Improved Assay Selectivity for the Determination of Hydroxymidazolam in Capillary Microsampling Extracts using LC-MS~3 on a Hybrid Linear Ion Trap

摘要

The gas phase selectivity afforded by MS~3 in the LIT for HMDZ reduced the need for exhaustive sample preparation or chromatographic resolution to eliminate co-extracted interferences when using CMS paired with SLE. The MS~3 isolation and dissociation efficiencies for HMDZ allowed the target LLOQ of 0.1 ng/mL to be achieved. The increased sensitivity and saturation point of the pulse-counting detector in the QTrap 6500 allowed a fixed injection time for Q3 trapping, providing a constant duty cycle for acquisition. The constant duty cycle provided a sufficient and consistent number of data points representing the chromatographic response for HMDZ, resulting in MS3 precision and accuracy data which mirrored that of the MRM scan function applied to MDZ, without detector saturation at the ULOQ. All acceptance criteria were met for a validatable bioanalytical method.