Translation of Carbon Dot Biosensors into an Embedded Optical Setup for Spoilage and Adulteration Detection

Abstract

This research demonstrates a carbon quantum dot (CQD) based fluorescence technique for milk quality assessment and detection of urea adulteration using a commercialized optical fiber spectrometer (OFS) and a developed color sensor device (CSD). The change in pH from the normal pH of milk (∼6.7) indicates spoilage. The CQDs were synthesized using phthalic acid (carbon source) and triethylenediamine (TED) (passivant). The CQDs were found to be sensitive in the pH range 3–10 with a quantum yield of about 18.9%. The accuracy of spoilage detection using CQDs was expressed in the form of mean percent recovery and found to be 99.2% (R2 = 0.97) by the OFS and 99.59% (R2 = 0.98) by the CSD. The mean percent recovery obtained for urea adulteration in milk was 103.0% (R2 = 0.98) by the OFS and 97.9% (R2 = 0.97) by the CSD. The results indicate that CQDs have excellent potential for use as biosensors for spoilage and adulteration detection.