Analysis of sulfonamide and quinolone antibiotic residues in Korean milk using microbial assays and high performance liquid chromatography

A reliable fluorescence "turn-on" aptasensor based on dual-emitting europium metal-organic frameworks for ultrasensitive and selective detection of sulfamethazine

A high-performance fluorescent "turn-on" aptasensor (Eu-MOFs@SMZ-Apt) for sulfamethazine (SMZ) determination was designed using dual-emitting europium metal-organic frameworks (Eu-MOFs) as a signal transducer and an amplifier. Eu-MOFs featuring dual emission peaks (430 nm and 620 nm) were first prepared via a facile self-assembly strategy employing Eu (III) ions and 2-aminoterephthalic acid as precursors. The high-affinity aptamer was bonded with Eu-MOFs to form Eu-MOFs@SMZ-Apt through the amidation reaction. Benefiting from the integration of inherent virtues from Eu-MOFs and aptamer, the Eu-MOFs@SMZ-Apt-based sensor allowed sensitive and selective determination of SMZ with good linear relationships in a range of 1.4-40 ng mL-1 and a low detection line (0.379 ng mL-1). This sensor was successfully applied to the determination of trace SMZ in real samples with satisfactory recoveries (86.47-113.52%) and a relative standard deviation (<6.51). Consequently, the Eu-MOFs@SMZ-Apt ratiometric fluorescence sensor furnishes new possibilities for the accurate detection of various pollutants in food.

Integration of glutathione disulfide-mediated extraction and capillary electrophoresis for determination of Cd(II) and Pb(II) in edible oils

A novel method is introduced for extracting and enriching Cd(II) and Pb(II) from edible oils using glutathione disulfide (GSSG) as both an extractant and a phase-separation agent. The ions in the oils were initially extracted into an aqueous solution containing GSSG. After mixing the solution with acetonitrile at the appropriate volume ratio, a new phase formed, resulting in enrichment of the analytes. The experimental conditions were optimized using response surface methodology with a central composite design. Under optimal conditions, the method offered a combined enrichment factor of >660, with combined extraction efficiencies of 84.31% and 83.35% for Cd(II) and Pb(II), respectively. Finally, the method was conjugated to capillary electrophoresis to determine Cd(II) and Pb(II) in edible oil samples, with detection limits of 0.45 and 1.24 ppb, respectively. In comparison to traditional approaches, the GSSG-based method demonstrates rapidity, efficiency, and recyclability in extracting heavy metal ions from complex matrices.

Electrospun nanofiber-based indicatorpaper sensing platform for fluorescence and visualization detection of norfloxacin

Norfloxacin (NOR) residues in water pose a serious threat to human health via the food chain, necessitating the development of a rapid on-site antibiotic detection technique. In this work, we utilize electrostatic spinning technology that combines polyacrylonitrile (PAN) fibers and adenosine triphosphate (ATP)-rare earth metal Tb3+ complexes (ATP/Tb) to construct a new ternary film-based sensor for sensitive, quick, and convenient field testing of NOR in water. The operating mechanism is that the ternary system produces gradually enhanced bright green fluorescence at increasing concentrations of NOR. The unique fluorescence property of the ternary systems is attributed to the use of ATP, rather than the commonly used adenosine monophosphate (AMP), to coordinate with Tb3+, which avoided the possible fluorescence quenching from competitive water binding. Benefiting from the PAN nanofiber's superior stability, acid, and alkali resistance, and flexibility as support, the ternary system exhibited a good linear response to NOR in a wide dynamic range of 0.04-30 μM at the detection limit of 16 nM. Additionally, the combination of a smartphone color recognition app allows for quick on-scene NOR detection. This film sensing strategy is instructive for the development of smart and portable sensing platforms for real-time detection of analytes such as antibiotics, pesticide residues, and hazardous materials in water bodies.

