Development of an immunoaffinity chromatography and HPLC-UV method for determination of 16 sulfonamides in feed

Distribution, lipophilicity and tissue half-life as key factors in sulphonamide clearance from porcine tissues

Introduction

Sulphonamides are some of the most widely used antimicrobial drugs in the treatment of bacterial diseases in pigs. The study was conducted to compare the total exposure of tissue to a group of active substances in a single formulation and evaluate the impact of the volume of distribution, lipophilicity and tissue half-life of sulfadimethoxine, sulphathiazole, sulphamethazine and sulphacetamide in two different veterinary drug formulations - Polisulfalent, which was preparation A, and Polisulfamid, which was preparation B.

Material and Methods

Each tested therapeutic preparation was administered to 15 piglets of the Polish Landrace breed. To assume general exposure expressed as the sum of all observed concentrations of all active substances, semi-log regression analyses were performed for both formulations.

Results

The estimated tissue half-life was 21.19 h for preparation A and 17.36 h for preparation B. The comparison of the semi-log regression parameters shows that formulation B's Y-intercept and slope values were higher than formulation A's. The upper-bound CI for the Y-intercept and slope value of formulation B was higher than those of formulation A, at 38.7 and 20.8%, respectively.The lower-bound CI for the Y-intercept and slope value of formulation B was also higher than those of formulation A, at 20.6 and 42.9%, respectively.

Conclusion

Current observations lead to the conclusion that in late-stage drug elimination, it is not the blood half-life, but rather a drug's volume of distribution which is key in determining the clearance period, this volume being dependent on the physicochemical characteristics of the drug.

Detection of Veterinary Drugs in Food Using a Portable Mass Spectrometer Coupled with Solid-Phase Microextraction Arrow

A portable mass spectrometer (PMS) was combined with a mesoporous silica material (SBA-15) coated solid-phase microextraction (SPME) Arrow to develop a rapid, easy-to-operate and sensitive method for detecting five veterinary drugs-amantadine, thiabendazole, sulfamethazine, clenbuterol, and ractopamine-in milk and chicken samples. Equipped with a pulsed direct current electrospray ionization source and a hyperboloid linear ion trap, the PMS can simultaneously detect all five analytes in approximately 30 s using a one-microliter sample. Unlike traditional large-scale instruments, this method shows great potential for on-site detection with no need for chromatographic pre-separation and minimal sample preparation. The SBA-15-SPME Arrow, fabricated via electrospinning, demonstrated superior extraction efficiency compared to commercially available SPME Arrows. Optimization of the coating preparation conditions and SPME procedures was conducted to enhance the extraction efficiency of the SBA-15-SPME Arrow. The extraction and desorption processes were optimized to require only 15 and 30 min, respectively. The SBA-15-SPME Arrow-PMS method showed high precision and sensitivity, with detection limits and quantitation limits of 2.8-9.3 µg kg-1 and 10-28 µg kg-1, respectively, in milk. The LOD and LOQ ranged from 3.5 to 11.7 µg kg-1 and 12 to 35 µg kg-1, respectively, in chicken. The method sensitivity meets the requirements of domestic and international regulations. This method was successfully applied to detect the five analytes in milk and chicken samples, with recoveries ranging from 85% to 116%. This approach represents a significant advancement in food safety by facilitating rapid, in-field monitoring of veterinary drug residues.

Evaluation the food safety of cultured fat via detection of residues of adipogenic differentiation cocktail in cultured fat with high performance liquid chromatography and enzyme-linked immunosorbent assay

Cultured fat is inducing adipose progenitor cells (APCs) to differentiate into mature adipocytes for consumption. The traditional adipogenic differentiation cocktail, including insulin, dexamethasone, indomethacin, isobutylmethylxanthine and rosiglitazone, has potential food safety problems in cultured fat. Therefore, the detection of these residues is necessary to ensure food safety. In this research, a method of high performance liquid chromatography (HPLC) was established to quantitatively analyze the potential residual content of dexamethasone, indomethacin, isobutylmethylxanthine and rosiglitazone in cultured fat and medium. Quantitative analysis showed that the content of four residues in cultured fat decreased to zero on Day 10. Subsequently, enzyme-linked immunosorbent assay (ELISA) was performed to detect the insulin content in the cultured fat and found that the insulin content in the cultured fat on Day 10 was 2.78 ± 0.21 μg/kg. After soaking with phosphate buffered saline (PBS), the insulin content decreased to 1.88 ± 0.54 μg/kg. In conclusion, this research provided an effective approach to clarify the content of potential residual components in cultured fat and it will provide reference for the safety of cultured fat in the future.

