Alan Walsh and the First Atomic Absorption Spectrometer

Alan Walsh was the originator and developer of the atomic absorption method of chemical analysis, which revolutionized quantitative analysis in the 1950's and 1960's.

Atomic absorption provided a quick, easy, accurate and highly sensitive method of determining the concentrations of more than sixty-five of the elements, rendering traditional wet-chemical methods obsolete. The method has found important application world-wide in areas as diverse as medicine, agriculture, mineral exploration, metallurgy, food analysis, biochemistry and environmental control, and has been described as 'the most significant advance in chemical analysis' in the twentieth century.

"On a Sunday morning in March 1952 Walsh was working in the vegetable garden of his home in the Melbourne suburb of Brighton when he suddenly had a revealing flash of thought, something that stemmed from his earlier work in related fields. He hurried inside, dirt still on his shoes, and phoned his colleague, John Shelton. 'Look John!' he exulted. 'We've been measuring the wrong bloody thing! We should be measuring absorption, not emission!' John reminded him: 'We've been through that before – you can't work out the concentration of a sample from the absorption because of the emitted light at the same wavelength'. Walsh replied: 'I've thought of that. We'll use a chopper on the source and a tuned amplifier, so the light emitted from the sample won't matter.'

Early next morning Walsh set up a simple experiment, using the element sodium. By morning tea he had a successful result. 'I was very excited and called in my colleague, Dr. J. B. Willis, who at that time was working on infrared spectroscopy and later was to make important contributions to the atomic absorption method of chemical analysis. "Look", I shouted, "that's atomic absorption". His reply, which I have never let him forget, was "So what?" This was typical of the general reaction to my early work on atomic absorption'."