Aggregation-Induced Near-Infrared Emission and Electrochemiluminescence of an Iridium(III) Complex for Ampicillin Sodium Sensing

A new iridium(III) complex was synthesized and characterized. Its photophysical properties and aggregation-induced emission and electrochemiluminescence in the near-infrared range were studied. The large conjugated cyclometallic ligand 1,2-phenylbenzoquinoline (pbq) was selected to form the Ir-C bond with the metal iridium(III) center and provide near-infrared emission of the complex. The auxiliary ligand 4,4'-diamino-2,2'-bipyridine (dabpy) can form hydrogen bonds, which was beneficial for the generation of aggregation-induced emission. The complex was aggregated into small spherical nanoparticles in 80% water and fascinating nanorings in 90% water. The sensing of ampicillin sodium (AMP) antibiotic by the iridium(III) complex were also investigated by photoluminescent and electrochemiluminescent methods. The complex showed a good selectivity toward AMP antibiotic compared to sodium phenylacetate and other eight antibiotics. The detection limits for AMP antibiotic was 0.76 μg/mL. This work provided a new strategy for the design of iridium(III) complex-based aggregation-induced emission and electrochemiluminescence probes for the sensing application.

Synthesis of a dual-functional terbium doped copper oxide nanoflowers for high-efficiently electrochemical sensing of ofloxacin, pefloxacin and gatifloxacin

The current effort introduces a facile construction of peony-like CuO:Tb³⁺ nanostructure (P-L CuO:Tb³⁺ NS), whose characterization was determined via techniques of X-ray diffraction, scanning electron microscopy and energy dispersive X-ray spectroscopy. We investigated ofloxacin, pefloxacin and gatifloxacin oxidation electrochemically on P-L CuO:Tb³⁺ NS-modified glassy carbon electrode (P-L CuO:Tb³⁺ NS/GCE), the results of which revealed the irreversible oxidation of drugs through a two-electron oxidation process. An admirable resolution was found for this modified electrode between voltammetric peaks of ofloxacin, pefloxacin and gatifloxacin, suggesting its appropriateness for simultaneous detection of these drugs in pharmaceutical media. In addition, our nanostructure synergistically influenced the electro-catalytic oxidations of these three compounds. Differential pulse voltammetric measurements of ofloxacin, pefloxacin and gatifloxacin through our sensor showed a limit of detection of 1.9, 2.3 and 1.2 nM a as well as a linear dynamic range between 0.01 and 800.0 μM in phosphate buffered solution (0.1 M, pH = 6.0), respectively. Moreover, as-fabricated sensor could successfully co-detect these drugs in real serum and tablets specimens. In addition, since we use animal foods such as milk it is very important to detect their fluoroquinolone residues. For this purpose, the proposed sensor was tested to determine the residues of ofloxacin, pefloxacin and gatifloxacin in milk.

Green and cost-effective voltammetric assay for spiramycin based on activated glassy carbon electrode and its applications to urine and milk samples

A simple, cost-effective, and efficient differential pulse voltammetric (DPV) assay for monitoring spiramycin adipate (SPA) in its dosage forms, urine, and milk samples at an activated glassy carbon electrode (GCE) was developed. GCE was electrochemically activated by anodization at a high positive voltage (2.5 V). The activated glassy carbon electrode (AGCE) was surface characterized, optimized, and utilized for the electrochemical assay of SPA. The electrochemical behavior of the AGCEs was investigated using cyclic voltammetry (CV) which shows a remarkable increase in the anodic peak of SPA in comparison with GCE. This behavior reflects a remarkable increase in the electrocatalytic oxidation of SPA at AGCE. The impacts of various parameters such as scan rate, accumulation time, and pH were investigated. The analytical performance of the activated glassy carbon electrodes was studied utilizing DPV. Under optimum conditions, the oxidation peak current exhibited two linear ranges of 80 nm to 0.8 μM and 0.85-300 μM with a lower limit of detection (LOD) of 20 nM. The developed assay exhibited high sensitivity, excellent repeatability, and good selectivity. Additionally, the developed SPA-sensitive modified GCE was successfully applied for SPA assay in its pharmaceutical dosage form and diluted biological fluids as well, with satisfactory recovery results which correlated well with the results obtained using spectrophotometry.

