Determination of some beer flavours by stir bar sorptive extraction and solvent back extraction

This work presents the development of a simple, rapid and low cost method for the determination of some beer flavours as esters such as isoamyl acetate, ethyl caproate, ethyl caprylate. phenyl acetate, ethyl caprate, phenylethyl acetate, ethyl laurate, ethyl myristate and ethyl palmitate using stir bar sorptive extraction (SBSE). The combination of this extraction technique with solvent back extraction and subsequent gas chromatographic analysis with flame ionisation detection was used for the determination of these compounds. The effects of different mixtures of organic solvents and the influence of sampling time and time of solvent back extraction were studied. An optimum procedure for the SBSE method was developed. The method had high repeatability (RSD 2.1-7.3%), good linearity (the correlation coefficients were higher than 0.9995 for quadratic fit over the concentration range from 0.015 to 30 mg/L) and acceptable recoveries (78-107%) and precision (RSD < 7.3%).