A solid-phase extraction-ultra-performance liquid chromatography-tandem mass spectrometry(SPE-UPLC-MS/MS)method was established for simultaneous determination of 10 kinds of neonicotinoid pesticide residues in aquaculture water.Based on the chemical properties of neonicotinoid pesticides and the matrix characteristics of aquaculture water,suitable temporary storage methods for water samples and appropriate solid-phase extraction columns were selected,and the extraction conditions(including elution solvents and sample loading volumes)were optimized.The method employed acetonitrile and 5 mmol/L ammonium acetate solution(containing 0.1%formic acid)as the mobile phase and an Oasis HLB solid-phase extraction column combined with PSA as a dispersive sorbent for sample purification.The method exhibited good linearity in detection of neonicotinoid in concentration range of 0.2-50 ng/mL(R2>0.99797),with a detection limit of 0.5 ng/L and a quantification limit of 1 ng/L,which were significantly lower than the maximum acceptable method detection limits(9-500 ng/L)for neonicotinoid insecticides in water published by the European Commission.In pond water,rice-fish water,and seawater,the average recoveries of the 10 target analytes were 74.6%-114.1%,with relative standard deviations ranging from 0.3%to 9.6%.Using this method,actual sample tests were conducted on the Pearl River water,Zhaoqing pond water,and Qingyuan rice-fish aquaculture water.The total concentration of five neonicotinoid pesticides in the Pearl River water ranged from 154.8 to 246.6 ng/L,the total concentration of four neonicotinoid pesticides in the Zhaoqing pond water was 95.0-176.1 ng/L,and the total concentration of three neonicotinoid pesticides in the Qingyuan rice-fish aquaculture water was 2.3-11.7 ng/L.This method was simple in operation,highly sensitive,and had strong resistance to interference.It was suitable for detection of trace neonicotinoid pesticides in aquaculture water and could provide technical support for construction of a green aquaculture environment and resolution of international trade disputes.

The selective removal of Fe particles from carbonized Fe-MOFs presents an intriguing strategy for developing efficient peroxydisulfate (PDS) activators. It is commonly accepted that their outstanding performance is largely attributed to the high specific surface area/pore volume. However, our investigation into the structure-function relationship of these materials has revealed new insights. In this study, a highly dispersed single-atom Fe and Fe3O4 clusters anchored hierarchical-pore carbon (CM88-H) was obtained via post-acid treatment of carbonized MIL-88B (CM88). Various characterizations were comparatively conducted to highlight the beneficial effects of iron dissolution. The CM88-H/PDS system achieved a notable BPA degradation efficiency, with a reaction rate of 0.323 min-1, which is 3.94 times higher than that of the CM88/PDS system. DFT calculations indicate that the Fe3O4 clusters optimize the charge distribution around single-atom Fe, promoting favorable PDS adsorption and facilitating a higher oxidation state of CM88-H. As a result, BPA can be completely degraded within 10 min with 0.1 g L-1 CM88-H and 0.05 g L-1 PDS via both radical and non-radical pathways. The CM88-H/PDS/BPA system performs effectively under various conditions, with a general reduction in toxicity. Furthermore, the CM88-H/ PDS system shows broad oxidation activity towards BPA substitutes and pollutants with high ionization potential (IP). Notably, the CM88-H sponge-based fixed-bed catalytic reactor demonstrated satisfactory BPA degradation, highlighting the promising application of CM88-H in water purification. This study provides a sustainable solution for water treatment and accelerates the practical application of powdered nanocatalysts to improve water quality.

