-02	14.2 ± 0.5	12.9 ± 0.6	12.8 ± 0.2	< 1.0^a a Considering the dilution of the samples.	0.22 ± 0.01	0.22 ± 0.01	13.3 ± 0.3	13.0 ± 0.5	13.1 ± 0.4
CT-01	4.3 ± 0.1	4.2 ± 0.1	4.1 ± 0.1	< 1.0^a a Considering the dilution of the samples.	0.34 ± 0.01	0.30 ± 0.01	0.29 ± 0.02	< 2.0^a a Considering the dilution of the samples.	< 10^a a Considering the dilution of the samples.
CT-02	5.1 ± 0.2	4.8 ± 0.3	4.8 ± 0.3	12.3 ± 0.6	12.6 ± 0.5	12.4 ± 0.2	0.87 ± 0.03	< 2.0^a a Considering the dilution of the samples.	< 10^a a Considering the dilution of the samples.
MA-01	1.86 ± 0.09	1.97 ± 0.02	1.94 ± 0.07	< 1.0^a a Considering the dilution of the samples.	< 0.2^a a Considering the dilution of the samples.	< 0.2^a a Considering the dilution of the samples.	0.24 ± 0.02	< 2.0^a a Considering the dilution of the samples.	< 10^a a Considering the dilution of the samples.
CN-01	2.82 ± 0.08	2.8 ± 0.2	2.78 ± 0.04	< 1.0^a a Considering the dilution of the samples.	< 0.2^a a Considering the dilution of the samples.	< 0.2^a a Considering the dilution of the samples.	< 0.5^a a Considering the dilution of the samples.	< 2.0^a a Considering the dilution of the samples.	< 10^a a Considering the dilution of the samples.
BF-01	1.9 ± 0.1	1.9 ± 0.1	< 0.05^a a Considering the dilution of the samples.	< 1.0^a a Considering the dilution of the samples.	0.22 ± 0.01	0.24 ± 0.01	0.39 ± 0.02	< 2.0^a a Considering the dilution of the samples.	< 10^a a Considering the dilution of the samples.
RO-01	1.70 ± 0.07	1.64 ± 0.09	1.66 ± 0.02	< 1.0^a a Considering the dilution of the samples.	0.28 ± 0.01	0.27 ± 0.02	0.92 ± 0.04	< 2.0^a a Considering the dilution of the samples.	< 10^a a Considering the dilution of the samples.
MX-01	4.3 ± 0.1	4.5 ± 0.2	4.4 ± 0.2	< 1.0^a a Considering the dilution of the samples.	0.46 ± 0.03	0.45 ± 0.01	4.3 ± 0.2	4.32 ± 0.05	< 10^a a Considering the dilution of the samples.
MX-02	5.8 ± 0.4	8.1 ± 0.2	5.3 ± 0.1	< 1.0^a a Considering the dilution of the samples.	< 0.2^a a Considering the dilution of the samples.	< 0.2^a a Considering the dilution of the samples.	4.9 ± 0.2	5.1 ± 0.2	< 10^a a Considering the dilution of the samples.

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