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The writer of this review published in 1978 a three‐part article on two‐dimensional gas chromatography in the first three issues of this journal [1]. The review was written at a time when capillary column GC was still in its infancy. Commercial columns were (essentially) unavailable and sample introduction into capillary columns was done exclusively in the split mode. Two‐dimensional separations were explored in only a few laboratories. The limitations of capillary column technology made this exercise rather difficult. The introduction of fused silica capillary columns in the early eighties drastically changed the landscape in which gas chromatography was practiced. It took the chromatographic community just a few years to convert from packed columns to capillary columns. Instrumentation and accessories specifically designed for capillary column use came onto the market. This writer had great hopes that the revolution in capillary column GC would be mirrored in the development of instrumentation for Two‐Dimensional Gas Chromatography. This never materialized. On the contrary, tentative steps taken by a few manufacturers and suppliers of chromatographic equipment fizzled out. It was perhaps the introduction of relatively inexpensive and user friendly GC/MS instrumentation, in combination with nearly indestructible fused silica capillary columns that took away the incentive to develop commercially viable Two‐Dimensional Gas Chromatography. Much of the thinking went like this: why insist on good chromatography if mass spectrometry can do the job without the need for complete separation. Some progress in the further development of conventional Two‐Dimensional Gas Chromatography has certainly been made over the last 20 years but there has not been a great deal of excitement. Applications have also been relatively sparse and they are limited to just a few areas. Science does not remain static and chromatography is no exception. Progress in gas chromatography is driven by new technology and ideas. Substantial improvements in two‐dimensional GC were not forthcoming until Phillips and his research group introduced and implemented an entirely new form of Two‐Dimensional Gas Chromatography, called comprehensive two‐dimensional GC, or GC×GC. This breakthrough occurred only in 1991 [2]. It does take some time before scientists change attitudes and habits. There is always a time lag between the introduction of new technology and its general acceptance. The public's attitude toward comprehensive Two‐Dimensional Gas Chromatography is probably no exception. The number of scientists who are actively pursuing this new branch of gas chromatography is still very small. It is often a single individual who carries the torch. J.B. Phillips' name is synonymous with comprehensive Two‐Dimensional Gas Chromatography. He is not only its inventor and proponent but his fertile mind has initiated research in other related areas. Sadly, he passed away shortly before this review was written. This contribution is dedicated to his memory.

Profiles of volatile metabolites of 150 urine samples from normal individuals and 40 samples from subjects with diabetes mellitus have been studied by gas chromatography and mass spectrometry. The technique involves adsorption of the urinary headspace volatiles on Tenax GC, heat desorption with helium, trapping on a cooled precolumn, and chromatography on 100-m X 0.50-mm i.d. nickel columns. Individual profiles were observed over a period of 2 months. Characteristic constituents in normal urines are 2-butanone, 2-pentanone, 4-heptanone, dimethyl disulfide, several alkyl furans, pyrrole, and carvone.

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