Tungsten disulfide (WS₂)/fluorescein ratiometric fluorescent probe for detection of cefixime residues in milk

In this research work, it has been reported a ratiometric fluorescent sensor based on tungsten disulfide quantum dots (WS₂ QDs) and fluorescein for the determination of Cefixime (CEF). When excited by radiation of 400 nm wavelength the probe illustrates dual emissions centered at 460 nm and 510 nm. CEF quenches the fluorescence (FL) intensity of fluorescein (510 nm), while it doesn't affect the FL emission of WS₂ QDs at 460 nm. The change in the ratio of the two peaks (F₄₆₀/F₅₁₀₎ of the prepared sensor (WS₂ QDs/fluorescein) is linearly proportional to the CEF concentration in the range of 200–2.500 ng/mL with a limit of detection (LOD) of 45 ng/mL. Hence, the proposed probe can be successfully used for CEF quantification in the milk samples.