Determination of quinolone antibiotics in honey by pH-induced natural deep eutectic solvent combined with vortex-assisted dispersive liquid-liquid microextraction

A green, fast, and efficient pH-induced natural deep eutectic solvent combined with vortex-assisted dispersive liquid-liquid microextraction method (pH-NADES-VA-DLLME) followed by HPLC was established for determination of ofloxacin (OFL), ciprofloxacin (CIP) and enrofloxacin (ENR) in honey. In this method, NaOH, as an emulsifier, can increase the contact area between the NADES and the sample solution, which can efficiently improve the extraction efficiency of the analytes. Moreover, HCl acts as the phase separation agent without centrifugation in the process, which can greatly enhance the efficiency of the sample analysis process. In addition, the main factors affecting the extraction effect were optimized by single factor experiments. Under the optimal conditions, the limits of detection (LODs), the limits of quantification (LOQs) and recoveries were in the range of 0.004-0.015 μg mL^-1, 0.012-0.050 μg mL^-1, and 98.0-112.5%, respectively. The RSD values of intra-day and inter-day precisions were no more than 5.5% and 6.0%, respectively. The developed method was successfully applied to determine the three quinolone antibiotics in honey.

Nanozyme based on ZIF-8 for the colorimetric detection of sulfonamides in cow milk

A simple and time-saving colorimetric method was developed to quantify sulfonamides (SAAs) in milk via inhibition of the human carbonic anhydrase II (hCAII)-like activity of ZIF-8 that can hydrolyze p-nitrophenyl acetate (pNPA) to p-nitrophenol (pNP), following the color change from yellow to colorless. Effects of different reaction conditions, including pH, temperature, amount of ZIF-8, and incubation time, were investigated. The value of Michaelis-Menten constant (K_m) is measured to be 0.15 mM, which exhibits high affinity to pNPA. The IC₅₀ (0.17, 0.24, and 0.60 mM) and inhibition constant (K_i) (0.09, 0.13, and 0.33 mM) of sulfamethazine (SD), sulfadimethoxine (SDM), and sulfathiazole (ST) on ZIF-8 were measured, respectively. Moreover, the activity of ZIF-8 remains more than 90.0% of its initial activity after 30 days' storage. The colorimetric method for SD, SDM, and ST determination was established at the linear ranges of 6.3-750.0 μM (1.75-208.75 mg/kg), 6.3-750.0 μM (1.96-232.75 mg/kg), and 5.0-1250.0 μM (1.28-319.15 mg/kg) with limit of detection of 4.3, 3.2, and 3.9 mΜ (1.2, 0.99, and 0.96 mg/kg), respectively. In addition, the spiked recoveries of SAAs in milk sample are in the range of 81.6%-106.7% with RSD less than 6.5%. In short, the developed colorimetric method can achieve rapid analysis of SAAs in milk with simple operations.

Inspection of antimicrobial remains in bovine milk in Egypt and Saudi Arabia employing a bacteriological test kit and HPLC-MS/MS with estimation of risk to human health

Veterinary medicine uses antibiotics randomly for treatment and growth promotion. Milk of dairy animals contains substantial quantities of antibiotics that have harmful effects on health. It is therefore necessary to test commercially available milk using immunological, chromatographic, or microbiological methods to confirm the absence of antibiotic residues. This study aims to perform a microbiological test, followed by a quantitative confirmation analysis, on raw milk to assess the presence of antibiotic residues. Tests were conducted on 200 milk samples collected from markets and farms in Saudi Arabia and Egypt. The microbial inhibitor test (Delvotest SP-NT) revealed that 40 samples were positive for antibiotic residues. The positive samples were further tested using liquid chromatography-tandem mass spectrometry (LC-MS/MS) as a confirmatory quantitative test for 29 antibiotics that belong to five groups: tetracyclines, sulfonamides, fluoroquinolones, macrolides, and lactamases. Only four samples tested positive for oxytetracycline residues above the maximum residue limit. Based on these results, researchers suggest a monitoring system that considers both microbial and HPLC-MS/MS methods when detecting antibiotic residues in bovine milk. The analysis of risk to human health revealed that antibiotic residues at the detected levels do not pose any health risks to consumers.

A robust molecularly imprinted electrochemiluminescence sensor based on a Ni–Co nanoarray for the sensitive detection of spiramycin

A simple and robust molecularly imprinted electrochemiluminescence sensor for the detection of spiramycin is fabricated based on Ni–Co LDH nanoarrays and is directly used as a sensor platform.