In recent years, the residue of psychotropic drugs such as diazepam in aquatic products has attracted widespread attention and is one of the important hidden dangers to the quality and safety of agricultural products. This study developed a modified QuEChERS method combined with UPLC-MS/MS to determine the residues of diazepam and its active metabolites, nordiazepam, oxazepam, and temazepam, in aquatic products and aquaculture environments. The important variables of the QuEChERS procedure were screened and optimized through single-factor experiments and response surface methodology. The recoveries of analytes in five aquatic products, pond water, and sediment were 87.4-97.8%, 90.4-96.4%, and 85.2-94.7%, respectively, with relative standard deviations of less than 15%. The limits of quantification were 0.1 μg kg-1 for the four analytes in aquatic products and sediments, and 5 ng L-1 in pond water. This method has been successfully applied to the analysis of diazepam and its active metabolite residues in 28 freshwater aquaculture farms in South China. The detected concentrations of the four analytes in aquatic products, sediments and pond water were 0.18-3.03 μg kg-1, 0.21-17.5 μg kg-1 and 5.56-391 ng L-1, respectively. The illegal abuse of diazepam in fishing bait may be an important source of pollution in aquatic products. The risk assessment results showed that the residues of diazepam in aquaculture posed an acceptable risk to human health and a medium risk to the ecosystem. These results confirmed that the established method is suitable for the simultaneous analysis of diazepam and its active metabolites in aquatic products and aquaculture environments.

A simple and sensitive method for the determination of amphenicol antibiotic (chloramphenicol, thiamphenicol and florfenicol) residues in aquaculture products was developed based on a response surface methodologymodified QuEChERS (quick, easy, cheap, effective, rugged and safe) method combined with ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The pretreatment method was optimized via single-factor experiments and response surface methodology based on central-composite design to maximize the extraction efficiency and purification effect. The results show that chloramphenicol, thiamphenicol and florfenicol had good linearity in the range of 0.1-50 ng/mL. The recoveries of these amphenicol antibiotics in 12 types of aquaculture products ranged from 78.6% to 106.2% with relative standard deviations less than 12.1%. The method had high sensitivity with the limit of quantification of analytes being 0.01-0.04 mu g/kg. Finally, the developed method was used to analyze actual samples. The results show that this method has good application potential for detecting residues of amphenicol antibiotics in aquaculture products.

Metalaxyl is widely used as a racemic mixture to control various plant and aquatic animal diseases caused by fungal infection. It has been proved that the two enantiomers of metalaxyl have significant differences in activity and toxicity, while little is known about the pharmacokinetics and residual elimination of the individual enantiomers of metalaxyl in aquatic animals. In this study, a simple, sensitive and reliable chiral liquid chromatography-tandem mass spectrometry method was established for the determination of metalaxyl and its metabolite metalaxyl acid enantiomers, which was applied to study the stereoselective pharmacokinetics and residue elimination of individual enantiomers in snakehead (Channa argus). The snakehead was bath administered with the racemic metalaxyl and the highly active enantiomeric R-metalaxyl, respectively. The results showed that the elimination of metalaxyl in the plasma and tissues of snakehead was enantioselective. The concentration of metalaxyl in tissues was kidney > liver > muscle, and preferential degradation of the R-metalaxyl enantiomer was observed in three tissues. However, no transformation between metalaxyl enantiomers was observed in snakehead plasma and tissues when R-metalaxyl enantiomer was administered. In addition, the distribution of metalaxyl acid enantiomers in tissues is closely related to the parent compound metalaxyl, and S-metalaxyl acid was only observed in the kidney and slowly eliminated. The highest concentrations of both metalaxyl and metalaxyl acid were observed in the kidney, suggesting that kidney is the major site of metalaxyl metabolism in snakehead. Given that the highly active R-metalaxyl has a shorter half-life and does not undergo transformation between enantiomers in snakehead, it may be a better choice to use R-metalaxyl instead of racemic metalaxyl in clinical practice. The results are helpful to understand the detailed fate of metalaxyl enantiomers and should be considered in future aquaculture, environmental pollution risk and food safety evaluations.

