Simultaneous detection of SO₃^2- and PO₄^3- anions, in aqueous solutions based on 4-(2-Pyridylazo) resorcinol (PAR) as a colorimetric chemosensor and analytical applications

ABSTRACT

Herein, we have presented a novel bare eye detection method which is based on the anion competing for a metal receptor with a chromogenic indicator. In this essay, there are highly specific interactions among the anions and the metal ions and 4-(2-Pyridylazo) resorcinol (PAR) probe in a competition assay format. The system designing is simple and it is fast in operation so that is promising than other methods because it did not need organic solvents, preparation and separation processes, chemical modification and equipped devices. In this way, Cd²⁺ and Cu²⁺ ions were detected by changing colour from yellow to light orange and red, respectively (in aqueous solution), which could be distinguished by naked eyes. The selectivity of these complexes towards anions wassurveyed by competition experiments in the presence of different anions. The obtained results were shownin which there were variations in the UV-Vis spectrum and colour of the solution of the [PAR-Cd²⁺] in the presence of SO₃^2- and PO₄^3- anions. The high sensitivity and selectivity for phosphate and sulphite were obtained by changing the metal ions. That is, by using Cu²⁺ instead of Cd²⁺in the PAR-metal, only SO₃^2- anion was detected and the detection limit of SO₃^2- ion was obtained 1.20 µmol L⁻¹. This novel system has employed for simultaneous determination SO₃^2- and PO₄^3- anions in some real samples by changing the metal ion in the complex. Furthermore, the INHIBIT molecular logic gate was obtained using chemical inputs (Cu²⁺ and SO₃^2-) and UV-Vis absorbance signals as the output.

KEYWORDS:

• Colorimetric chemosensor
• phosphate chemosensor
• sulphite chemosensor
• molecular logic gates

Acknowledgements

The authors wish to acknowledge the support of this work by Shiraz Payame Noor University Research council with grant IDs d/7/47416 and Layout code 3146.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the Shiraz Payame Noor University Hossein Tavallali Research council [grant IDs d/7/47416 and Layout code 3146.].