Dual fluorescent aptasensor for simultanous and quantitative detection of sulfadimethoxine and oxytetracycin residues in animal-derived foods tissues based on mesoporous silica

Herein, we developed a dual fluorescent aptasensor based on mesoporous silica to simultaneously detect sulfadimethoxine (SDM) and oxytetracycline (OTC) in animal-derived foods. We immobilized two types of aptamers modified with FAM and CY5 on the silica surface by base complementary pairing reaction with the cDNA modified with a carboxyl group and finally formed the aptasensor detection platform. Under optimal conditions, the detection range of the aptasensor for SDM and OTC was 3-150 ng/mL (R ² = 0.9831) and 5-220 ng/mL (R ² = 0.9884), respectively. The limits of detection for SDM and OTC were 2.2 and 1.23 ng/mL, respectively. The limits of quantification for SDM and OTC were 7.3 and 4.1 ng/mL, respectively. Additionally, the aptasensor was used to analyze spiked samples. The average recovery rates ranged from 91.75 to 114.65% for SDM and 89.66 to 108.94% for OTC, and all coefficients of variation were below 15%. Finally, the performance and practicability of our aptasensor were confirmed by HPLC, demonstrating good consistency. In summary, this study was the first to use the mesoporous silica-mediated fluorescence aptasensor for simultaneous detection of SDM and OTC, offering a new possibility to analyze other antibiotics, biotoxins, and biomolecules.

Separation of false-positive microplastics and analysis of microplastics via a two-phase system combined with confocal Raman spectroscopy

In the field of microplastics research, more accurate standardised methods and analytical techniques still need to be explored. In this study, a new method for the microplastics quantitatively and qualitatively analysis by two-phase (ethyl acetate-water) system combined with confocal Raman spectroscopy was developed. Microplastics can be separated from false-positive microplastics in beach sand and marine sediment, attributing to the hydrophobic-lipophilic interaction (HLI) of the two-phase system. Results show that the recovery rates of complex environment microplastics (polypropylene (PP), polyethylene terephthalate (PET), polyvinyl chloride (PVC), polyamide 66 (PA 66), polycarbonate (PC) and polyethylene (PE)) are higher than 92.98%. Moreover, the new technique can also be used to detect hydrophobic and lipophilic antibiotics, such as sulfamethoxazole (SMX), erythromycin (EM), madimycin (MD), and josamycin (JOS), which adsorbed on microplastics and are extracted based on the dissolving-precipitating mechanism. This innovative research strategy provides a new scope for further detection of marine environment microplastics and toxic compounds adsorbed on its surface.

Development of a Quantitative Method for Detection of Multiclass Veterinary Drugs in Feed Using Modified QuPPe Extraction and LC–MS/MS

A method was developed for the rapid and quantitative analysis of 30 veterinary drugs belonging to 17 classes (amphenicols (1), anthelmintics (1), cephalosporins (4), coccidiostats (1), lincosamides (1), macrolide (1), nitroimidazole (1), penicillins (3), phenylhydrazines (1), polypeptides (1), pyrethrins (1), quinolones (5), sulfonamides (3), tetracycline (3), neuroleptic agents (1), triazene trypanocidal agents (1), other. (1)) in feeds. The proposed method with a modified Quick Polar Pesticides (QuPPe) sample preparation was validated for the determination of 30 veterinary drugs in feed samples by liquid chromatography triple-quadrupole mass spectrometry (LC–MS/MS). The sample was extracted with methanol containing 1% acetic acid and purified by dispersive solid-phase extraction (d-SPE) with C18. Good linearity (r² ≥ 0.98) was observed, and the LOQ values ranged from 10 to 200 µg/kg. Average recoveries ranged from 70.8 to 118.4%, and the relative standard deviation was ≤ 18.7%. This validated method was used in the determination of 30 veterinary drugs in 142 feed samples obtained from South Korea. The results show that lincomycin was present in only one of the tested feed samples, although it was detected at a value lower than the LOQ. In conclusion, this multi-residue method can be used for screening through the detection and quantitation of residual multiclass veterinary drugs in feed samples.

