Flow-through photometric sensor for the determination of cadmium at the nanogram per millilitre level

Abstract

A sensor for the determination of cadmium based on retention of the CdI4" complex on a QAE Sephadex resin located in the flow-cell of a conventional photometric detector and on subsequent complex displacement reaction with 4-(2-pyridylazo)-resorcinol is proposed. Formation of the colored chelate and detection take place simultaneously. The method features a determination range between 30 and 500 ng/ml of Cd(II) with relative standard deviations of 1.8% and 3.4% for 200 and 50 ng/ml of Cd(II), respecttively. The selectivity involved in the use of the proposed sensor is shown in the study of interference.