A Water-soluble Fluorescent Probe Based on Chitosan for Hypochlorite and Nitrite Detection

Area of Science:

• Analytical Chemistry
• Materials Science
• Food Science

Background:

• Hypochlorite (ClO-) and nitrite (NO2-) are widely used in the food industry.
• Accurate and rapid detection methods for ClO- and NO2- are crucial for food safety and quality control.

Purpose of the Study:

• To develop a novel, cost-effective, and efficient fluorescent probe for detecting hypochlorite and nitrite.
• To enable rapid and portable analysis of these analytes in complex food samples.

Main Methods:

• A novel fluorescent probe, CS-BP, was synthesized by chemically incorporating phenothiazine derivatives (BP) onto chitosan (CS) via a Schiff base linkage.
• The probe's fluorescence response to ClO- and NO2- was investigated, along with its selectivity and detection limits.
• pH adjustment was used to differentiate between ClO- and NO2- detection.
• A smartphone-based detection system and test strips were developed for practical applications.

Main Results:

• The CS-BP probe exhibited a specific "turn-off" fluorescence response with a color change from yellow to colorless upon reaction with ClO- or NO2-.
• The detection limits for ClO- and NO2- were determined to be 0.54 µM and 0.83 µM, respectively.
• Effective differentiation between ClO- and NO2- was achieved by adjusting the solution's pH.
• The probe demonstrated excellent selectivity and versatility when incorporated into test strips, cotton swabs, and fluorescent films for analyzing complex samples.

Conclusions:

• The developed CS-BP fluorescent probe is a promising tool for the rapid, low-cost, and selective detection of hypochlorite and nitrite.
• The probe's adaptability for smartphone-based analysis and integration into various formats (test strips, films) highlights its potential for practical applications in the food industry.