Facile sonochemical synthesis of porous and hierarchical manganese(III) oxide tiny nanostructures for super sensitive electrocatalytic detection of antibiotic (chloramphenicol) in fresh milk

We report the preparation of a porous and hierarchical manganese(III) oxide tiny nanostructures (Mn₂O₃ TNS) by a simple sonochemical approach. The nanocatalyst was synthesized by a bath-type ultrasound washer (Honda Electronics, W-118T) at 700 W and 300 kHz frequency. The morphology and chemical composition of the nanocatalyst were characterized by X-rays diffractometry (XRD), transmission electron microscopy (TEM), energy dispersive x-rays (EDX), X-ray photoelectron spectroscopy (XPS) and electrochemical impedance spectroscopy (EIS). The electrocatalytic activity (ECA) was monitored by detection of toxic antibiotic drug (chloramphenicol) under phosphate buffer (pH 7.0). A facile sonochemical route was employed to prepare Mn₂O₃ TNS modified electrode. The screen-printed carbon electrode (SPCE) modified with Mn₂O₃ TNS was fabricated and applied for the electrochemical determination of chloramphenicol. Compared with bare SPCE, Mn₂O₃ TNS modified SPCE showed highest current response towards chloramphenicol. Furthermore, the modified sensor exhibits with a sharp peak and two linear ranges by using DPV (i) 0.015-1.28 μM with the sensitivity of 4.167 μA μM^-1 cm^-2 and (ii) 1.35-566.3 μM with the sensitivity of 7.205 μA μM^-1 cm^-2. Notably, we achieved a very low-level detection limit of 4.26 nM for the DPV detection of chloramphenicol. Further, the superior practicability of the nanosheets modified sensor can be used for real time sensing of chloramphenicol with good recover ranges.

Degradation of antibiotic chloramphenicol in water by pulsed discharge plasma combined with TiO2/WO3 composites: mechanism and degradation pathway

Pulsed discharge plasma (PDP) combined with TiO₂/WO₃ composites for chloramphenicol (CAP) degradation was investigated. The prepared TiO₂/WO₃ composites were characterized by scanning electron microscope, transmission electron microscope, nitrogen adsorption apparatus, zeta sizer, X-ray diffraction, Raman spectra, UV-Vis absorption spectroscopy, X-ray photoelectron spectroscopy, photocurrent and electrochemical impedance spectroscopy. The degradation performance showed that the addition of TiO₂/WO₃ composites significantly enhanced the removal efficiency of CAP in PDP system. At a peak voltage of 18 kV, the highest removal efficiency of CAP could reach 88.1% in PDP system with 4 wt% TiO₂/WO₃, which was 36.8% and 26.0% higher than that in sole PDP system and PDP/TiO₂ system, respectively. The TiO₂/WO₃ composites significantly accelerated interfacial charge transfer process compared to the pure TiO₂. Besides, the effect of catalyst dosage and peak voltage on CAP removal was evaluated. OH, O₃O₂^-, h⁺ and high-energy electrons contributed to CAP degradation in PDP-TiO₂/WO₃ system. Addition of TiO₂/WO₃ composites can decompose O₃ and produce more OH and H₂O₂. The degradation intermediates were measured by liquid chromatography-mass spectrometry (LC-MS) and ion chromatography (IC). The cycling degradation experiment showed that the TiO₂/WO₃ composites have good reusability as well as stability.

Development of a multicomponent immunochromatographic test system for the detection of fluoroquinolone and amphenicol antibiotics in dairy products

BACKGROUND

Ciprofloxacin (CIP) and chloramphenicol (CAP) are relevant antibiotics of the fluoroquinolone (FQ) and amphenicol (AP) groups, respectively, widely used in veterinary practice and they contaminate agricultural products. In this study, a rapid and sensitive immunochromatographic assay (ICA) was developed for simultaneous detection of CIP and CAP in dairy products. The ICA was carried out in a direct competitive format using gold nanoparticles as a label.

