2011 Volume 97 Issue 2 Pages 43-47
A novel flow injection (FI) system is presented for simple, rapid and sensitive determination of cadmium at μg/g to sub-μg/g levels in iron and steel. The anion-exchange column incorporated in-line in a FI system was utilized as an integrated media for both the separation/preconcentration of cadmium from a large excess of iron matrix and the detection reaction of adsorbed cadmium with TMPyP (5,10,15,20-Tetrakis(N-methylpyridinium-4-yl)-21H,23H-porphine,tetrakis(p-toluene-sulfonate)) which was directly introduced into the column by switching its flow. The spectrophotometric detection at 512 nm for Cd complex with TMPyP was directly coupled in-line with such separation/preconcentration and reaction in this FI system which consists of a multi-position valve and a syringe pump and is operated automatically under the control by a personal computer. The variables relating to such reactions and manifold were studied in detail to establish the optimum conditions and manifold configulations. A linear calibration using a 400 μL sample injection was obtained for cadmium in the range of 0–20 μg/L (in the presence of 1.0×104 μg/mL iron matrix). The coefficient of variation for 10 μg/L cadmium was 1.8% (n=3), and the estimated limit of determination was 1 μg/L corresponding to 0.05 μg/g (5×10−6 mass%) in iron and steel sample. Only 14 min was required for an analytical procedure. Satisfactory recoveries of spiked cadmium were obtained to the solutions prepared by dissolving steel samples in acid mixtures.
