Selective optical aqueous and nonaqueous detection of free sulfites
AssigneeThe Research Foundation for The State University of New York
InventorsLynn Schmitt, Alistair Lees
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Abstract
4-pyrrolylpyridine, a novel anion sensor, displays a substantial color loss upon addition of sodium sulfite in aqueous solvents. A variety of anions were tested, including halides, phosphates, sulfates, and hydroxide, but all solutions remained unchanged aside from the sulfite, which displayed bleaching. Described here is a method for which the exact concentration of sulfites in a consumer product can be determined. The test is sensitive over a broad range of sulfites, from 0.84 ppm to over 10,000 ppm, and is accurate with a standard deviation of 0.01 ppm.
Claims20
A method of binding free sulfite concentration in an aqueous analyte, comprising reacting the free sulfite with a compound having a 4-(1H-pyrrol-2-yl)pyridine ligand structure.
A method for determining a colorimetric change resulting from reacting free sulfite in an aqueous analyte with a 4-(1H-pyrrol-2-yl)pyridine ligand, comprising:
- reacting a mixture having a pH between pH 2 and pH 10, of the 4-(1H-pyrrol-2-yl)pyridine ligand and the free sulfite to cause a bleaching of the 4-(1H-pyrrol-2-yl)pyridine ligand;
- measuring a change of an optical absorption of the mixture;
- calculating a concentration of the 4-(1H-pyrrol-2-yl)pyridine ligand based on the change in the optical absorption.
A reagent for detecting free sulfite in a solution, comprising 4-(1H-pyrrol-2-yl)pyridine:
- in an aqueous solution comprising less than 50% acetone and having sufficient acid to catalyze a spontaneous reaction between the 4-(1H-pyrrol-2-yl)pyridine and the free sulfite to form sulfite 4-(1H-pyrrol-2-yl)pyridine:
- wherein the sulfite 4-(1H-pyrrol-2-yl)pyridine has an optical absorption spectrum which is distinct from an optical absorption spectrum of 4-(1H-pyrrol-2-yl)pyridine, to thereby permit quantitative spectrophotometric determination of sulfite in the solution.
Dependencies are inferred from the claim text.