EXTRACTION-ABSORBTIOMETRIC DETERMINATION OF CADMIUM CONTENT BY PYRONINE G WITH THE PRESENCE OF THE IODIDE ION IN TOBACCO

Abstract

An extraction-absorptiometric determination of Cd(II) by xanthene dye Pyronin G in the presence of iodide ion is carried out. The experiments were conducted using a spectrophotometric method on modern equipment. The quantitative extraction of Cd(II) from a sulphuric acid medium in the presence of iodide ion was achieved. The extraction of the ionic associate was studied in relation to the nature of the solvent. A high value of optical density was observed for the ionic associate and a low value for the control solution when a mixture of dichloroethane+toluene (1:2) was used. The maximum absorption was observed at λ=565…572 nm on a spectrophotometer of the model DR 2800. Further experiments were conducted at λ=570 nm. The dissolution coefficient was determined to be R=0.95. The dependence of the optical density of the ionic association on the amount of dye was studied. The extraction equilibrium was established within 60 seconds. The ionic associate was dissolved by single dissolution. After establishing the optimum light absorption conditions, the limits of compliance with the basic law of light absorption were derived. Based on the calibration data, the average molar extinction coefficient was calculated as ε₅₇₀= 7400. The molar ratio of components in the ionic association was determined by the methods of Asmus (straight line) and equilibrium displacement, which was 1:1. [PG]⁺[CdHal.]^- =1:1. The influence of a number of elements accompanying cadmium in natural sites on the dissolution process was studied. The presence of milligram quantities of numerous elements does not impede the determination of cadmium. This technique allows to determinetion cadmium in natural objects without the need for preliminary separation. The technique of cadmium determination developed on the basis of the conducted research was successfully applied for the determination of microgram quantities of cadmium in tobacco