[2] Determination of inositol phosphates by gas chromatography

Abstract

This chapter focuses on the determination of inositol phosphates by gas chromatography (GC). The GC of sugar phosphates followed quickly after the discovery of the utility of the trimethylsilyl (TMS) derivative for the GC of sugars. The quantitative analysis of a small group of sugar phosphates and the isomers of myo-inositol phosphate is described in the chapter. The three GC detectors of use for the measurement of small amounts of phosphorylated sugars are the flame ionization detector (FID), the flame photometric detector (FPD), and the mass spectrometer by the gas chromatographic inlet (GC-MS). The advantages of GC-MS over the FPD are principally in specificity; by using appropriate ions from a mass spectrum, near-absolute molecular specificity can be achieved, often with little compromise in sensitivity. Exposed metal surfaces and the complexity and cost of these instruments are the main drawbacks. A complete analysis of the inositol monophosphates is done with two derivatives: cM1,2P is measured as the TMS5 derivative and in the absence of significant amounts of M4P, M1P also may be analyzed as the per(trimethylsilyl) derivatives.