A Quick, Easy, Cheap, Effective, Rugged and Safe pre-treatment method (QuEChERS) was established to evaluate the risk of tetracycline residues in the muscle of Channa argus. The Box-Behnken design (BBD) response surface optimization method was used to optimize the extraction and purification conditions. The samples were extracted with 10 mL acetonitrile (containing 1% formic acid) and 2 mL 0.1 mol/L Na2EDTA-Mcllvaine buffer solution, and the extracts were purified by 150 mg primary secondary amine（PSA）and 200 mg C18, and detected with Ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The result showed that the calibration curve was linear in the range of 0.50~100 ng/mL, with high correlation coefficients (r≥0.999). The limits of detection (LOD) and quantification (LOQ) were 0.25～0.75 μg/kg and 0.84～2.00 μg/kg, respectively. The average recoveries of tetracycline, oxytetracycline, chlortetracycline and doxycycline at three different spiked levels in the muscle of Channa argus were 89.5%～118%, with relative standard deviations (RSDs) of 1.11%～8.88%. This method is simple, sensitive and accurate, and can be used for the rapid quantitative determination of tetracyclines in Channa argus.

•A sensitive and rapid method for the simultaneous determination of three amphenicol antibiotic (chloramphenicol, thiamphenicol and florfenicol) residues in aquaculture products was developed using UPLC-MS/MS.•A modified QuEChERS method was optimized using single-factor experiments and response surface methodology.•Mean recoveries of chloramphenicol, thiamphenicol and florfenicol in 12 types of aquaculture products ranged from 78.6% to 106.2% with RSDs less than 12.1%.•The limit of quantification of chloramphenicol, thiamphenicol and florfenicol were 0.01–0.04 μg/kg.

Enrofloxacin (ENR) is widely used in aquaculture practice, but little is known about its pharmacokinetic, withdrawal period and dietary risk in fish via bath administration. The purpose of this study was to provide data support for the use of ENR bath therapy in the northern snakehead (Channa argus). The pilot study was carried out to evaluate the therapy concentrations of ENR in northern snakehead with immersion concentrations ranged from 5 to 40 mg/L for 6 h. Based on results of the pilot study, an ENR immersion concentration of 20 mg/L was used for the formal experiment. At this dose, the peak concentrations of ENR in plasma, muscle plus skin, liver and kidney were 4.85, 4.55, 3.87 and 7.42 μg/mL (or g), respectively. According to the AUC0-∞ values, the distribution of ENR in northern snakehead followed the order of kidney > plasma > liver > muscle + skin. The elimination of ENR in northern snakehead was very slow, the half-lives (T1/2λz ) were up to 90.31, 85.5, 104.56 and 120.9 h in plasma, muscle plus skin, liver and kidney, respectively. Ciprofloxacin (CIP) was not detected in any samples in the pilot study and was only occasionally detected in muscle plus skin and liver samples in formal experiment. Based on the calculated PK/PD index AUC/MIC and Cmax /MIC, the current bath treatment regimen will have a good therapeutic effect on infections caused by bacteria with MIC below 0.6 μg/mL. The dietary risk assessment suggested that there was a dietary risk (Hazard Quotients > 10%) until day 6 after bath treatment. It is mandatory for ENR to maintain a withdrawal period of at least 450°C-day in northern snakehead after bath treatment ceased.

In this study, a multi-residue determination method of QuECHERS combined with UHPLC-MS/MS was developed to determine nine β-lactam antibiotics (penicillin G, amoxicillin, ampicillin, cephalexin, cefquinome, ceftiofur, cefazolin, cephapirin, cefuroxime) in aquaculture products. All the nine β-lactam antibiotics exhibited excellent linearity within the range of 2.0–200 ng/mL (cefuroxime: 5.0–200 ng/mL, r greater than 0.999), while the limits of detection (LODs) and quantification (LOQs) were 2.0–5.0 μg/kg and 5.0–10.0 μg/kg, respectively. The recoveries of this method in five aquaculture products (Penaeus Orientalis, Cyprinus Carpio, Channa Argus, Aristichthys Nobilis, and Ctenopharyngodon Idella) ranged from 85.4% to 113.3% and the intra-day and inter-day precisions (%RSDs) were less than 15%. The results suggested the feasibility of this method as a rapid, simple, and accurate approach for determining the residues of the β-lactam antibiotics in aquaculture products.