Ionic liquid-based dispersive liquid-liquid microextraction followed by magnetic solid-phase extraction for determination of quinolones

An ionic liquid-based dispersive liquid-liquid microextraction (IL-DLLME) combined with magnetic solid-phase extraction (MSPE) was developed for extraction of quinolones (quinolones) from honey and milk prior to high-performance liquid chromatography (HPLC) analysis. 1-Butyl-3-methylimidazolium hexafluorophosphate was used as the extraction solvent and an effective adsorbent based on chitosan modified magnetic core-shell functionalized multi-walled carbon nanotube (MWCNTs-Fe₃O₄@SiO₂-CS) nanoparticles was used to assist IL to adsorb quinolone residues in honey and milk samples. Extraction conditions were optimized through one-factor-at-a-time and response surface methodology using a Box-Behnken design. Under optimum conditions satisfactory linearity (R² > 0.999) and high sensitivity (method limits of quantification were 4-8 μg kg^-1 or μg L^-1 in honey or milk samples) was achieved. The recoveries of quinolones in honey and milk ranged from 81.2 to 109%. Based on this study, the proposed method was employed for the determination of antibiotic residues in honey and milk samples.

Accurate Determination, Matrix Effect Estimation, and Uncertainty Evaluation of Three Sulfonamides in Milk by Isotope Dilution Liquid Chromatography-Tandem Mass Spectrometry

Liquid chromatography-tandem mass spectrometry (LC-MS/MS) is the most commonly used method for sulfonamide determination. Its accuracy, however, can be affected by many factors. In this study, sulfadiazine (SDZ), sulfadimidine (SMZ), and sulfadimethoxine (SDM) in milk were selected to investigate an accurate determination method and the potential influencing factors in the use of ultrahigh-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). Milk samples were extracted by 25 mL perchloric acid solution (pH = 2) and cleaned up using HLB solid-phase extraction (SPE) cartridges. Four kinds of filters, including PTFE, GHP, nylon, and glass fiber, were compared, and PTFE was selected since it had the best recoveries of target sulfonamides (SAs). Three quantitative methods, including external standard (ES), matrix matching (MM), and isotope dilution mass spectrometry (IDMS), were compared, among which IDMS exhibited the best accuracy. The matrix effect under different mobile phase compositions and of different sample matrices were evaluated and discussed. Ion suppression effects were observed during the determination of all SAs, which got stronger with the increase of the methanol composition percent in the mobile phase. After correction by IDMS, the matrix effect could be neglected. Matrix spiked recoveries at three spiked levels (1 μg/kg, 10 μg/kg, and 20 μg/kg) ranged from 96.8% to 103.8% by IDMS. The expanded relative uncertainties were in the range of 2.02% to 5.75%. The method exhibited wide application range, high accuracy, good stability, and high sensitivity.

Upconversion luminescent nanomaterials: A promising new platform for food safety analysis

Foodborne diseases have become a significant threat to public health worldwide. Development of analytical techniques that enable fast and accurate detection of foodborne pathogens is significant for food science and safety research. Assays based on lanthanide (Ln) ion-doped upconversion nanoparticles (UCNPs) show up as a cutting edge platform in biomedical fields because of the superior physicochemical features of UCNPs, including negligible autofluorescence, large signal-to-noise ratio, minimum photodamage to biological samples, high penetration depth, and attractive optical and chemical features. In recent decades, this novel and promising technology has been gradually introduced to food safety research. Herein, we have reviewed the recent progress of Ln³⁺-doped UCNPs in food safety research with emphasis on the following aspects: 1) the upconversion mechanism and detection principles; 2) the history of UCNPs development in analytical chemistry; 3) the in-depth state-of-the-art synthesis strategies, including synthesis protocols for UCNPs, luminescence, structure, morphology, and surface engineering; 4) applications of UCNPs in foodborne pathogens detection, including mycotoxins, heavy metal ions, pesticide residue, antibiotics, estrogen residue, and pathogenic bacteria; and 5) the challenging and future perspectives of using UCNPs in food safety research. Considering the diversity and complexity of the foodborne harmful substances, developing novel detections and quantification techniques and the rigorous investigations about the effect of the harmful substances on human health should be accelerated.

