Determination of heavy metals in air particulate matter by using ion chromatography

Abstract

In recent years, ion chromatography has been increasingly used for the separation and determination of heavy metals. In this study, the separation of Cu2+, Ni2+, Zn2+, Co2+, Pb2+ and Fe2+ in airborne particulate samples was achieved by the use a complexing eluent containing 20 mM oxalic acid and 20 mM citric acid adjusted to pH 3.6 with lithium hydroxide. Upon elution, the separated metal ions were reacted with 4-(2-pyridylazo)resorcinol to form coloured complexes in a postcolumn reactor and detected by using a UV-Vis detector at 520 nm. The calibration graphs for the metal ions were linear in the range 1.0–3.0 μg/ml for Cu2+, Ni2+, Co2+ and Zn2+, 8.0–24.0 μg/ml for Pb2+ and 2.0–6.0 μg/ml for Fe2+. Detection limits for a 25-μl sample solution were 2.2, 0.9, 6.6, 0.9, 1.8 and 2.1 μg/l for Cu2+, Ni2+, Zn2+, Co2+, Pb2+ and Fe2+, respectively. The technique was optimized and validated by analysing the NIST standard reference materials SRM 1648 Urban Particulate Matter and SRM 1633b Coal Fly Ash.