Selective detection of antimony using a regenerative optical sensor for environmental and biological applications

A novel environmentally eco-friendly approach for developing an optical sensor membrane tailored for the detection of antimony ions (Sb³⁺) has been explored. The sensing membrane was developed by incorporating 2,3-dichloro-6-(2,7-dihydroxynaphth-1-ylazo)quinoxaline (DCHNAQ) and tri-(2-ethylhexyl) phosphate (TEHP) into a triacetylcellulose (TAC) polymer matrix. The sensor demonstrated a linear detection range for Sb³⁺ ions between 8.0 and 144 ng mL^-1, with a detection limit of 2.5 ng mL^-1. Additionally, employing a thiel buffer at pH 6.5 as the stripping phase facilitated efficient Sb³⁺ transfer, even in the presence of significant competing anions within the analyzed samples. Complete regeneration of the optode was achieved in 2 min using 0.1 M hydrochloric acid. The method showed excellent precision, with RSD of 2.20% and 1.45% for Sb³⁺ concentrations of 50 and 100 ng mL^-1, respectively. The membrane exhibited high selectivity for Sb³⁺ over other interfering ions, offering results comparable to those obtained from the colorimetric analysis of Sb³⁺ in solution. The proposed optode was successfully validated against ICP-OES and spiked recovery methods for determining total antimony in biological, food, and environmental samples, following the reduction of Sb⁵⁺ to Sb³⁺ using ascorbic acid and potassium iodide. Statistical analysis revealed that the calculated t- and F-values were within the expected range, confirming that no significant differences were found between the proposed and ICP-OES procedures.