Chlorination-induced pKa decrease: an improved strategy to design ratiometric hypochlorite fluorescent probes with ideally high selectivity.

Based on the selective ClO--triggered chlorination reaction and the subsequent pKa decrease of phenols, a new strategy was developed for rationally designing ratiometric ClO- fluorescent probes with high selectivity. By investigating the fluorescence responses of 6-cyano-2-naphthol toward ClO- and the pKa-dependent response mechanism, we developed a rapid, sensitive and selective two-photon ratiometric fluorescent probe, Naph-DFOB, to detect ClO-. This probe displayed a ratiometric fluorescence change (from 509 nm to 628 nm) toward ClO- and was successfully applied to image intracellular ClO- in living cells with two-photon excitation. Using Naph-DFOB as a useful tool, the investigation of lipopolysaccharide (LPS)-induced acute lung injury in a mouse model was effectively performed.

Determination, residue analysis, dietary risk assessment, and processing of flupyradifurone and its metabolites in pepper under field conditions using LC-MS/MS.

An effective method based on LC-MS/MS was established to determine the concentrations of flupyradifurone, difluoroacetic acid, and 6-chloronicotinic acid in pepper. On the basis of this method, the dissipation, processing factor, and dietary risk of flupyradifurone in pepper were investigated. The results show that the half-life of flupyradifurone in peppers was 2.6-3.8 days. The terminal residual concentration of flupyradifurone in the supervised trials was not higher than the maximum residue limit (MRL) for pepper in the Codex Alimentarius Commission (CAC) (0.9 mg kg-1 ) with the highest residual values of 0.53 mg kg-1 . The national estimated daily intake of flupyradifurone was 0.00094 mg kg-1 , based on the dietary structure of Chinese consumers and the terminal residues under field conditions. The risk quotient for flupyradifurone was 0.012, which was significantly < 1. The processing factor of flupyradifurone in dried pepper was 10.9-14.2, which indicated that drying increased the residual amounts of flupyradifurone in dried pepper, but the residual concentration was still lower than its MRL of 9 mg kg-1 established by CAC.