title: [Monitoring precursor chemicals through enantiomer profiling of methamphetamine].
abstract: OBJECTIVE
  The enantiomer profiling of methamphetamine is can be utilized for regulation of the precursors, investigatin of the drug case.
  
  
  METHODS
  In the present study, we investigated on the enantiomer of 114 crystalline methamphetamine samples seized in Beijing, Tianjin, Shijiazhuang and Chengdu. The methamphetamine samples were derivatized with (S)-(+)-a-methoxya-(trifluoromethyl)phenylacetyl chloride ((S)-(+)-MTPACl), and the derivatives were analyzed by GC-MS in selected ion monitoring (SIM) mode.
  
  
  RESULTS
  Most of the seizures were pure S (+)-enantiomer (90.4%), but 3.5% (4 of 114 samples) contained R(-)-enantiomer above 1%.
  
  
  CONCLUSIONS
  This indicates that the majority of samples were prepared from either (1R, 2S)-(-)-ephedrine or (1S, 2S)-(+)-pseudoephedrine. At the same time, there were methamphetamine drugs synthesized from (1S, 2R)-(-)-ephedrine or (1R, 2R)-(+)-pseudoephedrine.
authors.affiliation: Forensic Medical Examination Center of Beijing Public Security Bureau, Beijing 100085, China. zhangjianxin7292000@yahoo.com.cn
authors.forename: Jianxin
authors.initials: J
authors.lastname: Zhang
authors.forename: Daming
authors.initials: D
authors.lastname: Zhang
authors.forename: Wenfang
authors.initials: W
authors.lastname: Zhang
authors.forename: Jing
authors.initials: J
authors.lastname: Qiao
mesh_terms: D004809:Ephedrine / Q000737:chemistry*; D008401:Gas Chromatography-Mass Spectrometry; D008694:Methamphetamine / Q000138:chemical synthesis* / Q000737:chemistry*; D011355:Prodrugs / Q000737:chemistry*; D054199:Pseudoephedrine / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D011355:Prodrugs; D008694:Methamphetamine; D054199:Pseudoephedrine; D004809:Ephedrine