Stereospecific Derivatization of Amphetamines, Phenol Alkylamines, and Hydroxyamines and Quantification of the Enantiomers by Capillary GC/MS.

The enantiomers of amphetamines, phenol alkylamines, and hydroxyamines are separated by using α-methoxy-α-(trifluoromethyl)phenylacetyl chloride as the chiral derivatizing agent for amino groups. Prior to N-acylation, amine salts are converted into the free bases and hydroxyl groups into O-silyl ethers by reaction with N-methyl-N-silylamides. N-Methyl-N-(trimethylsilyl)trifluoroacetamide, N-methyl-N-(triethylsilyl)trifluoroacetamide, or N-methyl-N-(tert-butyldimethylsilyl)trifluoroacetamide was used to protect the hydroxyl groups by TMS, TES, or the tBDMS groups. All these N-methyl-N-silylamides were able to convert amino salts to the free bases. The reaction is selective and rapid, and the diastereomeric derivatives are well separated by capillary gas-liquid chromatography. This procedure is suitable for simultaneous determination by gas chromatography/mass spectrometry with selected-ion monitoring and is also applicable to quantification of the compounds in a biological matrix.