A simple optical sensor for cadmium ions assay in water samples using spectrophotometry

A new simple and inexpensive optical chemical sensor for cadmium(II) ions is presented. The cadmium sensing system was prepared by incorporating 2-amino-cyclopentene-1-dithiocarboxylic acid (ACDA) on a triacetylcellulose membrane. The absorption spectra of the optical sensor membrane in Cd(II) solution showed a maximum peak at 430 nm. The proportionality in intensity of the membrane color on the optode to varying amounts of Cd(II) suggests its potential applications for screening Cd(II) in aqueous samples by visual colorimetry. The sensor provided a wide concentration range of 3.0 × 10⁻⁶–3.4 × 10⁻⁴ M of Cd(II) ions with a detection limit of 1.0 × 10⁻⁶ M (0.2 μg/mL). The relative standard deviations for eight replicate measurements of 8.0 × 10⁻⁶ and 5.0 × 10⁻⁵ M Cd(II) were 2.7 and 2.3%, respectively. The response time of the optode was 6 min. The influence of interfering ions on the determination of 1.0 × 10⁻⁵ M Cd(II) was studied and the main interferences were removed by extraction method. The sensor was applied to the determination of Cd(II) in water samples.