ABSTRACT

   A sensitive and specific gas chromatography-mass spectrometry (GC-MS) method using selected ion monitoring (SIM) has been developed for quantification of pentazocine in urine.  This method uses solid-solid extraction (SPE) and N, O-bis (trimethylsilyl) trifluoroacetamide with 1% trimethylchlorosilane derivatization, followed by GC-MS analysis using dextromethorphan as the internal standard.  The method was linear between 125 and 1500 ng/mL (r² = 0.997).  The limit of quantification and limit of detection were 125 and 62.5 ng/mL, respectively.  The intraday accuracy and precision were -6.3~4.7% and 3.6~11.2%, respectively.  The interday accuracy and precision were -7.5~7.0% and 6.2~10.0%, respectively.  These data showed that the GC-MS method was suitable for the determination of pentazocine in urine.  This method was further applied to an interlaboratory study. The collaborative study was given by the Association of Official Analytical Chemists International (AOAC International).  Nine drug abuse urine testing laboratories in Taiwan participated to analyze 3 samples in duplicate.  The repeatability relative standard deviation (RSD_r) and reproducibility relative standard deviation (RSD_R) values were 3.0~5.2% and 6.8~10.3%, respectively.  The method showed acceptable reproducibility, as evidenced by HORRAT values of 1.1 to 1.5.  The method recommended for use by the drug abuse urine testing laboratories in Taiwan.