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Objectives: A ceftiofur hydrochloride long-acting oily suspension with no irritation was prepared by testing and optimizing the types and amounts of organic solvents, suspending agents, and surfactants. Methods: Its properties, stability, injection site irritation, in vitrorelease, and pharmacokinetics in pigs were evaluated. The optimum formulation was used ethyl oleate, aluminum monosterate, and span-80 as organic solvents, suspending agents, and surfactant, respectively. The drug microparticles were uniform long strip with size of 1.53 ± 0.11 μm and no agglomerations, and were evenly dispersed. The re-dispersed time, sedimentation rate and pH value of the suspension were 4 s under a magnetic shaker rotating at 20 r/min, 1 and 5.0, respectively. It could go through 7-gage needle smoothly with withdrawal volume of 9.9 mL/min. Results: The suspension showed good stability when stored away from light, no irritation at the injection site and sustained release in PBS buffer. After intramuscular administration, the drug concentration above 0.15 μg/mL was last for 120 h. Its elimination half-life (T1/2ke), mean residence time (MRT), and bioavailability were increased by 1.73, 1.62, and 2.16 times compared to Excenel®. Conclusion: The results suggested that the suspension had excellent sustained-release and will make ceftiofur hydrochloride more effective and convenient to use.

In the present study, sulfamethazine-imprinted polymers have been prepared by bulk polymerization method with a living radical photopolymerization using sulfamethazine (SM2) as the template molecule, methacrylic acid (MAA) as the functional monomer, ethylene glycol dimethacrylate (EGDMA) as the cross-linker, and azobisisobutyronitrile (AIBN) as the initiator in the porogenic solvent of acetonitrile. After estimating the recognition properties, the imprinting factor of the polymer reached up to 9.3779. Then, the polymer particles were incorporated into a solid-phase extraction (SPE) column for the selective separation and purification of the sulfonamides (SAs), including sulfadiazine (SD), sulfamerazine (SM1), and SM2, from edible swine tissues. By using the detection method of high-performance liquid chromatography with the optimum SPE conditions, the limits of detection and limits of quantitation were calculated as 0.7–2.3 μg kg−1 and 3.4–4.6 μg kg−1 in the complex samples, respectively. The recovery of SAs ranged from 85.5 to 88.3%. Compared with the commonly used Waters Oasis HLB® column, the proposed selective SM2-MI-SPE column has opened a promising new approach for trace enrichment of the residues. It will facilitate sulfonamide residue analysis in animal tissues.

Based on magnetic graphene (Fe3O4-G), a liquid chromatography with tandem mass spectrometric detection (LC-MS/MS) method coupled with magnetic solid-phase extraction was developed for the simultaneous detection of 47 kinds of nonsteroidal anti-inflammatory drug (NSAID) residues in meat of swine, chicken, and bovine. The samples were extracted with acetonitrile-phosphate, then the extracts were purified by dispersed solid-phase extraction based on magnetic graphene (Fe3O4-G). The linearity range is 0.1–50 μg L−1. Limits of detection were between 0.1 μg kg−1 and 0.5 μg kg−1, and limits of quantification were between 0.5 μg kg−1 and 1.0 μg kg−1. The average recoveries were 72.4–97.1% at spiking levels. The inter-day RSDs varied from 5.3 to 12.6%. Due to the advantages of easy collection of magnetic solid-phase extraction materials, the method was more rapid and efficient for the enrichment and separation without filling columns. The sensitivity, precision, and accuracy method was suitable for simultaneous detection of multi-component residues of nonsteroidal anti-inflammatory drugs.

To monitor the illegal use of olaquindox in animals, a monoclonal antibody-based surface plasmon resonance (SPR) biosensor method has been developed to detect 3-methyl-quinoxaline-2-carboxylic acid, the marker residues of olaquindox, in swine tissues. The limit of detection was 1.4 µg kg-1 in swine muscle and 2.7 µg kg-1 in swine liver, which are lower than the EU recommended concentration (10 µg kg-1). The recoveries were from 82% to 104.6%, with coefficients of variation of less than 12.2%. Good correlations between SPR and HPLC results (r = 0.9806, muscle; r = 0.9698, liver) and between SPR and ic-ELISA results (r = 0.9918, muscle; r = 0.9873, liver) were observed in the affected tissues, which demonstrated the reliability of the SPR method. This method would be a rapid and reliable tool for the screening of the residues of olaquindox in the edible tissues of animals.

We developed a sensitive and reliable method by coupling radiotracing with LC/MS-IT-TOF to identify diaveridine metabolites. Tritium-labeled diaveridine was orally administered to pigs and their organs, blood, bile, and excreta were collected. Under optimized conditions, radioactive recovery was >90% and the highest numbers of metabolites were detected. MCX-based solid-phase extraction was conducted for urine, plasma, and bile purification. Methanol-chloroform 1:1 (v/v), methanol-chloroform 6:1 (v/v), methanol, methanol-chloroform 1:1 (v/v), and methanol were used as solvents to extract feces, liver, kidney, fat and muscle, respectively. The method validation confirmed satisfactory 3H-H exchange efficiency (

An immunoaffinity column (IAC) for the selective purification of 3-methyl-quinoxaline-2-carboxylic acid (MQCA) from porcine muscle and the liver as well as the methods for its determination by high-performance liquid chromatography with ultraviolet detection (HPLC-UV) and a colloidal gold-based immunochromatographic assay (GICA) were developed. This is the first study that describes a clean-up method that employs an IAC for the determination of MQCA. Using the HPLC-UV method, the limits of detection and limits of quantification for MQCA in different samples were 1.0–3.0 μg kg −1 and 4.0–10.0 μg kg −1 , respectively. The average recoveries of MQCA that was spiked into samples at concentrations of 4.0–100 μg kg −1 were 80.1–87.7%, with relative standard deviations of less than 8.5%. Using the GICA method, the limits of detection for MQCA in different samples were 10 μg kg −1 and 50 μg kg −1 . No false negatives or false positives were observed.

This study attempts to develop an enzyme-linked immunoassay (ELISA) using a molecularly imprinted polymer (MIP) as an artificial recognition element. The MIP microspheres were prepared using precipitation polymerization with SM2 as the template molecule, methacrylic acid as the functional monomer and ethylene glycol dimethacrylate as the cross-linker. After the microspheres were coated in microtiter plate wells, the molecular imprinting ELISA (MI-ELISA) method was established based on the direct competition between free SM2 and horseradish peroxidase (HRP)-labelled SM2 in heterogeneous mode. The linear regression analysis data for the calibration curve showed a good linear relationship with a regression coefficient of 0.999 in the concentration range of 100μgL-1-3200μgL-1. Furthermore, following the selective solid-phase extraction (SPE) with bulk SM2 MIPs as the sorbent and MI-ELISA detection, the limits of detection and quantification were 6.8μgkg-1 and 20.4μgkg-1, respectively, for SM2 in swine muscle. For the first time, MI-ELISA combined with molecular imprinting SPE was developed to determine trace SM2 in real samples, and the results show that it can be a useful analytical tool for quick detection in residue analysis.

