Born in the Rhondda, South Wales, he graduated with a First Class degree in Chemistry at the University of Wales, Cardiff, in 1946. From 1947 to 1952 he was Assistant Lecturer, then Lecturer at Cardiff. But, he said, some of the undergraduates he taught there were "so damned clever that I decided to move to the University of Cambridge to study for another PhD". This he did under the Head of the Department of Physical Chemistry, Professor R.G.W. Norrish.
At Cambridge he rubbed shoulders with the giants in gas-phase chemical kinetics: T.M. Sugden, F.S. Dainton and G. Porter. Upon completion of his doctorate in 1954 he was appointed University Demonstrator, and from 1959 to 1965 he held the posts of University Lecturer in Physical Chemistry and Fellow and Director of Studies in the Natural Sciences at Trinity Hall. Appointed Professor of Physical Chemistry at Swansea in 1965, he was Head of the Department of Chemistry twice (1970-84 and 1988-90) and Vice-Principal of the college from 1982 to 1985.
In an extraordinarily busy life, Purnell held a record number of offices, many of them very demanding. He was founding chairman of the Gas Kinetics Discussion Group of the Chemical Society, Vice-President of the Faraday Division of the Royal Society of Chemistry and of the Royal Institute of Chemistry, Hon Treasurer and Chairman of the International Committee of the Royal Society of Chemistry, and Chairman of the Heads of Departments of Chemistry of the UK.
As a young lecturer in Cardiff, carrying heavy teaching loads, Purnell published competent papers on various aspects of the Phase Rule. On arriving at Cambridge, hitched, as he put it, to the wagon of a future Nobel prizewinner, he took up frontier research in the kinetics of gas-phase reactions. But he also ploughed his own furrow in the field of gas chromatography. Basically, chromatography depends on the distribution of desired substances between two immiscible phases. Its origins go back to the work of the Russian-Italian botanist Michel Tswett, who in the 1910s separated the principal plant pigments such as carotene and chlorophyll by passing them in solution in petroleum ether through a column of powdered chalk.
In 1952, A.T. James and A.J.P. Martin published their seminal paper on gas-liquid chromatography - this earned Martin a share of the Nobel Prize with R.L.M. Synge later that year - and the breakthrough caught Purnell's eye. He set about mastering the theory and practice of gas- solid and gas-liquid chromatography, techniques now of central operational importance in the experimental sciences. Not only do they make possible analyses that are very difficult by other methods, but they make it possible to do them rapidly and in large numbers. Purnell was instrumental in educating chemists in the merits of chromatography. His book Gas Chromatography, published in 1962, provided a vade-mecum for a massive army of investigators the world over.
From 1978 to 1994 Purnell devoted his scientific attention increasingly to the development and use of natural and synthetic alumina-silicate clays as novel catalysts for the chemical conversion of a wide range of organic compounds. This work, which led to several patents, covering entirely new routes to the large-scale production of important solvents and other industrially useful chemicals, began on a train journey from Paddington to Swansea, after an unusually protracted Science and Engineering Research Council meeting in London.
"Let's talk real science," he said with gusto to his fellow passenger, also a chemist. "If you were to give me a cocktail of organic compounds, consisting of some 50 distinct substances, I could guarantee separating them all - and telling you what they were - in no time at all. We have optimised out chromatographic procedures beautifully." "Done!" said his fellow passenger, who a few days earlier had, as it happened, produced a puzzling mixture of products by passing certain alcohols over a montmorillonite clay. Purnell identified all the components of the mixture: the occurrence of some of the constituents was quite unexpected.
Subsequent work led to many new discoveries; and British Petroleum, and then the EEC, supported Purnell's effort in this field for several fruitful years.
In parallel with his scientific and pedagogic work at Swansea, he built up the Department of Chemistry to be one of the best-balanced and liveliest in the UK. He attracted back J.H. Beynon from a professorship in Purdue University to establish the world-class Royal Society Research Unit in Mass Spectrometry. He made imaginative staff appointments; he exposed his students to eminent scientists from industry. His students idolised him. Several of them became captains of industry, and one of his postdoctoral assistants is now Head of the Cambridge University Examination Syndicate.
Howard Purnell had generosity of spirit and was completely devoid of malice. Because of his colourful character and powers of vivid presentation, he was a favourite at international conferences and formal dinners acquired an aura of extra excitement when it was known that he was to be an after- dinner speaker or was to "perform" at the piano.
He is to be succeeded as President of the Royal Society of Chemistry by one of those "clever" undergraduates that prompted his move to Cambridge in 1952: Professor E.W. Abel, of Exeter University.
John Meurig Thomas
John Howard Purnell, chemist: born Rhondda 17 August 1925; Lecturer, University College, Cardiff 1947-52, Demonstrator 1955-60; Lecturer, Cambridge University 1960-65; Professor, University College of Swansea 1965-96 (Emeritus); OBE 1992; President, Royal Society of Chemistry 1994-96; married 1954 Betty Edwards (one son, one daughter); died Swansea 12 January 1996.