Hair analysis for drugs of abuse VIII. Effective extraction and determination of 6-acetylmorphine and morphine in hair with trifluoroacetic acid—methanol for the confirmation of retrospective heroin use by gas chromatography—mass spectrometry

Abstract

A procedure for the detection and determination of 6-acetylmorphine (6AM) and morphine in rat and human hair is described. The efficiency of extraction of 6AM and morphine from hair was compared between five extraction methods using methanol, 0.1 M hydrochloric acid, methanol—5 M hydrochloric acid (20:1), helicase and methanol—trifluoroacetic acid (TFA) (9:1). Methanol—TFA was found to be the best solvent for extracting 6AM and morphine with minimum hydrolysis and maximum extraction efficiency of 6AM. The extraction rates of 6AM and morphine from heroin abuser's hair with methanol—TFA reached a plateau after 8–10 h. After the extraction from hair with deuterated internal standards added, the extract was purified by Bond Elut Certify in the usual manner. The 6AM and morphine were then derivatized with bis(trimethylsilyl)acetamide, which were characterized by GC—MS with electron impact ionization. Confirmation was accomplished by comparing their retention times and the relative abundances of major four selected ions with those of the standards. Quantification was based on the deuterated internal standards. Linearity was obtained in the concentration range 0.1–50 ng/mg. The overall recoveries after solvent extraction and solid-phase purification were 95% for 6AM and 97% for morphine. The limit of detection for confirmation was 0.2 ng/mg. The coefficients of variations for 6AM and morphine at concentrations of 4 ng/mg were generally less than 8%. 6AM was stable during extraction with methanol—TFA (9:1) at room temperature. This method was applied to the elucidation of heroin drug history by using hair sectional analysis.