Automatic solid phase extraction of cadmium exploiting a multicommutated flow system previous ICP-MS detection: Application to tobacco samples

Abstract

A miniaturized automatic sample pre-treatment system, based on multicommutated flow techniques, i.e. Lab on Valve (LOV) and Multisyringe Flow Injection Analysis (MSFIA) techniques, for cadmium determination by ICP-MS in organic samples is presented. The on-line extraction and preconcentration system retains the analyte on the resin (Dowex 50W-X8), followed of elution with 1molL−1 HNO3. The LOV-MSFIA system allows the fully automation of solid phase renewal, which shown a durability of 130 injections without its replacement. The optimal operating conditions were investigated using multivariate optimization tools. The detection limit was 0.05ng of cadmium, while the mass linear working range was 0.2–100ng. The precision of the proposed methodology was 2.4% (RSD, n=10) with a sample frequency of 9 injections h−1.The accuracy of the method was established by means of an organic matrix certified reference material (DORM-2), and the method has been successfully applied to different samples of tobacco (commercial cigarettes, pipe tobacco and tobacco leaves), obtaining recoveries between 90 and 105%. Main advantages of the proposed methodology are a minimal sample handling, good precision, high stability of the column and the versatility achieved by a variety of managed sample volumes.