Sulfonamide Residues Research Articles

Studies Regarding the Detection of Sulfonamide Residues and Evaluation of the Level of Contamination in Poultry Meat

The excessive or uncontrolled use of antibiotics in poultry farming can lead to contaminated food products. Subsequently, the human consumption of products contaminated with these substances increases the global phenomenon of antibiotic resistance. The aim of this study was to develop and validate a high-performance liquid chromatography (HPLC) method suitable for the determination of sulfonamide residues in poultry meat and to check the presence of residues in random samples. The level of antimicrobial resistance was identified in order to evaluate the current stage and to estimate the tendency of this phenomenon. The HPLC method validation was performed in accordance with Commission Regulation (EC) No 657/2002 of 14 August 2002 Samples of fresh meat collected from a poultry slaughterhouse were analysed using the validated method in order to reveal the level of contamination. The data from EFSA was collected and analysed following the antimicrobial resistance for isolates of Salmonella spp., E. coli and Campylobacter spp. The method had good selectivity, linearity (R2 ≥ 0.99), precision (<6%), recoverybetween 97.7-109.6% and low limits of detection (LOD) and quantification (LOQ) Sulfaquinoxaline residues were present in 2 samples and the level of contamination did not exceed the Maximum Residue Level (31.98 ± 5.18 µg/kg and 23.70 ± 3.84 µg/kg). The analysis of data from EFSA highlighted the general presence of antimicrobial resistance especially for the following antibiotics: ciprofloxacin, tetracycline, nalidixic acid, ampicillin, sulfamethoxazole and trimethoprim. The present study brings a contribution to the process of stopping antibiotic resistance through new methods of monitorization of sulfonamide residues. The statistical data shows that there is a direct correlation between the market availability of antibiotics used in poultry farming and the occurrence of antibiotic resistance.

Effect of Changes in Veterinary Feed Directive Regulations on Violative Antibiotic Residues in the Tissue of Food Animals from the Inspector-Generated Sampling in the United States.

The presence of antibiotic residues in the tissue of food animals is a growing concern due to the adverse health effects that they can cause in humans, such as antibiotic resistance bacteria. An inspector-generated sampling (IGS) dataset from the United States National Residue Surveillance Program, collected between 2014 and 2019, was analyzed to investigate the association of changes in the veterinary feed directive (VFD) regulations on the detection of violative penicillin, tetracycline, sulfonamide, desfuroylceftiofur, tilmicosin, and florfenicol, residues in the tissue of food animals. Multivariable logistic regression models were used for analysis. While the animal production class was significantly associated with residue violations for tetracycline, having a sample collection date after the implementation of change in VFD regulations was not. However, the odds of detecting violative sulfonamide and penicillin residues in the tissue of food animals following the implementation of the change in VFD regulations were 36% and 24% lower than those collected before the implementation of the change in VFD regulations period, respectively, irrespective of animal production class. Violative desfuroylceftiofur, tilmicosin, and florfenicol residues in the tissue of food animals were not significantly associated with the implementation of changes in the VFD regulations. Further investigation of the factors that influence the presence of violative antibiotic residues in the tissue of food animals following the change in VFD regulations would lend clarity to this critical issue.

Sulfonamide Residue in the Broiler Chicken Circulating in Makassar

The use of sulfonamide related to drug residual in the product of broiler chicken, like meat and egg. This research aimed to determine the sulfonamides (sulfamerazine, sulfanilamide, and sulfadiazine) on the broiler chicken meat, breast, and egg from the three different slaughterhouses circulating in the City of Makassar. The sample was extracted by acetonitrile and acetone then concentrated. The extract and sulfonamides then analyzed by HPLC method using C18 reverse phased column, UV-Visible detector in the wavelength of 270 nm. The result of study shows that the chromatogram of sample breast and egg has similar retention time with sulfonamides as a standard reference. The breast sample contains sulfamerazine residues, sample B and C contains 0.014 and 0.005 % (w/w), respectively. The egg sample A and D contains sulfadiazine 0.045 and 0.108 % (w/w), respectively. Sample B contains sulfanilamide 0.053 % (w/w). Sample A and B is egg yolk, while sample D is egg whites. Based on the results obtained, this is not suitable for the rules set by JECFA of 0.1 mg/kg (10-5 % w/w) as well as the standard of SNI. It can be concluded that generally broiler chicken breast and egg circulating in the City of Makassar was contaminated by sulfonamide with high concentration.

