Improved Gas Chromatography–Mass Spectrometry Method for Simultaneous Identification and Quantification of Opiates in Urine as Propionyl and Oxime Derivatives

Abstract

Several authors have reviewed existing methods (1)(2)(3)(4)(5)(6)(7)(8)(9) or presented new techniques (6)(7)(8)(9)(10)(11) for the analysis and separation of codeine, morphine, and the keto-opiates hydrocodone, hydromorphone, oxycodone, and oxymorphone. We present a modification of previously published procedures (6)(10) that incorporates the use of methoxyamine after enzymatic hydrolysis to form methoxime derivatives of the keto-opiates, which are then extracted using solid-phase columns and derivatized with propionic anhydride/pyridine. We used a gas chromatography–mass spectrometry system composed of a model 5890 gas chromatograph with splitless injection, a model 5970 mass-selective detector (both from Hewlett Packard), and a DB-5 capillary column [15 m × 0.25 mm (i.d.); 0.25 μm film thickness; JW helium (flow rate, 0.7 mL/min; linear velocity, 38 cm/s) was used as the carrier gas. The temperature program was as follows: initial temperature, 185 °C; ramp at 25 °C/min to 240 °C; hold for 0.5 min; ramp at 5 °C/min to 250 °C, then 40 °C/min to 290 °C; hold for 1.0 min. The injection temperature was 260 °C, and the transfer line temperature was 290 °C. The following were obtained from Radian Corporation: (a) codeine, morphine, hydrocodone, hydromorphone, and oxycodone, which were used to prepare calibrators; (b) deuterated codeine, morphine, hydrocodone, and hydromorphone, which were used as internal standards; and (c) oxymorphone and norcodeine, which were used for interference …