Analysis of sulphonamide residues in edible animal products: A review

A Cost-Effective and Sensitive Method for the Determination of Lincomycin in Foods of Animal Origin Using High-Performance Liquid Chromatography

BACKGROUND

Lincomycin (LIN) is extensively used for treating diseases in livestock and promoting growth in food animal farming, and it is frequently found in both the environment and in food products. Currently, most of the methods for detecting lincomycin either lack sensitivity and precision or require the use of costly equipment such as mass spectrometers.

RESULT

In this study, we developed a reliable high-performance liquid chromatography-ultraviolet detection (HPLC-UVD) method and used it to detect LIN residue in 11 types of matrices (pig liver and muscle; chicken kidney and liver; cow fat, liver and milk; goat muscle, liver and milk; and eggs) for the first time. The tissue homogenates and liquid samples were extracted via liquid-liquid extraction, and subsequently purified and enriched via sorbent and solid phase extraction (SPE). After nitrogen drying, the products were derivatized with p-toluene sulfonyl isocyanic acid (PTSI) (100 µL) for 30 min at room temperature. Finally, the derivatized products were analyzed by HPLC at 227 nm. Under the optimized conditions, the method displayed impressive performance and demonstrated its reliability and practicability, with a limit of detection (LOD) and quantification (LOQ) of LIN in each matrix of 25-40 μg/kg and 40-60 μg/kg, respectively. The recovery ranged from 71.11% to 98.30%.

CONCLUSIONS

The results showed that this method had great selectivity, high sensitivity, satisfactory recovery and cost-effectiveness-fulfilling the criteria in drug residue and actual detection requirements-and proved to have broad applicability in the field of detecting LIN in animal-derived foods.

Development of a Diethylcarbamazine Citrate‐Based Electrochemical Sensor for Quick and Affordable Detection of Sulfadiazine and Uric Acid in Environmental Monitoring

The widespread use of antibiotics like sulfadiazine (SDZ) in various industries has raised environmental and health concerns due to their potential for bioaccumulation and the subsequent effects on human health and the environment. Diethylcarbamazine citrate (DCZ), a well‐established antifilarial drug, has yet to be explored as a sensing agent despite its extensive use. This study proposes a cost‐effective and efficient method for detecting SDZ and Uric acid (UA) using a DCZ‐modified carbon paste electrode (poly‐DCZ/MCPE). The poly‐DCZ film is synthesized via cyclic voltammetry (CV) on the carbon paste electrode surface, demonstrating excellent electrocatalytic activity for SDZ and UA detection at pH 7.4. The diffusion‐controlled electrode process is observed with a lower limit of detection (LOD) and limit of quantification (LOQ) for SDZ as 3.8×10−9 M and 12.94×10−9 M respectively. For UA, LOD and LOQ were found to be 6.291×10−9 M and 20.97×10−9 M respectively at the poly‐DCZ/MCPE. Notably, the sensor exhibits simultaneous detection capabilities for SDZ and UA by CV and differential pulse voltammetry (DPV) methods, addressing the need to monitor antibiotic residues in aquatic ecosystems and animal‐derived products.

Screening for antimicrobial residues in poultry eggs in Bangladesh using Charm II radio-receptor assay technique following validation

The aim of the study was to screen for the presence of antimicrobial residues in poultry eggs from Bangladesh using the Charm II radio-receptor assay in the absence of expensive confirmatory instrumentation. This was based on cut-off values as set in the validation guidelines according to Commission Decision 2002/657/EC and Commission Implementing Regulation (EU) 2021/808. Fortified eggs spiked with fixed concentrations of doxycycline, erythromycin A, sulphamethazine, and benzylpenicillin were used to determine the cut-off values and detection capabilities (CCβ). Other validation parameters included were applicability, ruggedness, and robustness. A total of 201 egg mix samples from native organic chicken, duck, and commercial farm-raised laying hens (both brown and white eggs) were tested and after analysis 13%, 10%, and 4.5% of the egg mix samples showed positive signals for sulphonamides, macrolides/lincosamides, and tetracyclines, respectively. Presence of multiple drug residues were also suspected in 11 out of 201 egg mix samples.