A Review on Antibiotics Residue in Foods of Animal Origin

Foods of animal origin (example meat, milk, and eggs) samples occasionally, contain excessive amounts of antibiotics drug residues. Usually these are a result of not observing the withdrawal period or from off-label use of an antibiotic. Tetracycline is the most predominantly prescribed antibiotic and of all antibiotic-associated residues, followed by β-lactames. Residues of amino glycosides, Macrolides, and sulfonamides have also been detected. Antibiotics have the potential to cause allergic reactions; penicillin is most commonly implicated, affecting up to 10% of people receiving these drugs therapeutically. Sulfonamides may cause allergic reactions in up to 3% of those using these drugs. Other antibiotics are implicated less often. Concentrations of residual veterinary drugs in foods are not high enough to cause an initial hypersensitive reaction but may cause such an effect in a person who has already become sensitized to the drug. The detection methods of veterinary drug residues in food animal origin constitute a dynamic area in food processing and these include microbiological, immuno-enzymatic and chemical methods. In general, withdrawal period of veterinary drugs must be respected after drugs or medicines have been administered to animals in order to prevent the occurrence of drug residues.

Evolution of a natural dihydropteroate synthase and development of a signal amplified fluorescence method for detection of 44 sulfonamides in milk

In this study, the recognition mechanisms and affinities of a natural dihydropteroate synthase for 44 sulfonamides were studied respectively. Then the key contact amino acid Ser222 was mutated to Arg222 by using site-directed mutagenesis method to produce a mutant. Results showed that the binding energies and affinities for the 44 drugs were generally improved. Then this mutant was used as recognition reagent to develop a direct competitive fluorescence method on 96-well microplate for determination of the 44 drugs in milk. Due to the used signal amplified fluorescent tracer, the limits of detection for the 44 drugs were in the range of 0.025–0.65 ng/mL, and the sensitivities were improved for about 6–86 folds in comparison with the conventional fluorescent tracer. After comprehensive comparison, the present method showed generally better performances than the previously reported immunoassays for sulfonamides. Therefore, this method could be used as an efficient tool for the routine screening of sulfonamides residues in large number of food samples.

Hollow Fibre-Supported Liquid Membrane for the Determination of Sulfonamide Residues in Egg Samples

In this study, a three-phase hollow fibre-supported liquid membrane (HF-SLM) technique incorporated with high-performance liquid chromatography (HPLC) coupled with diode array detection (DAD) was developed for the extraction, clean-up, and determination of fifteen sulfonamide residues in chicken egg samples. The residues were extracted from the 5 mL sample solution of pH 2.5 into a thin layer of organic phase (1-octanol with 10% TOPO) immobilised in hollow fibre pores and then back-extracted into approximately 6 μL of aqueous phase (pH 13) located in the lumen of the hollow fibre. After extraction, 6 μL of the acceptor phase was injected into an HPLC instrument for subsequent analysis. Under optimum conditions, the limit of detection (LOD) and limit of quantification (LOQ) values ranged from 0.8–7.9 μg·kg−1 and from 2.4–21.0 μg·kg−1, respectively, linearity in the range of 5 1 000 μg·kg−1, and intra- and inter-day precision (%RSD) values at three concentration levels (50, 100, and 500 μg·L−1) ranged from 6.2–15.7%, 7.3–15.0%, and 7.3–14.6%; and 6.4–17.4%, 4.3–16.2%, and 8.3–16.5%, respectively, were obtained. The accuracy of the method, expressed as percentage recovery, was in the range of 71.0–98.7%, with corresponding %RSD (n = 6) values ranging from 1.9–9.9% being obtained. The developed method provided enrichment factors in the range of 17.1 to 541.4. The applicability of the proposed method was also evaluated by analysing egg samples, which were randomly collected from local supermarkets located in Gauteng Province, South Africa. The results obtained revealed that the developed method has the potential to be used as an alternative method for the determination of sulfonamide residues in egg and related complex samples.