Assessment of various veterinary drug residues in animal originated food products

The veterinary drugs are broad-spectrum antibacterial antibiotics; it uses to cure the animal disease. Many countries have banned veterinary drug residues like nitrofurans metabolites, chloramphenicol. However, the people were administrated veterinary drugs to animals as illegal to increase the milk production in animals for economic benefit. The results of illegally use of veterinary drugs remain as a residue in animal product like milk and it is very harmful to whom consume it cause cancer and allergic for human being which has entered the concern among milk consumers. To control illegal use of veterinary drugs, the government of India has restricted its use in animals. For the identification and confirmation of veterinary drug residues in animal products, analytical techniques such as liquid chromatography and mass spectrometry are available. These are very sophisticated equipments which are available nowadays and their methodologies for the analytical method validation are described by European commission 2002/657/EC. The use of veterinary drugs is a big challenge to effectively identify and authorization of their use. There are so many analytical techniques are using very effectively and taking very less time to protect the consumers from their adverse effects. These techniques take very less time to identify more groups of compounds such as tetracycline, sulfonamides, anthelmintic, and macrolides in single multi-residue method. These methods having validation parameters include system precision, calibration curve, accuracy, limit of detection, and quantification. Therefore, improvement in the existing technologies and accessibility of new screening methodologies will give opportunities for automation that helps in obtaining the results in very less time and improved sensitivity and specificity which contribute to better safety assurance, standard, and quality of various food products of animal origin.

A Green HPLC Method for Determination of Nine Sulfonamides in Milk and Beef, and Its Greenness Assessment with Analytical Eco-Scale and Greenness Profile

BACKGROUND

Sulfonamides have been widely used in the prevention and clinical treatment of bacterial diseases in livestock and poultry. The use of sulfonamides increases the risk of veterinary drug residues in animal derived foods. The traditional reversed phase liquid chromatography methods for sulfonamides residues detection in animal derived foods have the problem of high consumption of organic solvents.

OBJECTIVE

The aim of this study was to establish a green high-performance liquid chromatography method for the detection of sulfonamides residues in different animal-origin foods.

METHOD

The sample extraction solutions were purified by the Agela Cleanert PEP-2 cartridge and analyzed by the high-performance liquid chromatography method using ethanol as the green alternative solvent.

RESULTS

The proposed method was validated in terms of linear range (20-1000 μg/kg), limit of detection (3.0-12.3 μg/kg), limit of quantitation (10-43 μg/kg), accuracy (80.7-101.3%), and repeatability and reproducibility (RSD <5.9% and RSD <8.5% respectively).

CONCLUSIONS

The proposed method is an environmentally friendly, sensitive and reliable high-performance liquid chromatography method for simultaneous determination of sulfonamide residues in animal-origin foods.

HIGHLIGHTS

In this work, we firstly developed a green high-performance liquid chromatography method for simultaneous determination of the residues of nine sulfonamides in milk and beef with ethanol as the green alternative solvent.

Application of Micellar Mobile Phase for Quantification of Sulfonamides in Medicated Feeds by HPLC-DAD

Rapid chromatographic procedure for quantification of five sulfonamides in medicated feeds are proposed. Satisfactory separation of sulfonamides from medicated feeds was achieved using a Zorbax Eclipse XDB C18 column (4.6 × 150 mm, 5 µm particle size) with a micellar mobile phase consisting of 0.05 M sodium dodecyl sulphate, 0.02 M phosphate buffer, and 6% propan-2-ol (pH 3). UV quantitation was set at 260 nm. The proposed procedure allows the determination of sulfaguanidine, sulfadiazine, sulfamerazine, sulfamethazine, and sulfamethoxazole in medicated feeds for pigs and poultry. Application of the proposed method to the analysis of five pharmaceuticals gave recoveries between 72.7% to 94.7% and coefficients of variations for repeatability and reproducibility between 2.9% to 9.8% respectively, in the range of 200 to 2000 mg/kg sulfonamides in feeds. Limit of detection and limit of quantification were 32.7–56.3 and 54.8–98.4 mg/kg, respectively, depending on the analyte. The proposed procedure for the quantification of sulfonamides is simple, rapid, sensitive, free from interferences and suitable for the routine control of feeds. In the world literature, we did not find the described method of quantitative determination of sulfonamides in medicated feeds with the use of micellar liquid chromatography.

