Determination of Lead in Drinking Water by Icp-Aes With Ultrasonic Nebulization and Flow-Injection on-Line Preconcentration Using an Amberlite Xad-16 Resin

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-diethylaminophenol (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.