The Challenge of Standard Stability in LC-MS Based Multi-Analyte Approaches for Veterinary Drugs

The short-and long-term stability of multi-component mixtures and intermediate mixtures of analytical standards of veterinary drugs,which can potentially occur in food and feed chains,was examined by an isochronous measurement approach.Short-term stability testing of calibrants included storage for 1,2,4,and 7 days at-20℃(as a baseline)4℃,and 23℃(with and without exposure to sunlight),respectively.Long-term stability testing conditions of intermediate mixes were-20℃,4℃,23℃(with and without exposure to sunlight),and control temperature at-80℃while the testing period was 2,4,8,and 12 weeks,respectively.Results indicated that calibration standards should ideally be stored at 4℃for only 1~2 days,without the presence of acid.Neutral storage conditions were acceptable even at room temperature.Storage of intermediate mixtures containingß-lactams and cephalosporins for longer than 1 month under 4℃ and room temperature resulted in a loss of almost 90%.When it comes to the intermediate mixtures with penicillin V and G,acceptable storage conditions were 2 weeks at-20℃,without the presence of acid.Other classes of veterinary drugs were less critical as considers long-term stability.Overall,storage conditions at-20℃were considered optimal for long-term storage of intermediate mixes of veterinary drug standards.

Study on Anti-diarrhea Effect of the Prescription of 4 Tibetan Veterinary Drugs

This study was conducted to investigate the effects of extracts of 4 Tibetan veterinary drugs on bacterial diarrhea, and to guide the clinical treatment of the disease. The inhibitory effects of the extracts of the 4 Tibetan veterinary drugs, Veronica ciliate Fisch, Usnea diffracta Vain, Sophoraflavescens var. flavescens, Lamiophlomis rotata （ Benth. ） Kudo on 14 common diarrheagenic bacteria were detected by K-B diffusion method and micro-broth dilution method. Optimization was performed on prescriptions of the 4 Tibetan veterinary drugs using orthogonal design software, and a mouse bacterial diarrhea model was established with a clinical isolate, Salmonella blegdam. According to the LD50 value of the optimal prescription of the 4 Tibetan veterinary drugs, the established mouse bacterial diarrhea model was treated in 3 dose groups, i. e. , the high, middle and low dose groups （0. 060, 0. 030 and 0. 020 g/ml, respectively）. The results showed that the 4 Tibetan veterinary drugs had very good inhibitory effects on most of the tested diarrheagenic bacteria, and among them, U. diffracta had better inhibitory effects on all the tested bacteria. The optimal prescription of the d Tibetan veterinary drugs （high dose, 0.06 g/ml） exhibited very good inhibitory effect on mouse diarrhea, indicating that the prescription has very good anti-diarrhea effect, which is beneficial to the clinical treatment of such disease and the development of Tibetan veterinary drugs.

Fluorescence Nanobiosensor for Simultaneous Detection of Multiple Veterinary Drugs in Chicken Samples

Some veterinary drug residues in food products and environment have been widely regarded as severe threats to human health.Rapid and simultaneous detection methods are crucial to monitor and control veterinary drug usage.Here,we propose a fluorescence biosensor utilizing immunomagnetic beads(IMBs)and quantum dots(QDs)for the rapid and simultaneous detection of 1-adamantylamine(ADA),enrofloxacin(ENR)and tilmicosin(TIL)in raw chicken meat.A pretreatment method using sodium phosphotungstate–magnesium as extraction reagent was developed to simultaneously extract ADA,ENR and TIL from chicken meat with minor interference in background or response.By adding the IMBs modified with three types of antibodies and the QD-antigens modified with three types of BSA-antigens to sample,IMBs competitively conjugated to target antigens in a sample or QD-antigens.After magnetic separation,the residual QD-antigens were adopted to collect signals using fluorescence spectroscopy.Using QDs with well separated emission peaks,the detection of one type of targets was minorly interfered by the others.Under the optimum conditions,the biosensor exhibited the limit of detection of 0.96,3.32,and 3.17 ng/mL for ADA,ENR and TIL in chicken samples,respectively,as well as good specificity.Due to the way of direct collection of signals in extracts,the tedious and complicated multiple magnetic separation and signal amplification procedures in conventional methods were avoided,thus the procedures were significantly simplified,and the reduction of the operation time of 30 min for sample pretreatment and 40 min for detection part was achieved.The biosensor might be promising in the rapid,in-field and sensitive screening of multiple veterinary drugs to ensure agriculture and food safety.

