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Cold Hg Vapor Technique

Cold Hg Vapor Technique. Hg 2+ + Sn 2+ → Hg o + Sn 4+ The elemental Hg is swept from the flask into a long path absorption cell in the path of a Hg HCL. With a 50 mL sample, LOD is 20 ng/L (20 pg/mL). Hydride Generation. NaBH 4 is added to form hydride

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Cold Hg Vapor Technique

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  1. Cold Hg Vapor Technique • Hg2+ + Sn2+ → Hgo + Sn4+ • The elemental Hg is swept from the flask into a long path absorption cell in the path of a Hg HCL. • With a 50 mL sample, LOD is 20 ng/L (20 pg/mL)

  2. Hydride Generation • NaBH4 is added to form hydride • Works with As, Se, Te, Sb, Bi, Sn, Ge. • The hydride is decomposed to atoms in a flame, or a heated quartz cell. • LOD about 0.1 – 1 ppb – similar to furnace

  3. Advantages • Some of the hydride-forming elements have resonance lines at very short wavelength (eg As and Se, below 200 nm) • At these wavelengths, conventional flames absorb much radiation. • Therefore flame fluctuates →Noisy signals • The diffusion (low temperature) flames used to decompose hydrides are transparent at the low wavelengths. The heated quartz cell is even better.

  4. Additional Advantages • Interferences are often reduced • They are left behind when the hydride is swept away • Therefore you can analyze more complex samples – • viscous • High salt content • High suspended solids

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