Advances in solid-phase extraction techniques: Role of nanosorbents for the enrichment of antibiotics for analytical quantification

Antibiotics are life-saving medications for treating bacterial infections; however it has been discovered that resistance developed by bacteria against these incredible agents is the primary contributing factor to rising global mortality rates. The fundamental cause of the emergence of antibiotic resistance in bacteria is the presence of antibiotic residues in various environmental matrices. Although antibiotics are present in diluted form in environmental matrices like water, consistent exposure of bacteria to these minute levels is enough for the resistance to develop. So, identifying these tiny concentrations of numerous antibiotics in various and complicated matrices will be a crucial step in controlling their disposal in those matrices. Solid phase extraction, a popular and customizable extraction technology, was developed according to the aspirations of the researchers. It is a unique alternative technique that could be implemented either alone or in combination with other approaches at different stages because of the multitude of sorbent varieties and techniques. Initially, sorbents are utilized for extraction in their natural state. The basic sorbent has been modified over time with nanoparticles and multilayer sorbents, which have indeed helped to accomplish the desired extraction efficiencies. Among the current traditional extraction techniques such as liquid-liquid extraction, protein precipitation, and salting out techniques, solid-phase extractions (SPE) with nanosorbents are most productive because, they can be automated, selective, and can be integrated with other extraction techniques. This review aims to provide a broad overview of advancements and developments in sorbents with a specific emphasis on the applications of SPE techniques used for antibiotic detection and quantification in various matrices in the last two decades.

An electrochemical aptasensor for detection of streptomycin based on signal amplification assisted by functionalized gold nanoparticles and hybridization chain reaction

A ratiometric electrochemical aptasensor based on gold nanoparticles (AuNPs) functionalization and hybridization chain reaction (HCR) assisted signal amplification has been for the first time designed for the detection of streptomycin (STR). The double-stranded DNA (dsDNA) formed by the hybridization of ferrocene (Fc)-labeled STR aptamer (Apt) and capture probe (CP) is first immobilized on the gold electrode (GE) surface via Au-S reaction. The specific binding of the target and Apt results in numerous Fc detachment from the sensing interface. Then, the remaining single-stranded CP is combined with AuNPs modified with initiator DNA (iDNA) by auxiliary DNA (aDNA). Among them, the iDNA triggers HCR between two hairpin probes (H1/H2), thus capturing a large number of methylene blue (MB) electrochemical probe, which generates a strong electrochemical signal of MB and a weak electrochemical signal of Fc. Signals are collected by square wave voltammetry (the potential window ranging from -0.5 V to 0.6 V, vs. Ag/AgCl ), and the oxidation peak currents at -0.200 V (MB) and 0.416 V (Fc) are recorded. The use of the ratiometric method has effectively improved the accuracy and reliability of the analysis. The successful application of AuNPs and HCR greatly improves the sensitivity of the sensor, and the detection limit is as low as 0.08 pM. It can sensitively determine STR in the range 0.1 pM to 10 nM. In addition, the designed aptasensor has been successfully applied to the detection of STR in milk and honey samples.

Identification and characterization of Fe3O4/peroxodisulfate advanced oxidation products from sulfameter

Sulfonamides (SAs) are one of the most widely used antibiotics and their residuals in the environment could cause some negative environmental issues. Advanced oxidation such as Fenton-like reaction has been widely applied in the treatment of SAs polluted water. Degradation rates of 95%-99.7% were achieved in this work for the tested 8 SAs, including sulfisomidine, sulfameter (SME), phthalylsulfathiazole, sulfamethoxypyridazine, sulfamonomethoxine, sulfisoxazole, sulfachloropyridazine, and sulfadimethoxine, in the Fe₃O₄/peroxodisulfate (PDS) oxidation system after the optimization of PDS concentration and pH. Meanwhile, it was found that a lot of unknown oxidation products were formed, which brought up the uncertainty of health risks to the environment, and the identification of these unknown products was critical. Therefore, SME was selected as the model compound, from which the oxidation products were never elucidated, to identify these intermediates/products. With liquid chromatography-high resolution tandem mass spectrometry (LC-HRMS/MS), 10 new products were identified, in which 2-amino-5-methoxypyrimidine (AMP) was confirmed by its standard. The investigation of the oxidation process of SME indicated that most of the products were not stable and the degradation pathways were very complicated as multiple reactions, such as oxidation of the amino group, SO₂ extrusion, and potential cross-reaction occurred simultaneously. Though most of the products were not verified due to the lack of standards, our results could be helpful in the evaluation of the treatment performance of SAs containing wastewater.

