ANALYTICAL CHEMISTRY, VOL. 51, NO. 9, AUGUST 1979
Table VII. Sb 287.8-nm Signals Found for Various Amounts of Sb. Excitation Buffer 2 . 5 f i g Bi t 2.5 p g Cs as Iodides. Filler Gas H, Sb,Pg signal I I I/pgSb 0 0; 0 0 40 31; 2 6 ; 34 30 0.75 80 5 2 ; 5 2 ; 54 53 0.66 160 1 2 1 ; 1 0 5 ; 115 115 0.72 310 227; 229; 225 227 0.73 625 393; 378; 413 395 0.63 1250 803; 779; 826 802 0.64 Table VIII. Natural Sb Contents of 34 Preselected Blood Samples frequency contents, ng/mL 0.0-0.5 0.6-1.0 1 .l-1.5
5x 9x 1lX
1.6-2.0
3x
2.1-2.5 2.9 5.3
4x 1x I X
for sample VII. For this sample 0.15 ng/mL is found. T o determine the natural Sb content of human blood, we pooled blood samples of healthy people to give a reference blood sample. This reference sample was divided into several 1.5-mL portions. The signal from the natural S b content of human blood was measured for the reference sample. T h e same determinations were made with 1.5-mL portions of the reference blood sample spiked with 0.1, 1,and 5 ng/mL Sb, respectively. For the reextraction 5 mL of reextraction phase was used in all determinations giving a dilution in respect to the 1.5-mL blood sample of 5/1.5 times. T h e S b content of the reference blood sample was determined in two ways: (1) By plotting graphically as usual with the standard addition method. (2) By calculation using the data given in Table VII, analog to the T e determination. By both methods a Sb content of 1 ng/mL for the reference blood sample was found. Finally the S b content of 34 selected blood samples (the P b content already determined by flameless AAS) was determined. T h e samples were taken from people that might have been exposed to high lead concentrations. The sample volumes available were varying from 0.5 to 1.3 mL, giving after
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reextraction with 5 mL of reextraction phase, dilution factors of 10.0 to 3.8. Before and after each three measurements a blank was run, meaning a complete experiment except for the dried blood in the asher. For each run of three determinations, the mean of the blanks measured just before and after the run were taken into account. The recovery was checked eight times, a t regular intervals, during the 34 analyses. This was done by standard addition to the reference blood sample of 1.0 ng Sb/mL. T h e mean value of these eight recovery experiments (40.5%; RSD = 15%) was taken into account for each of the blood samples. The RSD for the measurement of the 34 blood samples may be expected to be in the same order of magnitude as the RSD of the eight recovery experiments, i.e. 15%. Sample B24A, sample volume 1mL, is taken as an example for the concentration calculation. An S b signal of 22 scale divisions is found. The mean of the blanks measured before and after the sample run of 7 scale divisions gives a net signal for sample B24A of 22 - 7 = 15 scale divisions. This net signal corresponds with 20 pg of Sb (see Table VII) introduced with 100 pL of reextract phase into the EDL. With 40.5% overall recovery and a dilution factor of 5, the S b content of blood sample B24A is 5 x 20 x 100/40.5 = 247 pg of Sb/100 pL or 2.5 ng of S b / m L of blood. The results of the determinations are summarized in Table
VIII. ACKNOWLEDGMENT The authors thank R. F. M. Herber, Amsterdam, for supplying the blood samples for the determination of S b and for the P b values of these samples.