Triazine-based porous organic polymer as pipette tip solid-phase extraction adsorbent coupled with HPLC for the determination of sulfonamide residues in food samples

In this work, triazine-based porous organic polymer (TAPT-BPDA) synthesized by simple solvothermal method with stable chemical properties was employed as pipette tip solid-phase extraction (PT-SPE) adsorbent for the extraction of sulfonamides for the first time. Under the optimal conditions, good linearities (1–300 μg L−1, R2 ≥ 0.9987) and low limits of detection (0.10–0.28 μg L−1) were obtained. The recoveries of sulfonamides in meat, egg and milk samples were in the range of 76.1–114.0 %. The prepared TAPT-BPDA showed good reusability with the recoveries of sulfonamides remained above 80.0 % after eight recycles. The adsorption mechanism between SAs and adsorbent might be the combined effects of electrostatic interactions, hydrogen bonding and π-π interactions. The results demonstrated potential applications of a TAPT-BPDA-based PT-SPE-HPLC method for the analysis of trace sulfonamide residues in food samples.

Determination of sulfonamide residues in cultured sea cucumber by pre-column derivatization capillary electrophoresis with fluorescence detection

A simple and mild method for the separation of sulfonamide residues based on a condensation reaction with O-phthalaldehyde solution (OPA) as labeling reagent with capillary electrophoresis has been developed. A 58.5 cm × 50 μm i.d. (50 cm effective length) untreated fused-silica capillary was used. To optimize the separation conditions, the background electrolyte concentration, pH, column temperature, voltage and other factors were evaluated. The optimal separation conditions were as follows: 20 mmol L−1 borate buffer; pH 9.1; column temperature 20 °C; separation voltage 18 kV, pressure 50 mbar and injection time 8 s. Under the optimal conditions, 10 kinds of sulfonamide derivatives could be well-separated within 8 min, and the linear ranges were 0.35–100 μg kg−1. The detection limit (at a signal-to-noise ratio of 3) was in the range of 0.12–0.25 μg kg−1, and the quantification limit (at a signal-to-noise ratio of 10) was in the range of 0.35–0.70 μg kg−1. The sulfonamide residues from cultured sea cucumber samples were determined under the optimal conditions with satisfactory results.

Detection of fluoroquinolone and sulfonamide residues in poultry eggs in Kunming city, southwest China

Antibiotic residues contained in poultry eggs pose threat to human health. However, the classes and concentrations of antibiotics in poultry egg in southwestern China is unknown due to insufficient monitoring and research. A total of 513 egg samples were collected from supermarkets and farm markets in Kunming city in 2020 and the levels of 7 antibiotics were analyzed using ultra high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method. The linear correlation coefficients were above 0.990 for all antibiotics tested. The limits of detection and limits of quantification in poultry eggs were 0.002 to 0.010 μg/g and 0.007 to 0.033 μg/g, respectively. The average recoveries of the 7 analytes from poultry egg samples were 80.00 to 128.01%, with relative standard deviations of less than 13.97%. A total of 93 (18.13%) samples tested positive for antibiotics, with the highest concentration being 2.48 μg/g. The concentration range of ofloxacin, danofloxacin, difloxacin, sulfadimethoxine, sulfamonomethoxine, sulfamethoxypyridazine, and sulfamethoxazole in poultry eggs was 0.01 to 0.37 μg/g, 0.06 to 0.48 μg/g, 0.05 to 0.29 μg/g, 0.03 to 0.16 μg/g, 0.06 to 1.00 μg/g, 0.05 to 0.37, and 0.07 to 2.48 μg/g, respectively. Sulfamonomethoxine was detected from hen eggs with the highest concentration level at 1.00 μg/g. Sulfamethoxazole was detected with the highest concentration level from both duck and quail eggs, at 1.87 and 2.48 μg/g, respectively. The antibiotic with the highest residue level in pheasant eggs was danofloxacin, which was 0.37 μg/g. Sulfamethoxypyridazine was identified in 30 samples with the highest positive rate of 5.85%, sulfadimethoxine was identified in 3 samples with the lowest positive rate of 0.58%. We observed that 7 targeted antibiotic residues in quail eggs and 3 targeted antibiotic residues in pheasant eggs. We also found that there were antibiotic residues in free-range hen eggs and the concentration was not low. The antibiotic with the highest residue level in free-range eggs was sulfamonomethoxine, which was 1.00 μg/g. These findings suggest that continual antibiotic residue monitoring of poultry eggs is essential in China.

