Reflectometric and visual test determination of Pd(II) in objects of complex composition using the indicator paper

Abstract

RIP-Pd-Test reagent indicator paper based on 1-phenyl-5-(3,4-dihydro-6-methyl-4-oxo-3H-pyrimidin-2-yl)-formazan-6-cellulose has been proposed for determining the palladium content using the sorption-reflectometry and visual-test methods in objects of complex composition. The RIP synthesis technique was described. The estimated composition of the metal complex formed as a result of the heterogeneous indicator reaction at pH 1.5–2.5 was indicated, and the forced coordination of palladium : reagent = 1:1 was ensured. When the RIP interacted with palladium (II) ions, the yellow indicator strip became green with different intensities. Under the selected conditions, the high selectivity for the detection and determination of Pd(II) was shown. With the help of the «Ecotest-2040» portable reflectometer, the reflectometry measurements were carried out using the red LED with the radiation wavelength of 660 nm. For the visual testing, the color scales were used. The indicator reaction was proposed to be carried out in three modes: without concentration and with concentration of the test solution in 100 and 1000 times on the reaction indicator zone of the paper strip (using the pocket pumping device). By the statistical method, the limit of Pd(II) determination for the visual test method (40, 0.47, 0.042 mg/l) was estimated. The palladium detection limit using the reflectometer (19, 0.22, 0.018 mg/l) for the three modes, respectively, was calculated by 3s criterion. The found values of the limiting concentrations were comparable with the metrological characteristics of the known analysis methods in which solid-phase reagents were used. The trueness of the palladium determinations in technological objects of complex composition and drugs has been proven by the independent methods - atomic emission, spectrophotometric and gravimetric methods of analysis. The value of the relative standard deviation of the determined Pd(II) concentration using the portable reflectometer did not exceed 7%.