Determination of Veterinary Drug Residues in Animal-derived Foods by Liquid Chromatography-Mass Spectrometry

[Objectives]This study was conducted to establish a rapid and effective method for simultaneous extraction of 54 kinds of veterinary drug residues in animal-derived food, including sulfonamides, quinolones, tetracyclines, malachite greens, penicillins, nitroimidazoles, tranquilizers and macrolides, by HPLC-MS. [Methods] The samples were extracted with 80% acetonitrile water(containing 0.1% formic acid), combined with QuEChERS extraction technology and C18 and PSA purification, analyzed by high performance liquid chromatography-mass spectrometry, and quantified by external standard method. The target substances were analyzed on ZORBAX Eclipse C18 chromatographic column using 0.2% formic acid water and 0.2% methanol as mobile phases. The gradient elution mode was used for chromatographic separation and multiple reaction detection. [Results] In the linear range of 0.5-50.0 ng/ml, the linear relationship of the 54 kinds of veterinary drug residues was good, with correlation coefficients(r~2) greater than 0.995, and the detection limits ranged from 0.30 to 1.00 μg/kg. The results showed that the recovery ranged from 75.4% to 118.2% when different matrixes were added for recovery. [Conclusions] This method is simple, efficient, accurate, stable, and highly operable. It is applicable to simultaneous batch screening of veterinary drug residues in animal-derived food, and has high practical application value.

Research Progress of Transdermal Patches in Veterinary Drug Preparations

With the development of pharmaceutics and other disciplines theories and advanced technologies, the application of many new drug delivery systems has gradually increased in clinical veterinary. Among the many drug delivery systems, transdermal patch can maintain stable and effective plasma concentration and therapeutic effect in vivo for a long time after skin dressing delivery, which provides a safe and effective drug-delivery way for the therapy and prevention of some chronic diseases and partial analgesia in a simple and convenient way. Veterinary drug transdermal preparations have been developed both at home and abroad, and satisfactory results have been achieved in the experimental application. Based on the study of veterinary transdermal patches at home and abroad, this paper systematically describes the development and characteristics of transdermal patches, the factors affecting skin permeation and the evaluation this type of preparations in veterinary drugs.

Advance in Effect of Veterinary Drug Residues on Ecological Environment

Thousands of tons of pharmaceutically active substances are used in veterinary medicines in intensive livestock and poultry production, but most of the drugs are poorly absorbed by animals and excreted with the animal feces. The veterinary medicines can cause various kinds of harmful impact to the environment. Now the relevant research has been a hot all over the world. With the feces excreted to the environment, the veterinary medicines can be accumulated in the soil and water, and produce all sorts of reaction. Some medicines can cause toxic effect to animals, plants and microorganisms. The article summarized the residue, the environmental impact, the transformation and the development direction of the veterinary medicine in the environment to supply frame of reference for further research.

UPLC-QTOF/MS Method for Screening and Determination of 59 Non-labeled Components in Veterinary Drug Preparations

[Objectives]This study was conducted to provide an accurate and reliable method for rapid high-throughput screening of veterinary drug preparations.[Methods]For the matrixes of veterinary drug preparations,high-performance liquid chromatography-high resolution quadrupole time-of-flight mass spectrometry(UPLC-QTOF/MS)was used to establish a fast screening method for 59 non-standard components in five categories of antiviral agents,aminoglycosides,quinolones,sulfonamides,and tetracyclines in veterinary drugs.The target drugs were separated by a Waters ACQUITY UPLC HSS T3 chromatographic column(50 mm×2.1 mm,1.8μm),and data were collected in the positive ion mode.Good separation of the 59 drugs was achieved within 7 min.[Results]In the concentration range of 0-100 ng/ml,each drug showed a good linear relationship,and the correlation coefficients were all greater than 0.999.The detection limits of the 59 drugs were in the range of 0.1-0.5 mg/ml,and the recovery under the addition concentration of 5 mg/ml was in the range of 85.2%-103.8%.[Conclusions]The method is fast,simple,accurate,and highly sensitive,and is suitable for high-throughput screening and qualitative identification of non-standard components in veterinary drug preparations.

