Pain management LC analyses can be difficult to optimize due to the limited selectivity of C18 and phenyl-hexyl phases. In contrast, the selectivity of Raptor™ Biphenyl superficially porous particle (SPP) LC columns provides complete resolution of isobaric pain medications with a total cycle time of 5 min.
Accurate, reliable analysis of pain medications is a key component in monitoring appropriate medical use and preventing drug diversion and abuse. As the demand for fast, multicomponent methods grows, LC–MS-MS methods are increasingly desired for pain management and therapeutic drug monitoring due to the low detection limits that can be achieved with this highly sensitive and selective technique. However, despite the selectivity offered by mass spectrometry, hydrophilic matrix components can still interfere with early-eluting drug compounds resulting in ion suppression. In addition, isobaric pairs must be chromatographically separated for positive identification. The need for highly selective and accurate methods makes LC column selection critical.
A standard containing multiple pain management drugs was prepared in blank human urine and diluted with mobile phase as follows, urine:mobile phase A:mobile phase B (17:76:7). The final concentration for all analytes was 10 ng/mL except for lorazepam, which was 100 ng/mL. Samples were then analyzed by LC–MS-MS using an AB SCIEX API 4000™ MS-MS in ESI+ mode. Chromatographic conditions, retention times, and mass transitions are presented here and in Tables I and II:
Column: Raptor™ Biphenyl, 50 mm × 3.0 mm i.d. × 2.7 µm