ABSTRACT
The abuse of organophosphate pesticides causes serious threats to human health, which threatens approximately 3 million people and leads to more than 2000 deaths each year. Therefore, it is necessary to determine the residue of fenitrothion (FT) in environmental and food samples. Herein, we developed a non-enzymatic electrochemical sensor with differential pulse voltammetry signal output to determine FT in model solutions and spiked samples. Delicately, the sensor was designed based on the fabrication of hydrothermally synthesized titanium-based metal-organic frameworks (MOFs) material (NH2-MIL-125(Ti))/reduced graphene oxide (RGO) (NH2-MIL-125(Ti)/RGO) nanocomposites for better target enrichment and electron transfer. The peak response of differential pulse voltammetry for FT under optimized conditions was linear in the range of 0.072-18 µM with the logarithm of concentrations, and the detection limit was 0.0338 µM. The fabricated sensor also demonstrated high stability and reproducibility. Moreover, it exhibited excellent sensing performances for FT in spiked agricultural products. The convenient fabrication method of NH2-MIL-125(Ti)/RGO opens up a new approach for the rational design of non-enzymatic detection methods for pesticides.
ABSTRACT
In order to assess the contamination degree and ecological risk of antibiotics in Gonghu Bay, Taihu Lake, the contamination characteristics of four kinds of antibiotics (tetracycline, quinolones, sulfonamides and macrolides) in surface water of the Gonghu Bay were analyzed using high performance liquid chromatography and tandem mass spectrometry (HPLC-MS/MS). The results showed that 13 of the 16 target antibiotics were detected in the Gonghu Bay. The mass concentrations of the 13 antibiotics ranged 0.005-4.720 µg·L-1, and OTC was of the highest concentration. The detection level of antibiotics was also different between the northern and the southern parts of Gonghu Bay, and the mass concentration of tetracycline in the northern part was higher than that in the southern part. Moreover, the concentrations of quinolones and sulfonamides in the southern part were larger than those in the northern part. The potential ecological risks of the detected antibiotics were assessed via using the risk quotients (RQs) approach. The preliminary results showed that 5 kinds of antibiotics: OTC, NOR, OFL, CIP and ENR were at high risk, accounting for 38.5% and 4 kinds of antibiotics TC, CTC, ROX and SMX were at medium risk, accounting for 30.8% in the antibiotics detected in Gonghu Bay, while the others (SMR, SMP, SQX, TMP) were at low risk. Ecological risk assessment revealed that some risks were present in antibiotics in the Gonghu Bay. The tetracyclines and quinolones were particularly prominent, which should be drawn enough attention, and corresponding preventive measures should be taken as well.
