Simultaneous determination of amphetamine and methamphetamine enantiomers in urine by simultaneous liquid-liquid extraction and diastereomeric derivatization followed by gas chromatographic-isotope dilution mass spectrometry.
A simple, rapid, reliable, and economic analytical scheme starting with in situ liquid-liquid extraction and asymmetric (or diastereomeric) chemical derivatization (ChD) followed by gas chromatography (GC)-isotope dilution mass spectrometry (MS) is described for the simultaneous determination of D- and L-amphetamine (AP) and methamphetamine (MA) in urine which could have resulted from the administration of various forms of questioned amphetamines or amphetamines-generating drugs. By using L-N-trifluoroacetyl-1-prolyl chloride (L-TPC) as chiral derivatizing agent, resolutions of 2.2 and 2.0 were achieved for the separation of AP and MA enantiomeric pairs, respectively, on an ordinary HP-5MS capillary column. The GC-MS quantitation was carried out in the selected ion monitoring (SIM) mode using m/z 237 and 251 as the quantifier ions for the respective diastereomeric pairs of AP-L-TPC and MA-L-TPC. The calibration curves plotted for the two pairs of analytes stretch with good linearity down to 45 ng/mL, and the limits of detection and quantitation determined were as low as 40 and 45 ng/mL, respectively. Also, a comparative study using 10 real-case urine specimens previously screened as positive for MA administration showed mostly tolerable biases between the two sums (of concentration) of D- and L-MA obtained via an asymmetric L-TPC-ChD approach and via an ordinary pentafluoropropionylation (PFPA-ChD) approach, respectively, as well as between the two sums of D- and L-AP obtained thereupon, thus validating the proposed analytical scheme as a promising forensic protocol for the detailed analysis of enantiomeric amphetamines in urine.
Wang
Sheng-Meng
SM
Department of Forensic Science, Central Police University, Kueishan, Taoyuan 33334, Taiwan, ROC. wang531088@sun4.cpu.edu.tw
Wang
Ting-Cheng
TC
Giang
Yun-Seng
YS
D000661:Amphetamine / Q000737:chemistry / Q000302:isolation & purification / Q000652:urine*; D003913:Dextroamphetamine / Q000737:chemistry / Q000302:isolation & purification / Q000652:urine; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D006801:Humans; D008694:Methamphetamine / Q000737:chemistry / Q000302:isolation & purification / Q000652:urine*; D011392:Proline / Q000031:analogs & derivatives* / Q000737:chemistry; D015203:Reproducibility of Results; D013237:Stereoisomerism
C047271:N-trifluoroacetylprolyl chloride; D008694:Methamphetamine; D011392:Proline; D000661:Amphetamine; D003913:Dextroamphetamine