which also predicts intersection of all tangents in a graph as discussed in one point. This correlation would predict the In Kj values with a mean squared error of 0.0089, which corresponds to a standard deviation of 10%in K. The possibility of using a unit vector for the solutes (1or a constant for all solutes, as occurs in the second term of Equations'7 and 10) or of using some measurable parameter can be very elegantly tested by the procedures discussed by Weiner et al. ( 4 - 6 ) . I t seems, however, that for meaningful investigations on this point, more extensive data sets, having both a larger range in character of phase systems and of solutes, should be used. Therefore a discussion on rotation of vectors to measurable parameters, or to unit vector (which, as is pointed out in Reference ( l ) , might be identified with the molar volumes) was not carried out in the paper in which the steroid partition coefficients were presented.
LITERATURE CITED (1) P. Menheere, C. Devillez. C. Eon, and G. Guiochon. Anal. Chem., 46, 1375 (1974). (2) J. F. K. Huber, E. T. Alderlieste, H. Harren, and H. Poppe. Anal. Chem., 45, 1337 (1973). (3) P. Whittle, Skand. Aktwrietidskrift, 35, 223 (1952). (4) P. H. Weiner. E. R. Malinowsky, and A. R. Levinstone, J. phys. Chem., 74, 4537 (1970). (5) P. H. Weiner and D. G. Howery, Can. J. Cbem., 50, 448 (1972). (6) P. H. Weiner and D. G. Howery, Anal. Cbem., 44, 1189 (1972).
H.Poppe Laboratory for Analytical Chemistry University of Amsterdam Nieuwe Achtergracht 166 Amsterdam, The Netherlands
RECEIVEDfor review February 3, 1975. Accepted February 21, 1975.
Loss of Osmium during Fusion of Geological Materials Sir: The recent paper by Nadkarni and Morrison ( I ) describes a procedure by which the noble metals can be determined in geological materials. In this method, thermal-neutron activation is used to produce the radioactive isotopes of interest. Following irradiation, the geological matrix is destroyed by fusion with Na202 and NaOH. The noble metals ,are separated from the gross radioactivity by adsorption on an ion-exchange resin (2) selective for the noble metal ds electronic configuration. The resin is then analyzed by gamma-ray spectrometric techniques to determine the amounts of noble metals present. In the course of examining this procedure, we have found that osmium is not quantitatively determined as had been implied by the authors (1).In fact, about half of the osmium in the sample can be routinely lost, and no acknowledgment of this fact has been incorporated into the procedure. We have used the radioactive tracer 15.3-d lglOs and appropriate Ge(Li) gamma-ray spectrometric equipment to study the radiochemical procedure outlined by the authors (1). Osmium losses were determined by comparing tracer fusion samples with appropriate unfused tracer standards. Mechanical losses were monitored with nonvolatilizing noble metal radioactive tracers. Osmium tracer, and presumably osmium standard, tend to oxidize to the volatile and poisonous tetroxide Os04 during the fusionldissolution step. During the fusion alone, approximately 5% of the osmium was routinely volatilized. Fusion temperature and duration appear to be important factors here. Upon dissolution of the melt with HzO and dilute HC1, the amount of osmium volatilized ranged from about 5% to as much as ~ 3 0 % The . most serious losses, however, were encountered when the dissolved melt was boiled with addition of "03 to destroy the peroxide. From ~ 3 0 % to as much as =95% of the remaining osmium was volatilized at this point. The losses are related to the duration of boiling and appear to be independent of the addition of HN03. By standardizing the fusion/dissolution step, we have observed total osmium volatilization losses around 60% with a relative standard deviation of no better than ~ 0 . 1 These . losses are compatible with chemical yield data observed for similar fusion techniques ( 3 , 4 ) . It is not known whether during fusion the percent losses of radioactive tracer osmium (and standard osmium) are different from percent losses of geologically bound osmium. This is obviously a subject of needed study. Notwithstand1484
ANALYTICAL CHEMISTRY, VOL. 47. NO. 8, JULY 1975
ing, our data indicate that tracer volatilization losses during fusion per se are
