Introduction: Pentazocine ( Fig. ) is a non-narcotic analgesic, but shows mild dependence; there are many cases of pentazocine abuse especially for medical and co-medical workers. The drug is being regulated as a subclass compound of narcotics (DEA class: IV). Pentazocine in both antemortem and postmortem specimens is being analyzed by GC [1–4], HPLC [5–7] and GC/MS [8]. In this chapter, a simple method for GC/MS analysis of pentazocine in human whole blood and urine is presented. ⊡ Figure Structures of pentazocine and dextromethorphan (IS). Reagents and their preparation i. Reagents Ampoules for pentazocine injection were purchased from Yamanouchi Pharmaceutical Co., Ltd., Tokyo,. | Pentazocine by Osamu Suzuki Introduction Pentazocine Fig. is a non-narcotic analgesic but shows mild dependence there are many cases of pentazocine abuse especially for medical and co-medical workers. The drug is being regulated as a subclass compound of narcotics DEA class IV . Pentazocine in both antemortem and postmortem specimens is being analyzed by GC 1-4 HPLC 5-7 and GC MS 8 . In this chapter a simple method for GC MS analysis of pentazocine in human whole blood and urine is presented. O Figure HsC .CH CIL CII C N CIL pentazocine dextromethorphan IS Structures of pentazocine and dextromethorphan IS . Reagents and their preparation i. Reagents Ampoules for pentazocine injection were purchased from Yamanouchi Pharmaceutical Co. Ltd. Tokyo Japan. Each ampoule 1 mL contains 15 mg of free pentazocine. The solution is transferred to a small glass centrifuge tube with a ground-in stopper followed by addition of several mg of solid K2CO3 and 3 mL of chloroform. The tube is vortex-mixed well and centrifuged at 3 000 rpm for 5 min. The upper aqueous phase is carefully removed with a Pasteur pipette and the lower organic phase is evaporated to dryness with a centrifugal freeze drier to obtain free pentazocine. However at the present time pure pentazocine is commercially available from Sigma St. Louis MO USA . Dextromethorphan-HBr to be used as internal standard IS was purchased from Sigma Sep-Pak C18 cartridges classic type from Waters Springer-Verlag Berlin Heidelberg 2005 220 Pentazocine Milford MA USA . Other common chemicals were of the highest purity commercially available. ii. Preparation Pentazocine and dextromethorphan solutions the drugs are separately dissolved in appropriate amount of methanol a 10-20 ph aliquot was added to 1 mL of whole blood or urine. 1 M NaHCO3 a aliquot of NaHCO3 is dissolved in distilled water to prepare 100 mh solution. Chloroform ethanol 9 1 v v a 100-mL volume of the mixture is prepared. GC MS conditions 8 .