A new calibration procedure for the determination of dimethyl sulfide in beer using gas chromatography with a flame photometric detector
Lee, S.S.; Siebert, K.J.
Journal of the American Society of Brewing Chemists 44(2): 57-66
Procedures used to calibrate the flame photometric detector for determination of dimethyl sulfide (DMS) in beer headspace by gas chromatography were investigated. Substantial differences in results were attributed to differential quenching responses to DMS and the internal standard caused by nonsulfur-containing compounds eluting at the same times, and to the use of inappropriate calibration methods. A calibration procedure using beer as the medium and iteration techniques at high levels of added DMS was developed. Its applicability was verified with several different beers. Results obtained with this procedure differed from those obtained by the commonly used square root method by as much as 36-206%. The results indicated that a calibration curve constructed for one beer cannot be applied to others. A simplified procedure for obtaining a correction factor for preparing calibration curves in different beers is proposed. The DMS concentrations and correction factors determined for six different beers ranged from 16 to 45 .mu.g/L and from 0.37 to 1.77, respectively. The approach to calibration described should also have application in the determination of other sulfur compounds with the flame photometric detector.