Long sample extraction time is usually necessary in the analysis of volatile flavour compounds to achieve high extraction efficiency. However, the long extraction time reduces sample throughput, which results in waste of labour and energy. Therefore, in this study, an improved headspace-stir bar sorptive extraction was developed to extract volatile compounds with varying polarities in a short time. With the aim of achieving high throughput, extraction conditions were selected and optimised based on the combinations of different extraction temperatures (80-160 °C), extraction times (1-61 min), and sample volumes (50-850 μL) through the response surface methodology with Box-Behnken design. After obtaining the preliminary optimal conditions (160 °C, 25 min, and 850 μL), the effect of cold stir bars with shorter extraction time on the extraction efficiency was evaluated. The cold stir bar improved the overall extraction efficiency with better repeatability, and the extraction time was further shortened to 1 min. Then, the effects of different ethanol concentrations and salt additions (sodium chloride or sodium sulfate) were studied, and 10% ethanol concentration with no salt addition provided the highest extraction efficiency for most compounds. Finally, it was verified that the high-throughput extraction condition was feasible for the volatile compounds spiked in a honeybush infusion.
Keywords: Cold stir bar; Headspace-stir bar sorptive extraction; High-throughput; Response surface methodology; Volatile compound analysis.
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