Derivatives suitable for GC-MS

The preparation of derivatives is often advantageous or necessary for GC-MS, for a variety of reasons. In respect of GC, these include the need for conferring volatility or stability; the improvement of chromatographic behaviour or separation; information on functional groups; and provision for selective detection. In MS, derivatives are important for producing characteristic mass shifts and for directing particular modes of fragmentation under electron impact or chemical ionisation. Reagents used for derivative formation may be general or selective: among the latter class, reagents that yield cyclic derivatives from bifunctional substrates are of special value. Typical examples are given of the applications of derivatives in the analysis, by GC-MS, of long-chain fatty acids, prostaglandins, mono- and diglycerides, sphingolipids, and sterols. Recent developments in instrumentation and in the use of computer data systems are outlined.