Facile nano-free electrochemiluminescence biosensor for detection of sulphamethoxazole via tris(2,2'-bipyridyl)ruthenium(II) and N-methyl pyrrolidone recognition

The electrochemiluminescence (ECL) system based on the ruthenium complex has become a powerful tool in the field of analytical chemistry. However, the non-aqueous ECL luminescence system, which does not involve complex nano-modification, has not been widely used for the determination of analytes. In this study, N-methyl pyrrolidone was selected as the solvent, and it could also act as a co-reactant of [inline-formula removed]. Based on this, a simple ECL system without nanomaterials was established. Strong ECL was generated. Furthermore, a quenching effect between the excited state of [inline-formula removed] and sulphamethoxazole (SMZ) was observed. Based on this, a sensitive ECL sensor for detecting SMZ is constructed. A linear relationship between ECL signal quenching intensity (ΔI) and the logarithm of SMZ concentration (log C) in the concentration range of 1 × 10^-7-1 × 10^-5 mol/l is obtained. The limit of detection is as low as 3.33 × 10^-9 mol/l. The method has been applied to the detection of SMZ in tap water samples with different concentration levels with satisfactory results, and the recovery was 95.3-102.6%.

Characterization and comparison of two peptide-tag specific nanobodies for immunoaffinity chromatography

Affinity chromatography is generally regarded as a powerful tool allowing the single step purification of recombinant proteins with high purity and yields. However, for most protein products, affinity purification methods for industrial applications are not readily available, mainly due to the lack of specific and robust natural counterparts that could function as affinity ligands. In this study, we explored the applicability of nanobody-based peptide-tag immunorecognition systems as a platform for affinity chromatography. Two typical nanobodies (BC2-nb and Syn2-nb) that are capable of recognizing specifically a particular peptide-tag, were prepared through prokaryotic expression and proved to be able to bind with nanomolar affinity to their cognate tag fused to enhanced green fluorescent protein (eGFP). Through an epoxy-based immobilization reaction, the two nanobodies were coupled on a Sepharose CL-6B matrix under the same conditions. The remaining antigen binding activity of the immobilized BC2-nb and Syn2-nb was determined to be 83.1% and 42.9%, yielding the resins with the dynamic binding capacity (DBC) of 21.4 mg/mL and 5.9 mg/mL, respectively. The immobilized affinity ligands exhibited high binding specificity towards their respective target peptides, yielding a product purity above 90% directly from crude bacterial lysates in one single chromatographic step. However, for the both affinity complexes, desorption has been found difficult, and effective recovery of the bound products could be only achieved with competitive elution or after employing harsh conditions such as 10 mM NaOH solution, which will compromise the reuse cycles of the affinity resins. This study shows the potential of nanobody-based affinity chromatography for efficient purification of recombinant proteins especially from complex feedstocks and reveals the primary issues to be addressed to develop a successful application.

Development of a Gas Chromatography-Flame Ionization Method for the Detection and Quantification of 12 Flavoring Agents in Supplementary Feed

A flavoring agent is a compound that serves to add flavor with a pleasant scent and is used as a feed additive. Current flavor analysis methods include reflux pretreatment, titration, neutralization titration, and inversion; these are all analytical methods in which deviations and errors between experiments are generated. Titration methods are characterized by difficult selectivity analysis both for mixtures containing two or more types of flavoring agents and also for very low content samples. Current analysis methods are therefore particularly unsuitable for these sample types. Thus, more precise and accurate analysis of flavor agents is needed. This study intends to develop and verify a multi-component simultaneous analysis method that can accurately confirm the guaranteed content of 12 flavor agents of supplementary feeds distributed in the market, the goal being to establish a universally trusted method. Method validation was performed according to the International Conference on Harmonization (ICH) and International Union of Pure and Applied Chemistry (IUPAC) guidelines. Method

validation was performed in terms of linearity, sensitivity, selectivity, accuracy, and precision. The limits of detection (LOD) for the instrument employed in these experiments ranged from 0.44–4.77 mg/kg, and the limits of quantification (LOQ) ranged from 1.32–14.31 mg/kg. Average recoveries of the 12 flavoring agents ranged from 75.1–111.4%. Maximum %RSD values for intraday and interday peak area variation are 13.09% and 13.08%, respectively. A novel and simple method for detecting 12 flavoring agents in animal feed supplements using a gas chromatography-flame ionization detector (GC-FID) was developed.

