High-resolution gas chromatography with nitrogen-phosphorous detection of saturated volatile aldehydes derivatized with 2-hydrazinobenzothiazole

An analytical method to measure highly volatile saturated aldehydes, degradation products of lipid peroxidation, was developed for fused-silica narrow-bore capillary gas chromatography with nitrogen-phosphorous detection. The carbonyl compounds were derivatized quantitatively with 2-hydrazinobenzothiazole (HBT) at room temperature to afford their corresponding water-insoluble hydrazones. The derivatives were extracted into non-polar phases and detected with high selectivity by high-resolution gas chromatography with nitrogen-phosphorous detection due to their high nitrogen content. Analyte concentration, pH and type of extraction technique were studied to determine optimal recovery conditions. The efficiencies for solid-phase extraction (SPE) on 3 mi C-18 octadecyl-bonded phase cartridges ranged from 81.1 +/- 1.1 to 98.1 +/- 1.4% compared to 70.1 +/- 1.4 to 92.4 +/- 1.0% obtained for liquid-liquid extraction (LLE) (hexane-isopropanol, 9:1, v/v) for spiked aldehyde solutions at concentrations of 20-60 mu g/ml. The recoveries from aqueous solutions at pH 2.96 were routinely 2-7% higher than those obtained at pH 5.99. SPE efficiencies were less affected by pH than LLE. Recoveries achieved by LLE showed an average decrease of 5-12% in comparison with those of SPE. The method was applied to the analysis of the volatile aldehydes generated during the thermal oxidation of olive oil at 220 degrees C.