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 method is its low sensitivity in comparison with GC/MS. In order to overcome 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 derivatization of vitamin D with a Cookson-type reagent (analog of 4-phenyl-1,2,4-triazoline-3,5-dione) gave satisfactory sensitivity, which was also observed on the derivatization of oxosteroids with O-methylhydroxylamine. Although the oxosteroid fatty acid esters gave a de-esterified ion as a base peak in atmospheric pressure chemical-ionization MS, the methyloxime of which gave a quasimolecular ion as a base peak, which is helpful to identify the compounds in the brain.