Application of Liquid Chromatography-Tandem Mass Spectrometry in Determination of Veterinary Drug Residues

With the long -term and irrational use of veterinary drugs and drug additives in the process of animal feeding, the veterinary drug resi- dues in animals and their additives can be ingested into the human body and pose potential threat to human health. Detection of veterinary drug resi- dues are extremely important practical significance to protect the ecological environment and human health. In recent years, liquid chromatography -tandem mass spectrometry has been widely used in vetednary drug residue detection because of its applicability, qualitative and quantitative fea- tures as well as high sensitivity. This article summarized the application of liquid chromatography -tandem mass spectrometry in detection veterinary drug residues from feed, animal products, arid udne as well as illicit drugs and harmful additives.

电子束辐照下兽药残留的降解

Clenbuterol and some kinds of antibiotic are banned strictly using as veterinary drug by Europe Union,America and Chinese Agriculture Ministry.Electronic irradiation can change difficultly degraded pollutants into easily degraded pollutants.Clenbuterol,SC and AOZ can be degraded more than 95% when the irradiation dosage was greater than 6kGy.These results indicated such irradiation method is applicable.

Rapid testing methods for food contaminants and toxicants

Food safety is one of the major concerns in every country regardless of the economic and social development. The frequent occurrence of food scandals in the world has led the Chinese government to implement several strategies to fortify the food supply system to a high food safety standard. This relies heavily on laboratory testing services but conventional methods for detection of food contaminants and toxicants are limited by sophisticated sample preparation procedures, long analysis time, large instruments and professional personnel to meet the increasing demands. In this review, we have incorporated most of the current and potential rapid detection methods for many notorious food contaminants and toxicants including microbial agents, toxic ions, pesticides, veterinary drugs and preservatives, as well as detection of genetically modified food genes and adulterated edible oil. Development of rapid, accurate, easy-to-use and affordable testing methods could urge food handlers and the public to actively screen for food contaminants and toxicants instead of passively relying on monitoring by the government examination facility. This review also provides several recommendations including how to encourage the public to engage in the food safety management system and provide optimal education and financial assistance that may improve the current Chinese food safety control system.

Application of Liquid Chromatography-High Resolution Time-of-flight Mass Spectrometry in the Detection of Raw Milk and Dairy Products

Milk and dairy products are more and more popular with consumers due to their various nutrients, and their quality and safety issues have always been concerned. Therefore, the development of rapid, accurate and simple screening techniques is of great significance. Liquid chromatography-high resolution time-of-flight mass spectrometry has high-resolution and high-throughput detection functions, and has gradually begun to be applied in the detection of milk and dairy products. This paper summarized the application of milk and dairy products in liquid chromatography-high resolution time-of-flight mass spectrometry, laying a foundation for the development of new methods.

Photoelectrochemical Immunosensor Array Based on Thioglycolic Acid Capped CdS Quantum Dots for Multiplexed Detection of Veterinary Drug Residues

A photoelectrochemical immunosensor based on multi-electrode array was developed for simultaneous and sen- sitive determination of veterinary drug residues. In this system, poly（dimethyldiallylammonium chloride） （PDDA）, Au nanoparticles （Au NPs） and thioglycolic acid （TGA）-capped CdS quantum dots （QDs） were layer-by-layer as- sembled onto the home-made Au electrode array. The assembling process of the （CdS/PDDA/Au NPs/PDDA）, mul- tilayer was characterized by electrochemical impedance spectroscopy. And then the antibodies for clenbuterol （CB）, ractopamine （RAC） and chloramphenicol （CAP） were covalently immobilized onto the Au electrode array by 1-ethyl-3-（3-dimethylaminopropyl） carbodiimide （EDC） coupling reaction, respectively. The concentrations of CB, RAC and CAP were measured based on the photoelectrochemical effects of CdS QDs. Under the optimal conditions the limits of detection （LOD） for CB, RAC and CAP were 25, 50 and 2.2 pg/mL （3a）, respectively, with acceptable recovery over the range of 95.40%--105.5% in pig liver samples. All results indicate that the immunosensor array system has potential application for practical, effective and high throughput analysis of veterinary drugs residues.

