An indirect method for determination of atmospheric sulfur dioxide was developed and tested. Air samples were collected in 30 % H 2 O 2 solution which converts SO 2 to SO 2À 4 . The sampling technique is the same technique used in the thorin spectrophotometric method for analysis of sulfur dioxide. The developed method, however, relied on voltammetric analysis of Pb(II) upon addition of an excess Pb(II) solution. The excess Pb(II) was determined by linear sweep anodic stripping voltammetric analysis at an iodine-coated polycrystalline platinum electrode. The electrode iodination was carried out from the gas phase. The calibration plot from cyclic voltammetric measurements of the cathodic deposition peak current and the Pb(II) concentration showed a remarkable linearity between the peak current and Pb(II) concentration (correlation coef®cient 0.9994). Stripping analysis of Pb(II) at the iodine-coated electrode showed better sensitivity and excellent linearity between the anodic stripping peak current and the concentration of Pb(II) (correlation coef®cient 0.9934). Application of voltammetric analysis for the indirect determination of SO 2 also showed remarkable linearity and a sensitivity not less than that of the thorin method (R 0X9993). The developed method passed the recovery and real-life analysis tests.

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