Determination of amphetamines, ketamine and their metabolites in hair with high-speed grinding and solid-phase microextraction followed by LC-MS

Figures & data

Table 1. MS conditions for the determination of analytes and IS by LC-MS.

Analytes	Select ions (m/z)	Collision energy (eV)
Methamphetamine	150.1, 91.1	15
Amphetamine	136.1, 119.1	17
Methamphetamine-d5	155.2, 91.1	15
MDMA	194.2, 163.4	15
MDA	180.1, 163.1	11
MDMA-d5	199.1, 163.4	15
Ketamine	238.1, 179.1	18
Norketamine	224.1, 207.1	15
Ketamine-d4	242.1, 183.1	18

internal standard: IS; LC-MS: liquid chromatography-mass spectrometry; MDMA: 3,4-methylenedioxymethamphetamine; MDA: 3,4-methylenedioxyamphetamine.

Figure 1. Effect of types of solid-phase microextraction (SPME) fibre on extraction efficiency conditions—extraction solvent: saturated sodium carbonate solution (pH 12), extraction temperature: 60 °C, extraction time: 15 min. Concentration of analytes: 4 ng/mg. MA: methamphetamine; AM: amphetamine; MDMA: 3,4-methylenedioxymethamphetamine; MDA: 3,4-methylenedioxyamphetamine; PP: polypropylene; PDMS: polydimethylsiloxane; DVB: divinylbenzene.

Figure 2. Effect of extraction temperature (A) and time (B) on extraction efficiency conditions. (A) solid-phase microextraction (SPME) fibre: polydimethylsiloxane/divinylbenzene (PDMS/DVB), extraction solvent: saturated sodium carbonate solution (pH 12), extraction time: 15 min; (B) SPME fibre: PDMS/DVB, extraction solvent: saturated sodium carbonate solution (pH 12), extraction temperature: 60 °C. Concentration of analytes: 4 ng/mg. MA: methamphetamine; AM: amphetamine; MDMA: 3,4-methylenedioxymethamphetamine; MDA: 3,4-methylenedioxyamphetamine.

Figure 3. Effect of ionic strength on extraction efficiency conditions—solid-phase microextraction (SPME) fibre: polydimethylsiloxane/divinylbenzene (PDMS/DVB), extraction temperature: 60 °C, extraction time: 15 min, pH 12. Concentration of analytes: 4 ng/mg. MA: methamphetamine; AM: amphetamine; MDMA: 3,4-methylenedioxymethamphetamine; MDA: 3,4-methylenedioxyamphetamine.

Figure 4. Chromatogram for target analytes spiked sample in SIM mode conditions—SPME fibre: PDMS/DVB, extraction solvent: saturated sodium carbonate solution (pH 12), extraction time: 15 min, extraction temperature: 60 °C. Concentration of analytes: 4 ng/mg. MDMA: 3,4-methylenedioxymethamphetamine; MDA: 3,4-methylenedioxyamphetamine.

Table 2. The performance of the proposed methods in spiked samples.

Analytes	Regression equation	Linear dynamic range (ng/mg)	r	LOD (ng/mg)	Added (ng/mg)	Recovery (%)	RSD (%), n = 5		MRE (%), n = 5
							Intra-day	Inter-day	Intra-day	Inter-day
Methamphetamine	y = 0.0158x – 0.034	0.1–10.0	0.9990	0.067	0.5	95.4	5.7	5.1	3.3	6.2
					2.0	93.3	5.4	4.3	6.5	3.4
					10.0	94.7	3.0	2.2	5.8	2.4
Amphetamine	y = 0.0214x – 0.0235	0.1–10.0	0.9993	0.067	0.5	91.4	3.4	4.3	4.6	3.2
					2.0	94.3	3.3	3.8	4.3	1.9
					10.0	94.3	2.1	3.7	6.2	1.7
MDMA	y = 0.0196x – 0.0195	0.1–10.0	0.9989	0.067	0.5	89.9	6.2	4.3	6.3	3.8
					2.0	91.3	1.6	2.3	5.3	6.5
					10.0	90.9	3.7	4.2	3.4	5.3
MDA	y = 0.0123x – 0.0405	0.1–10.0	0.9985	0.067	0.5	92.7	6.2	5.9	4.6	4.4
					2.0	93.6	2.3	3.6	6.9	3.0
					10.0	94.4	4.7	6.4	5.2	2.9
Ketamine	y = 0.0177x – 0.0415	0.1–10.0	0.9992	0.067	0.5	94.1	6.8	5.6	4.5	5.8
					2.0	93.3	3.6	5.0	5.1	5.8
					10.0	95.2	6.3	6.6	1.9	6.0
Norketamine	y = 0.0249x – 0.0900	0.1–10.0	0.9991	0.067	0.5	94.4	3.9	5.9	3.6	5.0
					2.0	95.8	2.9	3.9	3.3	4.2
					10.0	90.1	5.5	6.1	3.5	2.1

LOD: limit of detection; RSD: relative standard deviation; MRE: mean relative error; MDMA: 3,4-methylenedioxymethamphetamine; MDA: 3,4-methylenedioxyamphetamine.

Table 3. The analytic result of real sample with the proposed methods.

Samples	Property descriptions		Proposed method/standards^a (ng/mg)
	Age (yr)	Colour	MA	AM	Ketamine	Norketamine
Male 1	30	Black	5.4/5.6	1.2/1.0	9.7/10.1	8.6/8.3
Male 2	27	Black	2.3/2.2	0.8/1.0	3.7/3.5	4.1/4.0
Male 3	41	Black	1.9/2.4	–	4.6/5.0	3.6/4.3
Male 4	38	Black	7.9/7.4	3.2/3.0	–	–
Female 1	36	Dyed brown	–	–	8.2/7.8	7.4/6.4

^aThe results were obtained from the Fujian Police College Judicial Expertise Centre (Fuzhou, China). MA: methamphetamine; AM: Amphetamine.