Analysis of Selected Heavy Metals in Tap Water by Inductively Coupled Plasma-Optical Emission Spectrometry After Pre-Concentration Using Chelex-100 Ion Exchange Resin

Abstract

A sensitive, specific, precise, accurate, and fast method Swas suitably developed for the determination of selected heavy metals including Cd, Cu, Fe, Pb, and Zn in tap water samples by inductivity coupled plasma-optical emission spectrometry (ICP-OES) after pre-concentration using Chelex-100 ion exchange resin. This method is based on studying several parameters including pH, weight of Chelex-100, HNO3 concentration, flow rate, and column diameter. It was found that the suitable conditions used for pH, weight of Chelex-100, HNO3 concentration, flow rate, and column diameter were 6, 4 g, 2 M, 1 mL/min, and 1 cm, respectively. Under these conditions, high recoveries were achieved with values of 95%, 106%, 77%, and 91% for Cu, Fe, Pb, and Zn, respectively. A total of 90 tap water samples were collected from five sampling zones of Irbid City, North Jordan, including (A: Barha zone; B: West and Zabda zone, C: South zone, D: East and city center zone, and E: North zone), and analyzed for Cd, Cu, Fe, Pb, and Zn; also the pH and electric conductivity (EC) values were measured. Moreover, the correlations between metals’ concentrations and type of tanks (iron, plastic, or semantic), type of pipes (iron or plastic), age of tanks, and age of pipes were evaluated. The mean concentrations of tested metals in tap water samples collected from zone A, zone B, zone C, zone D, and zone E, respectively, were the following: Cu (9.9 μg/L, 56.2 μg/L, 139.3 μg/L, 139.5 μg/L, and ND μg/L), Fe (463.6 μg/L, 237.8 μg/L, 55.4 μg/L, 142.5 μg/L, and 359.4 μg/L), Pb (60.6 μg/L, 25.6 μg/L, ND, 7.7 μg/L, and 40.3 μg/L), and Zn (189.4 μg/L, 275.8 μg/L, 265.6 μg/L, 307.1 μg/L, and 147.6 μg/L), whereas Cd levels in all zones were below the detection limit. In addition, results indicated that Pb and Fe had the same trend that is exceeding the permissible limit set by WHO, EPA, and Jordanian guidelines. A high positive correlation (r = 0.93) was found between Pb and Fe. Also, the altitude had a positive correlation between Pb and Fe concentrations, that is, as the altitude increases the concentration of Pb and Fe increases.