Spectrophotometric determination of the total amount of rare-earth after solid-liquid extractive preconcentration with polyvinyl alcohol condensed p-formylchlorophosphonazo

The extraction and preconcentration of metal complex via surfactant-mediate d phase separation was studied. A new, high-sensitive and low-cost methodol ogy for the determination of rare-earth elements using polyvinyl alcohol co ndensed p-formylchlorophosphonazo (PV . CPApF), with a cloud point extracti on step prior to absorptiometric determination, was developed. Under the op timal experimental conditions, the apparent molar absorptivity of RExOy (th e general formula of rare-earth oxides) - PV . CPApF complex is 7.26 x 10(4 ) mol l(-1) cm(-1) at 668 nm, and Beer's Law is obeyed for the mixture of R ExOy, in the range 0-1.2 mg l(-1). The proposed procedure has been applied to the determination of the total amount of the rare-earth elements in duct ile iron and micronutrient fertilizer with satisfactory results. (C) 2000 E lsevier Science Ireland Ltd. All rights reserved.