Stoichiometry to Another Element
Yet another option for recalculation is the element relative to another element (by stoichiometry). This calculation is similar to the "element by stoichiometry to oxygen" as described below, however the user may select any other analyzed (acquired) or specified element as the stoichiometric basis element.
This calculation can be used in combination with the other calculations to handle unusual analytical situations. For example, in the following analysis of an silica sample, the results revealed significant contamination of the material with Fe and Ca. Investigation using other techniques, implied that the Fe was in the form of Fe2O3 (hematite), and the Ca was present as CaCO3 (calcium carbonate). Aside from the effect of inhomogeneity on the matrix correction, it was desirable to improve the calculation by calculating Si by difference and C by stoichiometry to Ca as follows :
Analysis of sample un 2 seoj #3 random
Total Number of Data Points = 6 Number of "G" Data Points = 3
Average Beam Counts = 79092. Average Base Time = 10.00
Average Sample Z-bar = 11.480 Average ZAF Iterations = 2.333
Oxygen Calculated by Cation Stoichiometry and Included in Matrix Correction
Element : Si is Calculated by Difference from a Sum of 100.0 Weight Percent
Element : C is Calculated Relative to Element Ca at 1.000 to 1.0 Atom
Results in Weight Percent :
O Si C La F SUB
SPEC 51.526 39.743 1.134 .000 .000 92.403
SDEV 2.932 11.897 1.939 .000 .000
BGD: MAN MAN MAN MAN MAN MAN
Fe Al Ca Mg Mn S SUM
133 .054 .018 .012 .009 .000 .000 100.000
134 10.696 .467 11.253 .010 .054 .000 100.000
135 .119 .013 .083 .004 .000 .000 100.000
AVER 3.623 .166 3.782 .008 .018 .000 100.000
SDEV 6.126 .261 6.470 .003 .031 .000
SERR 3.537 .151 3.735 .002 .018 .000
KRAT .0306 .0013 .0353 .0001 .0001 .0000
ZCOR 1.1992 1.2245 1.0981 1.3804 .9338 .8713
KRAW .0451 .0029 .2072 .0001 .0002 .0000
P/B: 14.07 4.78 43.69 1.45 1.07 .92
Results in Elemental Mole Percents :
O Si C La F
AVER 65.743 28.728 2.004 .000 .000
SDEV 1.571 7.841 3.430 .000 .000
Fe Al Ca Mg Mn S SUM
133 .019 .014 .006 .007 .000 .000 100.000
134 4.069 .368 5.965 .009 .021 .000 100.000
135 .043 .010 .041 .003 .000 .000 100.000
AVER 1.377 .130 2.004 .006 .007 .000 100.000
SDEV 2.332 .206 3.430 .003 .012 .000
Results in Oxide Weight Percents using Custom Cation Oxide Ratios :
O SiO2 CO2 La2O3 F
AVER .000 85.024 4.153 .000 .000
SDEV .000 25.452 7.104 .000 .000
Fe2O3 Al2O3 CaO MgO MnO SO3 SUM
133 .077 .035 .017 .014 .000 .000 100.000
134 15.293 .883 15.745 .017 .070 .000 100.000
135 .170 .024 .116 .006 .000 .000 100.000
AVER 5.180 .314 5.292 .013 .023 .000 100.000
Note that Fe was recalculated as Fe2O3 and C was added relative to Ca by stoichiometry. This calculation can be applied in numerous other ways to a variety of analytical situations. Consider the example below. Here, the user decides to calculate CO2 on the basis of moles of CaO, rather than by stoichiometry to oxygen.
Analysis of sample st 141 set 1 dolomite (Harvard #105064)
Total Number of Data Points = 3 Number of "G" Data Points = 3
Average Beam Counts = 9102. Average Base Time = 10.00
Average Sample Z-bar = 10.875 Average BNA Iterations = 5.000
CO2 is Calculated Relative to Oxide CaO at 2.000 to 1.0 Mole
Results in Weight Percent :
CO2 SUB
SPEC 47.791 47.791
SDEV .071
BGD: MAN MAN
CaO MgO SUM
9 30.501 21.735 100.109
10 30.424 21.769 99.947
11 30.420 22.135 100.301
AVER 30.448 21.880 100.119
SDEV .046 .222
SERR .026 .128
PUBL 30.560 21.880 100.186
%VAR -.365 -.001
*
UNBE 1.0496 1.2242
KRAW .5338 1.0000
P/B: .00 .00
Results in Oxide Mole Percents :
CO2
AVER 50.002
SDEV .139
CaO MgO SUM
9 25.053 24.841 100.000
10 25.028 24.917 100.000
11 24.922 25.233 100.000
AVER 25.001 24.997 100.000
SDEV .069 .208