RESULTS

The ICA developed here allowed for the detection of CIP and CAP in Triton X-100-containing buffered saline (PBST) within 15 min with instrumental detection limits of 20 pg mL^-1 and 0.5 ng mL^-1 , respectively, and with a visual detection limit of 5 ng mL^-1 for both antibiotics. The ICA showed cross-reactivity (69-160%) to 19 antibiotics in the FQ group and no cross-reactivity (<0.1%) to 2 antibiotics of the AP group. The ICA allowed detection of CIP and CAP in a panel of dairy products by employing a simple procedure of preliminary sample preparation. The detection limits for the two antibiotics were the same as in PBST. The analytical recoveries of CIP and CAP in dairy products ranged from 83% to 120%.

CONCLUSION

The analytical characteristics of the test system allow its use for the detection of antibiotics in milk and dairy products during all steps of production. © 2019 Society of Chemical Industry.

Development and comparison of liquid-liquid extraction and accelerated solvent extraction methods for quantitative analysis of chloramphenicol, thiamphenicol, florfenicol, and florfenicol amine in poultry eggs

Accelerated solvent extraction was investigated as a novel alternative technology for the separation and quantitative analysis of chloramphenicol, thiamphenicol, florfenicol, and florfenicol amine from poultry eggs, and the results were compared with the results of liquid-liquid extraction. Rapid quantification of the target compounds was carried out by ultra-performance liquid chromatography-electrospray ionization tandem triple quadrupole mass spectrometry. This optimized method was validated according to the requirements defined by the European Union and the United States Food and Drug Administration. Finally, the new approach was successfully applied to the quantitative determination of these analytes in 90 commercial poultry eggs from local supermarkets.

Response of antibiotic resistance to the co-existence of chloramphenicol and copper during bio-electrochemical treatment of antibiotic-containing wastewater

Concerns have been raised regarding co-selection for antibiotic resistance among microorganisms exposed to antibiotics and metals. As a promising approach for treating antibiotics and heavy metal-containing wastewater, a bio-electrochemical system (BES) can be used for antibiotic and heavy metal removal. This study determined the fate of antibiotic resistance genes (ARGs) in a BES when exposed to chloramphenicol (CAP) and Cu²⁺. The ARGs encoding the efflux pump (cmlA, floR, and tetC), the class 1 integron integrase-encoding gene, and the sul1 gene were analyzed. The results indicated that the co-existence of CAP and different concentrations of Cu²⁺ had significant influence on the relative abundances of the ARGs. The changes in the bacterial community structure and the results of a quantitative correlation analysis between the bacterial community and the ARGs confirmed that the shift in the potential hosts was the key reason for the changes of the ARGs. This study sheds new light on the mechanisms of ARGs variations in BES under the co-selection pressure of antibiotics and heavy metals.

Solution growth of 1D zinc tungstate (ZnWO4) nanowires; design, morphology, and electrochemical sensor fabrication for selective detection of chloramphenicol

Development of 1D nanostructures with novel morphology is a recent scientific attraction, so to say yielding unusual materials for advanced applications. In this work, we have prepared solution grown, single-pot 1D ZnWO₄ nanowires (NWs) and the morphology is assessed for label-free but selective detection of chloramphenicol. This is the first report where, such structures are being investigated for this purpose. Transmission electron microscopy shows the presence of strands of ZnWO₄ of about 20 nm in diameter. The formed NWs were highly dispersed in nature with uniform size and shape. X-ray diffraction analysis confirmed high purity of the designed NWs despite solution synthesis. X-ray photoelectron spectroscopy confirmed surface valence state of ZnWO₄. Fourier transform infrared spectroscopy was employed for the ascription of functional groups, whereas, optical properties were investigated using photoluminescence. NWs were employed for the detection of a model antibiotic, chloramphenicol. The developed sensor exhibited excellent limit of detection, 0.32 μM and 100% specificity as compared to its structural and functional analogues such as thiamphenicol and clindamycin. This work can broaden new opportunities for the researchers to explore unconventional nanomaterials bearing unique morphologies and quantum phenomenon for the label-free detection of other bioanalytes.

