Increasing the sensitivity of atomic absorption determination of iron

Abstract

543.422.5 We have studied the effect of the nature and concentration of surfactants on the atomic absorption of iron. We show that using sodium dodecylbenzenesulfonate as the modifier in flame atomic absorption determination of iron in real samples makes it possible to make the measurements in a low-temperature flame (propane-butane-air type) with increased sensitivity and selectivity and also a lower detection limit for iron. We have developed a procedure for atomic absorption determination of iron in food products using sodium dodecylbenzenesulfonate as the modifier. The detection limit for iron is C min = 0.008 µg/cm 3 . Introduction.In connection with solving a number of environmental problems and increased demands made on the quality of food products and drinking water, the problem of the detection limits for micro amounts of metals and improving the accuracy of methods for their determination has become increasingly acute. According to the international requirements of the Joint FAO/WHO Codex Alimentarius Commission, eight metals require the most careful hygiene monitoring: mercury, cadmium, lead, arsenic, copper, tin, zinc, iron.The atomic absorption spectroscopy method is the most widely used for analysis of food products. 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 iron [1]. When using a propane-butane-air flame, considerable interferences occur due to the chemical composition of the analyte solutions [2]. The use of this flame would be more valuable, since incorporation of the method into analytical practice in many laboratories is limited because acetylene is expensive and in short supply.The usual aqueous solutions are increasingly often taking second place to other working solutions: "organized media", in particular aqueous micellar solutions of surfactants [3]. Surfactants have been successfully used in atomic absorption analysis [4][5][6][7]. The aim of this work was to improve the sensitivity and selectivity of atomic absorption determination of iron by chemical modification, and also to establish the possibility of going from an air-acetylene flame to a low-temperature propane-butane-air mixture flame as a cheaper and more accessible option.Experimental Section. We used the following surfactants: sodium dodecylsulfate (SDS), sodium dodecylbenzenesulfonate (SDBS), Tween-20, Tween-80, Triton X-100, Bridge-35, mixtures of surfactants. In the initial solutions, the weight percent of surfactant was 0.5%. From these solutions, model solutions were prepared with volume percent of the surfactant solution 1%-20% (relative to the total volume of the solution). The surfactant concentration was the same in the blank solutions (without iron). The calibration solutions for the range of optimal iron concentrations (0.2, 0.3, 0.5, 0.7, 1.0 mg/dm 3 ) were obtained by diluting a solution with iron concentration 1 g/dm 3 .The program ORIGIN was used to plot the calibration curves. Soluti...

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