absorptivities and equations to routine analytical samples. MATRIX METHOD. In cases where several species contribute to the absorb ance at an analytically important wave length or if effects of base line shift and slope require correction, only the threewave length method discussed is adequate. The advantages and techniques of matrix methods have been described (1, 9). The evaluation of the constants for the equations relating absorbance a t the selected wave lengths to the concentration of each of the actinides is required. With these constants determined, the equations for the absorbance a t each of the selected wave lengths are written in the form : A I = K&l+ KdA
+ . . . + KnC. + a + b h
Solving this set of rn equations (m > n) gives an expression for the concentration of each species as well as for the base line shift, a, and the base line slope,
b.
to 1.2% and for plutonium from 1.5 to 1.0%, expressed in concentration units. As stated in the ratio method, further data should be obtained before applying the stated absorptivities and the resulting concentration equations to routine analytical samples. Analysis of Other Actinide Mixtures. Examination of the spectra presented in Figure 1 indicntes the following possibilities for analyzing other binary actinide mixtures and the ternary mixture. NEPTUNIUM-PLUTONIUM. Plutonium can be determined almost free of neptunium effects a t the 806-mp peak, especially if a two-wave length technique is used. (Sensitivity is about half that of the 502-mp peak.) For neptunium, the same technique as used for uraniumplutonium mixtures appears applicable with the 448-mfi neptunium peak. URANIUM-NEPTUNIUM. The determination of neptunium appears straighb forward by using a peak where uranium contributes no absorbance. The 564-mp peak is a logical choice. The determination of uranium is more difficult because of overlapping spectra. The 467-mp uranium peak seems best separated. Correction for neptunium absorbance would be required.
cant absorbance above 480 mp; thus, the plutonium determination is not affected. Chromium, which is oxidized to dichromate, extracts to a high aegree. The absorbance continuously increases with decreasing wave length. The determination of plutonium may be made using the 806-mp peak by a twoor threewave length procedure. The change in absorbance with wave length in this region is not significant even with 0.15 mmole of added chromium. T o analyze uranium-plutonium mixtures containing these elements, the matrix method is recommended. Fission Product Distribution. Data showing the distribution of fission product activity in this extraction Bystem with potassium permanganate as oxidant have been presented for 1month and 1.5-year cooled samples (6). Use of silver(I1) oxide does not change these distributions significantly. A decontamination factor of at least 100 was obtained for all nuclides. LITERATURE CITED
(1) Barnett, H. A., Bsrtoli, A., ANAL. Using the uranium and plutonium CHEM.32, 1153 (1960). data from this study, four absorbance (2) Baumann, R. P., Appl. Spectroscopy equations may be written in the follow13. 156 (1959). -, (3)Berkmxn M. G., Kaplan, Louie, ing matrix notation: U. S. At. hnergy Comm., Rept. ANL4573 (1951). (4) Maeck, W.J. Booman, G. I,., Elliott, Mg.u 0.00089f 0.0002 0.00649f 0.00015 1 10 M. C., Rein, E., ANAL. CHEM.30, Asia 0.0007 1 0.00044f0.0002 0.0085 A w1 1902 (1958). (6)Zbid., 31,1130 (1959). 0.00390f O.ooOo8 0.00927f 0.00016 1 1 (6) Maeck, W.J., Booman, G. L., Kussy, A ab 0.01005 f 0.00015 1 0 0.0333 f 0.0003 Atu M. E.. Rein. J. E..Ibid.,. 32.. 1874 (1960).' (7) Meta, C. F.,Zbid., 29, 1748 (1957). (8)Seils, C. A., Larsen, R. P., Meyer, URANIUMNEPTUNIUM - PLUTONIUM. R. J., 4th Conf. on Anal tical ChemThe precision of each of the absorpistry in Remtor TechnoLgy, GatlinOnly plutonium can be accurately detertivities is an estimate of one standard burg, Tenn., 1960. mined by using the 806-mfi peak. deviation. The four wave lengths were
5.
*
-
approximated by the series 0, 1, 7, and 10 to simplify the calculations. Expressions for the amount of uranium and plutonium in the sample as a function of the absorbance at the four selected wave lengths were: Mg. Uranium = +4.012 Aslo 0.2662 Am - 38.25Atso 34.50 Atsr
+
+
Mg. Plutonium = -10.84 Art$ 16.36Am - 6.15 Adso 0.6334Acsr
+
Figure 3 shows the position of these four wave lengths on a spectral recording of a uranium-plutonium mixture. These equations completely remove any absorbance contribution equivalent t o a base line shift or slope. Calculation in this manner is a perfectly general approach to improving any data of similar form and will have maximum usefulness where sharp absorption bands or their analogs are available. Using these derived equations, data from the mixtures in Table I11 were recalculated, with a resulting reduction in the coefficient of variation for uranium from 2.9
Multi-wave length measurements would be necessary to determine uranium and neptunium. Effects of Diverse Ions. The effects of 25 cations and 21 anions upon the extraction and determination of milligram levels of uranium with the same system, except for the oxidation step, have been studied (6). Only thorium and cerium interfered by combining with the tetraalkylamine to form a nonabsorbing thorium complex and a slightly absorbing cerium complex. This interference waa overcome b j using higher concentrations of the amine. No common anions interfered. The effect of the oxidation step becomes significant if some ion is oxidized to an oxidation state which extracts and spectrally interferes or if a precipitate forms that carries plutonium. Of the cations and anions previously investigated for uranium, chromium, cerium, and chloride were considered to merit further study. The effect of chloride has already been discussed in a previous section of this paper. With the silver(I1) oxide procedure, 0.25 mmole of cerium showed no signifi-
RECEIVEDfor review January 19, 1961. Accepted March 22,1961.
Correction Spectrochemical Determination of Boron in Saline Waters In this article by R. C. Reynolds, Jr., and John Wilson [ANAL. CHEM.33, 247 (1961)], the following corrections should be noted : Page 248, Table 11: The heading of the first column, which reads 2898 and 2894, should read 2498 and 2494; the symbol u should read S; 0.021/0.759 X 100 should be changed to (0.0211 0.759) X 100. Page 249, column 2, lines 9 and 11, salinity units should be given as 700, and not %OO. In column 3, the received date should be August 4, 1960 and the accepted date should be October 25, 1960. VOL. 33,
NO. 8, JULY 1961
1001