A colorimetric microfluidic paper-based analytical device for sulfonamides in cow milk using enzymatic inhibition

To increase milk production, antibiotics are administered to animals to provide weight gain and to prevent or treat diseases. The inappropriate use of these substances can lead to antibiotic resistance and allergic reactions and toxic effects to milk consumers. We describe the development of a simple, fast, portable, and low-cost microfluidic paper-based analytical device (μPAD) to quantify sulfonamides in milk using the inhibition of the colorimetric reaction between carbonic anhydrase (CA) and 4-nitrophenyl acetate. The main advantages presented by the μPAD include reproducible batch production, simple application, and precise analysis without previous treatment. The µPAD displayed good linearity (R² ≥ 0.986) in a wide range of sulfonamides in milk (2.5 to 40.0 µmol L^-1), being selective for the drugs even in a highly complex matrix. We expect that this device allows in situ monitoring of milk quality, reducing the prejudicial conditions associated with high concentrations of sulfonamides in milk.

An Easy Efficient Method of Veterinary Drug Residue Analysis in Raw Milk by RP-HPLC-UV with Application to Raw Milk

Background:

This study reports an easy method of a veterinary drug investigation in raw milk, based on QuECHERS extraction followed by RP-HPLC-UV analysis. Use of this benchtop system was motivated by its availability and moderate cost relatively to other sophisticated methods such as LC-MS which are more efficient.

Methods:

This developed method has been optimized and then after validation according to EU legislation, it demonstrated good linearity with R²>0.997, acceptable peak resolution within a short time (<9.5 min) and good recovery of the analyzed drugs (OXY, ALZ and IVR, respectively 87.08, 99.02 and 92.01 %). Additionally, we applied the method to the analysis of cow milk, collected in Nouakchott, capital of Mauritania.

Results:

The obtained results indicated a mixed level of drug use according to targeted molecules. In 42% of sampled farms, the anti-parasitics IVR and ALZ were detected whereas the antibiotic OXY was detected in 50%.

Conclusion:

This investigation shows that 17% of the sampled farms exceeded European standards for IVR drug.

Incidence, stability and risk assessment for sulfonamides and tetracyclines in aqua-cultured Nile Tilapia fish of Egypt

The current study was conducted to determine sulfonamides (SAs) and tetracyclines (TCs) residuals in farmed Nile Tilapia fish (Orechromis niloticus) using the solid phase extraction (SPE) technique and high performance liquid chromatography with diode array detection (HPLC-DAD). As well, to assess the potential health risk due to the consumption of contaminated fish following its household thermal processing. Tilapia samples were collected from four governorates in Egypt; El-Fayoum, Giza, Cairo, and Alexandria. The results showed that 56.3 % (27 out of 48 samples) of fish samples were free of antibiotics, while 10.4 % and 33.3 % of samples were contaminated by SAs and TCs, respectively. Besides, oxytetracycline (OTC) showed the highest detected concentrations ranged from 52.8 to 658.5 (μg/kg), followed by chlortetracycline (OTC) (35.89-109.76 μg/kg), and tetracycline (TC) (68.8-96.7 μg/kg). While the detected SAs were between 32.89 μg/kg (sulfamethazine: SMT) and 136.43 μg/kg (sulfadimethoxine: SDM). As well, sulfamethoxazole (SMX) showed an average concentration of 52.41 μg/kg. Notably, only 7 samples (out of 21 positive samples) had residual levels exceeded the permissible limits. The study also concluded that freezing fish at -18 °C for one week had no significant effect on the stability of SAs and TCs. As well, SAs showed more stability than TCs against the thermal processing for fish. Indeed, the stability of SAs and TCs antibiotics was arranged in a descending order, shown as follows: SMT > SDM > SMX > CTC > TC > OTC. Eventually, no potential risk to the Egyptian population was found from the consumption of the contaminated fish samples by SAs and TCs.

Analysis of Veterinary Drug Residues in Pasteurized Milk Samples in Chinese Milk Bars