Microbial Community Structure and Bacterial Lineages Associated with Sulfonamides Resistance in Anthropogenic Impacted Larut River

Anthropogenic activities often contribute to antibiotic resistance in aquatic environments. Larut River Malaysia is polluted with both organic and inorganic pollutants from domestic and industrial wastewater that are probably treated inadequately. The river is characterized by high biochemical oxygen demand, chemical oxygen demand, total suspended solids, ammonia, and heavy metals. In our previous study, sulfonamides (SAs) and sulfonamide resistance genes (sul) were detected in the Larut River. Hence, in this study, we further examined the microbial community structure, diversity of sulfonamide-resistant bacteria (SARB), and their resistance genes. The study also aimed at identifying cultivable bacteria potential carriers of sul genes in the aquatic environment. Proteobacteria (22.4–66.0%), Firmicutes (0.8–41.6%), Bacteroidetes (2.0–29.4%), and Actinobacteria (5.5–27.9%) were the most dominant phyla in both the effluents and river waters. SARB isolated consisted only 4.7% of the total genera identified, with SAR Klebsiella as the most dominant (38.0–61.3%) followed by SAR Escherichia (0–22.2%) and Acinetobacter (3.2–16.0%). The majority of the SAR Klebsiella isolated from the effluents and middle downstream were positive for sul genes. Sul genes-negative SAR Escherichia and Acinetobacter were low (<20%). Canonical-correlation analysis (CCA) showed that SAs residues and inorganic nutrients exerted significant impacts on microbial community and total sul genes. Network analysis identified 11 SARB as potential sul genes bacterial carriers. These findings indicated that anthropogenic activities exerted impacts on the microbial community structure and SAs resistance in the Larut River.

Room temperature fabrication of magnetic covalent organic frameworks for analyzing sulfonamide residues in animal-derived foods.

A magnetic solid phase extraction method based on magnetic covalent organic frameworks (TpBD@Fe3 O4 ; 2,4,6-triformylphloroglucinol (Tp) and benzidine (BD)) combined with high performance liquid chromatography has been developed to detect the sulfonamides including sulfadiazine, sulfamerazine, sulfamethazine, and sulfamethoxazole in milk and meat. TpBD@Fe3 O4 were synthesized at room temperature under mild reaction conditions with a simple and rapid operation. The TpBD@Fe3 O4 exhibited higher extraction efficiency because of the π-π and electrostatic interactions between the benzene ring structure of the TpBD and the sulfonamide molecules. The extraction conditions including the dosage of adsorbents, the type and dosage of eluent, the elution time, and the pH of the sample solution were fully optimized. The detection results showed good linearity over a wide range (50-5 × 104 ng/mL) and low detection limits (3.39-5.77 ng/mL) for the sulfonamide targets. The practicability of this magnetic solidphase extraction-high-performance liquid chromatography method was further evaluated by analyzing milk and meat samples, with recoveries of the targets of 71.6-110.8% in milk and 71.9-109.7% in pork. The successful detection of sulfonamides residues has demonstrated the TpBD@Fe3 O4 excellent practical potential for analyzing pharmaceutical residues in animal-derived foods.

