title: [Study on the linked samples of methamphetamine identified by the impurity profile].
abstract: OBJECTIVE
  To compare and classify the samples of MA crystals by using impurity profile to offer methods for identification of linked samples.
  
  
  METHODS
  50 mg samples of MA were dissolved in 1 ml of buffer solution (pH 7.0, four parts of 0.1 mol/L phosphate buffer, and one part of 10% Na2CO3), impurities were extracted with 0.5 ml of ethyl acetate containing four internal standards (n-decane, n-pentadecane, n-eicosane and n-octacosane) and analyzed by gas chromatography with a flame ionization detector on a DB-5 capillary column (30 m x 0.32 mm i.d. x 1.0 microm). Seventeen characteristic peaks on chromatograms were selected for the comparison and classification of samples, and the data were evaluated by the Euclidean distance of the relative peak areas after logarithmic transformation.
  
  
  RESULTS
  Eight different batches of MA (six samples from each batch) to be seized by the Beijing Public Security Bureau (BPSB) in 2006-2007 were analyzed. The results indicated that the samples from the same batch were successfully classified into one group.
  
  
  CONCLUSIONS
  The methods could be very useful for identifying the linked samples and could provide technique foundation for MA drug criminal inspection.
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: Jing
authors.initials: J
authors.lastname: Qiao
authors.forename: Shiyun
authors.initials: S
authors.lastname: Yang
mesh_terms: D002681:China; D002849:Chromatography, Gas / Q000379:methods*; D004340:Drug Contamination; D005410:Flame Ionization; D005554:Forensic Medicine / Q000379:methods; D013287:Illicit Drugs / Q000032:analysis*; D008694:Methamphetamine / Q000032:analysis* / Q000737:chemistry
chemical_list: D013287:Illicit Drugs; D008694:Methamphetamine