Development of a simple and rapid method for the determination of sulphite in sugar using digital image colorimetry

• Grant number: 25/05016-0
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: June 01, 2025
• End date: May 31, 2026
• Field of knowledge: Physical Sciences and Mathematics - Chemistry - Analytical Chemistry
• Principal Investigator: Orlando Fatibello Filho
• Grantee: Eduarda Martins de Barros
• Host Institution: Centro de Ciências Exatas e de Tecnologia (CCET). Universidade Federal de São Carlos (UFSCAR). São Carlos , SP, Brazil

Abstract

The presence of sulphites in foods such as refined sugar requires simple and rapid analytical methods for their quantification, due to their potential risks to consumer health. The most widely used method for determining sulphite in sugar is based on the colorimetric reaction with pararosaniline (basic fuchsin) in an acidic medium, in the presence of formaldehyde. However, this is a very time-consuming method that requires the preparation and standardization of several solutions. This IC project aims to develop and validate a colorimetric method based on the decolorization of the pararosaniline solution by sulphite without using formaldehyde. The reaction of sulphite with pararosaniline in a neutral medium result in the decolorization of the solution, the intensity of which will be monitored using digital image colorimetry using a smartphone (SDIC). The difference in colour intensity of the solution before and after the reaction will be used to quantify the sulphite present in the sample. The analytical parameters of the method will be evaluated, namely: linearity, sensitivity, accuracy, precision, limit of detection (LOD) and limit of quantification (LOQ). The results obtained will be compared with those determined by the reference method for the quantification of sulphite in refined sugar (ICUMSA GS2-33). The proposed method may represent a fast, sensitive and low-cost alternative for quality control analyses, ensuring efficient monitoring of sulphite levels in refined sugar samples.