Production of a Natural Dihydropteroate Synthase and Development of a Signal-Amplified Pseudo-Immunoassay for the Determination of Sulfonamides in Pork.

In this study, a type of magnetic photoaffinity-labeled activity-based protein profiling probe for sulfonamide drugs was first synthesized for the purpose of capturing the natural dihydropteroate synthase of Escherichia coli by using simple incubation and magnetic separation. After characterization of its identity with LC-ESI-MS/MS, this enzyme was used as a recognition reagent to develop a direct competitive pseudo-ELISA for the determination of the residues of 40 sulfonamides in pork. Because of the use of streptavidin-horseradish peroxidase and biotinylated horseradish peroxidase as a signal-amplified system, the limits of detection for the 40 drugs were in the range of 0.001-0.016 ng/mL. Compared to the steps in a conventional assay formation, the operation steps were the same, but the sensitivities increased 32-88-fold. Furthermore, the assay performances were better than the previously reported immunoassays performances for sulfonamides. Therefore, this method could be used as a practical tool for multiscreening the trace levels of sulfonamides residues in food samples.

The electrospun polyacrylonitrile/covalent organic framework nanofibers for efficient enrichment of trace sulfonamides residues in food samples

In this work, the electrospun polyacrylonitrile/covalent organic frameworks Tp-BD nanofibers (PAN/Tp-BD) were synthesized and applied as an adsorbent for thin film microextraction (TFME) of seven sulfonamides in animal derived food samples. The morphology, structure, porosity, and stability of the prepared nanofibers were investigated. The PAN/Tp-BD nanofibers exhibited good chemical stability, high flexibility, porous fibrous structure, and excellent extraction efficiency. Based on the PAN/Tp-BD nanofibers as the adsorbent, a thin film microextraction-high performance liquid chromatography (TFME-HPLC) method for the determination of seven sulfonamides (SAs) in food samples was developed. Under the optimal conditions, the TFME-HPLC exhibited the low limit of detection (0.10-0.18 ng·mL−1), the low limit of quantitation (0.33-0.60 ng·mL−1), the wide linear range (0.5-50 ng·mL−1) with correlation coefficients between 0.994 and 0.998, and good enrichment factors between 39.7 to 170.1 towards 20 ng/mL SAs solution. The relative standard deviation (RSD) was lower than 11% in the interday and intraday analysis. Furthermore, the applicability of PAN/Tp-BD nanofibers was demonstrated for measuring trace SAs residues in the spiked food samples with recoveries ranging from 85.3% to 115.2%. The results demonstrated that the PAN/Tp-BD nanofibers have great potential for the efficient extraction of sulfonamides from complex food samples.

Synthesis of the Magnetically Nanoporous Organic Polymer Fe3O4@SiO2-NH2-COP and Its Application in the Determination of Sulfonamide Residues in Surface Water Surrounding a Cattle Farm.

Efficient extractions of trace antibiotic residues in the environment are a key factor for accurate quantification of the residues. A new nanoporous material, namely, magnetically covalent organic polymer (MCOP, Fe3O4@SiO2-NH2-COP) was synthesized in this work and was used for magnetic solid-phase extraction (MSPE). The combination of MSPE with high-performance liquid chromatography separation together with ultraviolet detection (HPLC-UV) was established as an effective method for the determination of four sulfonamide (SA) residues in surface water surrounding a cattle farm. The synthesized magnetic material was characterized by SEM, TEM, FT-IR, magnetic properties measurement system (MPMS), and nitrogen gas porosimetry. The material possessed many attractive features, such as a unique microporous structure, a larger specific surface area (137.93 m2·g−1) than bare Fe3O4 (24.84 m2·g−1), high saturation magnetization (50.5 emu·g−1), open adsorption sites, and high stability. The influencing parameters, including pH, the used amount of MCOPs, the type of eluent, adsorption solution, and desorption time, were optimized. Under the optimized conditions, the method conferred good linearity ranges (R2 ≥ 0.9990), low detection limits (S/N = 3, LOD, 0.10–0.25 μg·L−1), and satisfactory recoveries (79.7% to 92.2%). The enrichment factor (EF) for the four SAs was 34.13–38.86. The relative standard deviations of intraday (n = 5) and of interday (n = 3) were less than 4.8% and 8.9%, respectively. The equilibria between extraction and desorption for SAs could be reached within 150 s. The proposed method was sensitive and convenient for detecting SA residues in complex environmental matrices, and the successful application of the new MCOPs as an adsorbent was demonstrated.

