Online Analyzer for Monitoring of Heavy Metals in Groundwater Using Diffusive Gradients in Thin Films and X-Ray Fluorescence Techniques

This paper aims at meeting the increasing demand of heavy metal monitoring in groundwater. An online analyzer is developed using diffusive gradients in thin films (DGT) and X-ray fluorescence (XRF) techniques. Compare to the spectrophotometric method and the anodic stripping method, the developed analyzer has the advantage of low reagent consumption and can measure multiple metallic parameters simultaneously. A novel analysis procedure including clipping, immersing, enriching and XRF analyzing of a DGT device is described in the paper. The procedure is automated by a IAC2000 PLC system. Experiments were undertaken to verify the performance of the analyzer. Cr and Pb were chosen to assess the repeatability, accuracy and limit of detection of the analyzer. A repeatability of 5%, accuracy of 10% and limit of detection of 0.15mg/L is achieved.