Hydrophilic interaction LC–MS/MS analysis of opioids in urine: significance of glucuronide metabolites

Background: In clinical laboratories, a large proportion of the toxicology workload is drug confirmations. Our GC–MS method for opioid confirmation detects total codeine, morphine, hydrocodone, hydromorphone, oxycodone and oxymorphone. The objective of this study was to develop a LC–MS/MS assay measuring the above drugs and glucuronide metabolites. In addition, to determine if measuring free drug only would lead to false negative results. Results: In 85 patient urines, 43% were positive for morphine glucuronide, but not morphine, 48% were positive for hydromorphone glucuronide, but not hydromorphone, 33% were positive for codeine glucuronide, but not codeine, and 44% were positive for oxymorphone...