Fluorescence labeled capillary electrophoresis fingerprint analysis of sulfonamides residues in tea garden soil and tea

A fluorescence labeled capillary electrophoresis fingerprint method for the analysis of sulfonamides residues in tea garden soil and tea was established by using o-phthalaldehyde (OPA) as precolumn derivatization reagent. The effects of background electrolyte concentration, pH, column temperature and voltage on the separation conditions were investigated. The optimum separation conditions were as follows: Glycine sodium hydroxide slow concentration: 20 mmol/L; pH: 9.0; Column temperature: 20 °C; Separation voltage: 17 kv, pressure: 50 mbar, injection time: 8 s. Under the established optimal conditions, 13 sulfonamide derivatives could be separated efficiently within 9 min, and the linear range is 0.35~100μg/kg, the detection limit (signal-to-noise ratio is 3) is in the range of 0.12-0.25 μg/kg, the quantitative limit (signal-to-noise ratio is 10) is in the range of 0.35-0.70μg/kg.

ANTIMICROBIAL DRUGS, PESTICIDES AND PAHs IN HONEY

Honey is a very popular food that is often consumed by immunocompromised people, so it is crucial that it is safe. The safety of honey is determined by numerous hazards- the chemical ones like residues of sulfonamides, lindane and PAHs. Honey from our country contains high concentrations of banned antimicrobial substances such as sulfonamides (3.9% of samples). The frequent presence of lindane in honey is not unexpected considering the fact that this pesticide is present in the soil, plants and animals from Serbia. PAHs (polycyclic aromatic hydrocarbons) as a relatively unexplored chemical hazard in honey proved to be widespread in the honey from Serbia- even 6.6% of honey samples contains toxic concentrations of these compounds. The control of chemical hazards and the production of safe honey in Serbia could be improved by implementing better measures to prevent illegal use of antimicrobial drugs, pollution control and further research in the field of risk assessment.

Development of a Dihydropteroate Synthase-Based Fluorescence Polarization Assay for Detection of Sulfonamides and Studying Its Recognition Mechanism.

In this study, the dihydropteroate synthase of Staphylococcus aureus was obtained, and its recognition mechanisms for 31 sulfonamide drugs were studied. Results showed that their core structure matched well with the binding pocket of para-aminobenzoic acid, and all the sulfonamide side chains were out of the binding pocket. Hydrogen bonds and hydrophobic interactions were the main intermolecular forces, and the key amino acids were Gly171 and Lys203. The binding sites in sulfonamide molecules were mainly around the para-aminobenzenesulfonamide part. This enzyme was used to develop a fluorescence polarization assay for detection of these drugs in chicken muscles. The change trends of half of inhibition concentrations and cross-reactivities for the 31 drugs were identical with the receptor-ligand affinities. The limits of detection were in the range of 2.0-38.5 ng/g, and one assay could be finished within several minutes. Therefore, this method could be used for multiscreening of sulfonamide residues in meat samples.

Rapid detection of sulfonamide antibiotics residues in swine urine by surface-enhanced Raman spectroscopy