Simultaneous analysis and measurement of uncertainty estimation of six isoflavones in Cheonggukjang by liquid chromatography-electrospray tandem mass spectrometry

A novel and simple method for detecting six isoflavones in Cheonggukjang using liquid chromatography-electrospray tandem mass spectrometry (LC-MS/MS) was developed. The method validation was performed in terms of linearity, sensitivity, selectivity, accuracy and precision. The limits of detection (LODs) for the instrument employed in these experiments ranged from 0.15 μg/kg to 1.50 μg/kg, and the limits of quantification (LOQs) ranged from 0.50 μg/kg to 5.00 μg/kg. The average recoveries of the six isoflavones ranged from 82.3% to 98.9%. Before assessing the uncertainty of the measurements, we identified the factors that affect the measured value using quantitative analysis to determine how each factor affects the measurement result. It was found that the sample weighing, standard material purity, dilution, calibration curve and reproducibility factor affect the uncertainty of measurement. The developed method was specific and reliable. Therefore, the method is suitable for the routine analysis of isoflavones in Cheonggukjang.

Robotic-assisted dynamic large drop microextraction

By proper design of an innovative extraction device, a lab-made multipurpose autosampler was exploited in the automated performance of the dynamic large drops based microextraction. The pluses of this new analytical strategy were demonstrated in the determination of sulfonamides and fluoroquinolones in surface water samples, by direct immersion single drop microextraction (SDME) and liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) analysis. Operational autosampler features and critical experimental factors influencing SDME, including the extraction mode (static or dynamic), extraction, stirring rate, salt addition, drop size, number of cycles and drop exposition time, were comprehensively investigated using both univariate and multivariate optimization. The lab-made autosampler allowed to performance challenging dynamic and static large drop based SDMEs in an automated and effortless way and with minimal requirements of hardware and software. Large stable drops provided high surface area, enhancing the phase ratio and in consequence increasing the analytes uptake. The best extraction efficiencies were obtained as a result of the synergic interaction between the use of large drops and the automated dynamic mode of extraction. The developed method proved to be a reliable, sensitive, and robust analytical tool, with intraday RSDs ranging between 4.0 and 7.6% (n = 6), and interday RSDs between 4.8 and 9.3% (n = 6), and, LOD and LOQ in the range of 15-50 and 35-100 ng L^-1, respectively.

Determination of Sulfonamides in Feeds by High-Performance Liquid Chromatography after Fluorescamine Precolumn Derivatization

A new multi-residue method for the analysis of sulfonamides (sulfadiazine, sulfamerazine, sulfamethazine, sulfaguanidine and sulfamethoxazole) in non-target feeds using high-performance liquid chromatography-fluorescence detection (HPLC-FLD) and precolumnderivatization was developed and validated. Sulfonamides (SAs) were extracted from feed with an ethyl acetate/methanol/acetonitrile mixture. Clean-up was performed on a Strata-SCX cartridge. The HPLC separation was performed on a Zorbax Eclipse XDB C18 column with a gradient mobile phase system of acetic acid, methanol, and acetonitrile. The method was validated according to EU requirements (Commission Decision 2002/657/EC). Linearity, decision limit, detection capability, detection and quantification limits, recovery, precision, and selectivity were determined, and adequate results were obtained. Using the HPLC-FLD method, recoveries were satisfactory (79.3–114.0%), with repeatability and reproducibility in the range of 2.7–9.1% to 5.9–14.9%, respectively. Decision limit (CCα) and detection capability (CCβ) were 197.7–274.6 and 263.2–337.9 µg/kg, respectively, and limit of detection (LOD) and limit of quantification (LOQ) were 34.5–79.5 and 41.3–89.9 µg/kg, respectively, depending on the analyte. Results showed that this analytical procedure is simple, rapid, sensitive, and suitable for the routine control of feeds.

A Cu(II)-anchored unzipped covalent triazine framework with peroxidase-mimicking properties for molecular imprinting-based electrochemiluminescent detection of sulfaquinoxaline

The authors describe a method of electrochemiluminescent quantitation of the antibiotic sulfaquinoxaline (SQX). It relies on the use of a molecularly imprinted polymer and a Cu(II)-anchored unzipped covalent triazine framework (UnZ-CCTF) with excellent dispersibility, electrical conductivity, and peroxidaze-like activity. The framework was prepared by unzipping a covalent triazine framework under retention of basic triazine units. It was morphologically and structurally characterized by a range of instrumental techniques. The excellent peroxidase-mimicking effect of UnZ-CCTF on the electrochemiluminescence of the luminol/H2O2 system was exploited to design an ultrasensitive SQX assay with a 1.0-20 pM detection range and a detection limit of 0.76 pM (at 3δ/m). The technique was used for SQX quantitation in spiked milk samples, achieving recoveries of 94.0-104.8%. Graphical abstract Scheme of the sulfaquinoxaline molecularly imprinted electrochemiluminescence sensor based on Cu-anchored unzipped covalent triazine frameworks.

