Atomic absorption spectrometry in aqueous phase has been tried with 0.03M K
2SO
4 and 1% H
2SO
4 solutions of Mn
2+, Fe
2+, Co
2+, Ni
2+, Cu
2+, Zn
2+, Cd
2+, Hg
2+, Hg
22+, Tl
+, Ag
+ and Pb
2+. As means of atomization, electrolysis and chemical reduction were employed. In the case of electrolytic reduction, the spectral change was examined
in situ using platinum minigrids as optically transparent electrodes or the platinum plate which was set parallel to the incident light beam. A spectrum with an intensive peak at 238nm was observed when the Hg
2+ solution was electrolyzed. This absorption peak did not decrease even if the applied potential was cut off, and is identified as the spectrum of Hg
22+ ions which was formed by: Hg
2++e=1/2Hg
22+ and/or Hg
2++Hg
0=Hg
22+. The peak at 231 nm was also obtained with Cd
2+ solution by electrolysis, which may be ascribed to Cd
+. Furthermore, Tl
+, Ag
+ and Cu
2+ gave broad absorption peaks at 240, (245, 310), and 277 nm, respectively. On the contrary, Mn
2+, Co
2+, Ni
2+, Zn
2+ and Pb
2+ gave no significant change in spectra although the applied potential went up to -2.5 V. The absorption peak at 207 nm obtained by electrolysis of Zn(II) solution, which is reported by Tyson and West, was found to be identical to that of Zn(II) in excess NaOH, suggesting that this is due to the Zn(II)-hydroxo complex rather than Zn(0) species. A new doublet spectrum which has peaks at 251 and 257 nm was found immediately after adding reducing reagent, SnCl
2, to Hg
22+ or Hg
2+ solution. This absorption decayed in 3min, and was not ascribed to SnCl
2, SnCl
4, or H
2SO
4 in aqueous solution. Therefore, it appears that the observed spectrum is responsible for the "atomic absorption" of hydrated mercury.
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