ABSTRACT

The milk bar is an emerging style of retail business that mainly produces pasteurized milk (PM) and other dairy products on-site in many large cities of the People's Republic of China. To date, no data about veterinary drug residues in PM samples produced from milk bars have been reported. The objective of this study was to investigate the safety of PM from a total of 182 PM samples collected from milk bars from 10 provincial capital cities and to analyze the residues of seven classes of 61 veterinary drugs. First, the chemical components were screened with test kits, and then the positive samples were further confirmed by ultraperformance liquid chromatography-tandem mass spectrometry. The results showed that 15 (8.24%) samples were screened positive for veterinary drugs, and six drugs in 11 (6.04%) samples were confirmed. The veterinary drugs detected were penicillin G (2.20%), tetracycline (1.10%), tylosin (1.10%), amoxicillin (0.55%), oxytetracycline (0.55%), and gentamicin (0.55%), with maximum residue levels of 3.4, 11.9, 28.2, 3.0, 26.9, and 63.5 μg kg-1, respectively. Veterinary drug residues were detected as positive in 7 of 10 cities, with the highest detection rate as 14.29% in Urumqi. No positive samples were found in the cities of Nanjing, Tianjin, and Nanning. All detected drug levels were far below the maximum residue levels regulated by China, the European Union, and the Codex Alimentarius Commission. This suggests that the overall veterinary drug residues in PM in milk bars reached the safety code of the country. However, potential risks still exist, and continuous attention should be paid to guarantee the safety of this milk product in the future.

HIGHLIGHTS

Monitoring and risk assessment of tetracycline residues in foods of animal origin

A total of 450 samples consisting of red meat, poultry meat, aquatic product and raw milk were collected during winter 2016 and summer 2017. 22.2% (100/450) of collected meat and raw milk samples were found to be contaminated with antibiotic residues in the initial screening using Premi^®test. According to the enzyme linked immunosorbent assay (ELISA) results, the mean tetracyclines (TCs) concentration of meat samples determined as follows: chicken (155.41 µg/kg) > turkey (138.68 µg/kg) > quail (130.7 µg/kg) > cow (108.92 µg/kg) > calf (105.18 µg/kg) > goat (99.4 µg/kg) > sheep (95.22 µg/kg) > rainbow trout (35.62 µg/kg) > shrimp (31.80 µg/kg). The content of TCs in cow, goat and sheep milk samples were found to be ranged 45.6-163.5 µg/L, 72.4-101.1 µg/L and 65.5-98.9 µg/L, respectively. 5.7% (26/450) of samples had TCs confirmed the ELISA results using high performance liquid chromatography coupled with ultra-violet detection, although the concentration of TCs residues in samples was higher than that of ELISA.

Antibiotic Residues in Food: Extraction, Analysis, and Human Health Concerns

The abundant use of antibiotics leads to antibiotic residues in frequently consumed foods. Residual antibiotics in food may have adverse effects on humans by directly causing disease via low-dose exposure and indirect harm via antibiotic resistance. However, the current methods for antibiotic extraction and analysis in food have not yet formed a uniform standard, and only a few data exist regarding the residual antibiotic condition in various types of foods. Hence, we review the literature since 2008 to summarize analytical methods and residue status of antibiotics in food. Then, we discuss the causes of antibiotic residues in food and the possible hazards to human health. We hope that the joint efforts of the scientific community and political circles will lead to the formation of a unified standard for the extraction and analysis of antibiotics in food, to allow for comprehensive monitoring of residual antibiotics and ensure human health.

Modifications of Au Nanoparticle-Functionalized Graphene for Sensitive Detection of Sulfanilamide

In this paper, we present a simple and feasible electrochemical sensor based on Au nanoparticle-functionalized graphene for the determination of sulfanilamide. Au nanoparticles were deposited on graphene, which acted as a platform to prepare excellent nanocomposites. Attributed to the graphene’s large surface area and the Au nanoparticles’ strong conductivity, many sulfanilamide molecules were enriched on the sensor surface and the signal response became more sensitive. Under the optimal conditions, the electrochemical sensors could be used for the efficient detection of sulfanilamide. Good linearity was observed in the range of 0.1–1000 μmol·L⁻¹ and the detection limit was 0.011 μmol·L⁻¹. Most importantly, the Au nanoparticle-functionalized graphene-modified electrode could be successfully applied for the detection of sulfanilamide in animal meat, and exhibited good stability, acceptable recovery, and offered a promising platform for point-of-care detecting in real samples.

