Sir Alan Walsh with a commercial model of the atomic absorption spectrophotometer, which is regarded as one of the most important aids to chemical analysis developed this century. Image Credit: Coutresy CSIRO

Australian inventors: Alan Walsh redefines chemical analysis

  • BY Lynda DeLacey |
  • August 06, 2015

From a eureka moment in the garden to an Australian innovation that launched a multi-million dollar industry

IN 1952, AN UNASSUMING Australian scientist was working in his garden when an idea came to him that would become one of the 20th century's most significant advancements in chemistry.

Prior to CSIRO scientist Alan Walsh's discovery, science was limited in the way trace elements could be detected in a compound. This impacted many fields of research, and industries from farming to health-care and mining.

For over 100 years, the most widely-used method of chemical analysis was based on measuring light emitted by atoms in a heated sample. This method - atomic emission spectroscopy - could only identify seven or eight elements.

Reinventing chemistry techniques

Walsh worked in the field of spectroscopy for many years before his breakthrough discovery. Born in 1916, he graduated from the University of Manchester with a BSc in physics in 1937. He spent the war years working on the analysis of metals, identifying elements used in enemy weapons, which showed how the German war effort was progressing. His methods also helped improve manufacturing for the British war effort.

In 1976, Walsh wrote: "By the end of the war I think there was a general feeling of satisfaction, and perhaps even a state of euphoria, regarding the development of spectrochemistry. I believe few workers shared my strong conviction, which I frequently expressed, that further progress would require a completely new line of attack. I tried desperately hard to conceive totally different approaches but came to a total impasse..."

In 1946, Walsh was appointed to the CSIR Division of Industrial Chemistry in Melbourne, Australia. He began working on infrared molecular absorption spectroscopy and atomic emission spectroscopy.

Alan Walsh's eureka moment in the garden

It seems that Walsh had been mulling over the idea of measuring atomic absorption, rather than emission, since World War II. But his eureka moment came one Sunday morning in his garden in 1952. With the dirt still on his shoes, he rang his colleague, John Shelton: "Look, John!" he exclaimed. "We've been measuring the wrong bloody thing!"

By the next morning, Walsh had constructed a prototype and, using sodium as his trial element, sent a beam of light through a vaporised sample. Because each element absorbs light of a specific frequency, he could then measure the resulting light to gain extremely accurate measurements of the elements in the sample. The new method could measure 65 distinct elements - a huge advancement in the field of chemistry.

From 1955 to 1957 Walsh and his team produced research papers to spread the word about atomic absorption spectrometry. Unfortunately, the discovery was met with almost universal indifference. Convincing the world of the importance of his discovery was an uphill battle for years to come.

"It was only because, really, of the cold shoulder treatment we were given that we got a bit mad and got involved in proving a point. So if the world had reacted differently, we might have come out of this with nothing," said Walsh in an interview in 1970.

Innovation of atomic absorption spectrometry takes off

By 1958, a few Australian labs had expressed interested in trying the technique, but nobody was prepared to manufacture the device. In a project he dubbed Operation Backyard, Walsh arranged for three small manufacturers to make separate parts and deliver do-it-yourself kits to the labs.

The instrument immediately proved to be a life-saver. A young boy suffering severe burns was brought to a Sydney hospital. He suffered terrible convulsions and no one understood why - until an atomic absorption spectrometer revealed that the magnesium levels in his blood were dangerously low. The boy was saved - and his photograph always had a special place in Walsh's office.

Other early successes included identifying mercury pollution in a fishery in Japan, revealing widespread lead poisoning in the town of Sudbury, Ontario, and finding huge mineral deposits in WA.

In 1962, one of the initial three small manufacturers, Melbourne's Techtron Proprietary Limited, began marketing a complete atomic absorption spectrometer. The market quickly expanded into a global industry.

Today, atomic absorption spectrometers are used every day by chemists and scientists in laboratories, hospitals and factories worldwide. The commercialisation of Walsh's breakthrough is said to have been the birth of Australia's multi-million dollar scientific instrument industry.

Walsh received honours, medals and awards from scientific and educational institutions all over the world, including a knighthood in 1977. He died in Melbourne on 3 August 1998, aged 81.