Volume 39, Issue 1 (January 1994)
Gas Chromatography/Mass Spectrometry for the Determination of Cocaine and Benzoylecgonine over a Wide Concentration Range (<0.005–5 mg/dL) in Postmortem Blood
The determination of cocaine and benzoylecgonine in blood by gas chromatography/mass spectrometry using selected ion monitoring was investigated. The method involved an extraction using rotation of an Amberlite® XAD-2-blood mixture and the use of deuterated internal standards with derivatization of benzoylecgonine using diazopropane. Standard curves with logarithmic-transformed data were constructed over the concentration range from 0.005 to 5 mg/dL. The use of a wide concentration range precludes using smaller sample sizes in repeated extractions to conform to a narrower concentration range of standards. The recovery of the extraction method was 85% for both cocaine and benzoylecgonine. The method was applied primarily to postmortem blood samples from 180 forensic cases and was statistically evaluated. The limit of detection for cocaine or benzoylecgonine extractions from 1 mL forensic blood samples is 0.00025 mg/dL. The method is routinely reliable and applicable to forensic toxicology investigations.