Detection of Atrazine Residue in Food Samples by a Monoclonal Antibody-based Enzyme-linked Immunosorbent Assay

Atrazine（AT,2-chloro-4-ethylamino-6-isopropyl-amino-s-triazine）has been detected in ground water in several areas of the United States for many years,as well as in China,wherein the growth rate of its gross

Application of differential pulse stripping voltammetry and chemometrics for the determination of three antibiotic drugs in food samples

A reliable method for simultaneous determination of three antibiotic drugs（levofloxacin,gatifloxacin and lomefloxacin） by differential pulse stripping voltammetry（DPSV） in Britton-Robinson buffer（pH 7.96） was presented.The method is based on adsorptive accumulation of the antibacterial drugs on a hanging mercury dropping electrode（HMDE）,followed by the reduction of the adsorptive species by the technique of DPSV.Optimal conditions,the deposition time of 80 s,the deposition potential of—1250 mV,and the scan rate of 25 mV/s,were obtained.The linear concentration ranges of 0.010-0.080μg/mL were obtained for all these three antibiotic drugs,while the detection limits were 2.38,3.20 and 1.60ng/mL for levofloxacin,gatifloxacin and lomefloxacin,respectively.In this work,chemometrics methods,such as classical least squares（CLS）,partial least squares（PLS）, principle component regression（PCR） and radial basis function-artificial neural networks（RBF-ANN）,were used to quantitatively resolve the overlapping signals.It was found that PCR gave the best results with total relative prediction error（RPE_T） of 7.71%.The proposed method was applied to determine these three drugs in several commercial food samples with spiked method and yielded satisfactory recoveries.

Sampling Methods and Countermeasures for Food Enterprises

In this paper,by combining sampling methods for food statistics with years of sample sampling experience,various sampling points and corresponding sampling methods are summarized.It hopes to discover food safety risks and improve the level of food safety.

Electrochemical Reduction Determination of N-Nitrosodiphenylamine in Food Based on Graphene Electrode Material

As a group of the most notorious carcinogens,N-nitrosamines(NAs)are highly toxic and usually involved in healthy issue of human daily life.An electrochemical sensor for N-nitrosodiphenylamine(NDPhA)detection was constructed based on graphene electrode material.The graphene was facilely obtained by direct reduction of graphene oxide(GO)with hydrazine hydrate,and further coated on the surface of the glassy carbon electrode(GCE)to fabricate the electrochemical sensor for NDPhA analysis in food samples.The present sensor showed excellent sensitivity and selectivity for the electrochemical determination of NDPhA under a reduction manner with the detection limit of 0.6μmol/L.It was also successfully used in beer and ham food samples with satisfactory recovery results.

Coagulase gene polymorphism of Staphylococcus aureus isolates: A study on dairy food products and other foods in Tehran, Iran

Coagulase is considered as a major determinant factor for the identification of Staphylococcus aureus strains.The 3-end coding region of the coagulase(coa)gene contains a series of 81-bp tandem repeats,which differ in the number and location of enzymatic restriction sites among different isolates.coa PCR-RFLP has been used widely to type S.aureus isolates in epidemiological studies.The current study was conducted to investigate the coagulase gene polymorphisms in S.aureus isolated from various food samples using an in house PCR-RFLP method.A total of 100 strains of S.aureus were isolated from food samples.Isolates were typed by PCR-RFLP analysis using NdeI restriction digestion of the coagulase gene PCR products.Results showed that amplification of coagulase genes from S.aureus produced different PCR products.The isolates were grouped into 18 genotypes using RFLP analysis results of the genes.In this study,the S.aureus isolates have been shown to include more than one coagulase genotype,but only had a few coa genotypes predominated.

