Comparison of gas- and liquid chromatography-mass spectrometry for trace analysis of anilines in groundwater

Figures & data

Table 1. Method parameters for GC/MS-MS.

Retention time	Analyte	Acronym	Precursor ion	Quantifier	Qualifiers	CE^a
(min)			(m/z)	(m/z)	(m/z)	(eV)
7.835	Aniline	ANL	93.4	66.0	92.1	15
9.630	2-/4-methylaniline	o/p-TOL	106.4	77.0	79.0	20
9.730	3-methylaniline	m-TOL	106.4	77.0	79.0	20
10.616	2-chloroaniline	o-CA	127.3	65.0	92, 100	25
11.255	2,6-dimethylaniline	2,6-DMA	121.4	92.1	65.1	25
11.340	2,5-dimethylaniline	2,5-DMA	121.4	92.0	65.2	25
11.400	3,5-dimethylaniline	3,5-DMA	121.4	92.2	64.7	25
11.740	3,4-dimethylaniline	3,4-DMA	121.4	106.2	120.1	15
11.773	3-chloroaniline	m-CA	127.3	92.0	65, 100	15
11.800	2,3-dimethylaniline	2,3-DMA	121.4	106.1	120	15
11.822	4-chloroaniline	p-CA	127.3	92.1	65, 100.1	15
12.393	2,6-dichloroaniline	2,6-DCA	161.3	90.0	63, 99, 126	25
13.749	2,5/2,4-dichloroaniline	2,5/2,4-DCA	161.3	90.0	63, 99, 126	25
14.044	2,3-dichloroaniline	2,3-DCA	161.3	90.0	99, 63, 126	25
14.721	3,5-dichloroaniline	3,5-DCA	161.3	90.0	99, 63, 126	25
15.115	3,4-dichloroaniline	3,4-DCA	161.3	99.0	99, 63, 126	25
12.166	3-chloro-4-fluoroaniline^b	3C4FA	145.0	83.0	110, 63	25

^aCollision energy

^bInternal standard

Table 2. Retention time, mass transitions and MS-MS-parameters for quantification of aniline and aniline derivatives with liquid chromatography (LC/MS-MS).

Retention time	Native aniline derivatives	Acronym	Precursor ion (M + H^+)	Quantifier	Qualifier	Respective internal standard	DP^a	EP^b	CE^c	CXP^d
(min)			(m/z)	(m/z)	(m/z)		(eV)	(eV)	(eV)	(eV)
0.67	Aniline	ANL	94.10	77.0	51.1	p-TOL-d9	61	10	27	14
0.73	4-methylaniline	p-TOL	108.0	93.1	91.1	p-TOL-d9	61	10	23	4
1.04	3-methylaniline	m-TOL	107.99	90.9	93.0	m-TOL-d9	56	10	25	4
1.19	3,4-dimethylaniline	3,4-DMA	122.02	107.0	76.9	2,4-DMA-d11	46	10	23	6
1.34	2-methylaniline	o-TOL	107.96	90.9	92.9	o-TOL-d9	66	10	27	4
1.78	2,3-dimethylaniline	2,3-DMA	122.01	105.0	76.9	2,4-DMA-d11	46	10	23	4
1.88	3,5-dimethylaniline	3,5-DMA	122.03	107.1	77.0	2,4-DMA-d11	51	10	23	6
2.23	2,5-dimethylaniline	2,5-DMA	122.02	105.0	107.0	2,4-DMA-d11	46	10	23	6
2.74	4-chloroaniline	p-CA	128.01	93.0	75.0	p-CA-d4	56	10	27	4
3.10	2,6-dimethylaniline	2,6-DMA	121.99	105.0	76.9	2,6-DMA-d11	51	10	23	6
3.45	3-chloroaniline	m-CA	128.00	93.0	75.0	m-CA-d3	51	10	27	4
4.59	3,4-dichloroaniline	3,4-DCA	161.96	127.0	73.9	3,4-DCA-d2	51	10	27	8
4.81	3,5-dichloroaniline	3,5-DCA	161.96	127.0	74.0	3,5-DCA-d3	66	10	29	8
	Labelled aniline derivatives^e
0.69	4-methylaniline-d9	p-TOL-d9	115.03	98.1	70.1		66	10	29	4
0.95	3-methylaniline-d9	m-TOL-d9	115.02	98.1	70.1		56	10	29	4
1.23	2-methylaniline-d9	o-TOL-d9	115.01	98.2	70.0		56	10	27	4
1.47	2,4-dimethylaniline-d11	2,4-DMA-d11	131.18	113.1	82.1		61	10	27	6
2.66	4-chloroaniline-d4	p-CA-d4	131.99	97.0	78.1		56	10	23	4
2.96	2,6-dimethylaniline-d11	2,6-DMA-d11	131.,2	114.2	82.1		51	10	25	6
3.39	3-chloroaniline-d3	m-CA-d3	130.98	96.1	77.0		56	10	25	4
4.58	3,4-dichloroaniline-d2	3,4-DCA-d2	163.96	129.1	74.9		31	10	27	6
4.80	3,5-dichloroaniline-d3	3,5-DCA-d3	164.94	130.0	76.2		31	10	29	6

^aDeclustering potential, ^b Entrance potential, ^c Collision energy, ^d Collision cell exit potential

^eThe deuterium on the amino groups of the labelled methylated anilines is exchanged for hydrogen in aqueous solution. Therefore, the respective precursor ions M + H⁺ resembles those derived from the d₇ (methylanilines) and d₉ labelled versions.

