Environmental catalysts clean up

Abstract

A method was developed for the simultaneous separation, preconcentration, and determination of platinum, palladium, and iridium by flow injection solid phase extraction coupled with online inductively coupled plasma optical emission spectrometry (SPE-ICP-OES). The system is based on the retention of the analytes onto a minicolumn filled with silica gel functionalized with 1,5-bis(di-2-pyridyl) methylene thiocarbonohydrazide (DPTH-gel) placed in the injection valve of a simple flow manifold. The determination of these elements through chemical vapor generation (CVG) was also tested and compared with the same method without CVG. So, the effects of chemicals and flow variables were investigated by both methodologies. The sensitivity of the method without CVG was better; this confirms the low yields of the reactions of these species compared with the yields of the classical hydrides and the necessity of more research work to improve these yields. With the SPE-ICP-OES method developed, the precision as relative standard deviation (n = 10) was 2.8% for Pt, 2.7% for Pd, and 2.9% for Ir. The enrichment factors were 6.3, 6.7, and 6.3 for Pt, Pd, and Ir, respectively. Detection limits (3 min sample loading time) were 1.4 μg L− 1 for Pt, 0.5 μg L− 1 for Pd and 0.6 μg L− 1 for Ir. The accuracy of the proposed method was checked with the certified reference material NIST-2557 autocatalyst. The results obtained using this method were in good agreement with the certified values. The recoveries for the method when applied to determine traces of analytes in spiked seawater were 94.5–105.8%.