In this study, a broadly specific monoclonal antibody was prepared and a sensitive monoclonal-based indirect competitive enzyme linked immunosorbent assay (ic-ELISA) was subsequently developed to determine the phenothiazines in animal feed with a simple sample preparation procedure for the first time. The obtained antibody 3A5 was of the immunoglobulin G1 (IgG1) isotype possessing a kappa light chain, which broadly cross-reacted to nine phenothiazines. The limit of detections of the method ranged from 1.1 μg kg −1 to 15.3 μg kg −1 in the swine feed and the fish feed. The recoveries of the phenothiazines were in the range of 78.2–116.6%. The coefficient of variations were less than 16.7%. A positive correlation (r > 0.9249) between the results of the ic-ELISA and the high-performance liquid chromatography were also observed, which indicated that the developed ic-ELISA is reliable and can be used to monitor phenothiazines in animal feed.

In-depth research on processing can promote the globalization of processed herbs. The purpose of this study is to propose an improved strategy for processing effect investigation. Frankincense and processed frankincense were used as research subjects. First, high-speed countercurrent chromatography (HSCCC) and preparation high-performance liquid chromatography (PHPLC) techniques were used for major compounds isolation and minor compounds concentration. Processed frankincense was subjected to two stepwise solvent systems, namely, n-hexane:ethanol:water (6:5:1) and n-hexane:methyl-acetate:acetonitrile:water (4:4:3:4), to yield 12 fractions, and 18 compounds were further separated. Second, a comprehensive metabolomic analysis conducted by ultrahigh-performance liquid-chromatography/electrospray-ionization mass spectrometry (UHPLC-Qtof-MS) coupled with multivariate statistics was performed to fully characterize the chemical components and discover the potential biomarkers between frankincense and processed frankincense. In total, 81 metabolites, including the 18 separated compounds, were selected as potential biomarkers between frankincense and processed frankincense among 153 detected compounds for their VIP values of greater than one. The tirucallane-type compounds and components with 9,11-dehydro structures clearly occurred at high levels in the processed frankincense, while lupine-type compounds and those with 11-keto structures were significantly higher in frankincense. Then, a network pharmacology model was constructed to decipher the potential mechanisms of processing. Intestinal absorption properties prediction indicated the possibility of processing-related absorption enhancement. A systematic analysis of the constructed networks showed that the C-T network was constructed with 18 potential biomarkers and 69 targets. TNF and IL-1β were among the top-ranked and were linked by 8 and 7 pathways, which were mainly involved in inflammation. The arachidonic acid metabolism pathway exhibited the highest number of target connections. Finally, the prediction was validated experimentally by an intestinal permeability and efficacy assay. The experiments provided convincing evidence that processed frankincense harbored stronger inhibition effects toward TNF-α-, IL-1β- and arachidonic acid-induced platelet aggregation. The processing procedure leads to changes of the chemical metabolites, which triggers the enhancement of absorption and cure efficiency. The global change of the metabolites, absorption and pharmacological effects of processing were depicted in a systematic manner.

In this study, two specific monoclonal antibodies, one for Sudan I and the other for leucocrystal violet, were prepared and then used to develop a sensitive indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) for the detection of two illegal synthetic dyes: Sudan I in duck egg and crystal violet in fish muscle. The Sudan I-specific antibody 1H7 was of the IgG2b isotype and had an IC50 of 3.1 μg L−1. Additionally, the crystal violet-specific antibody 4B10 was of the IgG2a isotype and had an IC50 of 5.3 μg L−1. Based on these antibodies, the limit of detection (LOD), recoveries, and coefficient of variation of the ic-ELISA developed for the detection of Sudan I residues in duck egg samples were 0.6 μg kg−1, 83.6∼113.8 %, and less than 8.4 %, and the values of the ic-ELISA developed for the detection of leucocrystal violet residues in fish muscle samples were 1.2 μg kg−1, 90.8∼108.4 %, and less than 12.3 %, respectively. Both assays exhibited a positive correlation (r > 0.99) with the results of HPLC-MS run on the samples. These data indicate that the developed ic-ELISAs are reliable and will be very reliable screening methods for the detection of the illegal dyes Sudan I and crystal violet in duck egg and fish muscle, respectively.

A simple multiresidue method was developed for detecting and quantifying 92 veterinary antimicrobial drugs from eight classes (β-lactams, quinolones, sulfonamides, tetracyclines, lincomycins, macrolides, chloramphenicols, and pleuromutilin) in livestock excreta and water by liquid chromatography with tandem mass spectrometry. The feces samples were extracted by ultrasound-assisted extraction with a mixture of acetonitrile/water (80:20, v/v) and edetate disodium, followed by a cleanup using solid-phase extraction with an amino cartridge. Water samples were purified with hydrophilic-lipophilic balance solid-phase extraction column. Urine samples were extracted with acetonitrile and edetate disodium. Detection of veterinary antimicrobial drugs was achieved by liquid chromatography with tandem mass spectrometry using both positive and negative electrospray ionization mode. The recovery values of veterinary antimicrobial drugs in feces, urine, and water samples were 75-99, 85-110, and 85-101% and associated relative standard deviations were less than 15, 10, and 8%, respectively. The limits of quantification in feces, urine, and water samples were 0.5-1, 0.5-1, and 0.01-0.05 μg/L, respectively. This method was applied to determine real samples obtained from local farms and provides reliable quantification and identification results of 92 veterinary antimicrobial drugs in livestock excreta and water.

Citrus fruit is an important health-promoting food that is rich in dietary phenolic metabolites. Traditional Chinese medicines, such as Zhishi and Zhiqiao, come from young and immature fruits of Citrus cultivars. The preparation of diversified bioactive phenolic products and establishment of the corresponding quality control methodology are challenging and necessary. In the current study, four types of solid-phase extraction sorbents for the enrichment and clean-up of the phenolic matrix were evaluated. A solid-phase extraction column coated with Strata-X was finally used in the procedure. Twenty phenolic compounds were selected to evaluate the extraction performances of the sorbents using high-performance liquid chromatography analysis. Under the optimized conditions, good linearities were obtained with R2 more than 0.9996 for all analytes with LODs of 0.04-1.012 μg/g. Intra- and interday relative standard deviation values were less than 3%, and the recovery was equal to or higher than 90.02%. Compared to non-solid-phase extraction process, the content of total phenolic products was elevated 35.55-68.48% with solid-phase extraction. Finally, the developed and validated method was successfully applied to the discrimination of Zhishi samples from different species as well as Zhishi and Zhiqiao samples in different development stages.

The residue kinetics of bacitracin in animals has rarely been quantitatively described due to inadequate sensitivity of analytical methods. A sensitive and selective quantitative liquid chromatography coupled with electrospray ionization tandem mass spectrometry (LC-MS/MS) method was developed to determine the residue depletion kinetics of zinc bacitracin in pigs. The tissues samples were extracted with acidified methanol/water solution (v/v, 1:1, 1 % formic acid) and followed by liquid-liquid extraction with saturated solution of 0.1 mmol dithizone in chloroform. The extracts were subjected to Phenomenex Strata-X cartridges for further cleanup with 0.1 % formic acid in methanol. Analysis was performed on a C18 column with positive-ion electrospray mass spectrometry and multiple-reaction monitoring mode. The product ions at m/z 199 and 227 were selected for bacitracin A confirmation and at 199 for quantification. The developed method was linear in the concentration ranges of 150–4000 μg/L for bacitracin with limit of detection (LOD) and limit of quantification (LOQ) of 25 and 50 μg/kg for kidney and 20 and 50 μg/kg for skin with fat, liver, and muscle. The recoveries from different tissues were higher than 82.1 % at three different spiking levels with relative standard deviations (RSDs) less than 8.8 %. The residue depletion study showed that higher concentration and longer residue time were detected in kidney than in other three tissues. The elimination half-life in kidney was 0.45 days, and the recommended withdrawal period was zero. These results suggest that the established method satisfactorily enables a closer study of residue depletion kinetics of bacitracin in swine.

