THE SPECTROPHOTOMETRIC DETERMINATION OF NITRITES WITH N,N-DIETHYLANILINE

Abstract

A method for spectrophotometric determination of the total IO3− and IO4—ions was proposed. The method is based on the oxidation of N,N-diethylaniline in an excess of potassium bromide in the presence of sulfuric acid medium and on the measurement of the bromination product absorbance at 226 nm. The influence of sulfuric acid concentration on the sensitivity of the measurement has been determined and the optimum conditions have been established. The detection limits (blank + 3s) for iodate, periodate and their total content equal to 0.73; 0.69 and 0.61 mg∙L−1, respectively. The linearity range of the calibration graph was found to be 1.0−11.0 mg∙L−1 (sr ≤ 0,10, n = 5). The possibility of separate determination of iodate and periodate based on selective extraction IO4− silica modified with a quaternary ammonium salt is proposed. The metrological characteristics of the procedure were checked by means of the “entered-found” method on the control samples. The relative error did not exceed 0.10 for iodate and periodate determination on the control samples, and the relative error was not higher than ± 8.00 %. The effect of foreign ions on the iodate and periodate determination at 2.0∙10−5 mol∙L–1 has been studied. The proposed procedure is simple and suitable for iodate and periodate determination in various objects.

Keywords

• йодат
• перйодат
• N,N-діетиланілін
• спектрофотометрія
• четвертина амонійна сіль