Determination of lead in drinking water by ICP-AES with ultrasonic nebulization and flow-injection on-line preconcentration using an amberlite XAD-16 resin

Abstract

An on-line lead preconcentration and determination system implemented with inductively coupled plasma atomic emission spectrometry (ICP-AES) associated to flow injection (FI) with ultrasonic nebulization (USN) was studied. For the retention of lead, 2-(5-bromo-2-pyridylazo)-5-diethyl-aminophenol (5-Br-PADAP) and Amberlite XAD-16 were used, at pH 9.2. The lead was removed from the microcolumn in counter flow with nitric acid. A total enhancement factor of 150 was obtained with respect to ICP-AES using pneumatic nebulization (15.0 for USN and 10.0 for column). The detection limit value for the preconcentration of 10 mL of aqueous solution of Pb was 0.2 ng mL-1. The precision for 10 replicate determinations at the 5 ng mL-1 Pb levels was 2.8% relative standard deviation (RSD), calculated with the peak heights obtained. The calibration graph using the preconcentration system for lead was linear with a correlation coefficient of 0.9997 at levels near the detection limits up to at least 100 ng mL-1. The method was successfully applied to the determination of lead in drinking water samples.