To quickly monitor fluoroquinolone (FQ) residues in eggs, three broadly specific monoclonal antibodies (mAbs; i.e., 5B11, 4B6, and 6A2) against FQs were generated. Among them, the 6A2 mAb exhibited the capability to recognize 19 FQs with equal or nearly equal efficacy and therefore was selected for the development of a simple and rapid indirect competitive enzyme-linked immunosorbent assay (ic-ELISA). The optimized ic-ELISA protocol was carried out using only acetonitrile with NaOH for the fast extraction of FQs in whole eggs. The CCα, the CCβ, and the limit of quantity values of 19 FQs in eggs ranged from 0.6 to 3.1, 0.7 to 3.6, and 1.6 to 4.2 μg kg−1, respectively. The recoveries from eggs spiked with the above FQs ranged from 60.2 to 119.9 %, with coefficients of variation (CVs) of less than 17.8 %. These results suggest that the prepared mAbs and the developed ic-ELISA protocol are reliable tools that can be applied for the screening of FQ residues in eggs.

Incorrect use of benzodiazepines could result in serious health problems. To monitor the illegal use of benzodiazepine compounds in animals, a group-specific monoclonal antibody (mAb) was prepared in this study. The obtained 3D7 mAb, which is an IgG1 isotype mAb, displayed an IC50 value of 8.9 ng mL−1 for diazepam and exhibited cross-reaction for diazepam (100 %), nitrazepam (49 %), nordiazepam (140 %), temazepam (32 %), oxazepam (17 %), estazolam (7.5 %), and alprazolam (2.4 %). Based on this mAb, for the first time in this study, an optimized indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) protocol that did not require complicated sample preparation and clean-up was developed. The detection limits of this ic-ELISA for benzodiazepines ranged from 1.2 to 3.3 μg kg−1 in muscle matrix and from 25.2 to 55.4 μg kg−1 in feed matrix. The recoveries ranged from 70.9 to 111.3 % with coefficients of variation below 15.0 %. Good correlations (r > 0.9494) between the results of the ic-ELISA and high-performance liquid chromatography were also observed. This simple method reduced the time required for sample preparation, ensured greater throughput, and met the requirements for benzodiazepine residue analyses. In conclusion, the proposed method is a sensitive and rapid multi-residue technique that offers a cost-effective alternative to current published procedures without any concession in the ability to detect benzodiazepine sedative misuse.

A sensitive monoclonal antibody (mAb) against aflatoxin M1 (AFM1) was generated to quickly monitor the AFM1 residues in milk. Then, a mAb-based indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) was established that utilizes simple sample preparation and clean-up methods. The obtained 3D8 mAb, which is an IgG1 isotype mAb, displayed an IC50 value of 64.75 ng L(-1) for AFM1 and did not exhibit measurable cross-reactivity with other aflatoxins and antibiotics. The decision limit (CCα, α = 1%), detection capability (CCβ, β = 5%), and LOQ value for the AFM1 matrix calibration method were 24 ng L(-1), 27.5 ng L(-1), and 35 ng L(-1) in the milk matrices, respectively. The AFM1 recovery ranged from 85.3% to 107.6%. The CVs were less than 13.8%. A positive correlation (r > 0.99) was observed between the ic-ELISA and HPLC-MS/MS results. This ic-ELISA would be a useful tool for screening the AFM1 residues in milk.

A method for the analysis of 120 drugs in animal derived food was developed using liquid chromatography-tandem mass spectrometry (LC-MS/MS). These analytes belong to 12 families of veterinary anti-microbial agents (quinolones, macrolides, β-lactams, nitroimidazoles, sulfonamides, lincomycines, chloramphenicols, quinoxalines, tetracyclines, polypeptides, and antibacterial synergists) as well as other compounds not assigned to a particular drug family. The animal derived food samples include muscle and liver of swine, bovine, sheep, and chicken, as well as hen eggs and dairy milk. The sample preparation included ultrasound-assisted extraction (UAE) with acetonitrile-water and a final clean-up with auto solid-phase extraction (SPE) on HLB cartridges. The detection and quantification of 120 anti-microbial agents was performed using LC-MS/MS in positive and negative ion mode. The chromatographic separation was performed on a C18 column using acetonitrile and 0.1% formic acid as the mobile phase. The limit of detection (LOD) and limit of quantification (LOQ) of all drugs in food-producing animals were 0.5–3.0 μg/kg and 1.5–10.0 μg/kg, respectively. The developed method was successfully utilized to monitor real samples, which demonstrated that it is a simple, fast, and robust method, and could be used as a regulatory to screen for the presence of residues from veterinary anti-microbial drugs in animal-derived foods.

To monitor the illegal use of florfenicol (FF) and thiamphenicol (TAP) in edible animal tissue and feed, a sensitive monoclonal antibody-based indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) has been developed with simple sample preparation and cleanup. The obtained monoclonal antibody (5F4) that has isotype IgG1 showed an IC50 value of 0.21 μg L−1 for FF and 0.35 μg L−1 for TAP, respectively. It did not exhibit measurable cross-reactivity with other antibiotics. The limits of detection (LODs) for FF and TAP in a muscle matrix ranged from 0.07 to 0.14 μg kg−1 and in a feed matrix ranged from 2.9 to 5.2 μg kg−1. The recoveries were 72.8 to 113.4 % with a coefficient of variation of less than 15 %. Good correlation between the ELISA and HPLC-MS/MS results in the tissues tested demonstrated the reliability of our ic-ELISA. This ELISA is a useful tool for screening FF and TAP in edible animal tissue and feed.

The misuse of nitroimidazoles (NDZs) can lead to NDZs residues in edible animal tissues, which would be harmful to consumer health. To quickly monitor NDZs residues in edible animal tissues and feed, a monoclonal antibody-based indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) with a simple sample preparation method and clean-up was developed in the present study. At first, a broad-specificity monoclonal antibody, 1D5, against NDZs has been produced, which the IC50 values of the NDZs, dimetridazole, ipronidazole, ronidazole hydroxydimetridazole, and hydroxyipronidazole, were 4.79μgL(-1), 0.47μgL(-1), 5.97μgL(-1), 23.48μgL(-1), and 15.03μgL(-1), respectively. The limit of detection of the method for the NDZ matrix calibration ranged from 4.2μgkg(-1) to 50.3μgkg(-1) in the feed matrices and from 0.11μgkg(-1) to 4.11μgkg(-1) in the edible animal tissues matrices. The recoveries of the NDZs were in the range of 75.5-111.8%. The CVs were less than 14.4%. A good correlation (r=0.9905) between the ELISA and HPLC-MS results of the tissues demonstrated the reliability of the developed ic-ELISA, which makes it a useful tool for screening of NDZs in animal edible tissue and feed.

