Simultaneous quantitation of volatile compounds in citrus beverage through stir bar sorptive extraction coupled with thermal desorption-programmed temperature vaporization.

Due to disparate concentrations and physiochemical properties of analytes, difficulties in terms of sensitivity and reproducibility are commonly encountered in flavour analysis. In this study, we attempted to improve the performance of stir bar sorptive extraction coupled with thermal desorption and programmed temperature vaporization (SBSE-TD-PTV) based on a model citrus beverage. Through response surface methodology, thermal desorption conditions (i.e. desorption flow, thermal desorption time and cryofocusing temperature) were optimised based on constrained optimisation. Solute discrimination during injection was alleviated by normalising the variability of peak responses of different analytes. In addition, the effects of extraction conditions (i.e. ionic strength, stirring speed, extraction time, temperature and pH) were also investigated using partial factorial design. The obtained method showed high precision and good linearity over the concentration ranged from 0.10 to 20.00 μg L(-1) with the correlation coefficients higher than 0.991 for most of the selected chemicals, except indole. The limit of detection ranged from 0.03 to 3.89 μg L(-1). Hence, our results indicated that through the systematic study, SBSE-TD-PTV method became much less solute discriminative and more reliable to quantitate complex analytes.