Physicochemical characterization and determination of chloramphenicol residues and heavy metals in Algerian honeys

The concentration of certain heavy metals in various foods (fruits, cereals, legumes, and bee products) produced in industrial and urban cities is increasing each year following industrial development. Quality of honey and its contamination by different polluting agents are related essentially to its production environment, or it can arise from beekeeping practices. In the present study, the determination of physicochemical properties: moisture, pH, total acidity, electric conductivity, hydroxymethylfurfural (HMF), sugars, and chloramphenicol (CAP) residues; the metal content by determination of two toxic metals levels: lead (Pb) and cadmium (Cd); and other trace elements: magnesium (Mg), iron (Fe), zinc (Zn), copper (Cu), and nickel (Ni) in 23 different honey samples collected from North regions of Algeria were investigated. The physicochemical properties and the metal contents were found within the ranges established by the international standards. For the antibiotic residues, only four honey samples are contaminated by CAP. Metals were found in non-significant values and are in safety baseline levels for human consumption except Mg which exceed the limits. These results suggested that honey could be used as an indicator to detect contaminating agents from the environment since bees are excellent sentinels for assessing environmental contamination because of their physiological and biological characteristics.

Aptasensors as the future of antibiotics test kits-a case study of the aptamer application in the chloramphenicol detection

Antibiotics are a type of antimicrobial drug with the ubiquitous presence in foodstuff that effectively applied to treat the diseases and promote the animal growth worldwide. Chloramphenicol as one of the antibiotics with the broad action spectrum against Gram-positive and Gram-negative bacteria is widely applied for the effective treatment of infectious diseases in humans and animals. Unfortunately, the serious side effects of chloramphenicol, such as aplastic anemia, kidney damage, nausea, and diarrhea restrict its application in foodstuff and biomedical fields. Development of the sufficiently sensitive methods to detect chloramphenicol residues in food and clinical diagnosis seems to be an essential demand. Biosensors have been introduced as the promising tools to overcome the requirement. As one of the newest types of the biosensors, aptamer-based biosensors (aptasensors) are the efficient sensing platforms for the chloramphenicol monitoring. In the present review, we summarize the recent achievements of the accessible aptasensors for qualitative detection and quantitative determination of chloramphenicol as a candidate of the antibiotics. The present chloramphenicol aptasensors can be classified in two main optical and electrochemical categories. Also, the other formats of the aptasensing assays like the high performance liquid chromatography (HPLC) and microchip electrophoresis (MCE) have been reviewed. The enormous interest in utilizing the diverse nanomaterials is also highlighted in the fabrication of the chloramphenicol aptasensors. Finally, some results are presented based on the advantages and disadvantages of the studied aptasensors to achieve a promising perspective for designing the novel antibiotics test kits.

Synthesis and Characterization of Samarium-Substituted Molybdenum Diselenide and Its Graphene Oxide Nanohybrid for Enhancing the Selective Sensing of Chloramphenicol in a Milk Sample

The electronic conductivity and electrocatalytic activity of metal chalcogenides are normally enhanced by following the ideal strategies such as substitution/doping of heterogeneous atoms and hybridization of highly conductive carbon supportive materials. Here, a rare earth element (samarium) was substituted with MoSe₂ using the simple hydrothermal method. The lattice distortion due to the substitution of Sm³⁺ with MoSe₂ was clearly observed by using high-resolution transmission electron microscopy analysis. As a consequence, the prepared SmMoSe₂ nanorod was encapsulated with graphene oxide (GO) sheets by using ultrasonication process. Furthermore, the GO-encapsulated SmMoSe₂ nanocomposite modified glassy carbon electrode (GO@SmMoSe₂/GCE) was used for the sensing of chloramphenicol. The results showed that the GO@SmMoSe₂/GCE revealed the superior electrocatalytic activity with low detection (5 nM) and sensitivity (20.6 μA μM^-1 cm^-2) to electrochemical detection of proposed analyte. It indicates that the substitution of Sm³⁺ and encapsulation of GO significantly increased both the electrical conductivity and electrocatalytic activity of MoSe₂.