本研究以QuEChERS作为样品前处理手段,建立了测定水产品饲料中地西泮残留的气相色谱-质谱法(GC-MS).样品经纯水和乙腈提取后加入无水硫酸钠除水及氯化钠盐析,提取液经吸附剂中性氧化铝、PSA、纳米二氧化锆结合GCB粉净化后上机检测,内标法定量.结果显示:地西泮在5～500μg/L质量浓度范围内线性关系良好,相关系数为0.9992,对配合饲料、浓缩饲料及饲料添加剂开展3个水平加标回收实验(0.15、0.25、0.50 mg/kg),方法加标回收率为86.3％ ～104.5％,相对标准偏差为1.4％ ～7.8％,地西泮的检出限为0.05 mg/kg,定量限为0.20 mg/kg,方法检出限远低于标准"NY/T 934—2005"的方法检出限1.00 mg/kg.该法具有前处理过程简单、快速、灵敏度高的优点,适合各种水产饲料中地西泮残留的测定.

采用QuEChERS前处理技术,建立了鱼肉中6种替考拉宁组分的高效液相色谱-串联质谱检测方法.搅碎均匀的鱼肉样品经乙腈-10％三氯乙酸(6:4,体积比)提取,100 mg乙二胺-N-丙基硅烷(PSA)净化后,使用Agilent SB C18(2.1 mm×100 mm,1.8μm)色谱柱分离,以0.1％甲酸乙腈和0.1％甲酸为流动相进行梯度洗脱,采用电喷雾电离正离子(ESI+),多反应监测模式(MRM)进行检测,内标法定量.考察了提取溶剂种类与体积、吸附剂种类与用量对目标化合物回收率的影响.评价了6种目标物在不同鱼肉基质中的基质效应.在优化条件下,6种替考拉宁组分在4 min内得到良好分离.目标物在各自浓度范围内线性良好,相关系数(r2)均不小于0.998;在5.0、10.0、25.0μg/kg 3个加标水平下,各组分的回收率为84.3％～93.3％,日内相对标准偏差和日间相对标准偏差(n=6)分别不大于7.0％和6.2％,方法的检出限和定量下限分别为0.5～2.0μg/kg和2.0～5.0μg/kg.采用该方法对采集的9种40个鱼肉样品进行检测,所有样品均未检出替考拉宁组分.该方法简单、灵敏、准确、可靠,可用于鱼肉中6种替考拉宁组分的定量分析.

利用固相萃取(SPE)/超高效液相色谱-串联质谱(UPLC-MS/MS)建立了稻渔水体中氟虫腈及其代谢物(氟甲腈、氟虫腈砜和氟虫腈亚砜)的分析方法.根据目标物的化学性质及稻渔水样的基质情况,筛选出适用于稻渔水样预处理的滤膜及稻渔水体中目标物的萃取方法,并对固相萃取条件、氮吹温度等参数进行优化.稻渔水样经玻璃纤维滤纸过滤后,由Supelco ENVI-18固相萃取柱富集、净化,采用SB-C18柱(2.1 mm×100 mm,1.8μm)进行分离,在电喷雾电离源负离子模式下进行检测,外标法定量.结果显示:目标物在0.5～100 ng/mL范围内线性关系良好,相关系数(r2)大于0.998,检出限为0.5 ng/L,定量下限为1.5 ng/L;在2、5、50 ng/L加标水平下的回收率为81.6％～105％,相对标准偏差为3.5％～7.0％.该方法操作简便、灵敏、高效、性价比高,可用于稻渔水体中氟虫腈及其代谢物的同时测定.

Pyrethroids pesticides (PPs) are the widely adopted synthetic pesticides for agriculture and fishery. The frequent use of these pesticides leads to the accumulation of residues in the freshwater environments in China, subsequently affecting aquatic organisms and ecosystems. However, there are few reports on the toxicological and risk assessment of aquaculture aquatic products. In this study, the uptake, depuration kinetics and potential risk to human health and ecology of fenpropathrin, cypermethrin, fenvalerate, and deltamethrin were assessed using tilapia. The results indicated that four PPs were readily accumulated by tilapia. The bioconcentration factors (BCF) of the PPs in plasma and muscle were between 71.3 and 2112.1 L/kg and 23.9–295.3 L/kg, respectively. The half-lives (t1/2) of muscle and plasma were 2.90–9.20 d and 2.57–8.15 d. The risks of PPs residues in the muscle of tilapia and exposed water were evaluated by hazard quotient (HQ) and risk quotient (RQ). Although PPs residues in tilapia had a low dietary risk to human health, the residues in the exposed water had a high ecological risk to fish, daphnia, and green algae. Therefore, assessing the PPs content in freshwater aquaculture and monitoring their dosages and frequencies are highly necessitated to avoid their adverse effect on the aquaculture environment.