In this study, a microbiological inhibition method in terms of test tubes was developed for the rapid screening of antibiotics in muscle from porcine, bovine, poultry and fish with a simplified sample pre-treatment method. The detection system in microwell plates consisted of an agar medium mixed with nutrients, sensitizers, indicator bacterium (Geobacillus stearothermophilus ATCC12980) and pH indicator (bromocresol purple). Performance of the present kit was validated for the detection of antibiotics in muscle from different animal species according to ISO13969:2003 guidelines. It indicated that the present kit was sensitive to β-lactams, tetracyclines, macrolides (tylosin) and sulfonamides in muscle from porcine, bovine and poultry at MRL levels established by EU No 37/2010. It was also sensitive to β-lactams, aminoglycosides, tetracyclines, macrolides (erythromycin, tylosin), sulfonamides and lincomycin in muscle from fish at MRL levels established by EU No 37/2010. Moreover, there was a consistence between the validation results and the results on incurred samples for the present kit. Additionally, the present kit was easy to operate, cost-effective and satisfactory in specificity and stability.

To monitor the abuse of antibacterial synergists, a hapten, trimethoprim carboxylic derivative (TMPCOOH), was designed by using molecular modelling technology. A broad-spectrum monoclonal antibody (mAb) TMP/2G1 was prepared, for which the IC50 values of trimethoprim, diaveridine, aditoprim, baquiloprim, ormetoprim, and brodimoprim were 0.232, 0.527, 1.479, 4.354, 0.965, and 0.119 µg L−1, respectively. Based on the broad spectrum mAb, an indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) was developed to determine the residues of antibacterial synergists. The limit of detection regarding the developed ic-ELISA for antibacterial synergists ranged from 0.025 to 1.126 µg L−1 in milk, honey and edible animal tissues. The recoveries ranged from 81.4% to 107.7%, with a coefficient of variation less than 20%. A good correlation (R2 = 0.994) between the ic–ELISA and HPLC–MS/MS showed the reliability of the developed ic-ELISA.

This paper presents a convenient and sensitive LC-MS/MS method for the simultaneous determination of carbadox and olaquindox residues, including desoxyolaquindox (DOLQ), desoxycarbadox (DCBX), quinoxaline-2-carboxylic acid (QCA), 3-methyl-quinoxaline-2-carboxylic acid (MQCA), and the glycine conjugates of QCA and MQCA (namely, QCA-glycine and MQCA-glycine, resp.) in swine muscle and liver tissues. Tissue samples were extracted with 2% metaphosphoric acid in 20% methanol and cleaned up by solid-phase extraction (SPE) on a mixed-mode anion-exchange column (Oasis MAX). Analysis was performed on a C18 column by detection with mass spectrometry in the multiple reaction monitoring (MRM) mode. The limits of detection (LODs) of the six analytes were determined to be 0.01 μg·kg−1 to 0.25 μg·kg−1, and the limits of quantification (LOQs) were 0.02 μg·kg−1 to 0.5 μg·kg−1. The total recoveries of the six analytes in all tissues were higher than 79.1% with the RSD% less than 9.2%. The developed method can determine the real residue level of QCA and MQCA, whether they are present in free form or as glycine conjugates in tissues, together with the carcinogenic desoxy metabolites DCBX and DOLQ with high recovery. Therefore, this method was suitable for routine analysis of residue control programmes and the residue depletion study of CBX and OLQ on swine.

To monitor the residues of albendazole (ABZ) in edible animal tissues, a monoclonal-based indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) was developed. The hapten albendazole 2-aminosulfone (ABZSO2NH2) was conjugated to a carrier protein as an immunogen. The spleen cells of the inoculated mice expressing specificity to ABZSO2NH2 were fused. The obtained monoclonal antibody 2A11 was selected for detailed study. The standard curves based on the ABZSO2NH2 matrix calibration ranged from 20.0 to 320.0 µg L−1, with an IC50 value of 85.2 ± 6.3 µg L−1 (n = 5). The limits of detection for ABZSO2NH2 ranged from 11.0 to 20.8 µg kg−1 in edible animal tissues. The recoveries ranged from 73.6% to 99.8% with a coefficient of variation of less than 20%. The developed ic-ELISA exhibited good correlation (r = 0.999) with high-performance liquid chromatography. Thus, it would be a very attractive alternative for the screening of ABZSO2NH2 residues in edible animal tissues.

To monitor the illegal use of olaquindox (OLA) in animals, a novel hapten and monoclonal antibody for 3-methyl-quinoxaline-2-carboxylic acid (MQCA), the marker residue for OLA, had been produced. And then, the monoclonal-based indirect competitive enzyme linked immunosorbent assay (ic-ELISA) has been established with simple sample preparation and clean-up. The obtained antibody 5B10 that has isotype IgG1 showed an IC50 value of 17.7 μg L−1 for MQCA and did not exhibit measurable cross-reactivity with other antibiotics. The limits of detection ranged from 1.9 μg kg−1 to 4.3 μg kg−1. The recoveries were from 74.2% to 98.9% with a maximum coefficient of variation of 17.3%. A good correlation between ELISA and HPLC results of the incurred tissues demonstrated the reliability of the developed ic-ELISA. It would be a useful tool for the screening of the residues of MQCA in the edible tissues of animals.

A broad-spectrum monoclonal antibody (mAb)-based indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) has been developed for rapidly screening zearalenone (ZEN) and its primary analogues in various samples using an easy sample preparation procedure. Primarily, a group-specific mAb, 6C2, was produced, which had IC50 values for ZEN, α-zearalenol, β-zearalenol, α-zearalanol, β-zearalanol and zearalanone of 114.0, 127.4, 290.4, 114.9, 205.6 and 257.1 ng L-1, respectively. The limit of detection and limit of quantitation of this method for ZEN and its five primary analogues in various matrix samples ranged from 114.2 to 812.3 ng L-1 and 237.1 to 1653.9 ng L-1, respectively. The recoveries of the above samples spiked with ZEN and its five primary analogues were in the range of 62.9-113.6%. The CVs were less than 13.2%. A good correlation (R2 = 0.995) between the ic-ELISA results and the HPLC-MS/MS results for swine feeds supported the reliability of the developed ic-ELISA.

Enrofloxacin-loaded docosanoic acid solid lipid nanoparticles (SLNs) with different physicochemical properties were developed to enhance activity against intracellular Salmonella. Their cellular uptake, intracellular elimination and antibacterial activity were studied in RAW 264.7 cells. During the experimental period, SLN-encapsulated enrofloxacin accumulated in the cells approximately 27.06–37.71 times more efficiently than free drugs at the same extracellular concentration. After incubation for 0.5 h, the intracellular enrofloxacin was enhanced from 0.336 to 1.147 μg/mg of protein as the sizes of nanoparticles were increased from 150 to 605 nm, and from 0.960 to 1.147 μg/mg of protein when the charge was improved from −8.1 to −24.9 mv. The cellular uptake was more significantly influenced by the size than it was by the charge, and was not affected by whether the charge was positive or negative. The elimination of optimal SLN-encapsulated enrofloxacin from the cells was significantly slower than that of free enrofloxacin after removing extracellular drug. The inhibition effect against intracellular Salmonella CVCC541 of 0.24 and 0.06 μg/mL encapsulated enrofloxacin was stronger than 0.6 μg/mL free drug after all of the incubation periods and at 48 h, respectively. Docosanoic acid SLNs are thus considered as a promising carrier for intracellular bacterial treatment.

