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which total Hg was determined. The total Hg that was computed in the various fractions ranged from 12.5 to greater than 70,000 ng/g Hg. Raw data along with AQ/QC for Phase I are shown in Appendix A.
It should be noted that in the digestion step, an excess of potassium permanganate (KMnO4), one of the oxidizers, had to be added so that the purple color would persist in the sample solution. The KMnO4 that was required was 30-45 mL versus the required 15 mL in the USEPA Method.
After total Hg was determined in each of the three fractions, total Hg in the composite samples was calculated by multiplying the percent of the composite weight that each fraction represented by the total Hg concentration in that fraction and adding the three numbers together. This gives the Hg (ng/g) in the composite sample, i.e.
Hg in Composite = EFiCi/100
where, Fi is the weight percent of one of the three fractions, Ci is the Hg concentration corresponding to the weight fraction i, and i goes from 1 to 3. Table 4-2 shows the percentages that each fraction comprised of the total composite sample weight, Fi. Values for Ci were taken from Table 4-1. Table 4-3 shows the Hg concentrations in the