UPLC-MS-MS-based Simultaneous Determination Of 23 Antibiotics In Seawater Samples And Its Application

Sulfonamides and quinolones are synthetic types of spectral antibacterial agents commonly used in animal husbandry and aquaculture,but uncontrolled use can seriously affect the health of humans and ecosystems,therefore,it is very important to investigate the residual amount in the environment.In this paper,the detection method of natural seawater antibiotics were optimized and the antibiotic residue types,residual concentration and distribution trend in the surface water of Dongzhai harbour were investigated by ultra performance liquid chromatography tandem mass spectrometry(UPLC-MS-MS),the main results of the paper are as follows:(1)Establishment and optimization of detection method based on ultra performance liquid chromatography tandem mass spectrometryUltra high performance liquid chromatography tandem mass spectrometry was used to analyze the analytes in the multi-reaction detection(MRM)and electrospray ionization(ESI)positive mode.The separation conditions include mass spectrometry parameters such as decluster voltage(DP)and collision energy(CE),mobile phase type,fixed solution type and gradient elution program were optimized.The conditions of the final optimized instrument were as follows:using A:methanol:acetonitrile(1:1,V:V),B:0.1%formic acid as the mobile phase,and the initial mobile phase was selected as the recombination solvent.The all determined antibiotics could peak within 15 minutes under these conditions,and all the analytes have a good linear relationship with R2 between 0.996-0.999 when the concentration range is 0.2～100μg/L.The optimized method by this experiment has the advantages of high sensitivity,low detection limit,good reproducibility and short time for the detection process.(2)Optimization of pretreatment methods for solid phase extraction of 23 antibiotics in seawaterIn this study,seawater was used as bases to establish 23 pretreatment methods for antibiotic residues by solid phase extraction,the enrichment ability of different types of solid phase extraction columns for antibiotics was compared and the solid phase extraction conditions such as column volume,water sample salinity and EDTANA2 addition amount were optimized.Under the optimal conditions,the recovery rates of antibiotics in seawater at 20 ng/L and 50 ng/L were 66.0～93.3%and 64.6～97.0%,respectively,the relative standard deviation(RSD)are 1.2%～12.8%,less than 14%and the method detection limit are between 0.03～1 ng/L,which meets the needs of detection in seawater samples.(3)Detection of 23 antibiotic residues in surface water of Dongzhai Harbour,Hainan ProvinceThe surface seawater samples of 10 sample locations from Dongzhai harbour were collected in April 2017,the 23 antibiotic residues were analyzed by optimized solid phase extraction-ultra performance liquid chromatography-tandem mass spectrometry(SPE-UPLC-MS-MS),the results showed that five sulfa drugs and five quinolones were detected in the surface water of 10 sampling sites in Dongzhai Harbour,Sulfamethoxazole,enrofloxacin and orbifloxacin were detected in all samples,the concentration range was 0.46～3.35,0.53～1.92,1.45～1.88 ng/L,respectively;Sulfamethoxime,sulfamethazine,sulfachloropyridazine,sulfadiazine,difloxacin,sparfloxacin and oxolinic acid were detected at most of the samples,the concentration range was nd～2.21,nd～0.49,nd～0.85,nd～1.95,nd～0.87,nd～2.32,nd～1.06 ng/L,respectively.Compared with other research areas,the concentration of antibiotics detected in Dongzhai Harbour is lower,and more types are detected.(4)Ecological risk assessmentRisk assessment of antibiotic residues in Dongzhai Harbor was carried out using risk quotient(RQs),the results showed that most of the sulfonamides and quinolone antibiotics pose a low level of ecological risk in the Dongzhai Harbour marine waters,among all the selected target antibiotics,only sulfamethoxazole,sulfamethoxazole and oxolinic acid were moderately toxic to algae(0.1≤RQs<1).