Validation of a headspace GC method for the analysis of a pyrolytic product of methamphetamine in urine.
A method has been developed and validated using headspace GC-FID for the identification of 1-phenylpropene in urine. This compound is a pyrolytic product of methamphetamine that has been previously proposed as a marker for smoked methamphetamine. The instrumentation used is the same as employed for blood alcohol determination. The extraction-free procedure is rapid, simple, and quantitative using 2-phenylpropene as the internal standard. The method was validated for linearity over a range of 0.1-20 microg/mL with a limit of detection of 0.05 microg/mL, limit of quantification of 0.1 microg/mL, interday accuracy within 3.2 to -5.3%, intraday accuracy better than 7.5%, interday precision of 7.5 to 10.7%, intraday precision of 2 to 8.6%, and recovery above 80%. For the robustness determination in urine, the accuracy of four different sources of urine at the mid control level (1 microg/mL) ranged from 1.6 to 19% error. The % relative standard deviation of the different urine sources ranged from 3.1 to 11%. Urine samples from nine methamphetamine-positive cases investigated by the Office of the Chief Medical Examiner of West Virginia were included in the study. 1-Phenylpropene was found in two methamphetamine-positive cases (0.25 and 0.44 microg/mL).