543.422.5 Systematic investigations of the influence of the elemental composition and concentration of surfactants on the atomic absorption of chromium have been carried out. It is shown that sodium dodecyl sulfate maximally increases the analytical signal and selectivity in chromium determination. The atomic-absorption technique of determining the quantitative content of chromium in sewage of industrial enterprises with application of sodium dodecyl sulfate as a chemical modifier has been developed. The detection limit for chromium is 1.2 µg/dm 3 .
Introduction.In connection with the solution of a number of ecological problems and more stringent requirements on determination of microquantities of metals in new materials as well as on the quality of foodstuff and drinking water, the problem of determining microquantities of metals and increase in the accuracy of their determination has become more and more pressing. Chromium is among the supertoxicants. Its content must be controlled in emissions, water, air, soil, and foodstuff. The atomic-absorption method is a basic method of determining microquantities of chromium in objects of complex chemical composition [1][2][3][4][5][6][7][8], with atomization of solutions being carried out in an airacetylene flame. However, nickel, iron, and phosphate ions present in the solutions analyzed decrease the chromium signal [8]. In using an oxidizing air-acetylene flame, the influence of these elements is decreased, but simultaneously there is a decrease in the sensitivity of the detection of chromium [1].More often, aqueous solutions give way to other working media. Water-organic and nonaqueous solutions have long been used; at the present time, supercritical fluids, ionic liquids and, of course, the so-called organized media are employed. There have been great advances and there is great promise in using organized media in organic chemistry, especially those based on water. The aim of the present work is to increase the sensitivity and selectivity of atomic-absorption determination of chromium by chemical modification and also to establish the possibility of passing from an air-acetylene flame to a low-temperature one -a propane-butane-air mixture as a cheaper and more accessible one.Influence of a Surfactant on the Sensitivity of the Atomic-Absorption Method of Determining the Quantitative Content of Chromium. Using model specimens of surfactants (sodium dodecyl sulfate, sodium dodecyl benzene sulfonate, twin-20, twin-85, triton X-100, bridge-35, surfactant mixtures as well as mixtures of surfactants with octanol or methanol), we carried out systematic investigations of the effect of their elemental composition and concentration on the absorptivity of chromium.In the original solutions, the mass fraction of the surfactant was 0.5%. They were used for preparing model solutions with a volumetric fraction of the surfactant solution from 1 to 20% (from the total volume of the solution). In blank solutions not containing chromium, the content of surfactants is the same. Cal...