Carbon nanotubes-magnetic nanoparticles, comprising ferroferric oxide nanoparticles and carbon nanotubes, were prepared through a simple one-step synthesis method and subsequently applied to magnetic solid-phase extraction for the determination of polyether antibiotic and s-triazine drug residues in animal food coupled with liquid chromatography with tandem mass spectrometry. The nanocomposites were characterized by transmission electron microscopy, X-ray diffraction, and vibrating sample magnetometry. The components within the nanocomposites endowed the material with high extraction performance and manipulative convenience. Compared with carbon nanotubes, the as-prepared carbon nanotubes-magnetic nanoparticles showed better extraction and separation efficiencies for polyether antibiotics and s-triazine drugs thanks to the contribution of the iron-containing magnetic nanoparticles. Various experimental parameters affecting the extraction efficiency had been investigated in detail. Under the optimal conditions, the good linearity ranging from 1 to 200 μg/kg for diclazuril, toltrazuril, toltrazuril sulfone, lasalocid, monensin, salinomycin, narasin, nanchangmycin, and maduramicin, low limits of detection ranging from 1 to 5 μg/kg, and satisfactory spiked recoveries (77.1-91.2%, with the inter relative standard deviation values from 4.0 to 12.2%) were shown. It was confirmed that this novel method was an efficient pretreatment and enrichment procedure and could be successfully applied for extraction and determination of polyether and s-triazine drug residues in complex matrices.

A sensitive liquid chromatography with tandem mass spectrometry method was developed for the determination of 11 β-agonists (clenbuterol, salbutamol, ractopamine, terbutaline, fenoterol, cimaterol, isoxsuprine, mabuterol, mapenterol, clenproperol, and tulobuterol) in swine feed. This rapid, simple, and effective extraction method was based on matrix solid-phase dispersion. The limit of quantification of clenbuterol, cimaterol, mabuterol, salbutamol, terbutaline, mapenterol, clenproperol, and tulobuterol was 1 μg/kg and that of ractopamine, fenoterol, and isoxsuprine was 2 μg/kg. The recoveries of β-agonists spiked in swine feeds at a concentration range of 1-8 μg/kg were >83.1% with relative standard deviations

Frankincense resins are extensively used as natural remedies in regions ranging from North Africa to China. Triterpenoid metabolites from frankincense exhibit notable anti-inflammatory and anti-tumor properties. In the present paper, without the use of an isolation process, the fragmentation rules and NMR spectral characteristics of triterpenoid metabolites in frankincense are summarized through a coupling method using high performance liquid chromatography-diode array detection/electrospray ionization tandem mass spectrometry (HPLC-DAD/ESI-MSn) combined with HPLC-nuclear magnetic resonance (NMR) experiments. Based on this groundwork, a coupling strategy for the comprehensive metabolic profiling of active triterpenoid metabolites from enriched fractions of frankincense was developed. The proposed strategy may serve as a method for the holistic screening of bioactive metabolites in complex TCM samples.

An increase in number of newly developed synthetic drugs displays bioavailability constraints because of poor water solubility. Nanosuspensions formulation may help to overwhelm these problems by increasing dissolution velocity and saturation solubility. In the present study, cyadox (Cyx) nanosuspension was successfully prepared by recrystallization based on acid–base neutralization combined with high pressure homogenization method using Polyvinylpyrrolidone K30 (PVP) as stabilizer. The nanosuspension had uniform particle distribution, excellent sedimentation rate and redispersibility. The nanosuspension significantly improved the solubility, dissolution and bioavailability. The saturation solubility of Cyx nanocrystal was higher than that of bulk Cyx and released the total drug in very short time. Further, pharmacokinetics of Cyx nanosuspension and normal suspension following oral administration was investigated in beagle dogs. Nanosuspension improved the bioavailability of Cyx which could be beneficial for intestinal bacterial infection in animals. Maximum concentration and area under concentration time curve were increased with particles size reduction which might give rise to pronounce fluctuations in plasma concentration and more intensified antibacterial effects. The terminal half-life and mean resident time of Cyx nanosuspension had also increased compared to normal Cyx suspension. In conclusion, nanosuspensions may be a suitable delivery approach to increase the bioavailability of poorly soluble drugs.

Boswellic acids (BAs), as the main components of frankincense, exhibit notable anti-inflammatory properties. However, their pharmaceutical development has been severely limited by their poor oral bioavailability. Traditional Chinese medicinal processing, called Pao Zhi, is believed to improve bioavailability, yet the mechanism is still completely unclear. Previous research suggested that the bioavailability of a drug can be influenced by physical properties. This paper was designed to investigate the physical properties of frankincense and processed frankincense, including the surface morphology, particle size, polydispersity index (PDI), zeta potential (ZP), specific surface area, porosity, and viscosity. The differences in the intestinal absorption characteristics and equilibrium solubilities between frankincense and processed frankincense were determined by an ultra-high-performance liquid chromatography coupled with a triple quadrupole electrospray tandem mass spectrometry (UHPLC-TQ-MS) analysis method. The results showed that vinegar processing can alter the surface morphology, decrease the particle size and PDI, raise the absolute values of the ZP, specific surface area and porosity, and drop the viscosity of frankincense. Meanwhile, the rates of absorption and dissolution of the main BAs were increased after the processing of frankincense. The present study proves that the physical properties were changed after processing, in which case the bioavailability of frankincense was enhanced.

β-Lactam antibiotics, including penicillins and cephalosporins, are commonly used in veterinary medicine. Illegal use and abuse of β-lactams could cause allergy and selected bacterial resistance. BlaR-CTD, the carboxy-terminal of penicillin-recognizing protein BlaR from Bacillus licheniformis ATCC 14580, was utilized in this study to develop a receptor-based ELISA for detection and determination of β-lactam antibiotics in milk, beef, and chicken. This assay was based on directly competitive inhibition of binding of horseradish peroxidase-labeled ampicillin to the immobilized BlaR-CTD by β-lactams. The assay was developed as screening test with the option as semiquantitative assay, when the identity of a single type of residual β-lactam was known. The IC50 values of 15 β-lactam antibiotics, including benzylpenicillin, ampicillin, amoxicillin, dicloxacillin, oxacillin, nafcillin, cefapirin, cefoperazone, cefalotin, cefazolin, cefquinome, ceftriaxone, cefotaxime, cefalexin, ceftiofur and its metabolite desfuroylceftiofur were evaluated and ranged from 0.18 to 170.81 μg L(-1). Simple sample extraction method was carried out with only phosphate-buffered saline, and the recoveries of selected β-lactam antibiotics in milk, beef, and chicken were in the range of 53.27 to 128.29 %, most ranging from 60 to 120 %. The inter-assay variability was below 30 %. Limits of detection in milk, beef, and chicken muscles with cefquinome matrix calibration were 2.10, 30.68, and 31.13 μg kg(-1), respectively. This study firstly established a rapid, simple, and accurate method for simultaneous detection of 15 β-lactams in edible tissues, among which 11 β-lactams controlled by European Union could be detected below maximum residue limits.

