Purification of the Chelating Polymer Poly-5-Vinyl-8-Hydroxyquinoline

Abstract

Preconcentration of solutions by the methods of precipitation and the related technique of co-precipitation generally involve the addition of organic chelating agents and the adjustment of pH through addition of buffer solutions. When dealing with large sample volumes, the analyst is not usually concerned with the possibility of also adding low levels of heavy metal contaminants along with these chemicals. However, when dealing with small sample volumes and in situations where duplicate analyses are not possible all sources of contamination including the precipitating agent and buffer solutions must be examined. Sample solutions of the chelating polymer poly-5-vinyl-8-hydroxyquinoline (PVO) were prepared and subjected to purification utilizing the technique of constant potential electrolysis (CPE). Differential pulse polarography (DPP) and atomic absorption spectroscopy (AAS) analysis were performed before, during, and after electrolysis to visually and quantitatively follow the decrease in lead contamination of the polymer solution. The procedure was successful in removing approximately 96% of the initial lead contamination from the sample solution. Ultraviolet work performed indicates that purification of the solution proceeded without any adverse effects on the integrity of the organic precipitant.