LITERATURE CITED (1) Picogram analyse door spectrale emissie vanuit een gesloten atoomreservoir, A. van Sandwijk. Ph.D. Thesis, Rijksuniversiteit Utrecht, April 1974. (2) A. van Sandwijk, P. F. E. van Montfort, and J. Agterdenbos, Talanta, 20, 495 (1973). (3) A. van Sandwijk and J. Agterdenbos, Talanta, 21, 360 (1974). (4) P. F. E. van Montfort and J. Agterdenbos, Talanla, 21, 660 (1974). (5) P. F. E. van Monttort, J. Agterdenbos, R . Denissen, M. Piet, and A. van Sandwijk, Spectrochim. Acta, Part B . , 33, 47 (1978). (6) H. Bode and F. Neumann, Fresenius' 2 . Anal. Chem., 169, 410 (1959). (7) G.Kaiser, P. Tschopel, and G. Tolg, Fresenius' Z. Anal. Chem., 253, 177 (1971). (8) B. A. H. G. Jiitte and J. Agterdenbos. Spectrochim. Acta, Part 8,in press. (9) P. F. Wyatt, Analyst (London), 80, 368 (1955).
RECEIVED for review January 29,1979. Accepted May 15,1979.
Elemental Concentrations in the United States Geological Survey's Geochemical Exploration Reference Samples -A Review Ernest S. Gladney," Daniel R. Perrin, James W. Owens, and Daryl Knab University of California, Los Alamos Scientific Laboratory P.O. Box 1663, Los Alamos, New Mexico 87545
Silicate standard reference materials have been largely depleted. The function and value of these materials and the adequacy of several certification processes is examined. Concentrations of 42 elements measured at this laboratory are presented along with the available comparative data.
Internationally recognized standard reference materials provide an invaluable means for comparing data among widely separated laboratories. Furthermore, they provide a method to compare the quality, accuracy. and precision of data derived from a variety of analytical techniques, all of which purport
0003-2700/79/0351-1557$01,00/0 0 1979 American Chemical Society
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_ I _
Table I. Elemental Concentrations in USGS GXR-1, (ppm unless % Indicated) A1 (90) previous work Allcott and Lakin ( 4 ) OES AA XRF color other Allcott and Lakin (3) OES AA others ( 2 4 , 25) AA and XRF
2 ’1 0 0.5 + 3.9 3.52 i 0.33 3.36
present work ITNA IENA AA other recommended value (RV) Br previous OES AA XRF color other OES AA others present ITNA IENA AA other RV
0.39 0.39
OES AA others present ITNA IENA AA other RV
1200 t 1050 i 1000 z 880 i
35
7 4 0 1 140 320 i 26
-ray SpeL'tr(Jhcop!. was
employed to study B, Fe, Si, and AI concentrations. Our laboratory techniques have been reported in the literature (I 7,18). Concentrations of Mo, W, and Se were also determined by radiochemical methods. In the first two cases, 200-mg samples were irradiated for 1 h in the OWR epithermal neutron facility and subsequently processed by the methods of Nadkarni and Morrison (29) for Mo and of Gladney (20) for W. A modification of the inorganic ion-exchange procedure for W also permits the determination of Se (21). For the last separation, 200-mg samples are irradiated for 7' h in the thermal flux of the OWR and permitted to decay for 3 weeks before chemical processing. Spectra of y rays from irradiation products formed by all four nuclear methods were observed with large Ge(Li) detectors coupled to 4096 channel pulse-height analyzers. The resolution of the detectors was typically 2.0-2.5 keV at the 1332-keV 6"Co line. All spectra were stored on computer-compatible magnetic tape and the data reduced off-line. Fourteen elements were determined by flame and flameless atomic absorption. Fe, Na, Ca, Cu, K, Mg, Si, Be, and Zn were measured on 500-mg samples which were fused in LiB02 and the melt dissolved in "0,. Details of this procedure are given in the literature (22). Fe, Mn, Na, K, Ba, Pb, and Sr were determined on 0.5-g samples dissolved in a mixture of HF, HXO,, and HC104 and then brought to volume in ,5% "OH. This latter approach is especially useful for elements
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Table IV. Elemental Concentrations in USGS GXR-4 (ppm unless % Indicated) A1 (%) previous work Allcott and Lakin ( 4 ) OES AA XRF color other Allcott and Lakin ( 3 ) OES AA others ( 2 4 , 2 5 ) AA and XRF
As
8.3 i 3.7 6.4 I1.0 7.99 z 0.50
B
Ba