Porous SnO2 nanoparticles based ion chromatographic determination of non-fluorescent antibiotic (chloramphenicol) in complex samples

Nowadays, there are rising concerns about the extensive use of the antibiotics such as chloramphenicol (CAP), has threatened the human life in the form of various vicious diseases. The limited selectivity and sensitivity of confirmatory techniques (UV and electrochemical) and non-fluorescence property of CAP make its determination a challenging task in the modern pharmaceutical analysis. In order to redeem the selective, sensitive and cost-effective fluorescence methodology, here by the dual role of synthesized porous SnO2 nanoparticles were exploited; (i) a porous sorbent in a µ-QuEChERS based sample preparation and as (ii) a stimulant for the transformation of non-fluorescent analytes namely CAP and p-nitrophenol (p-NP) into their respective fluorescent product. We report a green, simple, selective and cost effective ion chromatographic method for CAP sensitive determination in three complex matrices including milk, human urine and serum. The synthesized sorbent not only selectively adsorbed and degraded the matrix/interferences but also selectively reduced the non-fluorescent antibiotic CAP into a fluorescent species. This developed ion chromatographic method exhibited good selectivity, linearity (r2 ≥ 0.996) and limit of detection (LOD) was in the range 0.0201-0.0280 µg/kg. The inter- and intraday precisions were also satisfactory having a relative standard deviation (RSDs) less than 14.96% and excellent recoveries of CAP in the range of 78.3-100.2% were retrieved in various complex samples.

Selective detection of chloramphenicol based on molecularly imprinted solid-phase extraction in seawater from Jiaozhou Bay, China

This study highlights an efficient sample pre-treatment method for preconcentration and detection of chloramphenicol in marine water using molecularly imprinted solid-phase extraction (MISPE). Chloramphenicol molecularly imprinted microspheres were prepared and evaluated on the base of morphology, capacity and selectivity. The imprinted microspheres exhibited specific recognition and high retention capability to chloramphenicol and were applied as special solid-phase extraction adsorbents. An off-line MISPE protocol has been optimized and a creative analytical method coupled to HPLC-DAD was successfully developed for the cleanup and determination of chloramphenicol in seawater samples. Method performance was satisfactory with recoveries ranging from 81 to 90% and relative standard deviation (RSD) was <4.93% (n = 3). Accuracy of the method was assessed at three spiking concentration levels and the limit of detection was 5 ng L^-1. Finally, five seawater samples from Jiaozhou Bay of China were determined and the results showed that there was no chloramphenicol detected.

Magnetic molecularly imprinted polymer prepared by microwave heating for confirmatory determination of chloramphenicol in chicken feed using high-performance liquid chromatography-tandem mass spectrometry

A magnetic molecularly imprinted polymer (MMIP) for chloramphenicol was prepared using a surface-imprinted and microwave-heating-induced polymerization method. The surfaces of the magnetic particles were first double-bond functionalized with 3-(trimethoxysilyl)propyl methacrylate (γ-MPS), followed by the copolymerization of 4-vinyl pyridine (4-VP) and trimethylolpropane trimethacrylate (TRIM) in the presence of chloramphenicol as a template and 1,1-azobis(cyclohexane-carbonitrile) (ABCN) as an initiator in a mixture of dimethyl sulfoxide and water with microwave heating at 80°C. The magnetic polymer possesses supraparamagnetic properties and was used to concentrate and cleanup chicken feed extract, followed by chromatographic separation using a Lichrospher®100 RP C8 column and detection with two multi-reaction monitoring transitions at m/z 321→ 152 and m/z 321→ 257. The mean recoveries obtained at two spiking levels were in the range of 94.6-100% The relative intra- and inter-day standard deviations were in the range of 1.4-2.6% and 5.1-5.7%, respectively. The detection limit of the method was 0.12 µg kg^-1. This confirmatory method was successfully applied to determine chloramphenicol in chicken feed samples.

Accurate Quantitation and Analysis of Nitrofuran Metabolites, Chloramphenicol, and Florfenicol in Seafood by Ultrahigh-Performance Liquid Chromatography-Tandem Mass Spectrometry: Method Validation and Regulatory Samples