It is great challenge to design a simple approach to prepare Co-based N-doped carbon catalysts with high activity and minimum impact to the environment. Here, a novel carbonized poly(dopamine)-coated cobalt nanocomposite (CPDA@Co0) was synthesized via a simple and "zero-organic solvents" approach and employed to activate persulfate (PS) for sulfamethoxazole (SMX) degradation. The CPDA@Co0/PS system exhibited outstanding performance on SMX degradation over a wide pH range (3.0-8.5), and facilitated by acidic conditions and Cl-. For fair comparison, CPDA@Co0 under slightly acidic pH exhibited a much higher rate constant (0.121 min-1) than many reported catalysts. A direct electron-transfer pathway played a leading role in the oxidation, while adsorption of SMX on the surface of CPDA@Co0 might be the determining step. Since the synergistic effect between adsorption and catalysis, 10 mg/L SMX could be completely removed within 25 min, which provided a new strategy for removing organic pollutants from wastewater. Besides, the special core-shell structure could efficiently protect inner Co0 core from leaching. CPDA@Co0 could be easily separated via a permanent magnet and reused at least 5 times. This study might inspire others to develop effective and green PS activation processes for application in SMX treatment.

以QuEChERS作为样品前处理手段,建立测定水产品中扑草净残留的气相色谱-质谱法(GC-MS).样品以乙腈-二氯甲烷(V∶V=8∶ 2)混合溶液提取,提取液经吸附剂中性氧化铝、N-丙基乙二胺(PSA)、纳米二氧化锆结合石墨化炭黑(GCB)净化后上机检测,内标法定量.结果显示,扑草净质量浓度介于5～200 μg·L-1线性关系良好,相关系数(R2)为0.999 9.对草鱼(Ctenopharyngodon idellus)、鳜(Siniperca chuatsi)、中国对虾(Penaeus chinensis)、海参(Holothuria sp.)和文蛤(Meretrix meretrix)进行4个水平的加标回收实验(10、20、40和200 μg·kg-1),方法的加标回收率为85.8％～111.8％,相对标准偏差为1.2％～8.8％,满足GB/T 27404-2008《实验室质量控制规范食品理化检测》中实验室质量控制规范.扑草净的检出限(LOD,S/N≥3)和定量限(LOQ,S/N≥10)分别为5和10μg·kg-1.该方法简单、快速、灵敏、净化效果好,能满足水产品中扑草净残留的检测需求.

建立了水产品中5种硝基咪唑类药物(洛硝唑、甲硝唑、异丙硝唑、地美硝唑、氯甲硝咪唑)残留量的超高效液相色谱-串联质谱测定方法.样品经乙酸铵缓冲液分散后,用0.1％氨水乙腈超声提取,提取液经PRiME HLB小柱及PSA吸附剂净化后,UPLC-MS/MS检测,基质匹配标准曲线内标法定量.结果表明,水产品中5种硝基咪唑类药物的平均回收率在83.5％～110.3％之间,相对标准偏差在1.9％～12％之间,在0.5～10 ng/mL线性范围内,线性相关系数(r2)均大于0.997,检出限为0.5μg/kg,定量限为1.5 μg/kg.该方法能满足水产品中硝基咪唑类残留的检测需求.

