Serial capillary gas chromatography/Fourier transform infrared spectrometry/mass spectrometry (GC/IR/MS): qualitative and quantitative analysis of amphetamine, methamphetamine, and related analogues in human urine.

A method using serial capillary gas chromatography/Fourier transform infrared spectroscopy/mass spectrometry (GC/IR/MS) for the analysis of derivatized amphetamine, methamphetamine, and related analogues was developed. The GC/IR/MS was configured and optimized with a Hewlett-Packard (HP) 5890A gas chromatograph with a 12-m x 0.32-mm i.d. HP-5 capillary column serially interfaced through an HP 5965A infrared detector to an HP 5970 mass selective detector with a fused-silica 1.2-m x 0.10-mm i.d. column. Urine samples are extracted and derivatized as heptafluorobutyryl (HFBA) derivatives. For quantitation GC/MS in the selected ion monitoring (SIM) mode was used, with D,L-amphetamine-D5 as the internal standard. Gas chromatography/Fourier transform infrared spectrometry (GC/FT-IR) quantitation uses a selected wavelength chromatogram, spectral subtraction, double internal standard method using both D,L-amphetamine-D5 and 4-phenyl butylamine. Sensitivity for the combined GC/MS and GC/FT-IR system for amphetamine and methamphetamine shows limits of linearity of 100 to 5000 ng/mL, a limit of detection of 25 ng/mL, and a limit of quantitation of 98 ng/mL. The overall recovery for amphetamine and related analogues was greater than 85%. Precision studies for concentrations over the range of 200 to 1500 ng/mL showed coefficients of variations ranging from 2.8 to 13.0%. Correlation studies for quantitative GC/MS SIM and GC/FT-IR are greater than 0.98 for amphetamine, methamphetamine, and related analogues. Each analysis includes GC/MS SIM and GC/FT-IR quantitation, qualitative nonselective full spectra GC/FT-IR, and GC/MS scans of HFBA derivatives cross-referenced with an internal drug library, which provides high confidence and a means for the surveillance of amphetamine-like chemical analogues.