We developed and validated a method for the extraction, identification, and quantitation of four nitrofuran metabolites, 3-amino-2-oxazolidinone (AOZ), 3-amino-5-morpholinomethyl-2-oxazolidinone (AMOZ), semicarbazide (SC), and 1-aminohydantoin (AHD), as well as chloramphenicol and florfenicol in a variety of seafood commodities. Samples were extracted by liquid-liquid extraction techniques, analyzed by ultrahigh-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS), and quantitated using commercially sourced, derivatized nitrofuran metabolites, with their isotopically labeled internal standards in-solvent. We obtained recoveries of 90-100% at various fortification levels. The limit of detection (LOD) was set at 0.25 ng/g for AMOZ and AOZ, 1 ng/g for AHD and SC, and 0.1 ng/g for the phenicols. Various extraction methods, standard stability, derivatization efficiency, and improvements to conventional quantitation techniques were also investigated. We successfully applied this method to the identification and quantitation of nitrofuran metabolites and phenicols in 102 imported seafood products. Our results revealed that four of the samples contained residues from banned veterinary drugs.

Development of Lateral Flow Immunochromatographic Strips for Micropollutant Screening Using Colorants of Aptamer-Functionalized Nanogold Particles, Part II: Experimental Verification with Aflatoxin B1 and Chloramphenicol

Lateral flow immunochromatographic strips based on colorants of aptamer-functionalized nanogold particles were developed for the detection of micropollutants aflatoxin B1 (AFB1) and chloramphenicol (CAP). The lateral flow immunochromatographic strip was based on a competitive reaction of thiolated-aptamer between micropollutants and bio-DNA probe-streptavidin as capture material immobilized at the test line. General crucial parameters that might influence the sensitivity have been systematically investigated. To test the effectiveness and applicability of the optimized conditions, two structurally unrelated micropollutants, that is, AFB1 and CAP, were chosen for detection. In the present study, lateral flow immunochromatographic strips for AFB1 and CAP analysis by combining the high selectivity and affinity of aptamers with the unique optical properties of nanogold in municipal water samples were reported for the first time. With the optimized conditions, the immunochromatographic strip showed a visual LOD of 10 ppb and a quantitative LOD of 1.05 ppb using an immunochromatographic reader for AFB1 detection and a quantitative LOD of 63.4 ppb using an immunochromatographic reader for CAP detection. Furthermore, the sensitive strip provided a good linear detection range of approximately 0-50 ppm for AFB1 detection and a wider liner detection range of approximately 0-160 ppm for CAP detection. Moreover, the immunochromatographic strip provided recovery rates for water samples of 90-110% in the AFB1 analysis and 84-108% in the CAP analysis. The results demonstrated that the immunochromatographic strip has excellent potential for wide applicability and verified that the strip methods for the optimized conditions are applicable to a variety of micropollutants. The lateral flow immunochromatographic strip could be used as a simple, rapid, and efficient screening tool for rapid on-site detection of a variety of micropollutants.

Investigating nanohybrid material based on 3D CNTs@Cu nanoparticle composite and imprinted polymer for highly selective detection of chloramphenicol

Nanotechnology holds great promise for the fabrication of versatile materials that can be used as sensor platforms for the highly selective detection of analytes. In this research article we report a new nanohybrid material, where 3D imprinted nanostructures are constructed. First, copper nanoparticles are deposited on carbon nanotubes and then a hybrid structure is formed by coating molecularly imprinted polymer on 3D CNTs@Cu NPs; and a layer by layer assembly is achieved. SEM and AFM revealed the presence of Cu NPs (100-500nm) anchored along the whole length of CNTs, topped with imprinted layer. This material was applied to fabricate an electrochemical sensor to monitor a model veterinary drug, chloramphenicol. The high electron transfer ability and conductivity of the prepared material produced sensitive response, whereas, molecular imprinting produces selectivity towards drug detection. The sensor responses were found concentration dependent and the detection limit was calculated to be 10μM (S/N=3). Finally, we showed how changing the polymer composition, the extent of cross linking, and sensor layer thickness greatly affects the number of binding sites for the recognition of drug. This work paves the way to build variants of 3D imprinted materials for the detection of other kinds of biomolecules and antibiotics.

