Показана можливість йодометричного твердофазно-спектрофотометричного визначення тіоціанату шляхом окиснення його перманганатом, наступного додавання до реакційної суміші надлишку йодиду та детектування надміру окисника на поверхні пінополіуретану.
Показана возможность иодометрического твердофазно-спектрофотометрического определения тиоцианата путем окисления его перманганатом, последующего прибавления к реакционной смеси иодида и детектирования избыточного количества окислителя на поверхности пенополиуретана.
The possibility of indirect solid phase-spectrophotometrical determination of thiocyanate was studied by the use of permanganate as the oxidant: 5SCN- + 6MnO4 - + 13H+ ? 6Mn2+ + 5SO42- + 5HCN + 4H2O and polyurethane foam (PUF), as a sorbent foriodine, which is formed after the reaction of an excess of oxidant with added iodide: 2MnO4 - + 15I- + 16Н+ ? 2Mn2+ + 5I3 - + 8Н2О.
The effect of the acidity and the amount of permanganate in the oxidation of thiocyanate was studied. The optimum amountof iodide required for the formation of triiodide, was established. Effect of diverse ions was investigated.
For the study the oxidation of thiocyanate in the syringe with a capacity of 10.0 cm3 were took 1.0 cm3 of 0.5 M sulphuric acid, 1.6.10-4 M &solution of permanganate, 1.0-8.0 cm3 of the sample solution containing 0.1 mkmol SCN- and water to a total volume of 10.0 cm3.
The mixture was stirred for 10 minutes at room temperature (~293 K) and added 1.0 cm3 0.2 M of potassium iodide. Next, we&re measured the optical density of the solution triiodide ([lamtha]max=350 nm) or iodine was removed from the solution triiodide on the PUF.
For this, the solution from the syringe through the membrane was transferred into a separatory funnel and th&is solution was passed through PUF at the rate of 2.5 cm3/min.
Sorbent pressed between sheets of filter paper was placed in the cuvette of the spectrophotometer for solid samples ([lamtha]=370 nm). Light dispersion of the solid matrix was taken into& account using the method heterochromatin extrapolation.
The interference of nitrite and Fe(III) on the determination of thiocyanate could be eliminated by decomposing with sulfamic acid and by masking with fluoride.