Improved method for the determination of sugars using capillary gas chromatography with flame-ionisation and nitrogen-selective detection

Abstract

The treatment of reducing sugars with hydroxylamine hydrochloride and dimethylaminopyridine in pyridine-methanol (4 + 1) followed by acetylation yields aldonitrile acetates whereas the treatment of non-reducing sugars yields only polyacetates. All derivatives respond to flame-ionisation detection but only the nitrogen-containing derivatives of the reducing sugars respond to nitrogen-selective detection. The derivatisation procedure is a relatively rapid (ca. 40 min) two-stage process and yields a sample which is suitable for direct injection into the chromatograph without further processing. Separation is by capillary gas chromatography on a non-polar column and the primary identification of products is by mass spectrometry with routine identification by relative retention time. Linear calibration is obtained over at least two decades of concentration with a minimum detectable amount of 5 × 10^–6M for mannitol, cellobiose and raffinose.