To estimate the consumer exposure to olaquindox (OLA) residues in porcine edible tissues, a physiologically based pharmacokinetic (PBPK) model for methyl-3-quinoxaline-2-carboxylic acid (MQCA), the marker residue of OLA, was developed in pigs based on the assumptions of the flow-limited distribution, hepatic metabolism, and renal excretion. The model included separate compartments corresponding to blood, muscle, liver, kidney, adipose, and an extra compartment representing the remaining carcass. Physiological parameters were determined from literatures. Plasma protein binding, partition coefficients, and renal clearance for MQCA were determined in in vitro and in vivo studies. The metabolic conversion of OLA to MQCA was assumed as a simple, one-step process, and an apparent first-order rate constant (k) was employed to describe this metabolic process. The PBPK model was optimized and validated with plasma and tissue data from literatures and our study. Sensitivity analysis and Monte Carlo simulation were also implemented to estimate the influence of model parameters on the goodness of fit. When compared with the observed data, the PBPK model underestimated the MQCA level in all compartments at the early time points, whereas gave excellent predictions of MQCA concentration in porcine edible tissues at later time points. The correlation coefficients between the predicted and observed values were over 0.88. The consistency between the model predictions and the real residues of OLA in pigs proved the good applicability of our model in food safety risk assessment.

This study is to establish an HPLC fingerprint by HPLC-DAD method and simultaneous quantitative analysis of 17 components of 18 batches of Citrus aurantium and 10 batches of C. sinensis. The separation was performed on an Agilent Poroshell 120 SB-C₁₈ (4.6 mm×100 mm,2.7 μm) column with the gradient elution of methanol-0.1% formic acid water, the flow was 0.6 mL•min⁻¹. The detection wavelength was set at 318 nm. The column temperature was maintained at 30 ℃. The data calculation was performed with similarity evaluation system for chromatographic fingerprint of traditional Chinese medicine (Version 2004A) together with SIMCA-P 13.0 software to clarify the differential marker between these two different species of Aurantii Fructus Immaturus. This method has good precision stability and repeatability that could provide basis for quality control and evaluation of Aurantii Fructus Immaturus.

Fuzi Lizhong pill (FLP) is used to treat gastritis, and the monarch drug of it is Aconiti Lateralis Radix Praeparata (Fuzi, aconite roots) which is a toxic herbal medicine. To better control the safety and quality of FLP, an effective method to analyze the contents of 16 toxic and bioactive components using rapid resolution liquid chromatography-tandem triple-quadrupole mass spectrometer was established. The 16 constituents included aconine, mesaconine, hypaconitine, benzoylaconine, benzoylmesaconine, benzoylhypaconine, adenosine, liquiritin, liquiritigenin, glycyrrhizic acid, isoliquiritigenin, 6-gingerol, atractylenolide III, atractylenolide I, atractylenolide II and glycyrrhetic acid. Ideal separation was performed using gradient elution in 13 min by optimized conditions. All the isomerides were isolated to baseline. The improved method with a polarity switch in contiguous time segments could analyze the five types of components, including polar and nonpolar compounds, without decreasing sensitivity. The proposed method was fully validated. The results revealed that contents of six alkaloids from Fuzi were significantly different among the samples. Using the established method and multivariate statistical method, the quality consistency of two dosage forms of FLP from different companies were analyzed. The optimized method could be used for the quality control of FLP and investigate index compound variation between two dosage forms.

A monoclonal antibody (mAb) was produced in order to monitor the illegal use of amantadine and rimantadine in animals. The produced mAb 2G3 exhibited an IC50 value of 15.8μgL-1 for amantadine and exhibited cross-reactivity to both amantadine (100%) and rimantadine (70.6%). Standard curves ranged from 5 to 80μgL-1 for 2G3. The limits of detection of the developed indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) ranged from 5.0μgkg-1 to 5.4μgkg-1 in chicken muscle and liver. The recoveries were 81.3% to 98.1% with a coefficient of variation less than 15.7%. Good correlations were observed between the results of the ic-ELISA and liquid chromatography-mass spectrometry in the incurred tissues. These results suggest that ic-ELISA is a sensitive, accurate, and low-cost method that could be a useful tool for screening the residues of amantadine and rimantadine in chicken muscle and liver.

A quantitative LC-MS/MS method has been developed for simultaneous determination of bacitracin A, bacitracin B, colistin A, colistin B and virginiamycin M1 in feed. This rapid simple and effective extraction method was based on matrix solid-phase dispersion. Qualitative and quantitative analyses were performed by LC-ESI-MS/MS. CCβ of polypeptide antibiotics upon the method ranged from 9.6 to 15.8 μg kg-1 and 19.4 to 27.5 μg kg-1, respectively. The limit of quantification of polypeptide antibiotics was 25 μg kg-1 in feed samples. The recoveries of polypeptide antibiotics spiked in feed samples at a concentration range of 25-100 μg kg-1 were found above 75.9-87.9% with relative standard deviations within days less than 15.7% and between days less than 20.6%. This rapid and reliable method can be used to efficiently separate, characterize and quantify the residues of polypeptide antibiotics in feed with advantages of simple pretreatment and environmental friendly.

A comprehensive strategy combining a quantitative method was developed for 30 banned drugs including β-agonists, hormones, glucocorticoid and psychiatric drugs in swine and chicken feeds. This rapid, simple and effective extraction method was based on matrix solid-phase dispersion and electrospray ionization tandem mass spectrometry. The quantitative method was validated after previous statistical optimization of the main parameters of matrix solid-phase dispersion. The limit of quantification of dopamine hydrochloride, chlormadinone acetate, melengestrol acetate, testosterone propionate, nandrolone and midazolam was 2 μg/kg and that of the other 24 drugs was 1 μg/kg. The recoveries of β-agonists, hormones, glucocorticoid and psychiatric drugs spiked in swine and chicken feeds at a concentration range of 1-8 μg/kg were above 70.1% with inter-day relative standard deviations less than 15.8%. The analytical strategy was applied to 100 feed samples collected from a local market in Wuhan (China). Clenbuterol, ractopamine and melengestrol acetate were identified and quantified at the level 0.2∼3.5 μg/kg. The rapid and reliable method can be used to efficiently separate, characterize and quantify the residues of 30 banned drugs in swine and chicken feeds with advantages of simple pretreatment and environmental friendly nature.

Single standard to determine multi-components (SSDMC) method has been accepted as an efficient technique for the quality control of Traditional Chinese medicines (TCMs), especially for overcoming the shortage of reference standards. HPLC-UV methods have been applied to establish SSDMC method for quantitative analysis in several plant medicines and Chinese patent medicines, however, no LC-MS methods have been used. The purpose of this study is to put forward an improved strategy for the choice of single marker in SSDMC using rapid resolution liquid chromatography coupled with triple quadrupole tandem mass spectrometry (RRLC-QqQ-MS). Five different Panax genus plants, recorded in the Chinese Pharmacopeia 2015 edition, were used as research subjects. An improved SSDMC strategy for simultaneous characterization and determination of 18 bioactive saponins in five Panax plants was put forward, and which was validated to be more superior. Then, it was fully investigated with respect to linearity, LODs, LOQs, precision and accuracy. Coupling with multivariate statistical analysis, the established and validated SSDMC strategy could be successively used in discrimination of the five Panax genus plants.

