Icons of Chromatography: John Knox

Jun 01, 2009
Volume 22, Issue 6

Gert Desmet: What brought you to the field of chromatography?

Image Source/Getty Images
John Knox: I got into chromatography along with my great friend Howard Purnell in 1953. We were both PhD students working under R.G.W. Norrish at Cambridge. I was studying hydrocarbon combustion and Howard was investigating hydrocarbon pyrolysis. The analytical methods at the time were very primitive so trying to determine the mechanisms of these complex processes by analysis of the end products was actually a hopeless task. Nevertheless, the experiences in the Physical Chemistry Lab (PCL) started us both on our careers in gas kinetics and chromatography. It all started with my job interviews at ICI, first at Billingham, where Bradford, Harvey and Chalkley had just built a gas chromatograph that they were very excited about. Unfortunately, they could only show me the heating jacket for the column, which was a tube about 1 inch in diameter and 1 metre long wound with heating wire. I was interviewed at the Alkali Division where they made polyethylene by the high pressure process. The research director, Ray Richards, explained that a key analysis was the determination of traces of acetylene in ethylene because acetylene inhibited the process.

He said: "We have this chap Ray (Neil Ray) who has found out how to do this. He uses a thermal conductivity gauge. I have no idea how it works" It all clicked together. This was gas chromatography. It used a column about 1 metre long packed with adsorbent material, samples were injected into the column and as the different components emerged they were detected by a catharometer.

John Knox being presented with the Golay Medal by Ernst Beyer at the Lake Garda meeting of Capillary Chromatography in 2000.
Howard and I talked about this over a beer in the local bun shop. Within a few days we had a working GC with a catharometer that used the filament taken from an electric light bulb. Quite soon we could separate all the simple hydrocarbons. We wrote a paper, sent it to the Faraday Society. We explained how band spreading was determined by slow equilibration and how retention decreased as the temperature rose. We then proposed that analysis of a range of materials with a wide range of volatility could be speeded up by increasing the temperature as the analysis proceeded — temperature programming. The paper was rejected as being too speculative! This was just a year after Martin and James' famous paper and a year before Ray's important paper in 1964.

GD: Who did you collaborate with most during your scientific career?

JK: I was always more of a loner than collaborator, but I was greatly influenced by many of the pioneers in chromatography. I met Jack Kirkland initially at the first Houston Conference organized by Al Zlatkis, I think it was 1958 and we became long-term friends. These conferences were an inspiration and a huge stimulation, especially for a young scientist on his early visits to the USA. It was in Houston that I met Cal Giddings and was enormously impressed by his grasp of the dynamics of chromatography — later to be the subject of his book.

Sailing on: JHK demonstating the device he invented for monitoring anchor loading: Anchorwatch. (Photo courtesy of John Knox)
This led to a sabbatical with Cal in Utah — January to September 1964. I wanted to test his theory of the coupling of the two dispersion processes: eddy diffusion and slow mass transfer. To test this required that experiments be conducted at high "reduced velocities" (u dp/Dm). This meant using a liquid as the eluent, not a gas. This introduced me to column liquid chromatography with a post-column photometric detector. Subsequently, in 1969, I published a landmark paper with Mohammed Saleem, which suggested that the highest speed in LC would be obtained by using 2 micron porous particles.

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