Gas Chromatography with Flame Ionization Detection of 1,4-Dioxane in Palm-Based Fatty Alcohol Ethoxylates

During the ethoxylation of fatty alcohol, 1,4-dioxane, a toxic by-product may be formed. A simple and rapid method using gas chromatography with a flame ionization detector was developed for detection of 1,4-dioxane in commercial palm-based fatty alcohol ethoxylate (FAEO). The method involved spiking the 1,4-dioxane into FAEO samples, and directly injecting the spiked samples into GC with no clean-up steps. The method was validated in terms of linearity, accuracy, intra-day precision and inter-day precision, selectivity, limit of detection and limit of quantification. In terms of linearity, a calibration curve with a correlation coefficient of 0.9999 was obtained. The accuracy of the method was indicated by recovery obtained for spiked 1,4-dioxane samples at 5 levels of spiking, i.e. at 30, 60, 100, 200 and 500 μg/g, where recoveries were within 99–105 % with relative standard deviation (RSD) of <4.0 %. The RSD values of the intra-day and inter-day precision were <1.0 %. The limit of detection and quantification was 10 and 30 μg/g, respectively. The selectivity of the method was indicated by its ability to analyze commercial FAEO samples with different average moles of ethylene oxide (EO). The GC profiles of these FAEO with varying numbers of moles of EO were similar, and there were no other peaks interfering with the 1,4-dioxane peak.