Novel matrix separation—on-line pre-concentration procedure for accurate quantification of palladium in environmental samples by isotope dilution inductively coupled plasma sector field mass spectrometry

Abstract

A method for accurate on-line ultra-trace analysis of palladium by inductively coupled plasma mass spectrometry has been developed. After separation of interfering cations by cation exchange chromatography, palladium was selectively adsorbed on to a C₁₈ micro-column on-line which had been reversibly loaded with the complexing agent N,N-diethyl-N′-benzoylthiourea (DEBT). The palladium complex formed was eluted with methanol and introduced into an ICP-SFMS via microconcentric nebulization with membrane desolvation. Quantification of palladium was carried out by isotope dilution analysis. The results obtained via the isotope ratios of ¹⁰⁵Pd/¹⁰⁸Pd and ¹⁰⁶Pd/¹⁰⁸Pd agreed within their measurement uncertainty. For solid samples (total intake 100 mg, final sample volume of 10 mL after closed vessel microwave digestion) the limit of detection was 0.24 ng g⁻¹ palladium (2 mL of digested sample). The necessity of combining matrix separation and pre-concentration for elimination of spectral interferences was demonstrated using soil samples. The method was validated by analysis of the certified reference material BCR-723 (road dust).