Determination of Adulterants in Diesel by Integration of LED Fluorescence Spectra

Meira, Marilena; Quintella, Cristina M.; Ribeiro, Erika M. O.; Silva, Humbervânia R. G.; Guimarães, Alexandre K.; Luna, Saionara; Silva, Weidson L.; Brito, Irlane J. de

doi:10.5935/0103-5053.20150103

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Articles • J. Braz. Chem. Soc. 26 (7) • July 2015 • https://doi.org/10.5935/0103-5053.20150103 copy

Determination of Adulterants in Diesel by Integration of LED Fluorescence Spectra

Authorship SCIMAGO INSTITUTIONS RANKINGS

This paper describes a simple and rapid methodology for determining the content of adulterants in diesel by the integration of fluorescence spectra. The procedure consists of constructing analytical curves using the concentrations of each adulterant in diesel and the relative change in the fluorescence area of each blend with respect to the fluorescence area of the diesel. The results indicated that the proposed method can be used to determine adulterants such as non-transesterified residual cooking oil, kerosene, and turpentine in diesel. The detection limits were 3, 4 and 5% for non-transesterified residual cooking oil, kerosene and turpentine in diesel, respectively. The method was also successfully used to determine the non-transesterified residual cooking oil content in B5 biodiesel-diesel blend (5% biodiesel) in the range of 0-70%, with a limit of detection of 4%.

Keywords:
adulterants; diesel; LED fluorescence spectroscopy

Residual oil in diesel	Spectral area	δ / %
0	261222.6	0
2	258478.7	1.05
6	253151.7	3.09
8	252566.6	3.31
15	247393.2	5.29
20	236836.5	9.34
25	233117.9	10.76
30	222139.2	14.96
35	212757.3	18.55
40	209814.5	19.68
45	204319.3	21.78
50	200818.2	23.12
55	193699.7	25.85
60	188878.5	27.69
65	179500.5	31.28
70	175080.9	32.98
75	166975.9	36.08
80	163136.2	37.55
85	157585.5	39.67
90	150066.8	42.55
95	137899.9	47.21
100	135082.3	48.29

Actual RCO in diesel / %	Predicted RCO in diesel / %	d (actual – predicted)^a a Student's t-test for paired data: dm = –0.3, s = 2.88, Sm = 0.91, tcal = –0.336738, ttab = –2.262, where d is the difference between each pair, dm is the mean of the differences, s is the standard deviation, Sm is the standard error of the differences, and tcal = dm / Sm.
8	6.5	1.5
15	10.8	4.2
25	22.4	2.6
35	39.0	–4.0
40	41.4	–1.4
55	54.5	0.5
70	69.7	0.3
80	79.4	0.6
95	100.0	–5.0
100	102.3	–2.3

Actual kerosene in diesel / %	Predicted kerosene in diesel / %	d (actual – predicted)^a a Student's t-test for paired data: dm = –0.07, s = 1.27, Sm = 0.35, tcal = –0.19434, ttab = –2.179, where d is the difference between each pair, dm is the mean of the differences, s is the standard deviation, Sm is the standard error of the differences, and tcal = dm / Sm.
2	4.3	–2.3
4	4.7	–0.7
6	7.4	–1.4
8	7.1	0.9
10	10.8	–0.8
20	19.3	0.7
30	29.8	0.2
40	40.2	–0.2
50	51.2	–1.2
60	57.3	2.7
70	69.4	0.6
80	79.4	0.6
90	90.0	0.0

Actual turpentine in diesel / %	Predicted turpentine in diesel / %	d (actual – predicted)^a a Student's t-test for paired data: dm = –0.94, s = 2.10, Sm = 0.58, tcal = –1.62438, ttab = –2.179,where d is the difference between each pair, dm is the mean of the differences, s is the standard deviation, Sm is the standard error of the differences, and tcal = dm / Sm.
4	2.0	2.0
6	6.3	–0.3
8	8.1	–0.1
10	8.4	1.6
20	23.3	–3.3
25	28.4	–3.4
30	31.5	–1.5
40	45.1	–5.1
50	49.7	0.3
60	59.3	0.7
70	72.2	–2.2
80	81.1	–1.1
90	89.9	0.1

Validation parameters	RCO in diesel	Kerosene in diesel	Turpentine in diesel
Number of points	11	24	21
Degrees of freedom (DOF)	9	22	19
Residual sum of squares (RSS)	2.44154	14.5146	24.2346
Residual standard deviation (RSD)^a a RSD = √RSS / DOF ; / %	0.52	0.81	1.12
Limit of detection (LOD)^b b LOD = 3RSD / slope; / %	3	4	5
Limit of quantification (LOQ)^c c LOQ = 10RSD / slope. / %	11	12	15
Sensibility (slope)	0.5	0.6	0.7

Validation parameter	Value found (of the analytical curve)
Number of points	14
Degrees of freedom (DOF)	12
Residual sum of squares (RSS)	5.35908
Residual standard deviation (RSD)^a a RSD = √RSS / DOF ; / %	0.67
Limit of detection (LOD)^b b LOD = 3RSD / slope; / %	4
Limit of quantification (LOQ)^c c LOQ = 10RSD / slope. / %	14
Sensibility (slope)	0.5

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