Development of in-house ELISA for detection of chloramphenicol in bovine milk with subsequent confirmatory analysis by LC-MS/MS

This study was undertaken to develop and validate direct competitive ELISA for the determination of chloramphenicol residues in bovine milk. Antisera and an enzyme-tracer for chloramphenicol were prepared and used to develop an ELISA with inhibition concentrations, IC₂₀ and IC₅₀, of 0.09 and 0.44 ng mL^-1, respectively. Milk samples were spiked with standards equivalent to 0, 0.2, 0.3, 0.5, 1.0 & 1.5 ng mL^-1 and extracted in methanol. The mean recoveries were found to be 73-100% with coefficient of variance 7-11%. The decision limit (CCα) and detection capability (CCβ) were calculated as 0.10 and 0.12 ng mL^-1, respectively. The results were found comparable with the commercial ELISA, having recoveries of 87 to 100%, CCα 0.09 ng mL^-1 and CCβ 0.12 ng mL^-1. As per Commission Decision 2002/657/EC, in-house ELISA was further validated by using LC-MS/MS. Mass spectral acquisition was done by using electrospray ionization in the negative ion mode applying single reaction monitoring of the diagnostic transition reaction for CAP (m/z 152, 194 and 257). The calibration curve showed good linearity in concentrations from 0.025 to 1.6 ng mL^-1 with correction coefficient 0.9902. The mean recoveries were found to be 88 to 100%. The CCα was calculated as 0.057 ng mL^-1 and CCβ 0.10 ng mL^-1. Since CCα and CCβ are less than half of the MRPL (0.15 ng mL^-1), the test was found suitable for screening and quantification of CAP residues in bovine milk samples. Results of surveillance studies indicated that out of 31 analyzed milk samples, 12.9% samples were found with CAP residues but only 3.2% samples were declared positive with maximum concentration 0.31 ng mL^-1, slightly above the MRPL.

Preparation of green alga-based activated carbon with lower impregnation ratio and less activation time by potassium tartrate for adsorption of chloramphenicol

Potassium tartrate (C₄H₆K₂O₇) was utilized as a novel activating agent to prepare activated carbon with relatively high specific surface area by using less activating agent and activation time from marine waste-green alga (Enteromorpha prolifera) for the first time. The influences of activation temperature, impregnation ratio and activation time on the pore structure were investigated to obtain the optimum conditions (activation temperature: 700°C, impregnation ratio: 1:1, and activation time: 30min). Meanwhile, the activation temperature was evaluated to be the essential factor that dominated the form of pore structure in activated carbon. The green alga-based activated carbon that was prepared under optimum conditions has shown the high surface area of 1692m²/g and total pore volume of 1.22cm³/g, which could be used as an effective adsorbent to remove chloramphenicol. The thermodynamic data of chloramphenicol were well fitted by Langmuir isotherm model and the green alga-based activated carbon has showed high adsorption capacity of 709.2mg/g towards chloramphenicol.

An aptamer-based effective method for highly sensitive detection of chloramphenicol residues in animal-sourced food using real-time fluorescent quantitative PCR

Chloramphenicol (CAP) residues can not only harm human health through entering food chain, but also cause the spreading of drug-resistant bacteria, thereby leading to secondary environmental pollution. Therefore, it is in urgent need of establishing an efficient technology to detect CAP residues in animal-sourced food. In this study, a novel sensitive approach for detection of CAP was designed based on a CAP specific aptamer and real-time fluorescent quantitative PCR (qRT-PCR). The CAP specific aptamer was firstly hybridized with a biotin modified complementary probe, and then was immobilized on streptavidin conjugated magnetic beads through biotin. When CAP was added, the aptamer would specifically bind with CAP by forming a hairpin structure and be released from the magnetic beads for CAP detection by qRT-PCR. Factors (i.e., probe strand length, aptamer concentration, NaCl concentration and incubation time) that would influence the determination accuracy of this aptamer-based detection system were optimized. Under the optimized conditions, the present detection system exhibited a high sensitivity toward CAP with a limit of detection of 0.1ng/mL (linear range from 0.1 to 20ng/mL). Moreover, this detection system also showed high selectivity against thiamphenicol (TAP) and florfenicol (FF), which are CAP's structure analogs. Eventually, this detection system was applied for detecting CAP in real spiked milk. The recovery rate of CAP from spiked milk samples ranged from 94.0-102.0%. These results indicated this developed detection system a promising high sensitive and specific method of CAP residues detection in animal-sourced food.

