β-Phenylethylamine was converted to its trifluoroacetamide (TFA), pentafluoropropionamide (PFP), heptafluorobutyramide (HFB), pentadecafluorooctanamide (PDFO) and pentafluorobenzamide (PFBO) derivatives. The gas chromatographic characteristics and flame ionization versus electron capture detection properties were investigated. The PFBO derivative showed excellent detection enhancement, and consequently it was chosen for further study with the drugs amphetamine and various ephedrines. Linear electron capture detector responses were shown by these N-acyl derivatives in the sub-nanogram region and the limits of detection, depending upon the specific compound, were between 10 and 60 pg. It is proposed that the PFBO derivative, subsequent to the development of an isolation procedure, will prove admirably suitable to the determination of these and similar drugs in plasma after administration of therapeutic dosages.