Synthesis of carbon quantum dots from waste Phaseolus vulgaris for the development of a fluorescence sensing probe to detect plasticizer in cookies

Dibutyl phthalate (DBP) is a commonly used plasticizer in the fabrication of various packaging materials, however upon exposure, it poses significant health and environmental hazards. These plasticizers consist of low-molecular-weight components, which permeate easily into the food matrix. Hence, the development of a cost-effective detection technique is necessary for the detection and monitoring of DBP. Therefore, this research focuses on the utilization of broken Phaseolus vulgaris-derived carbon quantum dots (PV-CQDs) as a fluorescent probe for the detection of DBP in cookies. Herein, PV-CQDs were synthesized through a hydrothermal reaction, which exhibited a blue color under UV-luminescence and localized surface plasmon resonance spectrum at 238 and 270 nm. The highest fluorescence emission intensity was recorded at 428 nm. The resulting PV-CQDs exhibited an average particle size of 1.22 ± 0.05 nm and prominent peaks obtained during infrared spectroscopy were found to be of carboxylic and hydroxyl functional groups, respectively. Transmission electron microscopy and energy dispersive spectroscopy analyses confirmed the spherical morphology and elemental composition, which include C (58.05% by weight) and O (41.92% by weight), respectively. The topographical height profile of the PV-CQDs was observed by atomic force microscopy and it was found to be approximately 100 µm with a thickness of 2.9 µm . The inherent fluorescence of CQDs demonstrated notable quenching efficiency when exposed to varying concentrations of 0.1, 0.2, 0.3, 0.4, 0.5, 1, 5, and 10 µM of DBP residue, resulting in a linear relationship with a high detection sensitivity of 3.19634 µM. Furthermore, the developed method was successfully implemented to determine DBP in cookies, achieving recovery rates within the range of 97–99%. Thus, the rapid sensing capabilities of CQDs could be highlighted as their promising potential for the detection of DBP in food products.