Triple stage quadrupole mass spectrometric determination of bromocriptine in human plasma with negative ion chemical ionization.

A new MS/MS assay for the quantitative determination of bromocriptine in body fluids is presented. The selective reagent gas in combination with the registration of selected, characteristic negative ions (SIM) after collision activated decomposition (CAD) in a Triple-Stage-Quaddrupole-mass spectrometer, provides an exceptional selective and sensitive assay in the low pg/ml range. The lower limit of detection was about 1 pg/ml (at optimal measuring conditions) and the calibration curve was linear in the range of 10-200 pg/ml. The coefficient of variation for the imprecision and inaccuracy data was typically below 10%; the recovery from plasma always exceeded 75%. The sample introduction to the mass spectrometer was done by a direct exposure probe (DEP). Thus, the method is well suited for the reliable, rapid processing of large sample numbers generated e.g. from clinical studies evaluating the pharmacokinetics and/or bioavailability/bioequivalence of different formulations or from drug monitoring/clinical response programs. The assay has been successfully approved in several clinical studies evaluating different bromocriptine preparations.