Rhodamine B phenylhydrazide as a new chemosensor for sulfite quantification: Application to food samples

A simple and sensitive spectrophotometric method for the quantification of sulfite at trace level has been proposed. The method is based on the change in the intensity of the color developed on reaction of sulfite with Rhodamine-B Phenyl hydrazide (RBPH) in aqueous micellar medium. The experimental conditions such as pH, concentration of RBPH and Tween 80 have been optimized and calibration plot has been constructed. The proposed method offers a wide linearity in the concentration range 0–15 ppm of sulfite. The limit of detection and limit of quantification were found to be 0.006 and 1.5 ppm respectively, with the regression co-efficient R2 = 0.992. The proposed method has been successfully applied to measure the trace level sulfite in food samples such as tomato ketchup, jam, dry grapes, sugar and wine. Comparison of the developed method with standard protocol showed good recoveries.