Removal rates of antibiotics in four sewage treatment plants in South India

The occurrence and removal of seven selected pharmaceutical compounds (PCs) in sewage treatment plants (STPs) in South India were investigated. The PCs selected for this study were sulfamethoxazole (SMX), trimethoprim (TMP), chloramphenicol (CAP), erythromycin (ERY), naproxen (NPX), bezafibrate (BZF), and ampicillin (AMP). Wastewater samples were collected from inlet and outlet of the STPs during pre-monsoon, monsoon, and post-monsoon seasons to investigate the seasonal influences in occurrence and removal rates. The analytical method was based on simultaneous extraction of all target compounds by solid phase extraction (SPE), using a hydrophilic-lipophilic-balanced (HLB) sorbent followed by high performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS). The STP that catered exclusively to domestic wastewater had lesser concentrations of PCs compared to the STPs serving the combined hospital and domestic effluents. SMX was the dominant compound in all effluents with the highest concentration at 3.2 μg/L in the outlet of an STP. TMP and ERY were the other PCs present at higher concentrations in STP outlets (1 μg/L and 0-0.13 μg/L, respectively). Removal rates varied from 100 % for BZF to 60-100 % for SMX, CTX, and AMP.

Development of an Immunoassay for Chloramphenicol Based on the Preparation of a Specific Single-Chain Variable Fragment Antibody

Specific antibodies are essential for the immune detection of small molecule contaminants. In the present study, the heavy and light variable regions (V(H )and V(L)) of the immunoglobulin genes from a hybridoma secreting a chloramphenicol (CAP)-specific monoclonal antibody (mAb) were cloned and sequenced. In addition, the light and heavy chains obtained from the monoclonal antibody were separated using SDS-PAGE and analyzed using Orbitrap mass spectrometry. The results of DNA sequencing and mass spectrometry analysis were compared, and the V(H) and V(L) chains specific for CAP were determined and used to construct a single-chain variable fragment (scFv). This fragment was recombinantly expressed as a soluble scFv-alkaline phosphatase fusion protein and used to develop a direct competitive ELISA. Compared with the parent mAb, scFv exhibits lower sensitivity but better food matrix resistance. This work highlights the application of engineered antibodies for CAP detection.

Chemiluminescent aptasensor for chloramphenicol based on N-(4-aminobutyl)-N-ethylisoluminol-functionalized flower-like gold nanostructures and magnetic nanoparticles

A novel chemiluminescent aptasensor for the highly sensitive detection of chloramphenicol (CAP) in milk was successfully developed using biotinylated CAP aptamer-functionalized magnetic nanoparticles (MNPs) as capture probes and thiolated hybridized complementary strand-modified N-(4-aminobutyl)-N-ethylisoluminol (ABEI)-functionalized flower-like gold nanostructures (AuNFs) as signal probes. P-iodophenol (PIP) was also added to form an ABEI-H2O2-PIP steady-state chemiluminescence (CL) system. Based on a competitive format, the CL intensity was negatively correlated with the concentration of CAP in the range of 0.01-0.20 ng/mL and the detection limit was 0.01 ng/mL in buffer and 1 ng/mL in milk. The proposed method was successfully applied to measure CAP in milk samples and compared to a commercial ELISA method. The high sensitivity of AuNFs, excellent selectivity and stability of aptamers, and good overall stability of the chemiluminescent bioassay with magnetic separation make them a promising approach for the detection of small molecular illegal additives. Additionally, the high sensitivity, easy operation, and good reproducibility exhibited by the stable chemiluminescent bioassay demonstrate its applicability for the trace detection of CAP in applications, such as animal husbandry.

Comparative study of novel versus conventional two-wavelength spectrophotometric methods for analysis of spectrally overlapping binary mixture

Smart spectrophotometric methods have been applied and validated for the simultaneous determination of a binary mixture of chloramphenicol (CPL) and prednisolone acetate (PA) without preliminary separation. Two novel methods have been developed; the first method depends upon advanced absorbance subtraction (AAS), while the other method relies on advanced amplitude modulation (AAM); in addition to the well established dual wavelength (DW), ratio difference (RD) and constant center coupled with spectrum subtraction (CC-SS) methods. Accuracy, precision and linearity ranges of these methods were determined. Moreover, selectivity was assessed by analyzing synthetic mixtures of both drugs. The proposed methods were successfully applied to the assay of drugs in their pharmaceutical formulations. No interference was observed from common additives and the validity of the methods was tested. The obtained results have been statistically compared to that of official spectrophotometric methods to give a conclusion that there is no significant difference between the proposed methods and the official ones with respect to accuracy and precision.

