Rapid Screening of 82 Pesticide Residues in Feed by Liquid Chromatography Coupled with Quadrupole-Time of Flight Mass Spectrometry

[Objectives]This study was conducted to establish a qualitative method for rapid detection of pesticide residues in feed.[Methods]A rapid screening method for 82 pesticide residues in feed was established using ultra liquid chromatography coupled with quadrupole-time of flight mass spectrometry(UPLC-Q-TOF-MS)combined with optimized pretreatment methods.[Results]Feed samples were extracted with 0.2%formic acid-acetonitrile solution,shaken,centrifuged,and re-centrifuged,and the supernatant was filtered with a 0.22μm filter membrane for determination.The samples were separated on a Waters ACQUITY UPLC HSS T3 chromatographic column(2.1 mm×50 mm,1.8μm),and subjected to gradient elution with methanol-water solution as the mobile phase,and scanning was performed in ESI+mode.82 compounds could be accurately qualitatively detected in 13 min.[Conclusions]This method is simple to operate,time-saving,and can be applied to rapid screening of large-scale feed.This study provides a theoretical basis for the development of new methods in the future.

Rapid Screening of 26 Organophosphorus Pesticides in Fresh Milk by Ultra Liquid Chromatography Coupled With Quadrupole-Time of Flight Mass Spectrometry

[Objectives]A rapid screening and analysis method for 26 organophosphorus agrochemicals in fresh milk was established using ultra performance liquid chromatography coupled with quadrupole-time of flight mass spectrometry.[Methods]Raw milk was extracted with acetonitrile solution containing 0.2%formic acid by volume,and purified with a Dikma ProElut QuECHERS solid phase extraction cartridge.Target compounds were separated on a Waters ACQUITY UPLC HSS T3 chromatographic column(2.1 mm×50 mm,1.8μm)with methanol-water solution as a mobile phase for gradient elution,and through scanning with an electrospray ion source in positive ion mode,26 kinds of organophosphorus agrochemicals could be accurately qualitatively determined within 10 min.[Results]When using formic acid acetonitrile with a volume fraction of 0.2%,there were more types of detected compounds and a greater recovery;and using B cartridge could effectively eliminate the interference of non-polar substances such as phospholipids,achieve higher number of detected compounds than those of A and C,and well separate the 26 kinds of agrochemical residues.[Conclusions]This study provides a reference method for the rapid screening of agrochemical residues in dairy cows in the future.

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.

Preliminary Study on Biological Control of Mycotoxin Contamination in Agricultural Products and Its Mechanism

Aflatoxin is the most powerful carcinogen and highly toxic mycotoxin known in nature. It can cause serious toxin pollution to agricultural products, foods and fodders, and is extremely harmful to human and animal health. For aflatoxin pollution, the emphasis is on the control of source, and biological control is favored by scientists because of its advantages of environmental protection and ecological safety. According to the morphology, color and appearance of microbial colonies isolated from maize kernels, 300 bacterial strains were obtained from main maize-producing areas including Tangshan City, Handan City, Shijiazhuang City and Cangzhou City. Two biocontrol bacterial strains(B120 and B65) having a strong control effect on aflatoxins were screened. After identification by molecular biology and physical and chemical properties, the two biocontrol bacterial strains were identified as Bacillus amyloliquefaciens. Their effects on spore germination, mycelial growth and toxin degradation of Aspergillus flavus were investigated. The results showed that strains B120 and B65 could significantly inhibit the spore germination and mycelial growth of A. flavus and reduce aflatoxin production. This study provides a new way to prevent and control the pollution control of aflatoxins in agricultural products.

Correlation of Aflatoxin Contamination in Peanuts with Rhizosphere Microorganisms and Its Comprehensive Control

Aflatoxin contamination is an important hazard factor affecting the quality safety and food safety of peanut production, which seriously threatens people's health and safety. In this paper, the background and harmful causes of aflatoxin contamination were analyzed in detail, with attention focusing on its control measures, which has certain guiding significance for the comprehensive control of aflatoxin contamination.

The Development of Time-of-flight Mass Spectrometry( TOF-MS) and Its Applications in Screening Food Hazard Factors

The time-of-flight mass spectrometry(TOF-MS),one of the mass spectrometry techniques,has been widely applied in the field of rapid screening of food hazard factors as a superior analysis technique because of its wide mass range,high resolution and mass measurement accuracy,high sensitivity and high analysis speed.In this paper,research progresses of TOF-MS on the detection of food additives,food contaminants and residues,illegal additives,pesticide residues,veterinary drug residues and mycotoxin were reviewed,and its probable approaching applications were prospected.

