CZECH PHYSICAL CHEMIST
Jaroslav Heyrovský was born on November 20, 1890, in Prague (then part of the Austro-Hungarian Empire), where he also died on March 27, 1967. He began studying chemistry and physics at Prague University in 1909. Between 1910 and 1914 he studied at University College in London under William Ramsay and Frederick G. Donnan, where he earned a B.Sc. degree in 1913. Following war service in a military hospital during World War I, he earned a Ph.D. degree in Prague in 1918 and a D.Sc. degree in London in 1921. In 1922 Heyrovský was promoted to full professor and head of the Institute of Physical Chemistry at Charles University (in Prague); and in 1950 he became director of the Polarographic Institute of the Czechoslovak Academy of Sciences.
Heyrovský was the discoverer of polarography and the inventor of the polarograph, an instrument that analyzes the composition of solutions electrochemically. His discovery of polarography was a culmination of the work of other scientists in electrochemistry. Other scientists' investigations of electrolysis had demonstrated the dependence of the intensity of a current flowing through a saline solution on the voltage applied to electrodes immersed in the solution. They found that at certain voltages, currents began to flow and metals were deposited on the electrodes.
The second line of research that led to polarography was the investigation of the interface tension between mercury and saline solutions. Gabriel Lippmann (1845–1921) found that increasing the voltage applied to mercury in contact with a surrounding saline solution changed the mercury's surface tension in a characteristic manner, which he was able to represent as a parabolic curve called an electrocapillary parabola. Professor Bohumil Kucčera (1874–1921), Heyrovský's teacher in Prague, made a similar investigation, for which he used a mercury-dropping electrode. The electrode consisted of a capillary tube from which mercury dripped into the solution. Kucčera witnessed deviations in the shapes of the curves as he varied the voltages, and proposed that Heyrovský investigate the phenomenon.
Heyrovský in effect combined the investigations of electrolysis and electrocapillary parabolas. In 1922 Heyrovský constructed an electrical circuit whose voltage from a battery was applied through a Kohlrausch drum to a mercury-dropping electrode immersed in a saline solution. The electrical potential of this electrode was then changed incrementally from 0 to 2 volts. A layer of mercury on the bottom of the vessel served as the second electrode. A mirror galvanometer would then detect a current flowing through this circuit, and the values of current intensity would be plotted point by point (by hand) as a function of the applied voltage. As the dissolved ions reacted electrochemically with the mercury-dropping electrode, curves with characteristic steps (polarographic waves) at certain voltage values were obtained. The identity of the ion present in the solution was determined by the voltage (expressed in electrochemical potential) at half of the height of the polarographic wave (so-called half-wave potential). The intensity of the current, represented in the graph as the height of the polarographic wave, was found to be directly proportional to the concentration of the ion.
Heyrovský's method, later called polarography, became an excellent analytical tool because it yielded qualitative and quantitative analyses of a solution in a single experiment. With Masuzo Shikata (1895–1964), Heyrovský constructed the first polarograph, an instrument equipped with an electromotor that moved the Kohlrausch drum in accord with photographic paper rotating in a cylindrical cassette. It allowed the potential of the mercury-dropping
electrode to change continuously. Light from the mirror galvanometer entered the cassette through a narrow slit (requiring these experiments to be performed in darkness). A continuous polarographic curve appeared upon the development of the photographic paper.
The polarograph was the first fully automatic instrument used in chemistry. For decades polarography was the only precise method for the analysis of inorganic and organic compounds in solution. Polarographic analyses of human blood serum served as a tool for diagnosing cancer during the 1940s and 1950s. Modern polarographs equipped with computers use advanced techniques such as oscillopolarography and square-wave polarography. In 1959 Heyrovský was awarded the Nobel Prize in chemistry "for his discovery and development of the polarographic method of analysis."
Butler, John A. V., and Zuman, Petr (1967). "Jaroslav Heyrovský (1890–1967)." In Biographical Memoirs of Fellows of the Royal Society, Vol. 13. London: Royal Society.
Heyrovský, Jaroslav (1941). Polarographie. Vienna: Springer Verlag.
Heyrovský, Jaroslav, and Kůta, Jaroslav (1965). Principles of Polarography. Prague: Publishing House of the Czechoslovak Academy of Sciences.
Ihde, Aaron J. (1984). The Development of Modern Chemistry. New York: Dover.
Nobel e-Museum. "The Nobel Prize in Chemistry, 1959." Available from http://www.nobel.se/chemistry/laureates/1959/ .