|SOFT - TIAFT 1998||Poster Session 4||Friday October 9, 1998|
CONFIRMATION OF KETO-OPIOIDS IN URINE BY GC-MS|
Robert C. Meatherall
Dept. of Biochemistry, St. Boniface General Hospital, Winnipeg, Manitoba, R2H 2A6, USA
|A GC-MS method is described for the urinary confirmation of the keto-opioids: hydrocodone, hydromorphone, oxycodone and oxymorphone along with codeine, morphine and 6-monoacetyl-morphine(6-MAM).
The urine was hydrolysed with E. coli b-glucuronidase, alkaninized to pH 9 and extracted with methylene dichloride/trifluoroethanol (92:8). The dried extract was subjected to sequential derivatization. First, the keto-opioids were converted to their respective oximes with the addition of 2% methoxyamine HCl in pyridine. The reaction occurs at room temperature and is complete within 15 minutes. Next, propionic anhydride was added to the pyridine. The available hydroxyl groups at O3 and O6 are converted to propionyl esters. The reaction occurs at 56°C and is complete within 15 minutes. The excess derivitizing reagents were evaporated. The residue was purified by liquid extraction from 100 µL of 15% ammonium hydroxide into 1 mL of hexane/chloroform (3:1). The organic phase is dried, reconstituted in 50 µL of ethyl acetate and 1 µL analysed by GC-MS in full scan, m/z 50 to 550 at 1 scan/s.
Good separation was obtained between all opioids on a 15 m x 0.25 mm DB-1 column (J&W Scientific); a unique mass spectrum is obtained for each. Using naltrexone as the internal standard for the keto-opioids and nalorphine for the others, the day-to-day CVs for hydrocodone, hydromorphone, oxycodone, oxymorphone, codeine and morphine are 7.6, 8.7, 10.9, 8.3, 8.6 and 6.7% at 300 ng/mL and 9.1, 6.0, 10.2, 9.0, 8.3, and 7.9% at 1500 ng/mL. CVs for 6-MAM are 12.0% at both 30 and 150 ng/mL. The method is linear from 25 to 2,000 ng/mL.