Screening of antibiotic residues in fresh milk of Kathmandu Valley, Nepal

The prevalence of two groups of antibiotics; namely penicillin and sulfonamides was studied in fresh milk available in Kathmandu Valley of Nepal. The milk samples (n = 140) were collected from three different sources; individual farmers, cottage dairies and organized dairies of Kathmandu valley. Qualitative and semi-quantitative analysis with rapid screening kits revealed that 23% samples were positive for antibiotic residues in the fresh milk for penicillin and sulfonamide groups (1-256 µg/kg). High performance liquid chromatography (HPLC) analyses detected 81% samples positive for amoxicillin (68-802 µg/kg), 41% for sulfadimethoxine (31-69 µg/kg), 27% for penicillin G (13-353 µg/kg), and 12% for ampicillin (0.5-92 µg/kg). Due to the precision and accuracy of liquid chromatography method, it detected more positive samples and consequently presented higher prevalence than the rapid screening kits. The antibiotic residues were found above the maximum residue limits that presented serious threat to consumer health and raised a serious concern regarding the implementation and monitoring of international regulations in developing countries.

Survey of Veterinary Drug Residues in Raw Milk in Hebei Province, China

The objective of this study was to investigate the occurrence of veterinary drug residues in raw milk from Hebei, the second-largest dairy production province in the People's Republic of China. A total of 192 raw milk samples were collected from 64 milk stations in seven districts. Twenty-eight veterinary drug residues were analyzed by ultraperformance liquid chromatography with tandem mass spectrometry based on a China National Standard. Raw milk samples with multiple residues of veterinary drugs were not found in the present study. Residues of four veterinary drugs, penicillin G, sulfacetamide, trimethoprim, and lincomycin, were detected in 12 (6.25%) raw milk samples, with detection ratios of 1.04, 0.52, 3.13, and 1.56%, respectively. All veterinary drug residues detected were under the maximum residue levels as regulated by China, the European Union, the United States, and the Codex Alimentarius Commission. In general, raw milk from Hebei province was considered relatively safe for human consumption because of the low prevalence of veterinary drug residues. However, stringent control measurements for veterinary drug residues in raw milk are required because some veterinary drugs were detected in milk from some areas of Hebei province.

Determination of Sulfonamides in Chicken Muscle by Pulsed Direct Current Electrospray Ionization Tandem Mass Spectrometry

A simple and rapid approach for the simultaneous detection of trace amounts of six sulfonamides in chicken muscle was developed using pulsed direct current electrospray ionization tandem mass spectrometry (pulsed-dc ESI-MS/MS). The pretreatment of chicken muscle samples consisted of two steps: acetonitrile extraction and n-hexane delipidation. Sulfonamides do not need to be derivatized or chromatographed prior to pulsed-dc ESI-MS/MS. The factors affecting the performance of pulsed-dc ESI-MS/MS were studied. Under optimum conditions, the quantitative performance of pulsed-dc ESI-MS/MS was validated according to European Union Decision 2002/657/EC, and the sensitivity of pulsed-dc ESI-MS/MS was 3 times higher than that of ultrahigh-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The limits of detection obtained by pulsed-dc ESI-MS/MS were in the range of 0.07-0.11 μg/kg. The proposed method was simple, rapid, and sensitive, and was successfully used for quantitation and rapid screening of sulfonamides in real chicken muscle samples.

Assessment of antibacterial drug residues in milk for consumption in Kosovo

The objective of this study was to assess the occurrence of drug residues in the raw milk collected from individual farms and milk collection points during 2009–2010 in six different major regions of Kosovo (Prishtinë, Gjilan, Mitrovicë, Pejë, Gjakovë, Prizren). In the present study, a total of 1734 raw milk samples were collected, and qualitatively screened with two different tests, the Delvotest SP assay and an enzyme-linked receptor-binding assay (SNAP). Overall, 106 (6.11%) out of 1734 samples examined with Delvotest SP contained possible drug residues (5.12% and 7.51% of samples from 2009 and 2010, respectively). All suspect samples were further analyzed by three distinct enzyme-linked receptor-binding assays specific for β-lactams (new β-lactam test), tetracyclines (SNAP tetracycline test), and sulfonamides (SNAP sulfamethazine test). Only the new SNAP βlactam test detected residues in 40 out of 52 samples in 2009 and 54 out of 54 suspect samples in 2010. A confirmatory method based on liquid chromatography-tandem mass spectrometry was used to confirm the presence of β-lactam drug residues in samples detected by the enzyme-linked receptor-binding assay. Amoxicillin, penicillin G, and cloxacillin were the most frequently detected residues and were in a concentration range between 2.1 μg/kg and 1973 μg/kg. Seventeen of the positive samples exceeded the maximum residue levels for one or more β-lactam drug. The highest number of positive milk samples came from the Pejë Region (58.8%) and Gjakovë Region (23.5%), and the lowest number of positive samples originated from Gjilan (5.88%), with no positive samples detected in two regions, Mitrovicë and Prizren.