Surface enhanced Raman spectroscopy (SERS) combined with rapid pretreatment technique was used to determine sulfonamide antibiotics (sulfadiazine and sulfathiazole) residue in swine urine. Au nanoparticles (AuNPs) were synthesized as Raman enhance substrate and the extraction of swine urine was purified with primary secondary amine (PSA), octadecyl silane (C18) and graphitized carbon (GCB) to eliminate the interference of the matrix and different dosages of adsorbents (PSA, C18, GCB) were investigated. The results showed that the treatment with C18 of 150 mg, GCB of 200 mg and PSA of 200 mg were an excellent approach for rapidly detecting sulfonamide antibiotics residue in swine urine. Combined with density functional theory calculation (DFT), Raman characteristic peaks of 819, 1102, 1173, 1588 cm−1 and 825, 1127 cm−1 were selected for qualitative and quantitative assessment of sulfadiazine and sulfathiazole in swine urine, respectively. Based on raman characteristic peak of 819 cm−1, a good linear relationship between sulfadiazine concentration and Raman intensity was developed with R2 = 0.9912, and based on raman characteristic peak of 825 cm−1, a good linear relationship between sulfathiazole concentration and Raman intensity was developed with R2 = 0.9941. And recoveries for five unknown concentration samples predicted were 98.47 ∼ 105.18% with relative standard deviation (RSD) of 1.53% ∼ 5.18%. This study demonstrated that SERS coupled with a quick, easy, cheap, effective, rugged, and safe (QuEChERS) method could be employed to rapidly examine the sulfonamide antibiotics residue in swine urine towards its quality and safety monitoring.

Fate of sulfamethoxazole and potential formation of haloacetic acids during chlorine disinfection process in aquaculture water

There exist two common processes in fishery culture, i.e. antibiotic addition to reduce disease in fishery, and chlorination disinfection to inhibit infectious pathogenic microorganisms. However, antibiotic residues might play important reverse side roles for both aquaculture water pollution and potential formation of chlorination side products. Herein, the transformation behaviour, intermediates analyses and conversion pathway of antibiotic sulfamethoxazole (SMX), and potential generation of halogenated acetic acids (HAAs) in the process of chlorination in fishery water were examined, and the results revealed that the decomposing of SMX satisfied a pseudo first-order kinetic equation. Both the addition of available chlorine and high temperature had affirmative influences on the decontamination of SMX and production of HAAs, and the near-neutral pHs promoted the removal of SMX and generation of HAAs. Br− was favorable for the removal of SMX and yields of brominated acetic acids (Br-AAs). Based on the identified intermediate products, the transformation path of SMX in chlorination process was propounded, to wit, the C–S and S–N bonds in the SMX molecules were firstly cracked, and the primeval intermediate groups are then transformed to form chloroanilines, chlorophenols, etc., and subsequently, chlorophenols were chlorinated and ring-opened to generate toxic HAAs. This study might be meaningful to evaluate the effective removal of sulfonamide antibiotic residues and the potential generation of halogenated DBPs (H-DBPs) when chlorinated in aquaculture water.

The Residues and Risk Assessment of Sulfonamides in Animal Products

Objective. To investigate and assess the risk of sulfonamide residues in livestock and poultry products in Shijiazhuang and determine the risk level of the dietary intake of sulfonamides, in order to provide the basis for the safety production, consumption, and safety supervision of livestock products. Methods. Totally, 1200 samples of livestock products were collected, and the samples were detected by high-performance liquid chromatography-tandem mass spectrometry. Combined with the data of Chinese residents’ dietary survey in 2015, a nonparametric probability assessment model was constructed to assess the risk of sulfonamides in the livestock and poultry products of Shijiazhuang residents by using the professional risk assessment software @Risk. Risk assessment of the consumption of sulfonamide veterinary drugs in livestock and poultry products of Shijiazhuang residents was conducted. Results. Of the 1200 main livestock products tested, 8 were found to have sulfonamide residues, which were mainly sulfadiazine residue, sulfadiazine, and sulfadimethoxy, with the detection rates of 0.17%, 0.25%, and 0.25%, respectively. The average residual concentrations were 0.66, 0.50, and 0.50 g/kg, respectively, which were lower than the national residue limit of China (100 μg/kg). The food safety index was 2.95 × 10−4, which was far less than 1. Conclusion. The risk of residual exposure to sulfonamides in livestock and poultry meat in Shijiazhuang is very low and is at a very safe level. However, it is still necessary to strengthen the supervision of animal products in order to reduce the residues of veterinary drugs in the human body.