In order to investigate the retention and elimination of furacillin metabolites (semicarbazide,SEM) in the muscle of T.flavidus following the use of furacilin during the breeding process,the aquaculture pond was treated with 0.50 g/m³ of furacillin.Muscle samples of T.flavidus were then collected at regular intervals.The concentrations of SEM were determined using high-performance liquid chromatography-tandem mass spectrometry,and the data was analyzed by using Excel 2013.The results showed that furacillin was rapidly metabolized to SEM in T.flavidus after dosing.The levels of SEM in the muscles increased rapidly,reaching their highest value after approximately 4 days.The elimination rate of SEM was initially fast,but slowed down over time.Even after 77 days following dosing,the residual amount of SEM in the muscles was still around 2.50 μg/kg,which was above the limit of detection.This suggests that SEM has a prolonged residual time in T.flavidus after the administration of furacilin.Based on these findings,it is strongly recommended to strictly prohibit the use of nitrofurans,such as furacilin,during the breeding process of T.flavidus,in order to ensure the quality and safety of puffer fish.

A high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method was developed for the quantitative determination of mebendazole in aquaculture water.The limit of quantification was 0.5 μg/L.The average recoveries of the three spiked levels ranged from 79.0% to 93.9%.The intra-day and inter-day relative standard deviations (RSDs) were 7.57%-8.27% and 7.43%-8.11%,respectively.The actual application concentrations of 15 μg/L and 50 μg/L were used as the tested concentrations for the elimination experiments of mebendazole in aquaculture water,respectively.The results showed that mebendazole was a photosensitive drug whose photodegradation followed the first-order kinetics.The photolytic degradation rate of mebendazole in outdoor aquaculture water under natural light was more than 80% after 648 h.The elimination half-life of mebendazole was 231.05 h at 15-18℃.At the end of the experiment (648 h),6.4 μg/L of mebendazole was still detected in the high concentration group(50 μg/L).Therefore,the results of this study could provide basic data for the pharmacokinetic study of mebendazole in aquaculture animals.

A highly sensitive detection of 10 nitroimidazole drug residues in aquatic products has been achieved by optimizing the sample pretreatment methods combined with high performance liquid chromatography-tandem mass spectrometry(HPLC-MS).The nitroimidazole drug residues in samples were extracted with ethyl acetate and removed fat by n-hexane,then quantified by the external standard method after detected in the positive ion mode by high performance liquid chromatography-tandem mass spectrometry.Under the optimized pretreatment methods and instrument conditions,the calibration curves were linear in a concentrations range of 5.00~200 μg/mL with R>0.995 0.The average recovery was 70.2%~119% and the relative standard deviation was in the range of 1.46%~13.5% for spiked aquatic sample with 1.00 μg/kg,2.00 μg/kg and 5.00 μg/kg of nitroimidazoles.The accuracy and precision of the method was in accordance with the requirements of veterinary drug residue detection,and the operation was simple and fast.It showed that the method was suitable for the nitroimidazole drug residues detection of large quantities of samples.

In this study, the boron content of surimi products and processing materials was determined. A total of 33 surimi samples were collected with 7 samples detected for boron. The boric acid ranged from 0.743 to 2.00 mg/kg, and the average was 1.43 mg/kg. A total of 33 main processing materials for surimi products were collected according to the production process. The results showed that boron was detected from 11 samples, and background values of boric acid ranged from 0.732 to 53.4 mg/kg. The detection rate of soybean protein isolate was relatively high with 3 samples all detected, and the maximum concentration was 53.4 mg/kg. The results showed that boron was detected in surimi products because of background content of boron in processing materials. This study can provide a scientific basis for the establishment of boron limit standard and daily supervision of surimi products.