On-Line Preconcentration of Cadmium in Commercial Tea Samples using Polyurethane Foam as Filter Associated with Ultrasonic Nebulization-Inductively Coupled Plasma Optical Emission Spectrometric Detection

P.F. MARCHISIO, A. SALES, S. CERUTTI, E. MARCHEVSKY, L.D. MARTINEZ

INSTRUMENTATION SCIENCE AND TECHNOLOGY

Taylor and Francis

Año: 2005 vol. 33 p. 449 - 459

1073-9149

Tea is the most popular beverage, next to water, consumed by over two-thirds of the world’s population. The present paper proposes an on-line preconcentration procedure for cadmium determination in tea samples (Camellia sinensis) by ultrasonic nebulization associated with inductively coupled plasma optical emission spectrometry (USN-ICP-OES). It is based on the precipitation of cadmium(II) ion onto a conical minicolumn packed with polyurethane foam using2-(5-bromo-2-pyridilazo)-5-diethylaminophenol (5-Br-PADAP) as precipitating reagent.The collected analyte precipitate was quantitatively eluted from the minicolumn with20% (v/v) nitric acid. An enhancement factor of 240-fold (20 for preconcentration and12 for USN) was obtained. The detection limit (DL) value for the preconcentration of 10.0 mL of sample was 4.0 ng L-1. The precision for 10 replicate determinations at 0.1 ug L-1 cadmium levels was 3.2% relative standard deviation (RSD), calculated from the peak heights obtained. The calibration graph using the preconcentration system for cadmium was linear with a correlation coefficient of 0.9998, at levels near the detection limits up to at least 500 ug L-1. The preconcentration procedure was successfully applied to the determination of cadmium in tea samples.