Development of an immunoaffinity chromatography and LC-MS/MS method for the determination of 6 zearalenones in animal feed

A novel and simple method for detecting 6 zearalenones in animal feed using liquid chromatography coupled with triple quadrupole mass spectrometry (LC-MS/MS) and immunoaffinity columns (IAC) was developed. The chromatographic peaks of the 6 zearalenones were successfully identified by comparing their retention times and mass spectrum with reference standards. The mobile phase was composed of mobile phase A (water) and B (0.5% formic acid in ACN). Method validation was performed with linearity, sensitivity, selectivity, accuracy and precision. The limits of detection (LODs) for the instrument used to study zearalenones ranged from 0.3 to 1.1 μg/kg, and the limits of quantification (LOQs) ranged from 1.0 to 2.2 μg/kg. Average recoveries of the 6 zearalenones ranged from 82.5% to 106.4%. Method replication resulted in intra-day and inter-day peak area variation of <3.8%. The developed method was specific and reliable and is suited for the routine analysis of zearalenones in animal feed.

Ultrasensitive Immunochromatographic Strip for Fast Screening of 27 Sulfonamides in Honey and Pork Liver Samples Based on a Monoclonal Antibody

Group-specific monoclonal antibodies (Mabs) with selectivity for 27 sulfonamides were developed based on new combinations of immunogen and coating antigen. The Mab was able to recognize 27 sulfonamides with 50% inhibition concentration (IC₅₀) values ranging from 0.15 to 15.38 μg/L. In particular, the IC₅₀ values for five sulfonamides (sulfamethazine, sulfaquinoxaline, sulfamonomethoxine, sulfadimethoxine, and sulfamethoxazole) were 0.51, 0.15, 0.56, 0.54, and 2.14 μg/L, respectively. On the basis of the Mab, an immunochromatographic lateral flow strip test was established for rapid screening of sulfonamides in honey samples. The visual limit of detection of the strip test for most sulfonamides in spiked honey samples was below 10 μg/kg, satisfying the requirements of authorities. Positive honey and pork liver samples, which had been confirmed by high-performance liquid chromatography/mass spectrometry, were used to validate the reliability of the proposed strip test. The immunochromatographic lateral flow strip test provides a rapid and convenient method for fast screening of sulfonamides in honey samples.

Sulfonated poly(styrene-divinylbenzene) modified with amines and the application for pipette-tip solid-phase extraction of carbendazim in apples

Sulfonated poly(styrene-divinylbenzene) modified with five kinds of amine functional groups was applied to the determination of carbendazim in apple samples with a pipette-tip solid-phase extraction method. The structures of the polymers were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis. Five different modifications of the solid-phase extraction sorbent based on sulfonated poly(styrene-divinylbenzene) were tested under static and pipette-tip solid-phase extraction conditions. The polymer modified with p-methoxyaniline showed the best recognition capacity and adsorption amount for carbendazim. Under the optimum conditions, 3.00 mg of the adsorbent, 1.00 mL of ethyl acetate as washing solvent, and 1.00 mL of ammonia/acetonitrile (5:95, v/v) as elution solvent were used in the pretreatment procedure of apple samples. The calibration graphs of carbendazim in methanol were linear over 5.00-200.00 μg/mL, and the limits of detection and quantification were 0.01 and 0.03 μg/mL, respectively. The method recoveries of carbendazim were in the range of 91.31-98.13% with associated intraday relative standard deviations of 0.76-2.13% and interday relative standard deviations of 1.10-1.85%. Sulfonated poly(styrene-divinylbenzene) modified with p-methoxyaniline showed satisfactory results (recovery: 97.96%) and potential for the rapid purification of carbendazim in apple samples combined with the pipette-tip solid-phase extraction.

