Stability of morphine and buprenorphine in whole blood

Delays between time of sampling and time of toxicological analysis are common, therefore the length of time that postmortem blood can be stored at various temperatures (e.g. 4 degrees, 25 degrees, -20 degrees C) was evaluated for the effect on the stability of morphine and buprenorphine from day one up to one year. Solid phase extraction and GC-MS were used for the isolation and quantification of the drugs. Morphine and buprenorphine were found to be very stable for up to 6 months under these storage conditions, where at least 85% and 77% of morphine and buprenorphine respectively, were recovered. The study showed that a reasonable amount of the drugs (not less than 70%) was still detectable after one year of storage regardless of the temperature when blood samples were stored in silanized glass vessels.