constant to fission cross section ratios and possible misidentification of the isotopes present. In these rare cases other information (the Ala ratio from an epicadmium neutron irradiation or perhaps an a particle energy spectrum) would be required. Compared to conventional chemical methods, track detector autoradiography is rapid and inexpensive. The present method has been shown to provide data on isotopic identity as well as size characteristics for airborne actinides.
ACKNOWLEDGMENT The authors are grateful to Kurt Jackson for experimental assistance during the early stages of this work. Cooperative scheduling of irradiations by W. E. Wilson and the crew of the WSU reactor are appreciated. We thank John Sheppard and Claude Sill for helpful comments on the manuscript.
(3) W. J. Bair and R. C. Thompson, Science 183, 715 (1974). (4) A. R. Tamplin and T. B. Cochran, National Resources Defense Council Report, Washington, D.C., February 1974. (5) W. J. Bair, C. R. Richmond, and 5 . W. Wachholz, WASH-1320, USAEC, September 1974. (6) J. W. Healy, Los Alamos Report LA 5483-MS, 1974. (7) C. W. Sill and R. L. Williams, Anal. Chem., 41, 1624 (1969). (8) N. A. Talvitie, Anal. Chem., 43, 1827 (1971). (9) R. J. Budnitz, Report LBL-2039, Lawrence Berkeley Laboratory, 1973. ( I O ) R. L. Fleischer, P. B. Price, and Robert M. Walker, "Nuclear Tracks in Solids: Principles and Applications", University of California Press, Berkeley, Calif., 1975. (11) B. S.Carpenter, Anal. Chem., 44, 600 (1972). (12) G. Baroni, S. DiLiberto, S. Petreva, G. Romano. and C. Sgarbi, Nota interna, No. 458, lstituto di Fisica G. Marconi. Rome, 1973. (13) J. H.Hayden, unpublished data. (14) B. Center, thesis, Washington State University, Pullman, Wash., 1975. 115) R A Gussman. A. M. Sacco. and R . E. Ladd. umublished data Dresented at the 65th Annual Meeting of the Air Pollution Control Association, Miami, Fla. 1972. (16) L.-Proud, T. Hardt, J. Sheppard, B. Center, and F. H. Ruddy, unpublished data. 1
- I
LITERATURE CITED
RECEIVEDfor review May 3, 1976. Accepted September 7,
(1) R. Gillette, Science, 185, 1027 (1974). (2) R. Giliete, Science, 185, 1140 (1974).
1976.
Nondestructive Determination of Boron and Cadmium in Environmental Materials by Thermal Neutron-Prompt y-ray Spectrometry Ernest S. Gladney," Edward 1.Jurney, and David B. Curtis University of California, Los Alamos Scientific Laboratory, P.0. Box 1663, Los Alamos, N.M. 87545
Prompt y rays from thermal neutron induced nuclear reactions have been used to measure trace quantities of B and Cd in industrial and standard materials. The technique provides a rapid nondestructlve analysis for >0.05 pg of B. Repetitive analyses show the method to have a precision of 5 % . The presence of large quantities of Na degrades the accuracy and precision of the B analysis. The technique also provides a method for the determinationof Cd although it Is not sufflciently sensitive to provide a practical alternative to more conventional methods.
Boron is commercially important as a metallurgical additive, agriculturally significant as a component of fertilizers, and commonly used in the home for laundry and cleaning purposes. Boron is an important element in plant metabolism. The tolerance range between deficiency and toxicity is rather narrow for many agriculturally essential plants ( I , 2 ) . Discharge of B in waste water or in ash from large industrial processes could have important consequences for biotic activity in areas subjected to these waste products. Geochemical interest in B centers around the complexing abilities of clay minerals and studies of the paleoclimate and erosion (3-5). The geochemistry of B and the element's impact on the environment have not been widely studied owing to the relative difficulty of the available analytical procedures. A variety of procedures have been developed, most of them requiring sample dissolution. Several colorimetric methods utilizing curcumin (6-8), carminic acid (9),methylene blue (IO),and 1,l'-dianthrimide ( 1 1 ) have been reported. Some of these complexing agents have also been used for extraction of B into organic solvents and measurement by flame emission (12,13) or flame atomic absorption (8). Direct atomic absorption
(14-16) has a wide appeal because of the availability of the instrumentation; however, flame sensitivity is only 20-30 ppm ( I 7) and carbide formation renders the flameless approach useless. The feasibility of an indirect determination of B by flameless atomic absorption has been demonstrated using solvent extraction as (1,lO-phenanthroline) cadmium tetrafluoroborate to isolate the B and subsequent analysis of Cd, for which flameless atomic absorption is very sensitive (18). Several metal ions pose serious interferences to the application of this innovative technique to environmental samples. A very sensitive application of hollow cathode emission to B analysis has been reported (19),but this procedure suffers from severe instabilities in the cathode emission which make accurate work difficult. The determination of B as tetrafluoroborate by specific ion electrode is finding increasing application, but careful attention to interfering ions and masking agents is required, especially in silicate matrices (20). Recently the use of an ion microprobe mass spectrometer for the determination of B in steels was reported (21). Boron-10 has an exceptionally large cross section for thermal neutron capture (3840 barns) which has been exploited for analytical purposes. Neutron transmission has been investigated for analysis of B (22);however, the presence of elements with large thermal neutron cross sections (Cd, Gd) can seriously impair the usefulness of this method. Perhaps the best known nuclear technique involves counting a particles, emitted from the reaction lOB(n,~x)~Li, using a suitable plastic track detector (23). The a-track technique is a surface analysis, with the effective depth of analysis being restricted by the range of the LY particle. The work described in this paper explores the analytical capabilities of neutron capture prompt y rays for the determination of trace quantities of B and Cd in natural and in-
ANALYTICAL CHEMISTRY,
VOL. 48, NO. 14,DECEMBER 1976
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2139
Table I. Boron Content of Standard Materials, ppm No. of analyses 3 3 3 10 10 10
B std 358 f 15 2.6 f 1.5 1.2 f 0.2 24.8 f 1.4 102 f 13 32.8 f 2.3
H std 348 f 20 2.5 f 1.7 1.3 f 0.1 25.1 f 2.1 103 f 10 25.2 f 2.4a
Au std 363 f 17 2.9 f 1.5 1.2 f 0.2 25.0 f 1.4 104 f 13 33.3 f 2.3
10
47.0 f 1.6
47.7 f 1.8
47.7 f 1.6
Coal Fly Ash
10
490 f 14
492 f 13
497 f 14
Andesite Basalt Granodiorite Granite
1 1 1 1
Sample SRM-610 SRM-614 SRM-1093 SRM-1262 SRM-1264 SRM-1571
Material Glass Glass Steel Steel Steel Orchard Leaves
SRM-1632
Coal
SRM-1633 AGV-1 BCR-1 GSP-1 G-2
3.9 f 0.8 0.7 f 0.4 0.08 f 0.06 3.9 f 0.7
Other work 351' 1.3 f 0.2c 1.28 (28) 25 ll0C 33c 40 f 0.3 (28) 30 f 1.1(29) 43 (30) 434 f 9 (28) 500 f 29 (29) 5 b (31) 5b (31)
