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United States Department of Agriculture

Agricultural Research Service

Research Project: Technologies for the Detection of Chemical and Biological Contaminants in Foods

Location: Residue Chemistry and Predictive Microbiology

2012 Annual Report


1a.Objectives (from AD-416):
1. Develop methods to increase sample throughput in order to improve monitoring of chemical contaminants in foods. Specifically: investigate faster screening and/or analytical approaches, and faster data processing without loss of reliability. 1A. Develop and evaluate new, useful analytical multiresidue methods that are faster than existing methods without sacrificing quality of results. 1B. Investigate practical means of processing analytical results in multiresidue analysis that lead to reliable, objective decisions with minimal human review. 1C. Develop and evaluate improved analytical screening methods in the analysis of chemicals of interest in foods. 1D. Study and implement robotic sample preparation systems to increase speed and reduce manual labor for routine analysis of chemical residues in foods. 2. Conduct research to evaluate the validity of new approaches for regulatory monitoring of veterinary drug residues in foods and feeds. Specifically: an assessment of sampling procedures and addressing matrix effects in quantification. 2A. Lead and conduct an AOAC International Collaborative Study to update and harmonize the QuEChERS method for analysis of chemical residues in a wide variety of foods. 2B. Investigate sampling and sample processing of appropriate matrices, taking matrix effects into account, for veterinary drug residue analysis to yield meaningful results in a fast and practical procedure. 2C. Lead and conduct an interlaboratory validation study to quantitatively and qualitatively assess our multiclass, multiresidue method for veterinary drugs in food tissue matrices. 3. Develop biosensor methods with multi-analyte capability for biological toxins of concern. 4. Modify/refine novel method for routine measurement of total phenolics, phytoestrogens and/or estrogenic endocrine disruptors. 4A. Expand application of our total phenolics method to other food and dietary products; and identify the reaction products of the key reagent with select phenolic compounds. 4B. Modify the method to screen for estrogenic compounds, including bisphenol A. 5. Develop novel analytical methods for inorganic and organometallic heavy metals (for example forms of mercury (Hg) and arsenic (As)) in foods and supplements. 5A. Develop modern analytical methods for mercury speciation and quantification in foods and supplements. 5B. Develop modern analytical methods for arsenic speciation and quantification in foods and supplements.


1b.Approach (from AD-416):
1a) Evaluate novel mass spectrometric methods such as ambient mass spectrometry and supersonic molecular beam mass spectrometry combined with fast gas chromatography; 1b) use robotic systems to develop fast, automated sample cleanup approaches for routine monitoring purposes; 1c) devise data handling software that is faster and better at compiling the needed information for validating multi-class, multiresidue methods for analysis; 2a) multi-laboratory AOAC International collaborative studies will be pursued to achieve the gold standard quality in method validation; 2b) both gas chromatography and liquid chromatography (LC) combined with tandem mass spectrometry (MS/MS) will be used to assess and address matrix effects in chemical residue analysis of foods;.
3)surface plasmon resonance biosensing instrumentation and techniques will be used to develop advanced new methods for multiple toxins of concern;.
4)both LC-MS/MS and novel, quick chemical test methods will be used to measure total phenolics, phytoestrogens and endocrine disruptors; and.
5)LC combined with atomic fluorescence spectroscopy will be used to rapidly and accurately determine different organometallic species of Hg and As in foods and supplements.


3.Progress Report:
The project is devised to meet the needs of the USDA FSIS, FDA, and other organizations that monitor chemical residues in food, which also includes industry, consumer groups, and academic scientists.

A new method of analysis for a wide range of existing and emerging contaminants of concern in fish was developed using low-pressure gas chromatography – tandem mass spectrometry (LP-GC/MS-MS), which was more than 3 times faster than previous methods. The new method was validated for a wider range of contaminants at lower levels than commonly done in existing approaches and was used in multi-class, multi-residue analysis of novel flame retardants and other persistent organic pollutants in catfish.

An extensive Excel spreadsheet has been devised and transferred to the USDA-FSIS and other labs to provide automatic assessment of qualitative screening, identification, and quantification in fortified samples. The spreadsheet was used in method validation of an ultrahigh performance liquid chromatography-tandem mass spectrometric method for >120 veterinary drugs in meat, and for liquid- or gas chromatography-tandem mass spectrometric methods for pesticide residues in food.

A portable instrument was built which will be evaluated for the determination of triphenylmethane dyes in fish. Experiments were also conducted on conditions for arsenic extraction from food samples and cleanup, separation, speciation, and detection using an atomic fluorescence instrument.

Matrix effects have been evaluated for the multi-class, multi-residue analysis using ultrahigh performance liquid chromatography – tandem mass spectrometry for >120 veterinary drug residues in different meat tissues. Sampling concerns have been overcome based on sample tissue homogeneity experiments.

Several different muscle groups in slaughtered pigs in a dosing study for penicillin were tested to determine the drug distribution in the muscle tissues, which can lead to better decision-making about the muscle group that should be used for regulatory monitoring purposes.

Various food and beverage groups (coffee, tea, juices, fruits, grains, fermented juices and fermented grains) were analyzed with 30+ samples each using our Fast Blue BB method. Results were compared with the traditional method in a single laboratory validation study.


