New spectrophotometric protocol using tetra-thiosemicarbazone derivative chelating (TTSC) for the assessment of trace level of cadmium(II) in drinking water

The chromogenic sulphur containing reagent, tetra-thiosemicarbazone derivative (TTSC), has been sono-synthesised with high yield and characterised to develop a new reagent for the determination of cadmium ion (Cd(II)) in drinking water. The prepared reagent was successfully applied to determine the selective spectrophotometric of Cd(II) in drinking water. In this protocol, Cd(II) reacts selectively with TTSC in a buffer solution of pH 9 to generate an instantly green-coloured complex (Cd⁺²-TTSC) which has a maximum absorbance at wavelength 422 nm. For more than 24 hours, the Cd⁺²-TTSC complex remains stable and found to be composed of 2:1 [Cd⁺²: TTSC]. Variable parameters those affecting the Cd⁺²-TTSC efficiency were assessed and optimised. Under the optimum conditions, the Cd(II) complex adheres to Beer’s law up to 12 μg/L Cd(II). The analytical validation parameters of the methods in terms of limit of detection (LOD), limit of quantification (LOQ), precision, linearity (r²) and relative standard deviation (RSD%) were assessed and obtained 0.16 μg/L and 0.48 μg/L for LOD and LOQ, respectively, with the linearity of r² > 0.9995 and RSD% was found to be <2%. The developed method was successfully applied in the simultaneous assessment of Cd(II) in pure forms and spiked samples of water. The reliability and accuracy of the current protocol recommended to be applied for the determination of Cd(II) in all desalination plant and bottled water samples without utilisation of long procedures and sophisticated instrumentation.