GUIDELINES FOR SAMPLE COLLECTING AND ANALYTICAL METHODS USED IN THE U.S. GEOLOGICAL SURVEY FOR DETERMINING CHEMICAL COMPOSITION OF COAL
By Vernon E. Swanson and Claude Huffman, Jr.
U.S. GEOLOGICAL SURVEY CIRCULAR
735
1976
Table 2.--Comparative results for EPA-NBS interlaboratory trace element study
(All values in parts per million in moisture-free coal (NBS1632),except sulfur, in percent. Values in parentheses given for information only. Leaders (...) indicate no data available)
| U.S. Geological Survey | ||||||
| Element | NBS certified | All labs, | Quantitative | Six-Step emission | ||
| value | grand mean | methods described | spectrographic | |||
| As | 5.9 | ± | 0.6 | 6.24 | 5.3 | |
| Cd | 0.19 | ± | 0.03 | .9 | <1 | |
| Cr | 20.2 | ± | 0.5 | 22.7 | 15 | |
| Cu | 18.0 | ± | 2 | 17 | 15 | |
| Hg | 0.12 | ± | 0.02 | 0.22 | .13 | |
| Mn | 40 | ± | 3 | 41.3 | 42 | 30 |
| Ni | 15 | ± | 1 | 19.0 | 15 | 10 |
| Pb | 30 | ± | 9 | 30.4 | 28.3 | 20 |
| Se | 2.9 | ± | 0.3 | 4.6 | 2.9 | |
| Th | (3) | 4.7 | ||||
| U | 1.4 | ± | 0.1 | 1.7 | 1.43 | |
| V | 35 | ± | 3 | 34.9 | 20 | |
| Zn | 37 | ± | 4 | 29.51 | 38 | |
| Be | (1.5) | 1.75 | 1 | |||
| S | 1.28 | 1.19 | ||||
| F | 83.51 | 85 | ||||
1Questionable mean; wide-scatter or limited data.
Created by the EERT WWW Staff.
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