Molecular Imprinted ZnS Quantum Dots-Based Sensor for Selective Sulfanilamide Detection

Combining molecular imprinted polymers and water-soluble manganese-doped zinc sulfide quantum dots (Mn²⁺: ZnS QDs), a new molecule imprinted polymers-based fluorescence sensor was designed. The molecule imprinted quantum dots (MIP@QDs) were constructed by coating molecular imprinted polymers layer on the surface of ZnS: Mn²⁺ QDs using the surface molecular imprinting technology. The developed MIP@QDs-based sensor was used for rapid and selective fluorescence sensing of sulfanilamide in water samples. The binding experiments showed that the MIP@QDs has rapid fluorescent responses, which are highly selective of and sensitive to the detection of sulfanilamide. The respond time of the MIP@QDs was 5 min, and the imprinting factor was 14.8. Under optimal conditions, the developed MIP@QDs-based sensor shows a good linearity (R² = 0.9916) over a sulfanilamide concentration range from 2.90 × 10⁻⁸ to 2.90 × 10⁻⁶ mol L⁻¹, with a detection limit of 3.23 × 10⁻⁹ mol L⁻¹. Furthermore, the proposed MIP@QDs-based sensor was applied to the determination of sulfanilamide in real samples, with recoveries of 96.80%–104.33%, exhibiting good recyclability and stability. Experimental results showed that the prepared MIP@QDs has the potential to serve as a selective and sensitive sensor for the fluorescence sensing of sulfonamides in water samples.

Magnetic Molecularly Imprinted Polymers: Synthesis and Applications in the Selective Extraction of Antibiotics

Recently, magnetic molecularly imprinted polymers (MMIPs) have integrated molecular imprinting technology (MIT) and magnetic separation technology and become a novel material with specific recognition and effective separation of target molecules. Based on their special function, they can be widely used to detect contaminants such as antibiotics. The antibiotic residues in the environment not only cause harm to the balance of the ecosystem but also induce bacterial resistance to specific antibiotics. Given the above consideration, it is especially important to develop sensitive and selective methods for measuring antibiotics in the complex matrix. The combination of MMIPs and conventional analytical methods provides a rapid approach to separate and determine antibiotics residues. This article gives a systematic overview of synthetic approaches of the novel MMIPs materials, briefly introduces their use in sample pretreatment prior to antibiotic detection, and provides a perspective for future research.

Photochemical reactivity of nitrogen-doped biochars under simulated sunlight irradiation: Generation of singlet oxygen

This study explored the photochemical activity of nitrogen-doped biochars (NCMs) by investigating their role in the degradation of sulfamethazine under simulated sunlight irradiation. NCMs with different doping amounts were prepared from corn straw and urea. Results showed that nitrogen doping can notably enhance the photodegradation of SMT rather than raw char. NCMs are of photochemical activity under visible light, which was confirmed by monochromatic light experiments. Quenching experiments, ESR, pH effect, and the influence of O₂ were carried out to explore the involved oxidation mechanism in this system. Results showed that ¹O₂ was the main reactive oxygen species. ¹O₂ was produced from O₂ by both energy transfer and electron transfer. DFT calculations showed that pyridinic N doping can decrease the energy of intersystem crossing and thus benefit the generation of ¹O₂ by triplet-triplet energy transfer. Results underscore the explicit importance of nitrogen element in photochemical reactivity of chars under simulated light irradiation even when the nitrogen content is low. It is a meaningful reminder for us to pay more attention to the assessment of the fate and transport of contaminants in the soil where it is rich in NCMs as well as the potential use of NCMs for pollutants remediation, since visible light is very abundant near the earth's surface.

Multiresidue method for the simultaneous analysis of antibiotics and mycotoxins in feeds by ultra-high performance liquid chromatography coupled to tandem mass spectrometry

Residues in animal feeds and foods of animal origin have been important safety issue concerning both human and animal health. A multiresidue method for determination of eight mycotoxins and ten antibiotics was developed and validated in animal feeds by using QuEChERS (quick, easy, cheap, effective, rugged, and safe) extraction followed by UHPLC-MS/MS. Optimisation of UHPLC-MS/MS parameters was performed to achieve good separation and resolution. The method was validated according to the European Commission Decision 2002/657/EC. Matrix matched calibration curves showed good r2 (≥0.995) values, and limit of quantification (LOQ) values varied between 1.2 and 5.2 μg kg−1. Average recoveries ranged from 60 to 102% with relative standard deviations of 2.2 and 15.6% for all type of feed samples except for tetracyclines, lincomycin, tylosin, ochratoxin A, and fumonisin (B1 and B2).

