Author: E.P. Ramdhani, H. Pardi, D. Sarkity, D.S. Yusiani and T.W. Edelwis

DOI: http://doi.org/10.31788/RJC.2026.1929660

This work presents an alternative voltammetric approach for trace Cd(II) analysis based on complex formationwithAlizarin followed by cathodic adsorptive stripping detection. The analytical signal originates fromtheelectroreduction of the surface-accumulated Cd–AZ complex at about –0.46 V on an HMDE, where controlledpreconcentration enhances measurement sensitivity. Careful adjustment of chemical and instrumental factors suchasacidity of the medium, ligand concentration, deposition time, and deposition potential was carried out to ensurestable and reproducible responses while minimising matrix interference. Under optimised parameters (pH3.4; AZ0.6 mmol/L; accumulation time 60 s; accumulation potential 0.35 V; buffer strength 40 mmol/L), the methodprovided a broad linear working range between 0.05 and 100 µg/L with a detection capability down to 0.01 µg/L. Repeatability was excellent, showing an RSD of 0.5% for ten successive determinations at 10 µg/LCd(II). Comparative analysis with AAS confirmed the reliability of the results for real seawater samples obtained fromareas previously affected by bauxite extraction. These findings indicate that the developed procedure offers adependable and highly responsive tool for monitoring cadmium contamination in coastal environments.

Keywords: Alizarin, Hanging Mercury Drop Electrode, Atomic Absorption Spectrophotometry, AdsorptiveStripping Voltammetry.