A novel bulk optode for ultra-trace detection of antimony coupled with spectrophotometry in food and environmental samples

Abstract

A novel bulk optode was modified for ultra-trace detection of antimony. The optode was synthesized by incorporating fabricated ionophore, 6-{4-(2,4-di-hydroxyphenyl)diazenyl)phenyl}-2-oxo-4-phenyl-1,2-dihydropyridine-3-carbo-nitrile (DDPODC), 3-octadecanoylimino-7-(diethyl‑amino)-1,2-benzophenoxa-zine (ETH5294) as a chromoionophore, sodium tetraphenyl borate (NaTPB) as an anionic additive, and dioctyladipate (DOA) as a plasticizer in a poly vinyl chloride (PVC) membrane. In determining Sb³⁺, various parameters were implemented. Spectrophotometric procedure (λ_max of 661 nm) was applied to define Sb³⁺ within optimal conditions. The optode has a wide range of 2.5 × 10⁻⁸ to 4.0 × 10⁻⁵ M Sb³⁺ with the detection and quantification limits as low as 7.0 × 10⁻⁹ and 2.4 × 10⁻⁸ M, respectively. The response time of optode was 3.0 min, with a RSD% of 1.75% (for 2.0 × 10⁻⁵ M, n=6). A 0.15 M HCl solution could be used to regenerate the optode. The interfering ions were studied. It was revealed that the optode was highly selective to Sb³⁺ ions and had no significant response to common cations and anions. It can be appealed that the optode can specifically detect Sb³⁺ ions. The optode was favorable applied to assess total antimony ions after reduction of Sb⁵⁺ to Sb³⁺ using potassium iodide and ascorbic acid as reducing agents in various water, food and biological samples.