Biochar-mediated Fenton-like reaction for the degradation of sulfamethazine: Role of environmentally persistent free radicals

Swine manure biochar (SBC) pyrolyzed at 300 °C, 600 °C and 900 °C were utilized to degrade sulfamethazine (SMT) in heterogeneous Fenton-like systems which achieved excellent degradation efficiency (over 85% in 30 min). Experiments results demonstrated that SBC possessed the poor SMT adsorption capacity but high catalytic performance. Electron Paramagnetic Resonance (EPR) and X-ray photoelectron spectroscopy (XPS) analysis revealed that there were oxygen-centered environmentally persistent free radicals (EPFRs) and carbon-centered EPFRs with an adjacent oxygen atom in SBC. The oxygen-centered EPFRs played a major role in the catalytic process which tended to convert to carbon-centered EPFRs after the reaction. Besides, the electron transfer pathways were the most likely catalytic mechanism of SBC and the contribution of OH was dominant through Electron capture experiments and Linear sweep voltammetry (LSV) measurements. The acidic or alkaline condition can promote the catalytic ability of SBC. The presence of dissolved salts (NaCl) inhibited the catalytic process but the inhibition was slightly weakened at high concentration of NaCl, which showed the high tolerance of Cl^- in Fenton/Fenton-like systems. Moreover, real wastewater application suggested that SBC600/H₂O₂ system possessed excellent catalytic efficiency and good adaptability. This research provides a novel swine manure reuse process with high practicability and presents a more explicit perspective about the reaction mechanisms of EPFRs in biochar.

A twin enrichment method based on dispersive liquid-liquid microextraction and field-amplified sample injection for the simultaneous determination of sulfonamides

A twin enrichment method based on offline dispersive liquid-liquid microextraction (DLLME) coupled with online field-amplified sample injection (FASI) was developed for the simultaneous determination of four sulfonamide (SA) antibiotics, including sulfamethazine (SMZ), sulfamerazine (SMR), sulfadizine (SDZ) and sulfacetamide (SFA), in different environmental waters, followed by capillary electrophoresis (CE). Various parameters that affected the separation performance of CE and the enrichment efficiencies of DLLME and FASI were optimized in detail, and excellent CE separation was attained within 6 min. The DLLME-FASI-CE offered high sensitivity enrichment factors of 206, 166, 185 and 150 for SMZ, SMR, SDZ and SFA, respectively. Highly sensitive detection was realized with low limits of detection (LODs), which ranged from 2.0-23.0, 2.2-26.0 and 4.3-63.0 ng mL-1 in tap water, lake water and seawater, respectively, as well as limits of quantification (LOQs) within 6.0-63.0, 7.4-96.0 and 14.0-201.0 ng mL-1, respectively. Satisfactory recoveries in the range of 91-108% were obtained with the three spiked environmental water samples, and the relative standard deviations were from 1.09-7.45%. The simple effective twin enrichment method provided promising perspective for CE determination of SAs in complicated aqueous matrices, with rapidity, sensitivity, and accuracy.

Synergistic Enhancement Effect for Boosting Raman Detection Sensitivity of Antibiotics

In this paper, a two-step method is used to prepare a regenerative three-dimensional (3D) ZnO/Ag@Au substrate for developing a superior sensitive surface enhanced Raman scattering (SERS) method for detecting antibiotics. A great electromagnetic enhancement is observed from the as-prepared composite substrate, which is triggered by tuning the electron distribution of metals and semiconductor metal oxide. The strong interaction between target sample and the huge surface area of ZnO/Ag@Au composite promotes the charge transfer to produce promising chemical enhancement. The synergistic physical and chemical enhancement mechanisms are validated by density functional theory and finite difference time domain simulation. Additionally, the presence of light "echo effect" in the 3D structure of ZnO support could also amplify the efficiency of light excitation for Raman scattering. The above-stated merits benefit to boost the Raman scattering detection sensitivity for real samples. The ZnO/Ag@Au-based SERS substrate could detect rhodamine 6G molecules with an enhancement factor of up to 1.48 × 10⁹ and the lowest detectable concentration of 10^-10 M. As a real application, antibiotics sulfapyridine in milk is determined by using the proposed SERS protocol, and the limit of detection at 1 × 10^-9 M could be reached. As a prospective, the ZnO/Ag@Au-based SERS method would be extended for food safety and biomedicine analysis.

