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What we'll discuss

What we'll discuss. Recent advances in methods for total mercury Mercury speciation Arsenic speciation. Conventional total Hg analysis (cold vapor AAS). digest with aqua regia. digest with aqua regia. oxidize with potassium permanganate. oxidize with potassium permanganate.

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What we'll discuss

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  1. What we'll discuss • Recent advances in methods for total mercury • Mercury speciation • Arsenic speciation

  2. Conventional total Hg analysis(cold vapor AAS) digest with aqua regia digest with aqua regia oxidize with potassium permanganate oxidize with potassium permanganate add sodium chloride/hydroxylamine sulfate add sodium chloride/hydroxylamine sulfate reduce Hg with stannous sulfate reduce Hg with stannous sulfate 2+ measure evolved Hg by AAS at 253.7 nm measure evolved Hg by AAS at 253.7 nm

  3. Drawbacks of CV-AAS total Hg method • digestion requires 40 minutes/sample mitigated by parallel processing • contamination risk from reagents and processing • interferences from sulfide, chloride, organics • disposal of laboratory waste ….there is a better way

  4. dimethylmercury, methylmercury dimethylmercury, methylmercury neurotoxic, bioaccumulate neurotoxic, bioaccumulate Hg soluble salts Hg soluble salts 2+ toxic, bioavailable, methylated/reduced toxic, bioavailable, methylated/reduced Hg Hg 0 volatile, toxic volatile, toxic HgS HgS stable in anaerobic sediments stable in anaerobic sediments

  5. Toluene KCl/K SO 4 2 Organic Hg Water-Soluble Hg + HgCl HgCH , Hg(CH ) 2 3 3 2 0.2M HNO 3 Dil.-Acid Soluble Hg HgO 1:3 HNO + H O 2 3 HNO -Soluble Hg 3 Hg0 1:6:17 HNO 3 + HCl+ H O 2 HNO /HCl-Soluble Hg 3 HgS Sample

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