Separation of divalent lead from ayurvedic (herbal) medicines and alloys using extraction chromatography

Abstract

A selective, sensitive, less expensive and more precise method has been developed for the separation of lead(II) using <span style="mso-bidi-font-style:italic">N-<i>n</i>-octylaniline (liquid anion exchanger) coated silica gel as stationary phase. The quantitative extraction of lead(II) is found with 0.087 molL^-1 <span style="mso-bidi-font-style:italic">N-<i>n</i>-octylaniline and 0.007 - 0.15 mol/L^-1 ascorbic acid at <i style="mso-bidi-font-style:normal">p</i>H 9.0. The extracted lead(II) has been eluted from the column with 0.5 mol/L^-1 hydrochloric acid and analyzed by spectrophotometric method. The probable composition of the extracted species is deduced from log-log plots and extracted species is found to be [2RR'NH₂⁺.Pb(C₆H₇O₆)₄^2-]_(org.). The optimum extraction conditions are evaluated from a critical study of effects of <i style="mso-bidi-font-style:normal">p</i>H, ascorbic acid concentration, <span style="mso-bidi-font-style:italic">N-<i>n</i>-octylaniline concentration and elution time. The proposed method is found simple and efficient as it avoids large number of cation and anion interferences. Lead(II) is successfully separated from binary mixtures with bismuth(III), gold(III) and osmium(VIII). The method is also extended for separation of lead(II) from ayurvedic medicine and synthetic mixtures corresponding to alloys.

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