Thiocyanate hydrogen peroxide determination

Iron(III) thiocyanate, hydrogen peroxide determination, 626, 628 Iron(IV) 0X0 species, fenozan degradation, 1292, 1293, 1294... 

Kawabuchi and Kuroda have concentrated molybdenum by anion exchange from seawater containing acid and thiocyanate [497] or hydrogen peroxide [497,498], and determined it spectrophotometrically. Korkisch et al. [499] concentrated molybdenum from natural waters on Dowex 1-X8 in the presence of thiocyanate and ascorbic acid. 

Methanesulfonic acid, dimethyl sulfoxide and dimethyl sulfone are potential intermediates in the gas phase oxidation of dimethylsulfide in the atmosphere. We nave measured the rate of reaction of MSA with OH in aqueous solution using laser flash photolysis of dilute hydrogen peroxide solutions as a source of hydroxyl radicals, and using competition kinetics with thiocyanate as the reference solute. The rate of the reaction k (OH + SCN ) was remeasured to be 9.60 1.12 x 109 M 1 s 1, in reasonable agreement with recent literature determinations. The rates of reaction of the hydroxyl radical with the organosulfur compounds were found to decrease in the order DMSO (k = 5.4 0.3 x 109 M-i s 1) > MSA (k = 4.7 0.9 x 107 M l S 1) > DMS02 (k = 2.7 . 15 x 107 M 1 s ). The implications of the rate constant for the fate of MSA in atmospheric water are discussed. 

Complexes of metal ions with inorganic reagents are also applied in spectrophotometric methods, e.g., thiocyanate [Fe(III), Co, Nb, Mo, Re, W, U, Ti], iodide (Bi, Sb, Pd), or hydrogen peroxide (Ti, V, U). Determinations based on such complexes are carried out in aqueous solutions or after extraction with oxygen-containing organic solvents. 

At higher concentrations titanium is determined by the hydrogen peroxide method. Higher sensitivities are attained with the methods using chromotropic acid. The thiocyanate (with extraction) and fluorone methods are the most sensitive. 

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