While traditional methods for determining mercury in solid samples involve the use of aggressive chemicals to dissolve the matrix and the use of other chemicals to properly reduce the mercury to the volatile elemental form, pyrolysis-based analyzers can be used by directly weighing the solid in a sampling boat and initiating the instrumental analysis for total mercury. Although not well suited for trace-level analyses of liquids because of the limited capacity (0.5 mL) of the sampling boat, such pyrolysis-based mercury analyzers (EPA Method 7473) have the following advantages:
- Throughput: a measurement every 10-15 minutes (including the weighing and logging time)
- Learning Curve: operation simple enough for those with no prior analytical skill
- Low Cost: capital cost about $35K
- Green: generation of waste virtually eliminated
- Sample Size: 1.00 mg to 500 mg, or 0.5 mL, (but use less if absorbance starts before 5 s)
- Detection Limit: 0.01 nanogram Hg
- Applications:
- non-lethal monitoring of fish (e.g., tissue biopsy)
- longitudinal analysis of hair (to locate peak-exposure periods)
- exposure assessments for other tissues (e.g., feathers, fur, toenails, botanicals)
- near real-time monitoring of contaminated-soil and sediment during remediations
- coal-fired power plant emissions (from difference between coal Hg and solid waste Hg)
- speciation for mercury in tissues (via suitable extracts of the methyl mercury)
Notice:
Although this work was reviewed by EPA and approved for publication, it may not necessarily reflect official Agency policy.