Design novel optical sensor for determination of cadmium based on immobilization of β-2-hydroxybenzyl-5-chloro-2-hydroxyazastyrene on agarose membrane

Abstract

An optode featuring high selectivity was prepared for cadmium detection via chemically binding β-2-hydroxybenzyl-5-chloro-2-hydroxyazastyrene (HCHAS) onto a clear agarose membrane. Colorimetric analysis of complexation between HCHAS and various metal ions at pH 2.75 revealed that the Cd2+ complex exhibited a markedly higher stability constant than others. As a result, HCHAS was applied as a suitable ionophore for fabricating a Cd2+-selective optode, via chemically anchoring it onto a transparent agarose matrix. The immobilization experimental parameters were optimized and the resulting optode represented a conspicuous color transition from yellow to purple as a result of increasing Cd2+ concentrations in a pH 2.75 buffered solution. Detailed investigations were conducted to assess the influence of pH, ionophore loading, ionic strength, stirring conditions, and reaction duration on the optode’s performance. A strong linear relationship was noted over the 4-140 ng mL–1 concentration range, with R2 of 0.9882 and 0.9990, respectively. Furthermore, the Cd2+ detection was not consider- ably influenced by the existence of various potentially interfering ions at concentrations 500-fold higher. The fabricated optode was effectively utilized for the quantification of cadmium ions in fortified food, environmental and biological specimens.