title: Improved Chiral Separation of Methamphetamine Enantiomers Using CSP-LC-MS-MS.
abstract: To determine the true enantiomeric composition of methamphetamine urine drug testing results, chiral separation of dextro (D) and levo (L) enantiomers is necessary. While enantiomeric separation of methamphetamine has traditionally been accomplished using gas chromatography-mass spectrometry (GC-MS), chiral separation of D- and L-methamphetamine by chiral stationary phase (CSP) liquid chromatography-mass spectrometry/mass spectrometry (LC-MS-MS) has proved more reliable. Chirally selective detection of methamphetamine by GC-MS is often performed using L-N-trifluoroacetyl-prolyl chloride (TPC). L-TPC, a chiral compound, is known to have impurities that can affect the chiral composition percentages of the methamphetamine sample, potentially leading to inaccurate patient results. The comparative analysis of the samples run by GC and LC methods showed preferential bias of the GC method for producing error rates, consistent with previous research, of 8-19%. The CSP-LC-MS-MS method produces percent deviation errors of <2%. Additionally, the GC method failed to produce results that were 100% D- or L-isomer even for enantiomerically pure standards. A higher rate of D- and L-methamphetamine isomer racemization is seen in samples when analyzed by GC-MS using L-TPC-derivatizing agent. This racemization is not seen when these samples are tested with CSP-LC-MS-MS. Thus, a more accurate method of enantiomeric analysis is provided by CSP-LC-MS-MS.
authors: Ameritox Ltd, 486 Gallimore Dairy Road, Greensboro, NC 27409, USA lauren.ward@ameritox.com.
authors: Lauren F
authors: LF
authors: Ward
authors: Ameritox Ltd, 486 Gallimore Dairy Road, Greensboro, NC 27409, USA.
authors: Jeffrey R
authors: JR
authors: Enders
authors: Sigma-Aldrich/Supelco, 595 North Harrison Road, Bellefonte, PA 16823, USA.
authors: David S
authors: DS
authors: Bell
authors: Sigma-Aldrich/Supelco, 595 North Harrison Road, Bellefonte, PA 16823, USA.
authors: Hugh M
authors: HM
authors: Cramer
authors: Ameritox Ltd, 486 Gallimore Dairy Road, Greensboro, NC 27409, USA.
authors: Frank N
authors: FN
authors: Wallace
authors: Ameritox Ltd, 486 Gallimore Dairy Road, Greensboro, NC 27409, USA.
authors: Gregory L
authors: GL
authors: McIntire
mesh_terms: D002138:Calibration; D002849:Chromatography, Gas; D002851:Chromatography, High Pressure Liquid; D005463:Fluoroacetates / Q000737:chemistry; D006801:Humans; D007202:Indicators and Reagents; D057230:Limit of Detection; D008694:Methamphetamine / Q000737:chemistry / Q000302:isolation & purification* / Q000652:urine; D015203:Reproducibility of Results; D052616:Solid Phase Extraction; D013237:Stereoisomerism; D053719:Tandem Mass Spectrometry
chemical_list: D005463:Fluoroacetates; D007202:Indicators and Reagents; D008694:Methamphetamine; C500395:trifluoroacetyl chloride