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Isotopic Tracers: Remember George de Hevesy

The largest controlled isotopic tracer test that I’ve ever heard of is underway out in Arizona, in the huge “Biosphere 2” greenhouses. They’re simulating a drought in the rainforest section and comparing the carbon flux under normal and dry conditions through the use of 13C-labeled carbon dioxide. A few weeks ago the sealed system (under normal watering conditions) got a pulse of the labeled gas, and samples have been taken to quantify its uptake in the soil and all the plant species.

Now the irrigation in the rainforest area has been shut off for six weeks, and at the end of the drought another pulse of labeled CO2 will go in. Comparison of the two labeling experiments should give a unique view of how such ecosystems handle stress and what the differences in carbon flux might be – people have tried such experiments with semi-enclosed conditions in the wild, but as I understand it those results are not definitive. There’s no other place to do such an experiment under controlled conditions, and this seems like exactly the sort of experiment that the facility is suited for.

Isotopic labeling of this sort will be familiar to many chemists and biologists. It’s a mainstay of mechanistic experiments in both fields, and it’s a technique that has only increased in power and importance as mass spectrometry equipment has improved. One thing mass spec has done is shift some work away from radioactive isotopes to “cold” ones, which also allows for some very ingenious molecular-weight-bar-coding setups as well. The very first isotopic label/tracer experiments, though, were done by George de Hevesy, who later won the chemistry Nobel for the work (technically the 1943 prize awarded in 1944, because 1943 itself was actually a “no award” year for the chemistry prize, strangely). The technique was a revelation; the idea that you could track actual specific sources of matter through both in vitro chemical reactions and living organisms had been only a fantasy.

de Hevesy himself noted this in his 1934 paper on his personal ingestion of deuterated water (a gift from Harold Urey and a very exotic substance indeed in 1934). Having tea one day with Henry Moseley while he worked at Manchester (1910-1913), the two of them speculated about tracking the water in the tea through its journey through the body, and de Hevesy was glad both to reduce the experiment to practice and to memorialize his old colleague. Moseley had volunteered in WWI, despite pleas not to, and died at Gallipoli in a tremendous loss to science – of course, the losses to the human race in general as a result of that war are too numerous to count, and it’s better not to even start totaling them up. de Hevesy himself was drafted into the Austro-Hungarian army, bodies from whose campaign in the Alps have been recently re-emerging as the glaciers retreat. de Hevesy could have been one of them, but he fortunately ended up doing technical work in a copper factory.

Another de Hevesy/Manchester story, which I hope is true, is that one of his very first practical experiments with radioactive tracers was to prove that his landlady there was recycling uneaten roast beef from her tenants’ plates back into midweek hash. He was also the guy who dissolved von Laue and Franck’s gold Nobel medals in aqua regia at the Bohr Institute to hide them during the German occupation of Denmark during the next war, the one that World War I and its aftermath opened the door for. de Hevesy himself (who was Jewish) made it over to Sweden in 1943, and after the war returned to his old lab and found the bottle of acid sitting on the same shelf where he’d left it. Famously, the gold was then precipitated out and the medals recast. A man to reckon with!


10 comments on “Isotopic Tracers: Remember George de Hevesy”

  1. Eugene says:

    The 1934 paper is behind a paywall. How much time has to pass before a paper such as this is freely available? I guess 85 years is not enough time. Maybe another century or two.

    1. NotAChemist says:

      95 years. In the US publications from 1924 come into the public domain on January 1st 2020.

      1. eyesoars says:

        Alas, thanks to Sonny Bono and because the Disney Corporation doesn’t want Mickey Mouse to enter the public domain, things copyrighted a few years after 1924 won’t be entering the public domain any time soon.

  2. Anon says:

    The people who work in the area of tracer studies revere Prof. George de Hevesy! A very practical solution to make use of isotopes.

  3. MrXYZ says:

    Actually, there is a larger isotopic tracer experiment: The Turin Isotopic Lead Experiment

    This occurred back in 1975, when gasoline was leaded. The isotopic ratio of the lead (206/207) added to gasoline was purposefully changed in the region of Turin, Italy and the change used to measure the flux of lead in the environment. Experiment lasted over about a decade.

    1. Derek Lowe says:

      Now that I did not know about!

  4. franko says:

    Re: 1943. As John LeCarre wrote, “I seem to recall there was an interlude around that time.”

  5. gippgig says:

    There was once an experiment that involved the release of C-13D4. As I recall, that isotope was so distinctive it could be detected worldwide.
    It should also be noted that isotopes weren’t the first use of a tracer. The fatty acid degradation pathway was worked out by using fatty acids labeled with a phenyl group at the end.

  6. Anonymous says:

    I’m also miffed that the 1934 Hevesy paper is not easily accessed. I think that self-experimentation has come up In The Pipeline before. One of my faves: “An Experiment in Human Vitamin A-Deficiency” by George [Nobel Prize] Wald and David Steven. PNAS, 1939, 344. “… The subject D. S. is 22 years of age, 5 feet and 10 1/2 inches in height and weighs 155 pounds. …” (D.S. was deprived of Vit A until visually compromised. Oral Vit A then restored normal vision.)

    While looking for access to the cited paper, I came across a few more Hevesy stories here:

    And just to mention … Biosphere 1 (or maybe it was just “Biosphere”) had some ethical lapses in the conduct of their research (sneaking in fresh air, extra food, etc.). I think that Nakanishi (CU Chem) was asked to help with Biosphere 2.

    1. dhodonov says:

      Are you sure you’re not confusing reality with a certain Pauly Shore movie?

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