An automated method had been developed for the determination of Malachite green and Gentian violet as well as their leuco-metabolites in shrimp and salmon by liquid chromatography-tandem mass spectrometry with accelerated solvent extraction and auto solid-phase clean-up. The target analytes were extracted using accelerated solvent extraction (ASE) and then purified using auto solid-phase clean-up. The ASE conditions as: solvent, temperature, pressure, static time, and cell size were optimized. The optimum extraction conditions were set as the following aspects: using 22 mL ASE cell, McIlvaine buffer (pH 3)/acetonitrile/hexane (2/10/2, v/v) as the extraction solvent; pressure at 1500 psi; temperature at 60 °C; static time 5 min (static time); one cycles. The extracts were purified on OASIS MCX SPE column. Detection and quantification of Malachite green; gentian violet; leucomalachite green; leucogentian violet were performed by reversed-phase liquid chromatography coupled with electrospray ionization triple quadrupole mass spectrometry (LC-ESI-MS/MS). An averaged decision limits (CCα) and detection capability (CCβ) of the method were in the range of 0.005 μg/kg ～ 0.012 μg/kg and 0.08 μg/kg～0.13 μg/kg in shrimp and salmon. The recoveries of Malachite green; Gentian violet; Leucomalachite green; Leucogentian violet at levels of 0.1–1.0 μg/kg averaged from 82.1 to 102.9% with the relative standard derivation less than 14.6%. This method is precise, sensitive and highly efficient in extraction. What’s more, after routine applications, it’s turned out that this method is suitable for the determination of Malachite green, Gentian violet and their leuco-metabolites in shrimp and salmon.

Cyadox (CYX), 2-formylquinoxaline-1,4-dioxide cyanoacetylhydrazone, is an antimicrobial and growth-promoting feed additive for food-producing animals. To reveal biotransformation of CYX in swine intestine, CYX was incubated with swine intestinal microsomes and mucosa in the presence of an NADPH-generating system and swine ileal flora and colonic flora, respectively. The metabolites of CYX were identified using high-performance liquid chromatography combined with ion trap/time-of-flight mass spectrometry (LC/MS-ITTOF). Structural elucidation of the metabolites was precisely performed by comparing their changes in molecular mass, full scan MS/MS spectra and accurate mass measurements with those of the parent drug. Finally, seven metabolites were identified as follows: three reduced metabolites (cyadox 1-monoxide (Cy1), cyadox 4-monoxide (Cy2) and bisdesoxycyadox (Cy4)); hydroxylation metabolite (3-hydroxylcyadox 1-monoxide (Cy3)); hydrolysis metabolite of the amide bond (N-decyanoacetyl cyadox (Cy5)); a hydrogenation metabolite (11,12-dihydro-bisdesoxycyadox (Cy6)) and a side-chain cleavage metabolite (2-hydromethylquinoxaline (Cy7)). Only one metabolite (Cy1) was found in intestinal microsomes. Cy1, Cy2 and Cy4 were detected in intestinal mucosa, ileal and colonic flora. In addition, Cy3 and Cy5 were only obtained from ileal flora, and Cy6 and Cy7 alone were observed in colonic bacteria. The results indicated that N → O group reduction was the main metabolic pathway of CYX metabolism in swine ileal flora, intestinal microsomes and mucosa. New metabolic profiles of hydrogenation and cleavage on the side chain were found in colonic bacteria. Among the identified metabolites, two new metabolites (Cy6, Cy7) were detected for the first time. These studies will contribute to clarify comprehensively the metabolism of CYX in animals, and provide evidence to explain the pharmacology and toxicology effects of CYX in animals. Copyright © 2011 John Wiley & Sons, Ltd.

A high-performance liquid chromatography (HPLC) method with UV detection was developed for the simultaneous determination of arsanilic acid, roxarsone, nitarsone, and carbarsone in the feeds of swine and chicken. Feed samples were extracted with methanol/1% acetic acid (90:10, v/v) in an ultrasonic bath and the protein was precipitated with 2% Cu2SO4. The samples were further purified by solid phase extraction (SPE) on SAX cartridges. Separation was performed on a Zorbax SB-Aq C18 HPLC column using an isocratic procedure with methanol and 1% acetic acid (3:97, v/v) at a flow-rate of 0.7 mL min−1, and the UV detector was set at a wavelength of 260 nm. The recoveries of organoarsenic compounds spiked at levels of 2, 20 and 200 μg g−1 ranged from 81.2% to 91.3%; the inter-day relative standard deviation values were less than 7.0%. The limits of quantification for four organoarsenic compounds were 1.0–2.0 μg g−1. This simple and fast method could be applied to the determination of multi-residues of organic arsenic compounds in animal feeds.

Simple and sensitive methods have been developed for simultaneous detection of cyromazine, melamine and their metabolites (ammeline, ammelide and cyanuric acid) in samples of animal origins. These include a high performance liquid chromatography (HPLC) method and a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method and are useful in regular monitoring and in toxicity studies of these molecules. Representative samples used in this study include muscles and livers of swine, bovine, sheep and chicken, kidneys of swine, bovine and sheep, and milk powder. A new sample preparation procedure with pressurized liquid extraction (PLE) at 1400psi and 70°C was investigated. Quantification of these five compounds by HPLC was achieved using an APS-2 column with UV detection at 230 nm. Limit of detection (LOD) was at 10 μgkg(-1), and limit of quantification (LOQ) was at 40 μgkg(-1). Recoveries of the five analytes in spiked samples ranged from 72.2% to 115.4% with RSD less than 12%. Confirmatory analysis of the analytes was performed using LC-MS/MS in selected reaction monitoring (SRM) mode. The LOD and LOQ were 5 μgkg(-1) and 15 μgkg(-1), respectively. This is the first simultaneous analysis of cyromazine, melamine, ammeline, ammelide and cyanuric acid residues in complex tissue samples using PLE and HPLC. It is expected that these methods will find many practical applications in evaluating the safety of cyromazine, melamine and their metabolites.

A confirmatory and quantitative method using liquid chromatography-tandem mass spectrometry (LC-MS/MS) to determine the presence of eight glucocorticoids (prednisone, prednisolone, hydrocortisone, methylprednisolone, dexamethasone, betamethasone, beclomethasone, and fludrocortisone) in the muscles and livers of swine, cattle, and sheep and the muscle of chicken is described. After deconjugation in alkali media, samples were extracted with ethyl acetate for glucocorticoids followed by solid-phase extraction clean-up and reconstitution in the LC mobile phase. The hydrolysis procedure with sodium hydroxide was used to reduce handling time. A single-step solid-phase extraction method was optimized which is suitable for the clean-up of the compounds of interest in many diverse tissue matrices. LC separations were performed on a C(18) column with gradient elution using acetonitrile and water (containing 0.2% formic acid) and the two epimers betamethasone and dexamethasone were successfully separated. LC-electrospray ionization (ESI)-MS/MS in negative mode with selected reaction monitoring (SRM) mode was performed to improve method sensitivity and reduce matrix interference. Two SRM transitions were used for each compound. The recovery of glucocorticoids spiked at levels of 0.5-16 microg kg(-1) ranged from 55% to 107%; the between-day relative standard deviations were no more than 15%. The limits of quantification were 0.5-2.0 microg kg(-1) in muscle and 1-4 microg kg(-1) in liver. The optimized procedure was successfully applied to monitor the food at the 2008 Summer Olympics Games in Beijing, China, demonstrating the method to be simple, fast, robust, and suitable for identification and quantification of glucocorticoids residues in foods of animal origin.

