Spectrophotometric determination of the total amount of rare-earth elements in agricultural samples with p-chloro-chlorophosphonazo

Abstract

A simple, sensitive and accurate spectrophotometric method for determination of the total amount of rare-earth elements in agricultural samples with p-chloro-chlorophosphonazo [ pCCPA, i.e., 2-(4′-chloro-2′-phosphon-benzylazo)-7-(4″-chlorophenyl)-1,8-dihydroxynaphthalene-3,6-disulphonic acid] in sulphuric acid medium has been developed. The apparent molar absorptivity of RE xO y (the general formula of rare-earth oxides)- pCCPA complex is 8.17 × 10 4 1.mole −1 cm −1 at 676 nm, and Beer's law is obeyed for the mixture of RE xO y in the range 0–12 μg/25 ml. The proposed method has been successfully applied to the determination of the total amount of rare-earth elements in soils, herbs, vegetables, dried stems of maize, water samples and rare-earth microelement fertilizer samples with satisfactory results.