OBJECTIVE: The goal of this work was to further validate the subcritical water chromatography (SBWC) methods for separation and analysis of preservatives through the evaluation of analyte stability in subcritical water.METHODS: In this study, the degradation of preservatives was investigated at temperatures of 100-200°C using two different approaches. First, the peak areas obtained by SBWC at high temperatures were compared with those achieved using the traditional high-performance liquid chromatography (HPLC) at 25°C. In the second approach, several preservatives and water were loaded into a vessel and heated at high temperatures for 30 or 60 min. The heated mixtures were then analysed by GC/MS to determine the stability of preservatives.RESULTS: The t- and F-test on the results of the first approach reveal that the peak areas achieved by HPLC and SBWC are not significantly different at the 95% confidence level, meaning that the preservatives studied are stable during the high-temperature SBWC runs. Although the results of the second approach show approximately 10% degradation of preservatives into mainly p-hydroxybenzoic acid and phenol at 200°C, the preservatives studied are stable at 100 and 150°C. This is in good agreement with the validation results obtained by the first approach.CONCLUSION: The findings of this work confirm that SBWC methods at temperatures up to 150°C are reliable for separation and analysis of preservatives in cosmetic and other samples.
Chromatography, High Pressure Liquid Cosmetics