Trends in Microextraction-Based Methods for the Determination of Sulfonamides in Milk

Sulfonamides (SAs) represent a significant category of pharmaceutical compounds due to their effective antimicrobial characteristics. SAs were the first antibiotics to be used in clinical medicine to treat a majority of diseases, since the 1900s. In the dairy farming industry, sulfa drugs are administered to prevent infection, in several countries. This increases the possibility that residual drugs could pass through milk consumption even at low levels. These traces of SAs will be detected and quantified in milk. Therefore, microextraction techniques must be developed to quantify antibiotic residues, taking into consideration the terms of Green Analytical Chemistry as well.

Fate of tetracycline resistance in synthetic livestock carcass leachate for two years

To simulate the fate of antibiotic resistance in leachate from anaerobic carcass landfill site, anaerobic reactors were set-up and their antibiotic resistance activities were monitored for 2 years. Initially, Escherichia coli DH5α with tetracycline resistance pB10 plasmid was inoculated in nutrient rich anaerobic reactors. The fate of tetracycline resistant bacteria (TRB) was tracked by analysis using culture-based method, EC₅₀ (half maximal effective concentration), and quantitative polymerase chain reaction (qPCR). Based on the temporal pattern of EC₅₀ during the study period, TRB continuously increased during Phase I (0-250th day), went down in Phase II (after 250th day to 500th day), and then increased again by the end of Phase III (after 500th day to the 774th day). Interestingly, pB10 plasmid accumulated in the system as the community diversities increased over time. At the end of experiment, the tetracycline resistance microbial communities were investigated by 16s RNA gene-based pyro sequencing. The results of this study indicated that leachate with high organic strength in anaerobic conditions could be an antibiotic resistant point source in several year periods.

Upconversion Nanoparticles and Monodispersed Magnetic Polystyrene Microsphere Based Fluorescence Immunoassay for the Detection of Sulfaquinoxaline in Animal-Derived Foods

A novel fluorescence immunoassay for detecting sulfaquinoxaline (SQX) in animal-derived foods was developed using NaYF4:Yb/Tm upconversion nanoparticles (UCNPs) conjugated with antibodies as fluorescence signal probes, and monodisperse magnetic polystyrene microspheres (MMPMs) modified with coating antigen as immune-sensing capture probes for trapping and separating the signal probes. Based on a competitive immunoassay format, the detection limit of the proposed method for detecting SQX was 0.1 μg L(-1) in buffer and 0.5 μg kg(-1) in food samples. The recoveries of SQX in spiked samples ranged from 69.80 to 133.00%, with coefficients of variation of 0.24-25.06%. The extraction procedure was fast, simple, and environmentally friendly, requiring no organic solvents. In particular, milk samples can be analyzed directly after simple dilution. This method has appealing properties, such as sensitive fluorescence response, a simple and fast extraction procedure, and environmental friendliness, and could be applied to detecting SQX in animal-derived foods.

Development of a novel carbon paste sensor for determination of micromolar amounts of sulfaquinoxaline in pharmaceutical and biological samples

A potentiometric carbon paste sensor was fabricated for determination of sulfaquinoxaline (SQX) based on the use of ion-association complex of sulfaquinoxaline sodium with 2,3,5-triphenyltetrazolium chloride. The proposed sensor exhibited Nernstian slope of 58.4 ± 0.3 mV per decade for sulfaquinoxaline over a wide concentration range of 5.0 × 10(-6) to 1.0 × 10(-2)M, with a low detection limit of 3.0 × 10(-6)M. The sensor manifested advantages of fast response time, satisfactory reproducibility, long life time, high thermal stability and, most importantly, excellent selectivities for sulfaquinoxaline relative to a wide variety of common foreign inorganic cations, anions, sugars and amino acids. The sensor was successfully used for determination of sulfaquinoxaline in pharmaceutical solution, blood serum, urine and milk samples. The isothermal coefficient of the electrode was calculated by the investigation of temperature effects on the electrode potential response.

Visualized detection of vancomycin by supramolecular hydrogelations

Here we report on a visualized detection system for vancomycin based on supramolecular hydrogelations.

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.