Розглянуто йодиметричні титриметричні, фотометричні та твердофазно-спектрофотометричні методики визначення сульфурвмісних органічних відновників у кислому й нейтральному середовищах.
Рассмотрены иодиметрические титриметрические (визуальные и электрохимические), фотометрические, твердофазно-фотометрические методики определения серасодержащих органических восстановителей в кислой и нейтральной средах.
The paper discusses the principles of iodimetry and iodometry for the titrimetric (visual and electrochemical establishment of the titration end point), photometric and solid phase spectrophotometrical determination of sulfuring organic reductants in acidic and neutral media. These methods overcome the shortcomings of iodimetry and iodometry caused by the sublimation of iodine and the ability of iodide ions to be oxidized in acidic media by atmospheric oxygen. The class of sulfur containing organic compounds with respect to their properties as reducing agents has been discussed. A critical review of themethods for iodimetric determination of mercaptopyridines, mercaptopyrimidines, thiols and other sulfur-containing organic compounds in acidic and neutral media has been done. The mechanisms of their oxidation by iodine has been considered. In the ca&se of quantitative running of the reaction (2RSH + I2 - RS-SR + 2HI) the iodometric quantitative determination of thiols takes place. Metrological characteristics of iodometric determination of captopril С9Н15NO3S in pharmaceutical preparations have &been discussed in detail. In the cases when the formation of disulfide by oxidation of thiols is not stoichimetric, or when the reaction rate is too low or when the reaction is reversible, which normally leads to the equilibrium between the analyte a&nd the titrant (iodine), it is impossible to successfully perform the determination of organic sulfur-containing reducing agents. In such cases iodimetric titrimetry in an alkaline medium (in fact, it appears to be the titration by strong oxidants, s&uch as the iodate(I) and iodate(V) can be used).
