A Simple and Rapid Phosphorescence Probe Based on Mn-Doped ZnS Quantum Dots for Chloramphenicol Detection

An innovative phosphorescence probe based on Mn-doped ZnS quantum dots (Mn:ZnS QDs) was developed for selective detection of chloramphenicol (CAP) via inner-filter effect (IFE). Mn:ZnS QDs were synthesized by water method and modified with L-Cysteine for better stability, and the average diameter of the nanometer particle was 3.8 $$ nm. With the excitation wavelength at 289 $$ nm, the strong phosphorescence of Mn:ZnS QDs can be emitted at 583 $$ nm. The excitation spectrum of Mn:ZnS QDs was substantially overlapped with the absorption spectrum of the target CAP. The excited light of Mn:ZnS QDs can be absorbed partially by CAP when they coexist, the phosphorescence intensity decreased with the increasing concentration of CAP, and it has a good linear relationship. Under optimal conditions, the linear relational concentration range achieved four orders of magnitude from 25 to 1 . 2 × 1 0 5 ng ⋅ mL − 1 $1.2\times 10^5\mathrm{\text{ng}}\cdot {\mathrm{\text{mL}}}^{-1}$ ( R 2 = 0 . 9 9 9 $R^2=0.999$ ), with a detection limit (LOD; S ∕ N = 3 $S∕N=3$ ) down to 0.81 $$ ng ⋅ mL − 1 $\mathrm{\text{ng}}\cdot {\mathrm{\text{mL}}}^{-1}$ . The simple, rapid and low cost IFE phosphorescent probe exhibited satisfactory recoveries ranging from 88.9% to 98.5% for CAP analysis in spiked honey, which shows a potential for routine screening of CAP in ensuring the food safety.