LOW TEMPERATURE ANALYTICAL CLOUD POINT EXTRACTION. 2: PRECONCENTRATION AND SPECTROPHOTOMETRIC DETERMINATION OF GE(IV)

Abstract

Cloud point extraction is a powerful tool for the analytical preconcentration of trace amounts of analytes. The standard cloud point extraction procedure requires prolonged heating of the solution, which is not always appropriate in the case of thermally unstable analytes or analytical forms and significantly limits the capabilities of the method. One of the ways to modify cloud point extraction is to find approaches to intensifying the process of analytical concentration. The main disadvantage of cloud point extraction is the need for thermal, ultrasonic, infrared or any other initiation of the formation of the surfactant rich phase. It has been shown that salts of aromatic carboxylic acids can cause instantaneous formation of a surfactant-rich phase. In this work, the conditions of micellar extraction concentration of Ge(IV) in the form of a complex with 6,7-dihydroxy-2-phenyl-4-methylbenzopyrylium bromide into the micellar phase of the nonionic surfactant triton X-100 were studied and optimized. It is shown that the introduction of ammonium benzoate into the system at a pH of 1.0 and a triton X-100 concentration of 0.5 vol.% leads to the initiation of the formation of a micellar phase at room temperature. The method of spectrophotometric determination of Ge(IV) with 6,7-dihydroxy-2-phenyl-4-methylbenzopyrylium bromide after its micellar- extraction concentration has been developed. The calibration graph is linear in the concentration range of 4.36–472 μg/L, and the limits of detection and determination are 1.31 and 4.36 μg/L, respectively. The proposed method was tested in the analysis of model solutions and biologically active additives, and the relative standard deviation does not exceed 5.1%.