DERIVATIZATION IN LC MS

LC/MS is now considered to be the most promising analytical method for the determination of biological substances, especially nonvolatile or high molecular weight substances. But one of the drawbacks of this me thod is its low sensitivity in comparison with GC/MS. In order to over come this problem, the derivatization methods are used in LC/MS. This report overviews the detection-oriented derivatization methods in LC/ MS including our results. The typical examples are as follows. The der ivatization of vitamin D with a Cookson-type reagent (analog of 4-phen yl-1,2,4-triazoline-3,5-dione) gave satisfactory sensitivity, which wa s also observed on the derivatization of oxosteroids with O-methylhydr oxylamine. Although the oxosteroid fatty acid esters gave a de-esterif ied ion as a base peak in atmospheric pressure chemical-ionization MS, the methyloxime of which gave a quasimolecular ion as a base peak, wh ich is helpful to identify the compounds in the brain.