The standardization of gas—liquid chromatography for the analysis of simple hydrocarbon mixtures

Nine European laboratories have taken part in a joint exercise in which two samples, one containing about 98% benzene and the other 90% toluene, were analysed, using chromatographic equipment available to each laboratory. For each sample, a known quantity of a specified internal standard was used and the composition of the samples was calculated from calibration data based on (I) peak height, (2) peak height X retention distance, (3) peak height x width of peak at half peak height. The precision of the results is least for method (3), but method (I) is preferred because it is the simpliest. The results for the toluene sample were less precise than those for the benzene sample. Further work is in progress.