Cold vapor mercury derivatives

Mercury is most accurately determined by the cold vapor atomic absorption spectroscopic method. The instrument is set at the wavelength 253.7 nm. The metal, its salts and organic derivatives in aqueous solution can be measured by this method. The solution or the solid compounds are digested with nitric acid to convert into water-soluble mercury(ll) nitrate, followed by treatment with potassium permanganate and potassium persulfate under careful heating. The excess oxidants in the solution are reduced with NaCl-hydroxylamine sulfate. The solution is treated with stannous chloride and aerated. The cold Hg vapor volatdizes into the absorption cell where absorbance is measured. 

---