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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 1.--Approximate visual lower limits of determination in ash for the elements in coals analyzed by the six-step spectrographic method

[Si and Na not reported because quartz and sodium carbonate are added as part of method. Some combinations of elements raise or lower the limits of determination]

Element Percent   Element Percent
Fe 0.002   Si  
Mg 0.005   Al 0.02
Ca 0.005   Na  
Ti 0.0005   K 1.5
      P .5
Element ppm   Element ppm
Mn 2   Ce 500
Ag 1   Ga 10
As 2,000   Ge 20
Au 50   Hf 200
B 50   In 20
Element ppm   Element ppm
Ba 5   Li 200
Be 3   Re 100
Bi 20   Ta 1,000
Cd 100   Th 500
Co 10   Tl 100
Element ppm   Element ppm
Cr 2   Yb 2
Cu 2   Pr 200
La 100   Nd 150
Mo 7   Sm 200
Nb 20   Eu 200
Element ppm   Element ppm
Ni 10   Gd 100
Pb 20   Tb 700
Pd 5   Dy 100
Pt 100   Ho 50
Sb 500   Er 100
Element ppm   Element ppm
Sc 10   Tm 50
Sn 20   Lu 70
Sr 10   Ir 100
Te 5,000   Os 100
U 1,000   Rh 5
Element ppm   Element ppm
V 15   Ru 20
W 200      
Y 20      
Zn 700      
Zr 20      
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