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...

543.422.5 We have studied the effect of the nature and concentration of surfactants on the analytical signal of zinc. We show that of all the studied surfactants, sodium dodecylbenzenesulfonate increases the sensitivity and selectivity of the zinc determination the most. We have designed a method for atomic absorption determination of zinc in food products using sodium dodecylsulfate as a modifier. The detection limit for zinc according to the proposed procedure is C min = 0.003 µg/mL. Introduction.Increasing demands on chemical analysis are due to both the appearance of new objects to be monitored and also awareness of the significance of previously known objects. The problem of the detection limit for micro amounts of toxicants in food products and improving the accuracy of methods for their determination has become increasingly acute. According to the international requirements of the Joint FAO/WHO 1 Codex Alimentarius Commission, eight metals require careful hygiene monitoring: mercury, cadmium, lead, arsenic, copper, tin, zinc, iron. The atomic absorption spectroscopy method is the most widely used for determination of zinc in various objects of complex chemical composition [1][2][3][4]. In this case, atomization of the solutions is carried out in an air-acetylene flame, in which no significant elemental interferences are observed in the determination of zinc [5]. When using a propanebutane-air flame, we have established that considerable interferences occur due to the chemical composition of the analyte solutions. The use of this flame would be more valuable, since incorporation of the method into analytical practice is hindered because acetylene is expensive and in short supply.The usual aqueous solutions today are increasingly often taking a back seat to other working solutions: "organized media", in particular aqueous micellar solutions of surfactants [6]. Surfactants have been successfully used in atomic absorption analysis [7][8][9][10][11][12][13].The aim of this work was to improve the sensitivity and selectivity of atomic absorption determination of zinc by chemical modification of the analyte solution, and also to establish the feasibility of going from an air-acetylene flame to a low-temperature propane-butane-air flame as a cheaper and more accessible mix.Experimental Section. We used the following surfactants: sodium dodecylsulfate (DSNa), sodium dodecylbenzenesulfonate, Tween-20, Tween-80, Triton X-100, Bridge-35, and cetylpyridinium chloride. In the initial solutions, the surfactant fraction was ω = 0.5 wt%. From these solutions, model solutions were prepared with weight fraction of the surfactant solutions equal to 0.005, 0.010, 0.015, 0.025, 0.035, 0.050, 0.075, 0.100, and 0.125 wt%. The surfactant concentration was the same in the blank solutions (without zinc). The calibration solutions for the range of optimal zinc concentrations (0.1, 0.3, 0.5, 0.7, and 1.0 mg/L) were obtained by diluting the interstate standard sample for composition of a zinc ion solution 0032:1998 (DSZU 2 022.63-9...

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ISRA (India) = 1.344 ISI (Dubai, UAE) = 0.829 GIF (Australia) = 0.564 JIF = 1.500 SIS (USA) = 0.912 РИНЦ (Russia) = 0.207 ESJI (KZ) = 4.102 SJIF (Morocco) = 2.031 ICV (Poland) = 6.630 PIF (India) = 1.940 IBI (India) = 4.260

ISRA (India) = 1.344 ISI (Dubai, UAE) = 0.829 GIF (Australia) = 0.564 JIF = 1.500 SIS (USA) = 0.912 РИНЦ (Russia) = 0.207 ESJI (KZ) = 4.102 SJIF (Morocco) = 2.031 ICV (Poland) = 6.630 PIF (India) = 1.940 IBI (India) = 4.260