Synthesis of Graphene Oxide Based Sponges and Their Study as Sorbents for Sample Preparation of Cow Milk Prior to HPLC Determination of Sulfonamides

In the present study, a novel, simple, and fast sample preparation technique is described for the determination of four sulfonamides (SAs), namely Sulfathiazole (STZ), sulfamethizole (SMT), sulfadiazine (SDZ), and sulfanilamide (SN) in cow milk prior to HPLC. This method takes advantage of a novel material that combines the extractive properties of graphene oxide (GO) and the known properties of common polyurethane sponge (PU) and that makes sample preparation easy, fast, cheap and efficient. The PU-GO sponge was prepared by an easy and fast procedure and was characterized with FTIR spectroscopy. After the preparation of the sorbent material, a specific extraction protocol was optimized and combined with HPLC-UV determination could be applied for the sensitive analysis of trace SAs in milk. The proposed method showed good linearity while the coefficients of determination (R²) were found to be high (0.991-0.998). Accuracy observed was within the range 90.2-112.1% and precision was less than 12.5%. Limit of quantification for all analytes in milk was 50 μg kg^-1. Furthermore, the PU-GO sponge as sorbent material offered a very clean extract, since no matrix effect was observed.

Multiresidue Method for Quantification of Sulfonamides and Trimethoprim in Tilapia Fillet by Liquid Chromatography Coupled to Quadrupole Time-of-Flight Mass Spectrometry Using QuEChERS for Sample Preparation

A multiresidue method for detecting and quantifying sulfonamides (sulfapyridine, sulfamerazine, sulfathiazole, sulfamethazine, sulfadimethoxine, sulfamethoxazole, and sulfamethoxypyridazine) and trimethoprim in tilapia fillet (Oreochromis niloticus) using liquid chromatography coupled to mass spectrometry was developed and validated. The sample preparation was optimized using the QuEChERS approach. The chromatographic separation was performed using a C18 column and 0.1% formic acid in water and acetonitrile as the mobile phase in the isocratic elution mode. Method validation was performed based on the Commission Decision 2002/657/EC and Brazilian guideline. The validation parameters evaluated were linearity (r ≥ 0.99); limits of detection (LOD) and quantification (LOQ), 1 ng·g^-1 and 5 ng·g^-1, respectively; intraday and interdays precision (CV lower than 19.4%). The decision limit (CCα 102.6-120.0 ng·g^-1 and 70 ng·g^-1 for sulfonamides and trimethoprim, respectively) and detection capability (CCβ 111.7-140.1 ng·g^-1 and 89.9 ng·g^-1 for sulfonamides and trimethoprim, respectively) were determined. Analyses of tilapia fillet samples from fish exposed to sulfamethazine through feed (incurred samples) were conducted in order to evaluate the method. This new method was demonstrated to be fast, sensitive, and suitable for monitoring sulfonamides and trimethoprim in tilapia fillet in health surveillance programs, as well as to be used in pharmacokinetics and residue depletion studies.

Efficacy of carbonaceous nanocomposites for sorbing ionizable antibiotic sulfamethazine from aqueous solution

This paper investigated the key factors and mechanisms of sulfamethazine (SMT) sorption on a novel carbonaceous nanocomposite, and the effects of harsh aging on SMT sorption in the presence and absence of soil and before as well as after aging. The carbonaceous nanocomposites were synthesized by dip-coating straw biomass in carboxyl functionalized multi-walled carbon nanotubes solution and then pyrolyzed at 300 °C and 600 °C in the absence of air. The sorption performance of high temperature carbonaceous nanocomposite on SMT was excellent, as measured sorption distribution coefficient in the order of 10(3)-10(5.5) L kg(-1). Carbonaceous nanocomposites were aged either alone or mixed with soil via exposure to nutrients and soil extract (biological aging) or 80 °C for 100 d (chemical aging). No obvious effects of harsh aging on SMT sorption were observed in the presence of soil and/or biological and chemical aging. The primary mechanisms for SMT sorption included partition caused by Van der Waals forces and adsorption caused by hydrogen bonding and π-π electron-donor-acceptor interaction. Comprehensively considering the cost, renewability, and the application to real water samples, the carbonaceous nanocomposites have potential in removal of SMT and possibly other persistent organic pollutants from wastewater.

