Determination of sulphur compounds in beer using headspace solid-phase microextraction and gas chromatographic analysis with pulsed flame photometricdetection

A simple and sensitive method for the analysis of volatile and semi-volatil e sulphur compounds in beer at trace levels was developed using headspace s olid-phase microextraction (SPME) and gas chromatography with pulsed flame photometric detection. Different SPME fibres were tested and a Carboxen-pol ydimethylsiloxane coated fibre was found to be the most appropriate. The ad sorption and desorption conditions were optimised. The effect of ethanol co ncentration in the sample on the extraction of analytes was examined. A 60 m non-polar capillary column preceded by a 10 m length of a polar column wa s found to be capable of separating a wide range of C-1-C-6 sulphur compoun ds. The pulsed flame photometric detector enabled increased sensitivity to be obtained over previous methods, such as dynamic headspace followed by co nventional flame photometric detection or sulphur chemiluminescent detectio n, with high sulphur selectivity. Two sulphur compounds, 2-methyl-1-butanet hiol and 3-methylthiophene, were identified in beer for the first time. (C) 2000 Elsevier Science B.V. All rights reserved.