Energy & Fuels 1990, 4 , 436-439
436
The computer algorithm calculates the coefficients of first- and second-degree polynominals for the analytical curve of the natural logarithm of the intensity versus the natural logarithm of the concentration. It evaluates the curve for an acceptable range, goodness of fit, and slope, and it suggests a working concentration range for the line with a lower limit defined by a signal-to-noise ratio of 2.
Results and Discussion For these premium coals, an in-depth study was made for specific interference corrections which were not automatically performed. Due to heterogeneity problems associated with Ba coupled with the suppression of the most sensitive analytical lines for Ba due to the matrices of these coals, values from less sensitive lines were used. The values for Sr were improved after adjustments were made for interferences from Fe and Ni. This semiquantitative approach achieves ranges and detectability comparable to those of the visual estimation pr~cedure.'~Since the standards used to not closely match the approximate composition of the samples to be analyzed, the expected accuracy is limited to *1 step, which corresponds to roughly +50% or -33%. (13) Myers, A. T.; Havens, R. G.; Dunton, P. J. In A Spectrochemical Method for the Semiquantitative Analysis of Rocks, Minerals, and Ores; US. Geologial Survey Bulletin 1084-1; USGS: Washington, DC, 1961; p 207.
In the analyses of these premium coals, NIST Standard Reference Materials 1633 and 1633a14 were included as control samples for evaluation of both precision and accuracy of this method. Table I1 lists the concentrations provided by NIST certificates, the mean concentrations determined over a 5-month period, and the associated relative standard deviations. Compositions determined for coal ashes are within the limits of precision and accuracy for which the method was designed. The high relative standard deviations for barium and zirconium indicate the heterogeneity documented for these reference materials.15 Heterogeneity possibly explains the large range of values for barium and zirconium in the premium coals as well as the interferences discussed above. Tables 111-V list data for all 62 elements in these eight Argonne Premium Coals. The < symbol indicates the lower limit for a value for that element, and a > symbol indicates the highest value determined for that element. An H denotes the occurrence of an unresolved interference. Major elements are reported in percent and the trace elements in ppm. (14) National Bureau of Standards, Certificates of Analysis, Standard Reference Materials 1633 and 1633a; Office of Standard Reference Materials, US. Department of Commerce: Washington, DC, 1975 and 1979. (15) Filby, R. H.; Mguyen, Son; Grimm, C. A,; Markowski, G. R.; Ekambaram, Vanaran; Tanaka, Tsuyoshi; Gossman, Lawrence. Anal. Chem. 1985, 57, 551.
Determination of Twenty-Nine Elements in Eight Argonne Premium Coal Samples by Instrumental Neutron Activation Analysis Curtis A. Palmer US.Geological Survey, Reston, Virginia 22092 Received April 9, 1990. Revised Manuscript Received July 19, 1990
Twenty-nine elements have been determined in triplicate splits of the eight Argonne National Laboratory Premium Coal Samples by instrumental neutron activtaion analysis. Data for control samples NBS 1633 (fly ash) and NBS 1632b are also reported. The factors that could lead to errors in analysis for these samples, such as spectral overlaps, low sensitivity, and interfering nuclear reactions, are discussed.
Introduction Instrumental neutron activation analysis (INAA) has been used for the determination of major, minor, and trace elements in thousands of coal and lignite samples by the United States Geological Survey'-5 and other laborator(1)Zubovic, P.; Oman, C. L.; Coleman, S. L.; Bragg, L. J.; Ken, P. T.; Kozev. K. M.: Simon. F. 0.: Rowe, J. J.; Medlin. J. H.: Walker. F. E. Chemical Analysis of 617 coal samples from the Eastern'United States. U S . Geol. Suru. 1979, ORF 70-665. (2) Zubovic, P.; Oman, C. L.; Bragg, L. J.; Coleman, S. L.; Rega, N. H.; Lemaster, M. E.; Golightly, D. W.; Puskas, J. Chemical Analysis of 659 coal samples from the Eastern United States. U.S. Geol. Sura 1980, ORF 80-2003.
