Gas chromatographic determination of 29 organic acids in foodstuffs after continuous solid-phase extraction

A simple and expeditious method based on continuous solid-phase extraction and gas chromatography–mass spectrometry (GC–MS) was reported for the direct determination of 29 organic acids in food and beverages. A sorbent column packed with 80 mg of LiChrolut EN–Supelclean ENVI-18 (1:1) was employed for extraction and clean-up purposes. After elution with 200 μL of methanol, the methanolic extract was directly injected into the GC–MS without prior derivatization. The method provided good linearity (0.5–1000 μg kg−1) and fairly good precision for all compounds (RSD lower than 6.2%). The recoveries of the organic acids from diluted samples that were spiked at three different concentrations (10, 40 and 100 μg kg−1) ranged from 93 to 98%. The applicability of the method was demonstrated by analyzing the target compounds in a wide variety of foodstuffs including beer, wine, fruit juice, soy sauce, soya milk and honey samples.