ANALYSIS OF 11-DEHYDROTHROMBOXANE B-2 IN HUMAN URINE IMPROVED BY USE OF GAS-CHROMATOGRAPHY HIGH-RESOLUTION SELECTED-ION MONITORING WITH O-18(2)-LABELED ANALOG AS AN INTERNAL STANDARD

Gas chromatography/high-resolution selected ion monitoring (GC/HR-SIM) for the determination of 11-dehydrothromboxane B-2 (11-dehydro-TXB(2) ) in human urine is described, Combined use of the lactone ring openin g reaction and dimethylisopropylsilylation has been adopted for the an alysis of 11-dehydro-TXB(2), to give a new chemically stable derivativ e. The feasibility of using this derivative for the analysis of 11-deh ydro-TXB(2) in human urine has been evaluated. Following the addition of O-18(2)-labelled analogue, for use as an internal standard, the sam ples were extracted using chromatographic separation with Bond Elut C- 18 and silica gel. Derivatization of the extracted 11-dehydro-TXB(2) w as followed by GC/SIM at resolution of 5000. This method enables selec tive detection of 11-dehydro-TXB(2) in human urine without serious int erference from other endogenous substances. In 11 volunteers, the mean urinary excretions of 11-dehydro-TXB(2) was 547.6 +/- 217.6 ng per da y.