Determination of Sulfonamide Residues in Food by Capillary Zone Electrophoresis with On-Line Chemiluminescence Detection Based on an Ag(III) Complex

The presence of sulfonamide (SA) residues in foods is largely due to the raising of animals with sulfonamide antibiotics added or polluted feedstuff. In this paper, a sensitive method was developed for the determination of the residues of three sulfonamides in animal-derived food; the SAs include sulfadimidine (SDD), sulfadiazine (SDZ), and sulfathiazole (STZ). The method is based on capillary zone electrophoresis (CE) with online chemiluminescence (CL) detection, using an Ag(III) complex as an oxidant. These SAs have an inhibiting effect on the Ag(III)-luminol CL reaction. The electrophoretic buffer is 12.0 mM sodium borate. Under a set of optimized conditions, the linear ranges for the detections were found to be 10.0-200 µg·mL^-1 for SDD and SDZ, and 2.0-50.0 µg·mL^-1 for STZ. The detection limits were 2.75, 3.14, and 0.65 µg·mL^-1 for SDD, SDZ, and STZ, respectively. Relative standard deviations (RSD) for the peak heights were between 2.1% and 2.8% (n = 7). The proposed method was used in the analysis of the SAs in samples from pork meat, chicken meat, and milk, showing satisfactory detection results. A reaction mechanism was also proposed for the Ag(III)-luminol-SA CL reactions. The method has potential applications for the monitoring of residue levels of the three SAs in food, providing food safety data.

Affinity chromatography: A versatile technique for antibody purification

Antibodies continue to be extremely utilized entities in myriad applications including basic research, imaging, targeted delivery, chromatography, diagnostics, and therapeutics. At production stage, antibodies are generally present in complex matrices and most of their intended applications necessitate purification. Antibody purification has always been a major bottleneck in downstream processing of antibodies, due to the need of high quality products and associated high costs. Over the years, extensive research has focused on finding better purification methodologies to overcome this holdup. Among a plethora of different techniques, affinity chromatography is one of the most selective, rapid and easy method for antibody purification. This review aims to provide a detailed overview on affinity chromatography and the components involved in purification. An array of support matrices along with various classes of affinity ligands detailing their underlying working principles, together with the advantages and limitations of each system in purifying different types of antibodies, accompanying recent developments and important practical methodological considerations to optimize purification procedure are discussed.

Preparation and characterization of chitosan microparticles for immunoaffinity extraction and determination of enrofloxacin

The use of chitosan microparticles as chromatographic support has received much attention. In this study, the effects of process parameters, namely, chitosan molecular weight, chitosan concentration, molar ratio of amino group to aldehyde group, volume ratio of water to oil phase and stirring speed on the size and size distribution of chitosan microparticles and their application for immunoaffinity extraction were extensively investigated. Size distribution analysis indicated that the average diameter of the microparticles was 124μm with Span value of 1.1. The obtained microparticles exhibited low non-specific adsorption and kept stable in the pH range 4.0-10.0. Immunoaffinity chromatography (IAC) column was prepared by coupling antibody against enrofloxacin (ENR) with chitosan microparticles. Further characterization indicated that the binding capacity of the column was 4392ng ENR/mL gel and the variation of ENR extraction efficiency among columns was less than 5.2%. When challenged with ENR-fortified bovine milk samples, recoveries of ENR by immunoaffinity extraction were found to be in the range of 85.9% to 101.9%, demonstrated the feasibility of the prepared IAC columns for sample clean-up in ENR residue determination.

Development of an Ion-Pairing Reagent and HPLC-UV Method for the Detection and Quantification of Six Water-Soluble Vitamins in Animal Feed

A novel and simple method for detecting six water-soluble vitamins in animal feed using high performance liquid chromatography equipped with a photodiode array detector (HPLC/PDA) and ion-pairing reagent was developed. The chromatographic peaks of the six water-soluble vitamins were successfully identified by comparing their retention times and UV spectra with reference standards. The mobile phase was composed of buffers A (5 mM PICB-6 in 0.1% CH3COOH) and B (5 mM PICB-6 in 65% methanol). All peaks were detected using a wavelength of 270 nm. Method validation was performed in terms of linearity, sensitivity, selectivity, accuracy, and precision. The limits of detection (LODs) for the instrument employed in these experiments ranged from 25 to 197 μg/kg, and the limits of quantification (LOQs) ranged from 84 to 658 μg/kg. Average recoveries of the six water-soluble vitamins ranged from 82.3% to 98.9%. Method replication resulted in intraday and interday peak area variation of <5.6%. The developed method was specific and reliable and is therefore suitable for the routine analysis of water-soluble vitamins in animal feed.