4.Accomplishments
1. Development of an efficient method for analysis of novel flame retardants and other persistent organic pollutants in catfish. Novel flame retardants are emerging food contaminants of interest as due to their toxicology, persistence in the environment, and bioaccumulation/biomagnification in the food chain. Catfish have become of particular interest to USDA-FSIS due to recent changes in legislation. ARS researchers at Wyndmoor, Pennsylvania have developed and evaluated a highly sensitive and selective, laboratory-based, multiclass, multiresidue method for analysis of flame retardants and other persistent organic pollutants, including pesticides, polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and polybrominated diphenyl ethers (PBDEs). The new method uses efficient sample preparation coupled to low-pressure gas chromatography-tandem mass spectrometry for improved analysis of over 60 contaminants simultaneously. The generated data on occurrence of these contaminants in foods may advance the understanding of the potential risk posed by these emerging chemicals and aid in future risk assessment and regulations.

2. Development, evaluation, and transfer of latex agglutination tests (LATs) for detection and confirmation of six pathogenic non-O157 Escherichia coli. Since 1994, USDA-FSIS declared E. coli O157:H7 an adulterant and has included it in its monitoring program. However, prior to June 4, 2012, the other US top-6 non-O157 E. coli strains (O26, O45, O103, O111, O121 and O145) were not monitored. Rapid and simple testing methods were first needed for confirmatory tests of presumptive positive non-O157 STECs to better protect the food supply and consumer. FSIS requested ARS to develop an agglutination method to confirm the identity of E. coli O26, O45, O103, O111, O121 and O145. ARS researchers at Wyndmoor, Pennsylvania tested the assays against 38 E. coli strains, and the reagents and test protocols were transferred to FSIS for further testing and validation using 78 strains. The agglutination method has been incorporated in FSIS Microbiology Laboratory Guidebook (MLG) Chapter 5B.02 to monitor these STECs from raw non-intact beef products. The successful adoption of this method contributed to the implementation of the USDA ‘zero tolerance policy’ for the six non-O157 STECs in June 4, 2012.

3. Optimization, extension, validation, and technology transfer of multiclass, multiresidue method for veterinary drugs in animal tissues. Until now, USDA-FSIS used a 7-plate microbial growth inhibition assay to screen for antimicrobial drug residues in beef samples from slaughter establishments throughout the US. Last year, ARS researchers at Wyndmoor, Pennsylvania, developed, validated, and transferred to FSIS an improved screening method using ultrahigh performance liquid chromatography – tandem mass spectrometry (UHPLC-MS/MS) that improved their screening logistics and capabilities for 60 of the most important drugs of regulatory concern. This year, the qualitative screening and identification plus quantitative method was optimized and extended to 120 drugs and validated for meat tissue. A single analyst can perform sample preparation of 60 samples with the method in an 8-hour day for a series of sequential 10 minute analyses. Implementation of the method in the USDA-FSIS National Residue Program has already found additional residues of concern missed previously. This new method serves to improve the monitoring and enforcement of veterinary drug residues, and thereby assure better animal husbandry practices, reduce environmental contamination, decrease microbial antibiotic resistance, and increase food safety.

4. Evaluation of a multiclass multiresidue method for analysis of veterinary drug residues in beef kidney. Monitoring methods for veterinary drug residues in food have traditionally been designed for single drugs, or for multiple drugs belonging to the same class. Methods which allow for simultaneous monitoring of multiple drug residues from multiple classes can provide increased efficiency. In this work, ARS researchers at Wyndmoor, Pennsylvania, optimized and validated in kidney, a multiclass multiresidue method using liquid chromatography-tandem mass spectrometry for use in the monitoring process. Control kidney samples were fortified at 4 different levels with a mixture of 120 veterinary drugs. After extraction of these samples, recoveries, precision, and lowest calibration levels for each drug were reported. The method was judged to be successful for a majority of the drugs tested, and serves as an efficient and useful option for monitoring veterinary drug residues in food.

5. Confirmation of triphenylmethane dye residues in retail catfish nuggets. Samples of retail catfish nuggets collected from domestically raised catfish in New Jersey, Pennsylvania, New York and Delaware had tested positive for dyes such as malachite green, gentian violet, brilliant blue, and their metabolites using an enzyme-linked immunosorbent assay (ELISA). These test results needed to be confirmed using an alternative protocol. In response, ARS researchers at Wyndmoor, Pennsylvania, examined these samples using high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS), and confirmed ultratrace levels of gentian violet in nugget samples, including one sample with levels exceeding the action level set by the FDA. This study also found that the contamination may be caused by the ink used on packaging materials. The methodology developed in this study can be used by regulatory agencies for verification and confirmation of dye residues in foods.


Review Publications
Chen, G. 2011. Screening of fluoroquinolone residues in caprine milk using a 5-kg luminescence photometer. Journal of Food Analytical Methods. 5:1114–1120.

Chen, G. 2012. A 5-kg time-resolved luminescence photometer with multiple excitation sources. Journal of Applied Spectroscopy. 66(33):341-346.

Medina, M.B., Shelver, W.L., Fratamico, P.M., Fortis, L., Narang, N., Cray, Jr., W., Esteban, E., Tillman, G., Debroy, C. 2012. Latex agglutination assays for detection and of non-O157 Shiga toxin-producing E. coli serogroups O26, O45, O103, O111, O121 and O145. Journal of Food Protection. 75(5):819-826.

Geis-Asteggiante, L., Lehotay, S.J., Fortis, L.L., Paoli, G., Wijey, C., Heinzen, H. 2011. Development and validation of a rapid method for microcystins in fish and comparing LC-MS/MS results with ELISA. Analytical and Bioanalytical Chemistry. 401:2617-2630.

Chen, G. 2012. Determination of oxytetracycline residue in shrimp using a portable time-resolved analyzer and HPLC-MS/MS validation. Sensing and Instrumentation for Food Quality and Safety. 5:165-171.

Last Modified: 8/22/2014
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