Molecularly Imprinted Polymer-Decorated Magnetite Nanoparticles for Selective Sulfonamide Detection

Sulfonamides are known not only to be antimicrobial drugs that lead to antimicrobial resistance but also to be chemotherapeutic agents that may be allergenic and potentially carcinogenic, which represents a potentially hazardous compound once present in soil or water. Herein, a hybrid material based on molecularly imprinted polymer (MIP)-decorated magnetite nanoparticles for specific and label-free sulfonamide detection is reported. The composite has been characterized using different spectroscopic and imaging techniques. The magnetic properties of the composite are used to separate, preconcentrate, and manipulate the analyte which is selectively captured by the MIP onto the surface of the composite. Screen printed electrodes have been employed to monitor the impedance levels of the whole material, which is related to the amount of the captured analyte, via electrochemical impedance spectroscopy. This composite-based sensing system exhibits an extraordinary limit of detection of 1 × 10(-12) mol L(-1) (2.8 × 10(-4) ppb) (S/N = 3), which is close to those obtained with liquid chromatography and mass spectrometry, and it was demonstrated to screen sulfamethoxazole in a complex matrix such as seawater, where according to the literature sulfonamides content is minimum compared with other environmental samples.

Degradation of Oxytetracycline, Streptomycin, Sulphathiazole and Chloramphenicol Residues in Different Types of Honey

Some of the most frequently used antibiotics in apiculture for the treatment of bacterial brood diseases are oxytetracycline, chloramphenicol, sulphathiazole and streptomycin. Therefore, the aim of this research is to determine the degradation kinetics of the residua these antibiotics leave behind in different types of honey stored in dark at 25 °C. The examined honey samples (N=74) originating from the Croatian market had satisfactory physicochemical properties and pollen characteristics. Quantitative analyses of antibiotic residues were done using HPLC and ELISA methods. No antibiotic residues were found in any of the tested acacia, chestnut, floral, meadow and honeydew honey samples (N=74). In the next step, each of the tested honey samples was supplemented with one of the following antibiotics (in mg/kg): oxytetracycline 10, chloramphenicol 200, sulphathiazole 200 or streptomycin 0.5. Relatively high mass fractions of antibiotics have been added to the honey because the stability of each antibiotic is highly dependent on the spiked antibiotic mass fraction and also on its chemical structure. During a 6-month storage in the dark at 25 °C, the dynamics of degradation of the studied antibiotics was proven to differ dependent on the type of honey into which the antibiotic was added. The half-life of oxytetracycline in the acacia, floral, meadow and honeydew honey stored in the dark at 25 °C was 15, 16, 17 and 19 days, respectively, while in the chestnut honey the decomposition failed to be seen even after 60 days of storage. In all examined honey samples, the half-life of chloramphenicol and sulphathiazole was proven to be longer than 6 months. The fastest decomposition was seen of oxytetracycline added into the acacia honey, followed by streptomycin and sulphathiazole added into the same, while the longest decomposition delay was seen when chloramphenicol was added into the floral honey. According to the results obtained using a linear model of degradation kinetics, the longest oxytetracycline degradation was expected to occur in chestnut honey (116 days). Chloramphenicol and sulphathiazole are preserved the longest in floral (for 661 and 581 days, respectively) and streptomycin in meadow honey (for 321 days).

Recent advances in sample preparation techniques and methods of sulfonamides detection - A review

Sulfonamides (SAs) have been the most widely used antimicrobial drugs for more than 70 years, and their residues in foodstuffs and environmental samples pose serious health hazards. For this reason, sensitive and specific methods for the quantification of these compounds in numerous matrices have been developed. This review intends to provide an updated overview of the recent trends over the past five years in sample preparation techniques and methods for detecting SAs. Examples of the sample preparation techniques, including liquid-liquid and solid-phase extraction, dispersive liquid-liquid microextraction and QuEChERS, are given. Different methods of detecting the SAs present in food and feed and in environmental, pharmaceutical and biological samples are discussed.

Screening and determination of sulphonamide residues in bovine milk samples using a flow injection system

A new, simple, rapid and sensitive flow injection spectrophotometric method was developed for the screening and determination of sulphonamides in bovine milk samples. The method is based on the condensation of sulphathiazole, sulphamethazine, and sulphadimethoxine with p-dimethylaminobenzaldehyde (p-DAB) in acid medium, in the presence of sodium dodecyl sulphate (SDS), producing a yellow compound (λmax=465 nm). Optimisation of the experimental parameters was performed using a multivariate methodology. The linear range was 90-500 μg/L and the limits of detection and quantification were in the ranges 25-29 μg/L and 84-88 μg/L, respectively. The procedure was applied for the determination of sulphonamide antibiotics in bovine milk samples submitted to a prior extraction procedure based on QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) methodology. Recoveries of 60.5-70.5% were achieved for milk samples spiked with 0.09, 0.1, 0.2, and 0.3 μg/g of each sulphonamide.