Determination of icariside,hyperoside and psoralen in food by liquid chromatography-tandem mass spectrometry

A high performance liquid chromatography-tandem mass spectrometry(HPLC-MS/MS)method was built to determine icarside,hyperoside and psoralen in food.The samples were extracted with 70%methanol,the solid and semi-solid hotpot seasoning samples were purified by solid phase extraction column,and then determined by HPLC-MS/MS.Acetonitrile and 0.1%formic acid solution were used as the mobile phase,and the gradient elution was adopted for analysis.As shown in the results,the analytes had good linearity in the range of 0.05−100 ng/mL,and the correlation coeffificients(R^(2))were greater than 0.999.In this method,the limits of quantitation(LOQ)of psoralen,icariside and hyperoside in liquid samples were 1.25,25.0 and 12.5μg/L respectively;while the LOQs of psoralen,icariside and hyperoside in solid samples and hotpot seasoning samples were 1.25,25.0 and 12.5μg/kg,respectively.The liquid beverage,solid beverage,health food(in the form of oral liquid,capsule,tablet),integrated alcoholic beverage and solid hotpot seasoning were selected as representative samples and used for method validation.The average spiked recoveries at 3 levels(LOQ,2 LOQ,10 LOQ)were in the range of 83.7%−115.0%,and the relative standard deviations were in range of 0.5%−9.4%(n=6).The method is rapid,accurate and sensitive,which is suitable for the simultaneous determination of icariside,hyperoside and psoralen in different food matrices.

Development of Rapid,Sensitive,and Effective Plasmonic Nanosensor for the Detection of Vitamins in Infact Formula and Milk Samples

The aim of the present study is to develop a surface plasmon resonance sensor for the detection of vitamin B2,vitamin B9,and vitamin B12 in food samples by using the molecular imprinting technique.The vitamin B2,vitamin B9,and vitamin B12 imprinted and the non-imprinted surface plasmon resonance sensor chip surfaces were characterized by using contact angle measurements,atomic force microscopy,ellipsometry,and Fourier transform infrared-attenuated total reflectance.The real-time detection of vitamin B2,vitamin B9,and vitamin B12 was analyzed by using aqueous solutions in the concentration range of 0.01 ng/mL−10 ng/mL for vitamin B2,0.1 ng/mL−8.0 ng/mL for vitamin B9,and 0.01 ng/mL−1.5 ng/mL for vitamin B12.The limit of detection values was calculated as 1.6×10^(−4) ng/mL for vitamin B2,13.5×10^(−4) ng/mL for vitamin B9,and 2.5×10^(−4) ng/mL for vitamin B12,respectively.Selectivity experiments were performed by using vitamin B1 and vitamin B6.The reproducibility of surface plasmon resonance sensors was investigated both on the same day and on different days for four times.Validation studies of the prepared surface plasmon resonance(SPR)sensors were performed by liquid chromatography-tandem mass spectrometry(LC-MS/MS).

A new aggregation-induced emission-based fluorescent probe for effective detection of Hg^(2+)and its multiple applications

Detection of mercury ions(Hg^(2+))in actual samples is of significant importance due to the toxicity of Hg^(2+)to human health.In this work,a simple tetraphenylethene(TPE)derived fluorescent probe TPE-Hg based on aggregation-induced emission(AIE)mechanism was synthesized.TPE-Hg can visually recognize Hg^(2+)in THF/HEPES(1:9,v/v,HEPES 20 mmol/L,pH 7.3)system with rapid response,strong anti-interference ability,large Stokes shift(203 nm),and low detection limit(7.548×10^(-7)mol/L).The results show that Hg^(2+)triggered elimination of TPE-Hg lead to releasing of an AIE-active compound 2 is responsible to the sensing mechanism.TPE-Hg is applicable to detect Hg^(2+)in actual water samples and image Hg^(2+)in living MCF-7 cells.In addition,TPE-Hg is suitable to assay the Hg^(2+)level in seafood and tea samples,and it is alsoapplicable intest strips.

Synthesis and characteristics of a novel artificial hapten using the copper mercaptide of penicillenic acid from penicillin G for immunoassay of heavy metal ions

In this paper, we describe the synthesis of a novel copper ion hapten using the copper mercaptide of penicillenic acid （CMPA） derived from penicillin. Results from tests with immune rabbits indicate that： （i） A new antigen synthesized with CMPA has good stability and is safe for immunizing animals with no toxic phenomena being found in animal experiments; （ii） the immunogenic antigen （CMPA-BSA） can stimulate the immune system to produce specific antibodies with high titrations, up to 150000; and （iii） antibodies in antisera showed higher affinity to OVA-GSH-CuC1 than OVA-GSH, which indicates that the antibodies have specific affinity towards copper ions. These results confirm that the novel hapten and relevant antigen for copper ion have been successfully synthesized, giving progress towards an immunoassay for copper ions in environmental and food samples.