Detection and recognition of veterinary drug residues in beef using hyperspectral discrete wavelet transform and deep learning

A fast,non-destructive recognition method for veterinary drug residues in beef was proposed to mitigate the laborious sample preparation and long detection times associated with conventional chemical detection techniques.Control beef samples free of veterinary drug residues and four groups of beef sprayed with relevant concentrations of metronidazole,ofloxacin,salbutamol,and dexamethasone under ambient conditions were analyzed by 400-1000 nm hyperspectral imaging followed by multiplicative scatter correction preprocessing.Data dimension reduction was performed using Competitive Adaptive Reweighted Sampling(CARS),Principal Component Analysis(PCA),and Discrete Wavelet Transform(DWT)based on Haar,db3,bior1.5,sym5,and rbio1.3 wavelet basis functions.Treated data were subjected to Convolutional Neural Network(CNN),Multilayer Perceptron(MLP),Random Forest(RF),and Support Vector Machine(SVM)modelling.CNN,MLP,SVM,and RF algorithms achieved overall accuracies of 91.6%,88.6%,87.6%,and 86.2%,respectively,when combined with DWT(wavelet basis functions and numbers of transform layers being Haar-4,db3-2,bior1.5-4,and sym5-3,respectively).The algorithm Kappa coefficients(0.89,0.86,0.85,and 0.83,respectively)and time consumption for prediction(140.60 ms,57.85 ms,70.67 ms,and 87.16 ms,respectively)were also superior to models based on CARS and PCA.DWT combined with deep learning can shorten prediction times,considerably improve the accuracy of classification and recognition,and alleviate the Hughes phenomenon,thus providing a new method for the fast,non-destructive detection and recognition of veterinary drug residues in beef.

Dairy manure as a potential source of crop nutrients and environmental contaminants

Although animal manure is applied to agricultural fields for its nutrient value,it may also contain potential contaminants.To determine the variability in such contaminants as well as in valuable nutrients,nine uncomposted manure samples from Idaho dairies collected during 2.5 years were analyzed for macro-and micro-nutrients,hormones,phytoestrogens,antibiotics,veterinary drugs,antibiotic resistance genes,and genetic elements involved in the spread of antibiotic resistance.Total N ranged from 6.8 to 30.7(C:N of 10 to 21),P from 2.4 to 9.0,and K from 10.2 to 47.7 g/kg manure.Zn(103-348 mg/kg)was more abundant than Cu(56-127 mg/kg)in all samples.Phytoestrogens were the most prevalent contaminants detected,with concentrations fluctuating over time,reflecting animal diets.This is the first study to document the presence of flunixin,a non-steroidal anti-inflammatory drug,in solid stacked manure from regular dairy operations.Monensin was the most frequently detected antibiotic.Progesterones and sulfonamides were regularly detected.We also investigated the relative abundance of several types of plasmids involved in the spread of antibiotic resistance in clinical settings.Plasmids belonging to the Inc I,Inc P,and Inc Q1 incompatibility groups were found in almost all manure samples.Inc Q1 plasmids,class 1 integrons,and sulfonamide resistance genes were the most widespread and abundant genetic element surveyed,emphasizing their potential role in the spread of antibiotic resistance.The benefits associated with amending agricultural soils with dairy manure must be carefully weighed against the potential negative consequences of any manure contaminants.

Total Synthesis and High Performance Liquid Chromatography Analysis of Phenylethanolamine A

A simple, effective and reliable synthetic method was developed to construct beta-agonist phenylethano- lamine A（PEAA） in good yield with 4-nitrobenzyl bromide as the starting material, which underwent SN2 reaction with ethyl acetoacetate, followed by hydrolysis with concentrated HC1 and amination by Lettkart reaction to furnish 4-（4-nitrophenyl）butan-2-amine（A）. A one-pot reaction was studied to construct PEAA skeleton and reduced carbonyl with KBH4, the conditions were optimized, including reaction temperature, reaction time, solvent and the molar ratio of 2-bromo-l-（4-methoxyphenyl）ethanone（B） to A. Meanwhile, a reliable and practical high performance liquid chromography（HPLC） method with UV detector was developed after screening wavelength, chromatographic column and optimization of mobile phase. The optimal conditions of detecting PEAA were water（0.1% formic acid and 0.1% triethylamine）-methanol（volume ratio 44：56） at 278 nm with plus-C^8 column. The above synthetic method would be used to synthesize standard reference materials and advance extensive application of analytical method. In order to ensure food safety and safeguard human health, the analytical method might be used as a standard method in detection and supervision of PEAA.