A method is described for the determination of the percentage of Hg-202 present in small samples of mercury. An electrodeless discharge tube containing Hg-202 is used as a source of the Hg-202 hyperfine component of the 2537-A resonance line of mercury. By determining the absorbance of this component by mercury vapor, the quantity of the isotope present in the vapor can be determined. The analyses of samples of mercury containing various percentages of Hg-202 agree with values obtained by mass spectrometric methods to within two percent. The method has the advantage over the mass spectrometer of requiring very much smaller samples. Furthermore, contamination from “hangup” of previous samples is avoided. Through the use of other isotopic sources it is shown that the method could be extended to the analysis of the remaining isotopes of mercury.
K. R. OSBORN and H. E. GUNNING, "Determination of Hg202 and Other Mercury Isotopes in Samples of Mercury Vapor by Mercury Resonance Radiation Absorbiometry," J. Opt. Soc. Am. 45, 552-555 (1955)