Multi-element determination of copper, iron, nickel, manganese, lead and zinc in environmental water samples by ICP OES after solid phase extraction with a C18 cartridge loaded with 1-(2-pyridylazo)-2-naphthol

A pre-concentration solid-phase procedure has been developed for the sensitive and simple determination of copper, iron, nickel, manganese, lead and zinc in environmental water samples by inductively coupled plasma optical emission spectrometry (ICP OES). After pH adjustment, the samples were percolated with the aid of a peristaltic pump on a Sep-Pak C18 cartridge loaded with 1-(2-pyridylazo)-2-naphthol (PAN). The analyte elution was carried out with the passage of HCl through the cartridge for subsequent determination by ICP OES. The experimental conditions for pre-concentration were optimized considering the following factors: the concentration and volume of the eluent, sample volume, flow-rate and pH. The optimized conditions corresponded to the use of 5 mL of 0.8 M HCl as the eluent, a sample volume of 50 mL, a flow-rate of 1.9 mL min(-1) and pH 9.0. Under these conditions, the detection limits for Cu, Fe, Mn, Ni, Pb and Zn varied between 0.11 and 21 mu g L-1. The relative standard deviation (RSD) for the analytes of this study did not exceed 9%, after the application of the proposed pre-concentration procedure (n = 10, 0.50 mg L-1). The effect of possible interfering species on the recovery of the analytes was also investigated. The accuracy of the method was evaluated by the analysis of a certified reference material (SLEW-3 Estuarine Water Reference Material for Trace Metals) and the proposed method was applied to samples of groundwater, drinking water and river water. The samples were analyzed by using inductively coupled plasma mass spectrometry (ICP-MS) as a comparative method and no significant differences among these results and the results obtained by the proposed method were observed.