OPTIMIZATION OF THE SIMULTANEOUS DETERMINATION OF ACIDS AND SUGARS AS THEIR TRIMETHYLSILYL(OXIME) DERIVATIVES BY GAS-CHROMATOGRAPHY MASS-SPECTROMETRY AND DETERMINATION OF THE COMPOSITION OF 6 APPLE VARIETIES

A GC-MS method is reported for establishing the reproducibility of the determination of widely different amounts of sugars and acids as their trimethylsilyl derivatives simultaneously, from one solution with one injection. Optimum conditions were achieved on a 30-m DB-5 column. The determination of the components was based on their TIC and on selected ion monitoring. Data furnished by a Varian Saturn II GC-MS system equipped with a Varian Model 8200 AutoSampler showed that 4-20 ng of the minor constituents, in the presence of 50-250 ng of the main components, could be determined with a relative standard deviation of 10.6% or less. The utility of the procedure was demonstrated by the analysis of the composition of six different apple varieties, gathered at three different time of ripeness, in two consecutive years (1991, 1992), and stored for various periods of time. The separated carboxylic acids and sugars were phosphoric, succinic, pyruvic, 5-hydroxy-N-valeric and malic acid, butanal, 3-methyl-2-hydroxy-2-butenoic acid, 1,2-hydroxycyclohexene, pimelic acid, 2-deoxy-D-erythrose, tartaric acid, xylitol, arabinose, caffeic acid, D-ribose, citric acid, rhamnose, quinic acid, D-erythro-tetrafuranose, talose, 2-ketogluconic acid, mannitol, sorbitol, fructose, galactose, glucose, fructose (open form), glucaric and galacturonic acid, lactose, meso-inositol, gluconic, linoleic, glucuronic, stearic and arachidic acid, sucrose, turanose, maltose, chlorogenic acid, beta-sitosterol, raffinose and maltotriose.