A simple and reliable LC-MS/MS method was established for simultaneous determination of 12 components from acetylkitasamycin and kitasamycin in swine plasma. The analytes were separated on a Shim-pack VP-ODS column with a 25 min gradient elution using 5 mmol/L ammonium acetate and acetonitrile as the mobile phase at a flow rate of 0.2 mL/min. Identification and quantification were accomplished by electrospray ionization) in positive mode using multiple reaction monitoring. The limits of quantitation of acetylkitasamycin A1 A3 , A13 and kitasamycin A3 , A13 were 3 μg/L, and that of the other eight components was 5 μg/L. The mean recoveries of kitasamycin and acetylkitasamycin ranged from 85.3 to 103.5%. The developed method was successfully applied to a pharmacokinetic study in swine after intravenous (i.v.) and oral (p.o.) administration of acetylkitasamycin. The result showed that the plasma concentrations of acetylkitsamycin components were much higher than that of kitasamycin in swine after i.v. and p.o., in which acetylkitsamycin A4 A5 was the highest component at each time point.

Furazolidone has been prohibited for use in food animal production worldwide for its carcinogenicity and mutagenicity, but it is still illegally used in some farms because of its effectiveness and cheap price. Because of the food safety and economical concerns, it is necessary to find an efficient and low-cost way to monitor the misuse of furazolidone in food-producing animals. For this regard, the tissue depletion and tissue-biological fluid concentration correlations of 3-amino-2-oxazolidinone (AOZ), which is the marker residue of furazolidone, were studied in pigs. Pigs were dosed with 400 mg/kg of furazolidone in feed for 7 days and were sacrificed at the withdrawal time of 0.5, 7, 21, 35, 56, and 63 days. Muscle, liver, kidney, urine, and plasma were collected to detect the AOZ by a simplified indirect competitive enzyme-linked immunosorbent assay (ic-ELISA). Results showed that AOZ was widely distributed in pigs and eliminated slowly after the digestion of furazolidone. The half-lives of AOZ in the plasma, urine, liver, kidney, and muscle were 13.7, 14.7, 13.6, 13.6, and 15.0 days, respectively. Good correlations of the AOZ concentration were found between plasma and muscle, plasma and liver, urine and liver, and urine and kidney in the depletion period of 7-63 or 21-63 days, with correlation coefficients of more than 0.97 and p values less than 0.05. These correlations can provide a basis for a simple and economical way using plasma/urine to monitor the illegal use of furazolidone in pigs without slaughter.

In this paper, an HPLC-QqQ-MS method for determination of 5 different ginsenosides of Panax japonica collected from different cultivated geographic regions was established. The separation was performed on a Zorbax XDB-C₁₈ (4.6 mm×100 mm, 1.8 μm) column with the gradient elution of acetonitrile (contained 0.1% formic acid)-0.1% formic acid water. The flow rate was 0.5 mL•min⁻¹. The colunm temperature was maintained at 30 ℃. The analytes were detected using electrospray ionization (ESI) in multiple reaction monitoring (MRM) modes. Reaction selected ions were 203.2 for ginsenoside Re, 202.9 for ginsenoside Rg₁, 365.0 for ginsenoside Rf, 789.1 for ginsenoside Rd, 360.9 for ginsenoside Ro. Ginsenosides Re, ginsenosides Rg₁, ginsenosides Rf, ginsenosides Rd, ginsenosides Ro had good linearity in the ranges of 3.33-66.60 μg (r=0.999 1),2.83-56.54 μg (r=0.999 2), 0.32-6.51 μg (r=0.999 2), 12.55-251.00 μg (r=0.999 3), 0.85-16.90 μg (r=0.999 5), respectively. The results of recovery were among 100.8% to 104.6%, and the values of RSD were blow 3.0%. This method is simple, reliable and accurate, and can provide basis for P. japonica basic research.

In order to effectively control the bacterial pneumonia in pigs, doxycycline hydrochloride (DoxHcl) and florfenicol (FF) microparticle suspension together with inclusion complexes was prepared by using hydroxypropyl-β-cyclodextrin (HP-β-CD) as host molecules, polyvinylpyrroliddone (PVP) as polymer carriers and hydroxypropyl methyl cellulose (HPMC) as suspending agents. In vitro antibacterial activity, properties, stability and pharmacokinetics of the suspension were studied. The results demonstrated that DoxHcl and FF had a synergistic or additive antibacterial activity against Streptococcus suis, Actinobacillus pleuropneumoniae and Haemophilus parasuis. The size, polydispersity index and zeta potential of microparticles were 1.46 ± 0.06 μm, 0.30 ± 0.02 and 1.53 ± 0.04 mV, respectively. The encapsulation efficiency (EE) of DoxHcl and FF was 45.28% ± 3.30% and 89.69% ± 2.71%, respectively. The re-dispersed time and sedimentation rate of the suspension were 1 min and 1. The suspension went through the 9-gage needle smoothly with withdrawal volume of 9.12 ± 0.87 mL/min. The suspension showed good stability when stored away from light, no irritation at the injection site and sustained release in PBS buffer. After intramuscular administration to pig, DoxHcl and FF could maintain over 0.15 μg/mL for 72 h. Compared to the control injection, the suspension increased the elimination half-life (T½ke) as well as mean residence time (MRT) of DoxHcl from 5.73 to 9.77 h and from 12.02 to 18.81 h, and those of FF from 12.02 to 26.19 h and from 12.02 to 28.16 h, respectively. The suspension increased the bioavailability of DoxHcl and FF by 1.74 and 1.13-fold, respectively. These results suggest that the compound suspension is a promising formulation for pig pneumonia therapy.

A rapid multi-residue screening method that includes 128 veterinary anti-parasitic drugs and metabolites in meat of chicken, porcine and bovine has been developed. The scope of the method focuses on screening the following main families of veterinary anti-parasitic drugs: avermectines, benzimidazoles, the polyether ionophore, anti-tapeworm, anti-trematode, anti-piroplasmosis and chemical classes of coccodiostats. The method described a QuEChERS sample preparation procedure prior to LC-MS/MS analysis. The modified QuEChERS technology minimises sample complexity and ion suppression effects. The method was validated according to European Union guidelines (2002/657/EC) for a quantitative screening method. The validation results demonstrate that the described LC-MS/MS method provides sensitive, repeatable and meets residue screening monitoring requirements.

Fluoroquinolones (FQNs) are broad-spectrum antibacterial agents widely used in animal husbandry and aquaculture. The residues and antimicrobial resistance of such antibiotics are a major public health concern. To realize multianalyte detection of FQN residues, a genetically modified bacterium, Escherichia coli pK12 harboring plasmid pRecAlux3, was constructed in this study to develop a bioluminescent-bacteria-based assay for the detection of FQNs in animal-derived foods. This assay was based on the principle of induction of an SOS response by FQNs via inducing the recA-promoter-fused luciferase reporter gene existing on the plasmid pRecAlux3. E. coli pK12 was able to recognize 11 FQNs: difloxacin, enrofloxacin, ciprofloxacin, sarafloxacin, norfloxacin, danofloxacin, ofloxacin, pefloxacin, lomefloxacin, marbofloxacin, and orbifloxacin. This method could be applied to 11 edible tissues, including milk, fish muscle, and the muscles, livers, and kidneys of cattle, chickens, and pigs, with a very simple and rapid sample extraction procedure using only phosphate-buffered saline. The limits of detection of the FQNs were between 12.5 and 100 μg kg(-1), all of which were lower than the maximum residue limits. Most of the recoveries of the FQNs were in the range from 60 to 120 %, and the interassay coefficients of variation were less than 30 %. This method, confirmed by high-performance liquid chromatography, is reliable and can be used as both a screening test and a semiquantitative assay, when the identity of a single type of FQN is known.