A strategy based on CsPbBr 3 quantum dots (QDs) is described for the determination of ziram pesticide. A facile and inert gas-free method was used for the synthesis of CsPbBr 3 QDs. The obtained CsPbBr 3 QDs displayed turn-off fluorescence behavior for ziram. The fluorescence intensity of the CsPbBr 3 QDs ( E x / E m = 365/516 nm) was inversely proportional to the concentration of ziram (0.10 to 50.0 ppm) with a detection limit of 0.086 ppm. Notably, satisfactory recoveries (100 ± 0.25 to 107 ± 5.72%) were obtained in spiked fruit samples, which demonstrated that this method is capable of detecting ziram in real samples. In addition, the mechanism for the detection of ziram was investigated in detail. According to the results, this mechanism can be tentatively explained by fluorescence quenching originating from the increased surface defects and the structural changes of the CsPbBr 3 QDs. The detection ability of this strategy shows promising applicability in food safety. Graphical abstract
Precise administration of tirofiban must be carefully considered to achieve the best treatment efficacy and maximize safety for patients. Herein, a paper spray ionization (PSI) linear ion trap (LIT) portable mass spectrometer (pMS) based point-of-care testing (POCT) technique was developed for on-site sampling, clinical testing, and immediate analysis of tirofiban blood drug concentrations. The results showed that tirofiban formed a significant and stable parent ion peak at m/z 441.3 by MS1 full scan in positive ion mode, which fragmented into product ions at m/z 395.4, m/z 321.3, m/z 276.3, and m/z 260.3 through collision-induced dissociation (CID) in MS/MS. To improve ion response, the parameters were optimized to the voltages of ionization 3600 V, ion isolation 1 (ISO1) 8 V, ion isolation 2 (ISO2) 2 V, and collision-induced dissociation (CID) 3 V. This method was validated, and the limit of detection (LOD) and limit of quantification (LOQ) were found to be 10.1 and 33.7 μg·L–1, respectively. For precision, it had the relative standard deviation (RSD) of interday precision of 4.8 to 6.7% and the RSD of intraday precision of 7.8 to 8.3%. The recovery of the method ranged from 87.5 to 93.4%. Although matrix effects in blood samples had some inhibitory effects on the target signal formation, the method compensated for part of the matrix effects by establishing a matrix-matched calibration curve, which exhibited good linearity with a R2 of 0.9987. Finally, the method was applied to the detection of tirofiban in clinically collected blood samples. Out of 12 samples, ten had tirofiban concentrations between 35.4 and 72.1 μg·L–1 while the remaining two were below the LOQ. The method needs further optimization and validation in the future to improve its sensitivity and stability.
危险品化学品经营许可证（带存储）