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.

Dietary host-associated Bacillus subtilis supplementation improves intestinal microbiota,health and disease resistance in Chinese perch(Siniperca chuatsi)

The purpose of this study was to evaluate the potential of a host-associated Bacillus subtilis 1-C-7 as a probiotic for Chinese perch(Siniperca chuatsi).Four test diets were formulated to contain graded levels of B.subtilis 1-C-7 at 0(CY),0.85×10^(8)(Y1),0.95×10^(9)(Y2)and 0.91×10^(10)(Y3)CFU/kg diet.The test fish with initial weight 30.0±1.2 g were fed the 4 test diets with 3 replicates in an indoor water-flow aquaculture system with 12 net cages(40 fish/cage)for 10 wk.At the conclusion of the feeding trial,the probiotic effects of B.subtilis on Chinese perch were analyzed based on growth performance,serum biochemical indices,histologic morphology of liver and gut,gut microbiota and the resistance to Aero-monas hydrophila.The results showed that the percentage of weight gain had no significant change in the Y1 and Y2 groups(P>0.05)but decreased in the Y3 group compared to that in the CY group(P<0.05).The fish in the Y3 group displayed the highest activity of serum alanine aminotransferase(ALT)and aspartate aminotransferase(AST)among these 4 groups(P<0.05).The fish in the CY group had the highest value of malondialdehyde in the liver(P<0.05)and showed severe nuclear migration and vacuolization of hepatocytes.The morphology indicated that all test fish had poor intestinal health.However,the fish in the Y1 group had a relatively normal intestinal histologic structure.The mid gut microbial diversity analysis showed that dietary B.subtilis supplementation increased the abundance of probiotics such as Tenericutes and Bacteroides,whereas it reduced the abundance of pernicious bacteria such as Proteobacteria,Actinobacteria,Thermophilia and Spirochaetes.The challenge test showed that dietary B.subtilis supplementation increased the resistance to A.hydrophila in Chinese perch.In conclusion,dietary supplementation of 0.85×10^(8)CFU/kg B.subtilis 1-C-7 could improve the intestinal microbiota,intestinal health and disease resistance in Chinese perch,but more or excessive supple-mentation could reduce growth performance and have negative effects on health.

The probiotic effects of host-associated Bacillus velezensis in diets for hybrid yellow catfish(Pelteobagrus fulvidraco♀×Pelteobagrus vachelli♂)

This study was to evaluate the potential of a host-associated Bacillus velezensis as a probiotic for hybrid yellow catfish(Pelteobagrus fulvidraco♀×Pelteobagrus vachelli♂).Diets(B0 to B5)containing 0,0.90×10^(8),0.80×109,0.85×10^(10),0.90×10^(11),0.83×10^(12)CFU/kg B.velezensis YFI-E109 were fed to the fish with initial weight(3.07±0.08 g)in a recirculating aquaculture system for six weeks with three replicates,respectively.Probiotic effects were analyzed based on growth,body composition,liver and gut morphology,gut microbiome,and liver metabolome.Analysis of the bacterial genome has shown that the most abundant genes in B.velezensis YFI-E109 were distributed in carbohydrate and amino acid metabolism.Fish in groups B3 and B4 had better growth performance,and higher intestinal amylase(AMS)and lipase(LPS)activities compared with other groups(P<0.05).Fish in groups B0 and B5 showed significant liver damage,while this status improved in group B3.The liver malondialdehyde(MDA)content in group B3 was lower than that in other groups(P<0.05).The abundance of Mycoplasma,Ralstonia and Acinetobacter was significantly reduced in B3 and B5 compared to B0.The amino acid and carbohydrate metabolism pathways were enriched in group B3 compared with group B0.In conclusion,dietary B.velezensis YFI-E109 supplementation has the potential to improve growth,liver metabolism,and liver and gut health,and reshape the gut microbiome of hybrid yellow catfish.Excessive B.velezensis YFI-E109 reduced the prebiotic effects.The recommended dietary supplementation of B.velezensis YFI-E109 is 0.31×10^(10) to 0.77×10^(11)CFU/kg for hybrid yellow catfish according to the quadratic regression method by plotting specific growth rate(SGR),feed conversion ratio(FCR),MDA and activities of AMS against dietary B.velezensis YFI-E109 levels.