Table 3. Overview of aniline derivative concentrations.

Compound groups		Batch	Concentration ring test sample (µg L^−1)
Aniline	groundwater	A	1.09 ± 0.16^a
Methylanilines	groundwater	A	8.35 ± 0.94^a
Dimethylanilines	groundwater	A	21.74 ± 3.44^a
Chloroanilines	groundwater	A	38.20 ± 6.40^a
Dichloroanilines	groundwater	A	79.95 ± 6.70^a
Aniline	fortified	B	< 1
Methylanilines	fortified	B	5.69 ^b
Dimethylanilines	fortified	B	28.20 ^b
Chloroanilines	fortified	B	15.74 ^b
Dichloroanilines	fortified	B	10.24 ^b

^aGrand mean and expanded uncertainty (U, k = 2) from the interlaboratory comparison according to DIN 38405–45(2014) [34]

^bfortified values

Figure 1. GC/MS-MS chromatogram of the standard mixture of aniline derivatives (each native compound: 10 µg L⁻¹), for acronyms see .Table 1

Figure 2. LC/MS-MS chromatogram of the standard of mixture of aniline derivatives (each native compound: 10 µg L⁻¹, deuterated compounds: 15 µg L⁻¹), for acronyms see .Table 2

Figure 3. GC/MS-MS chromatogram of groundwater sample A (above) and fortified tap water sample B (below).

Figure 4. LC/MS-MS chromatogram of groundwater sample A (above) and fortified tap water sample B (lower).

Table 4. Calibration curve equations for LC/MS-MS, coefficients of determination (R²), limits of detection (LOD) and quantification (LOQ), and repeatability (relative standard deviation, RSD, n = 10) at fortification levels of 0.1 and 50 µg L^−1.

Compound	linear regression y = axe + b			linear working range		RSD	LOD	LOQ
	a	b	R^2	min (µg L^−1)	max (µg L^−1)	(%)	(µg L^−1)	(µgL^−1)
Aniline	0.0376	0.0213	0.9998	0.15	100	10–23	0.05	0.15
2-Methylaniline	0.0904	0.0263	0.9993	0.1	100	5–12	0.02	0.08
3-Methylaniline	0.0681	0.0146	0.9993	0.1	100	4–14	0.02	0.08
4-Methylaniline	0.1157	0.0340	0.9995	0.1	100	7–15	0.02	0.08
2,3-Dimethylaniline	0.0565	0.0126	0.9998	0.1	100	4–10	0.02	0.08
2,5-Dimethylaniline	0.0560	0.0204	0.9988	0.1	100	6–10	0.02	0.06
2,6-Dimethylaniline	0.0782	0.0135	0.9999	0.1	100	4–7	0.02	0.08
3,4-Dimethylaniline	0.0791	0.0209	0.9992	0.1	100	4–8	0.01	0.03
3,5-Dimethylaniline	0.0793	0.0212	0.9997	0.1	100	5–8	0.01	0.04
3-Chloroaniline	0.0629	0.0036	0.9999	0.1	100	2–10	0.01	0.06
4-Chloroaniline	0.0807	0.0181	0.9998	0.1	100	2–5	0.01	0.03
3,4-Dichloroaniline	0.0931	0.0070	0.9997	0.1	5	4–8	0.02	0.08
3,5-Dichloroaniline	0.1265	0.0259	0.9997	0.1	100	2–9	0.02	0.06

Figure 5. Quantification results of methylated anilines – comparison of GC/MS, GC/MS-MS and LC/MS-MS (in-house, means and standard deviations) with the interlaboratory comparison results (robust means and expanded uncertainties U) on groundwater (sample A, above) and fortified water (sample B, below).

Figure 6. Quantification results of chloroanilines – comparison of GC/MS, GC/MS-MS and LC/MS-MS (in-house, means and standard deviations) with the interlaboratory comparison results (robust means and expanded uncertainties U) on groundwater (sample A, above) and fortified water (sample B, below).

DIN 32645:2008, Chemical Analysis - Decision Limit, Detection Limit and Determination Limit under Repeatability Conditions - Terms, Methods, Evaluation, Beuth Verlag GmbH, Berlin, Germany (2008)

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