安非他命與甲基安非他命分別有一種及四種具有相同分子量之2-苯乙胺位向異構物，渠等在GC-MS分析上之性質與區分方法，將於本文中予以詳盡的探討。 安非他命與甲基安非他命之2-苯乙胺位向異構物，在�禨礞W均無取代基存在。因而以EI質譜對未衍生之二類位向異構物作分析時。安非他命者產生乙基亞胺(c�浹�硼)之m/z44基峰;甲基安非他命者則產生丙基亞胺(C�蚜�偡)之m/z58基峰。然兩類位向異構物之其餘碎裂離子峰之強度均很弱，因而產生相似之質譜。而利用phenylmethylsilicone(HP-5)固定相的GC毛細分離管對未衍生之二類位向異構物作分析時。亦顯示渠等具有類似的滯留性質。因此，若無參考標準品，將難以特異性的區分出安非他命、甲基安非他命及其2-苯乙胺類位向異構物。利用五氟丙酸酐(PFPA)對一級或二級胺進行衍生化反應後，各該位向異構物之五氟丙醯胺衍生物可得到良好的GC分離效果及具特異性之質譜，亦即能有效區分各該2-苯乙胺位向異構物。

　　　　　Analytical profiles are described for seven amines, i.e., two isomeric 2-phenethylaminesof amphetamine and five isomeric 2-phenethylamines of methamphetamine. These amines allcontain an unsubstituted benzyl moiety and are regioisomeric with respect to the iminefragment, the latter showing a base peak in the electron impact mass spectrum at either m/z 44 for amphetamines or m/z 58 for methamphetamines. Furthermore, these compounds showsimilar gas chromatographic retention property on phenylmethylsilicone (HP-5) stationaryphase. Therefore, without appropriate reference standards it would be difficult to specificallydifferentiate amphetamine and methamphetamine from their isomeric amines. In this study,the primary and secondary amines were acylated with pentafluoropropionic anhydride (PFPA)in an effort to obtain more specific structural information from mass spectrometry and toimprove chromatographic resolution as well. The pentafluoropropionyl amide derivativesprovide adequate GC resolution and mass spectrometric data that can be used tounambiguously distinguish among all regioisomeric amines.