Hydrolysis of amphenicol and macrolide antibiotics: Chloramphenicol, florfenicol, spiramycin, and tylosin

Antibiotics that enter the environment can present human and ecological health risks. An understanding of antibiotic hydrolysis rates is important for predicting their environmental persistence as biologically active contaminants. In this study, hydrolysis rates and Arrhenius constants were determined as a function of pH and temperature for two amphenicol (chloramphenicol and florfenicol) and two macrolide (spiramycin and tylosin) antibiotics. Antibiotic hydrolysis rates in pH 4-9 buffer solutions at 25°C, 50°C, and 60°C were quantified, and degradation products were characterized. All of the antibiotics tested remained stable and exhibited no observable hydrolysis under ambient conditions typical of aquatic ecosystems. Acid- and base-catalyzed hydrolysis occurred at elevated temperatures (50-60°C), and hydrolysis rates increased considerably below pH 5 and above pH 8. Hydrolysis rates also increased approximately 1.5- to 2.9-fold for each 10°C increase in temperature. Based on the degradation product masses found, the functional groups that underwent hydrolysis were alkyl fluoride, amide, and cyclic ester (lactone) moieties; some of the resultant degradation products may remain bioactive, but to a lesser extent than the parent compounds. The results of this research demonstrate that amphenicol and macrolide antibiotics persist in aquatic systems under ambient temperature and pH conditions typical of natural waters. Thus, these antibiotics may present a risk in aquatic ecosystems depending on the concentration present.

Rapid surface enhanced Raman scattering detection method for chloramphenicol residues

Chloramphenicol (CAP) is a widely used amide alcohol antibiotics, which has been banned from using in food producing animals in many countries. In this study, surface enhanced Raman scattering (SERS) coupled with gold colloidal nanoparticles was used for the rapid analysis of CAP. Density functional theory (DFT) calculations were conducted with Gaussian 03 at the B3LYP level using the 3-21G(d) and 6-31G(d) basis sets to analyze the assignment of vibrations. Affirmatively, the theoretical Raman spectrum of CAP was in complete agreement with the experimental spectrum. They both exhibited three strong peaks characteristic of CAP at 1104 cm(-1), 1344 cm(-1), 1596 cm(-1), which were used for rapid qualitative analysis of CAP residues in food samples. The use of SERS as a method for the measurements of CAP was explored by comparing use of different solvents, gold colloidal nanoparticles concentration and absorption time. The method of the detection limit was determined as 0.1 μg/mL using optimum conditions. The Raman peak at 1344 cm(-1) was used as the index for quantitative analysis of CAP in food samples, with a linear correlation of R(2)=0.9802. Quantitative analysis of CAP residues in foods revealed that the SERS technique with gold colloidal nanoparticles was sensitive and of a good stability and linear correlation, and suited for rapid analysis of CAP residue in a variety of food samples.

Quantitation of Chloramphenicol and Nitrofuran Metabolites in Aquaculture Products Using Microwave-Assisted Derivatization, Automated SPE, and LC-MS/MS

This paper describes a rapid and robust method utilizing microwave-assisted derivatization, automated SPE, and LC-MS/MS for the quantitation and confirmation of chloramphenicol (CAP) and nitrofuran metabolites in various aquaculture matrixes. The use of equipment presented in this work allowed extractions to be completed on average within 6 h, with quantitation accuracy ranging from 89 to 107% and RSD≤8.3%. The demonstrated detection limits for all the nitrofuran metabolites of interest in three different matrixes were ≤0.06 ng/g, with a quantitation limit of ≤0.2 ng/g. Additionally, the method exhibited a CAP detection limit for all matrixes≤0.01 ng/g and an LOQ of ≤0.03 ng/g.