Carbon dots derived from citric acid and urea as fluorometric probe for determining melamine contamination in infant formula sample

Souliyanh Phimmasone; Pornthip Boonsri; Weena Siangproh; Nuanlaor Ratanawimarnwong; Piyada Jittangprasert; Thitirat Mantim; Nunticha Limchoowong; Kriangsak Songsrirote

doi:10.1088/2050-6120/acf547

Carbon dots derived from citric acid and urea as fluorometric probe for determining melamine contamination in infant formula sample

Methods Appl Fluoresc. 2023 Oct 12;12(1). doi: 10.1088/2050-6120/acf547.

Authors

Souliyanh Phimmasone¹, Pornthip Boonsri¹, Weena Siangproh^{1

2}, Nuanlaor Ratanawimarnwong^{1

2}, Piyada Jittangprasert^{1

2}, Thitirat Mantim^{1

2}, Nunticha Limchoowong^{1

2}, Kriangsak Songsrirote^{1

2}

Affiliations

¹ Department of Chemistry, Faculty of Science, Srinakharinwirot University, Sukhumvit 23, Wattana, Bangkok 10110, Thailand.
² Center of Excellence in Agricultural Innovation and Food Safety, Faculty of Science, Srinakharinwirot University, Bangkok, 10110, Thailand.

PMID: 37647911
DOI: 10.1088/2050-6120/acf547

Abstract

Melamine has been intentionally added into food products to increase the protein count at less cost, especially in dairy products for infant resulting in serious adverse effects on health of consumers. Therefore, this study aimed to develop a method to quantify melamine in dairy products based on the change of fluorescent properties of carbon dots (CDs) as sensing probe. CDs with green-fluorescent emission were synthesized from citric acid and urea under microwave irradiation. The synthesized CDs emitted fluorescence at the maximum wavelength of 538 nm with excitation wavelength of 410 nm. Thus, they provided high sensitivity and selectivity on melamine detection by which fluorescent emission of the CDs was increasingly quenched upon increasing melamine concentrations. Optimal conditions for melamine determination using the CDs was under pH 6, volume ratio between CDs and sample of 2:8 and reaction time of 15 min. The developed method provided high precision of melamine determination with less than 5% of %RSD (n = 5), wide detection range from 1.0 to 200.0 ppm, and high sensitivity with limit of detection (LOD) of 0.47 ppm and limit of quantification (LOQ) of 1.56 ppm, which is within the regulated level by the Food and Drug Administration of the United States for melamine in dairy products. Several analytical characterization techniques were conducted to elucidate the reaction mechanism between CDs and melamine, and the hydrogen bonding interaction was proposed.

Keywords: carbon dots; detection; fluorescence quenching; infant formula; melamine.