ies.6-8 In addition, the application of INAA for the analysis of coal has been described in several papers.+'* Most other methods of trace element coal analyses require the coal sample to be ashed prior to analysis. The analysis (3) Oman, C. L.; Bragg, L. J.; Nook, H. M.; Schwarz, L. J.; Harris, J. L., Jr.; Rega, N. H.; Crowley, S. S. Chemical Analysis of 45 Maryland coal samples. U S . Geol. Sdru. 1981, OFR 81-1099. (4) Currens, J. C., Bragg, L. J., and Hower, J. C. Analysis of coal samples for the Princess District, Kentucky (Boyd, Carter, Greenup, and Lawrence Counties and part of Lewis County). Ky. Geol. Surv. Info.Circ. Series X I 1986, 18. (5) Currens, J. C.; Bragg, L. J.; Hower, J. C. Analysis of coal samples from the Hazard District, Kentucky (Breathitt, Knott, Leslie, and Perry Counties and parts of Letcher and Harlan Counties). Ky. Geol. Suru. Info. Circ. Series X I 1986, 19.
This article not subject to U S . Copyright. Published 1990 by the American Chemical Society
INAA of Argonne Premium Coal Samples ~~~
element Na
indicator radionuclide 24Ns
K
42K
sc Cr Fe
"SC 51Cr 5gFe
co
mco
Ni Zn As Se Br
MCO 66Zn
Rb
cs Ba La
@Rb Wr %b lZ4Sb 134cs 131Ba lroLa
Ce Nd Sm Eu
14'Ce l4INd lS3Sm la2Eu
Tb
l q b
Yb
lI5Yb
Lu Hf
177Lu lslHf
Ta
le2Ta
W
187W
Th
293Pa 239Np
Sr Sb
U
16As
I6Se 82Br
Energy & Fuels, Vol. 4, No. 5, 1990 437
T a b l e I. Radionuclides Used (Table Modified from Reference 14) limit of determn, PPm (ccg/g) potential spectral interferences preferred except % (cg/g) half-life y-energy as indicated radionuclide energy radionuclide 15.0 h 1368.9 10 2753.9 12.4 h 0.01% 1524.7 84 d 1120.5 0.01 27.8 d 1771u 321.3 141nd 0.5 320.1 45.6 d 1099.3 50 152ta 1289.1 1291.5 75 1173.2 5.3 yr 0.2 1332.5 71.3 d 10 152E~ 810.8 810.8 1 '60Tb 1115.1 245 d 1115.4 26.4 h 0.1 559.0 1 152ta 264.1 120.0 d 264.6 0.5 35.4 h 554.3 0.5 776.5 5 1076.8 18.7 d 50 64.0 d 514.0 67.2 h 0.05 564.0 1691.0 0.1 60.0 d 2.1 yr 0.1 795.8 12.0 d 50 476.3 0.02 40.2 h 1596.6 0.05 487.0 lSEu 145.6 32.5 d 0.5 145.4 11.1 d 2 531.0 23gNp 103.7 0.5 46.8 h 103.2 12.7 yr 0.04 779.1 1408.1 0.01 233Pa 299.9 72.1 d 0.05 298.6 0.1 1178.1 1r7nd 398.2 133Pa 101.0 h 0.1 396.1 0.2 282.6 23QNp 209.7 6.7 d 0.01 208.4 42.5 d 0.1 482.2 0.05 133.1 115.1 d 0.02 1221.3 0.03 1189.2 24.0 h 0.1 479.5 1r7nd 685.9 0.1 685.7 27.0 d 0.1 311.9 2.3 d 0.5 277.6
of coal by INAA is especially useful because determinations are made on the whole coal and, therefore, can be used to measure elements that might be volatilized during ashing, such as Br. In addition, INAA has very low detection limits for many elements, can be easily automated, and provides precise data for many major, minor, and trace elements.
Experimental Section T h r e e splits of approximately 500 mg of each of the eight Premium Coal Samples were weighed, as received, and heat sealed into 1.5-cm3 polyethylene vials. (Moisture contents were deter(6) Gluskoter, H. J.; Ruch, R. R.; Miller, W. G.; Cahill, R. A.; Dreher, G. B.; Kuhn, J. K. Trace elements in coal: occurrence and distribution. Ill. Geol. Suru. Circ. 1977, 499, 154 pages. (7) Foscolos, A. E.; Goodazzi, F.; Koukouzas, C. N.; Hadziyanris. Chem. Geol. 1989, 76,107-130. (8) Eskengzy, G. M. Int. J. Coal Ceol. 1987, 7,301-314. (9) Block, C.; Dams, R. Anal. Chem. Acta 1973,68 (l), 11-24. (10) Gladney, F. S.; O'Malley, B. T.; Roelandts, I.; Gillis, T. E.