Residues of fipronil and its metabolites in paddy fish soil were detected using high performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS). Samples were extracted with oscillation and acetonitrile in constant temperature, and subsequently purified by solid phase extraction using ENVI 18 column and 10 mg GCB. The target compounds were separated on an Agilent ZORBAX Extend C18 column (2.1 mm× 100 mm×1.8 μm), and determined using electrospray ionization (ESI) source at negative mode with multiple reation monitoring (MRM). The analytes were quantified with external standard using the matrix matched standard calibration curve method. The results indicated that the average spiked recoveries of fipronil, fipronil desulfinyl, fipronilsulfone and fipronilsulfide in paddyfish soil were 83.5%~110.3% with the relative standard deviations (RSDs) of 1.9%~11.5%. Good linearities were obtained in the range of 0.5~100 μg/L, and the correlation coefficients were greater than 0.998, the limits of detection (LODs) were 1.0 μg/kg, and the limits of quantification (LOQs) were 3.0 μg/kg. This method is simple, accurate and reliable, which can meet the detection requirements of fipronil and its metabolites in paddy fish soil.

本研究优化了样品贮运条件及前处理步骤,建立了气相分子吸收光谱仪测定渔业水质中氨氮的方法.实验将样品采集于棕色玻璃瓶中,调节pH至1～3,采样运输时间小于6 h可常温运输.样品摇匀后,直接上机检测,外标法定量.结果发现:氨氮在0.1～2.0 mg/L范围内线性良好,相关系数>0.9999.检出限为0.003 mg/L,定量限为0.013 mg/L.对两个浓度为(1.49±0.06)mg/L、(2.02±0.12)mg/L的水质氨氮环境标准样品进行测定,结果分别为(1.49±0.02)和(1.99±0.01)mg/L.两家实验室使用该方法对相同的养殖淡水和海水进行了检测以及加标回收实验,实验室间的相对相差为3.60％ ～7.40％,方法回收率为90.00％ ～105.00％,相对标准偏差为0.36％ ～3.26％.结果表明:本方法简单、快速、准确度高、重复性好、易于推广,适用于渔业水质中氨氮的批量检测.

A simple, sensitive, and simultaneous method was established and validated for the active clinical components of teicoplanin and ramoplanin in environmental water by LC-MS/MS coupled with cascade elution. Moreover, a cascade elution method, which was rapid, solvent-less, and high-extraction efficient was successfully proposed to realize the extraction and purification of seven targets in one step. Under optimized conditions, the method showed excellent linearity with the correlation coefficient (R 2) ≥0.998 in the range of 1.0–100.0 ng L−1. Low matrix effects and good recoveries which ranged from 86 to 114% were reached with RSDs lower than 3.0% for most targets. The limits of detection and limit of quantification were 0.1–1.3 and 0.3–4.0 ng L−1, respectively. This method was successfully applied for the determination of teicoplanin and ramoplanin in water samples from the Pearl River and the South China Sea. TA2-2,3 was quantified in only one sample with the concentration of 8.0 ng L−1.

A sensitive method for determination of nine herbicides (prometryn, acetochlor, butachlor, quinclorac, bensulfuron methyl, metsulfuron methyl, atrazine, linuron and bentazone) in sediments and muscle of aquatic products was developed and validated using QuEChERS and ultra-high performance liquid chromatographytandem mass spectrometry (UHPLC-MS/MS). The results demonstrated that the matrix-matched calibration curves for sediment and fish muscle were satisfactory linearly of a concentration (0.50 to 100 mu g/L) (r 0.999). The limit of detection (LOD) and limit of quantification (LOQ) ranged from 0.10 - 0.50 mu g/kg and 0.50 - 1.50 mu g/kg, respectively. The recoveries ranged from 82.94 to 114.41%, with the relative standard deviations (RSDs) lower than 13.11% for nine herbicides. Finally, the validated method was applied to detect nine herbicides in 68 rice-fish and 30 sediment samples in the rice-fish co-culture system (RFCS) in six provinces of China. The dietary and ecological risks were evaluated through a calculated hazard quotient (HQ) and risk quotient (RQ). The residues of herbicides in the paddy fish did not harm the human body (HQ < 0.002408). However, the ecological risks of herbicides in the RFCS could not be ignored. The seven herbicides were detected in the sediment of RFCS. They had ecological risks to the fish, daphnia and algae (RQ values ranged from 0.1666 to 28.4381).