ANALYSIS OF HUMAN SWEAT VOLATILES - AN EXAMPLE OF PATTERN-RECOGNITIONIN THE ANALYSIS AND INTERPRETATION OF GAS CHROMATOGRAMS

The analysis of the volatile components of human body odour is describ ed with a view to establishing how individual identity can be reflecte d in an odour profile. In order to get good chromatographic replicatio n, a recirculating system was built to load the samples of axillary sw eat head-space into Tenax concentrating traps. The loading temperature and humidity could be controlled and trace volatiles concentrated. Th e head-space samples were desorbed from the trap and analysed by GLC. The GC/FID was interfaced with an ATARI ST 1040 computer which stored the output on disc. Pairs of chromatograms were then compared in a pat tern-matching programme which allowed irrelevant differences, such as variations in running time and sample size, to be corrected and then v arious match parameters to be measured. These were alignment coefficie nt, profile correlation, Euclidian distance and box car distance. The whole and selected parts of the chromatograms could be matched so that each range of volatiles could be assessed for its contribution to an identity signal. The pattern of sweat volatiles from two pairs of iden tical twins showed significantly higher match correlations than that o f unrelated people. The range of compounds eluting between 80 and 150- degrees-C showed the highest match correlations. These techniques coul d be used to match chromatograms from any source, for example, in drug s and pesticide research, environmental monitoring, food, flavour and perfume analysis or clinical and forensic investigations.