Standard Reference Materials compilation of elemental concentration data for NBS clinical, biological, geological and environmental Standard Reference Materials. NBS Spec. Publ. 1987,260-111,1631-1-1633A-14. (11) Rowe, J. J.; Steinnes, E. Talanta 1977, 24, 433-439. (12) Rowe, J. J.; Steinnes, E. J. Radioanal. Chem. 1977, 37 (2), 849-856. (13) Swaine, D. J. Modern methods in bituminous coal analysis: Trace elements. Crit. Reu. Anal. Chem. 1985, 15 (4), 315-346. (14) Palmer, C. A.; Baedecker, P. A. Methods for sampling and inorganic analysis of coals. In Golightly, D. W., Simon, F. O., Us.; US.Ceol. SUW. Bull. 1989, 1823, 27-34.
energy
319.4
398.2
mined on separate splits). These samples were irradiated for 8 h in t h e TRIGA research reactor facility of t h e U.S. Geological Survey in Denver, CO. After a delay of 3 days t o eliminate or reduce short-lived activity, the samples were shipped by ovemight delivery t o our counting laboratories in Reston, VA. T h e samples were counted at three different times on highresolution coaxial Ge and Ge(Li) detectors for y-ray spectroscopy. T h e first count was started 4 days after irradiation, as soon as the samples were received. A second count was started a t 17 days after irradiation to allow t h e elements with half-lives less t h a n 70 h (especially Na, tIl2= 15 h) to decay, and then a third count was begun approximately 2 months after irradiation. T h e y-ray detectors were coupled to multichannel pulse-height analyzers that are capable of dividing the spectrum into 4096 energy increments or channels. An automatic sample changer similar to that described by Massoni and others15was used. All spectra were processed by using the computer program SPECTRA.^^ T h e half-lives, y-ray lines, detection limits, and potential interferences for the indicator radionuclides of the elements determined in this study are given in Table I.
Samples and Standards The eight Argonne National Laboratory Premium Coal Samples analyzed have been described previously." Three (15) Massoni, C. J.; Fones, R. V.; Simon, F. 0. Rev. Sci. Instrum. 1973, 44 (9), 1340-1352.
(16) Baedecker, P. A.; Grossman, J. N. The computer analysis of high resolution gamma-ray spectra from instrumental neutron activation analysis experiments. U.S.Geol. Suru. 1989, OFR 89-454, 54.
438 Energy & Fuels, Vol. 4, No. 5, 1990 Table 11. Comparison of Concentrations Determined ( a g / g ) from This Work with Literature Valuesn 1632B 1633 element controlb lit: controlb lit.d 3060 f 64 3130 f 200 513 f 5 515 f 11 Na 748 f 28 K 16000 f 640 16900 f 900 740 f 37 2.060 f 0.02 1.9 27.3 f 0.27 26 f 3 sc 10.4 f 0.3 11 Cr 113.4 f 8.6 127 f 10.6 7590 f 450 62600 f 630 61600 f 2100 7780 f 160 Fe 2.33 f 0.04 2.29 f 0.17 41.5 f 1.2 co 40.8 f 2.0 8.1 f 2 6.1 f 0.27 Ni 92 f 10 98 f 6 11.89 f 0.78 11.7 f 1.4 183 f 9.5 210 f 20 Zn 3.80 f 0.11 3.73 f 0.09 61.0 f 4 As 56.0 f 1.6 1.29 f 0.11 1.24 f 0.10 9.6 f 0.6 9.0 f 0.54 Se 21.3 f 1.1 17 8.4 f 2.2 Br 6.5 f 0.32 5.05 f 0.11 4.2 f 0.76 102 f 6.3 115 f 8 Rb 97 f 5.8 102 1380 f 100 Sr 1340 f 67 6.8 f 0.7 0.259 f 0.01 0.24 6.61 f 0.2 Sb 0.414 f 0.012 0.44 cs 7.76 f 0.23 8.6 f 0.6 67.5 f 2.1 69 f 2.8 2450 f 74 2665 f 160 Ba 4.80 f 0.01 5.1 79 f 5 La 80.4 f 1.6 9.19 f 0.18 9 139.3 f 2.7 144 f 10 Ce
