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ARS Home » Northeast Area » Wyndmoor, Pennsylvania » Eastern Regional Research Center » Residue Chemistry and Predictive Microbiology Research » Research » Research Project #430153

Research Project: Development, Evaluation, and Validation of Technologies for the Detection and Characterization of Chemical Contaminants in Foods

Location: Residue Chemistry and Predictive Microbiology Research

2017 Annual Report


1a. Objectives (from AD-416):
1. Develop, validate, and transfer multiclass, multiresidue methods for pesticides, environmental, and emerging contaminants in FSIS-regulated foods, and conduct a survey of food samples for the contaminants. 1A. Simultaneous analysis method for diverse pesticides, legacy and emerging environmental contaminants in meats. 1B. Multiresidue method for food packaging (FP) contaminants in packaged foods. 1C. Conduct a survey of food samples for emerging environmental and FP contaminants. 2. Develop qualitative screening and identification criteria with automated data processing that meets regulatory needs to minimize/avoid false positives and negatives. 3. Develop sample processing methods for regulatory analysis that improve the ability to detect combinations of veterinary drug residues in the same sample preparation. 3A. Simultaneous analysis method for diverse veterinary drugs residues, including aminoglycoside antibiotics, in meats. 3B. Evaluate cryogenic sample processing to achieve meaningful representative sample size of 100 mg in multiresidue analysis of pesticides and veterinary drug residues in foods. 4. Develop automated high-throughput sample processing, preparation, and analysis methods using flow-injection and/or open probe techniques coupled with mass spectrometry to monitor >500 veterinary drugs, pesticides, and environmental contaminants in foods. 5. Develop novel analytical methods for inorganic and organometallic heavy metals [for example forms of mercury (Hg) and arsenic (As)] in foods. 5A. Develop novel analytical methods for mercury speciation and quantification in foods. 5B. Develop novel analytical methods for arsenic speciation and quantification in foods. 6. Develop and use bioanalytical methods (including mass spectrometry) to monitor for antibiotic resistant organisms and/or their biomarkers in conjunction with antibiotic residues in seafood and meats.


1b. Approach (from AD-416):
The specific approaches for meeting the project’s objectives and milestones are as follows: 1) develop, validate, and transfer multiclass, multiresidue methods for pesticides, environmental, and emerging contaminants in FSIS-regulated foods, and conduct a survey of food samples for the contaminants; 2) develop qualitative screening and identification criteria with automated data processing that meets regulatory needs to minimize/avoid false positives and negatives; 3) develop sample processing methods for regulatory analysis that improve the ability to detect combinations of veterinary drug residues in the same sample preparation; 4) develop automated high-throughput sample processing, preparation, and analysis methods using flow-injection and/or open probe techniques coupled with mass spectrometry to monitor >500 veterinary drugs, pesticides, and environmental contaminants in foods; 5) develop novel analytical methods for inorganic and organometallic heavy metals [for example forms of mercury (Hg) and arsenic (As)] in foods; and 6) develop and use bioanalytical methods (including mass spectrometry) to monitor for antibiotic resistant organisms and/or their biomarkers in conjunction with antibiotic residues in seafood and meats.


3. Progress Report:
Progress was made on all objectives, all of which fall under National Program 108 – Food Safety, Component I, Foodborne Contaminants. Progress on this project focuses on Problem Statement D - Chemical and Biological Contaminants: Detection and Characterization Methodology, Toxicology, and Toxinology. Progress was made in all objectives, and the project is progressing according to schedule, and even ahead of schedule on Objective 3. A Research Chemist was hired in Sept. 2016 to meet Objective 6, which is intended to meet needs for better methods of analysis for antimicrobial resistance research using mass spectrometry for detection. To help meet this objective, a new Orbitrap tandem hybrid high resolution mass spectrometer was purchased and installed in Dec. 2016 for use Center-wide. Also, an inductively-coupled plasma – mass spectrometer (ICP-MS) was purchased and installed in March, 2017 for use by one of the investigators to help meet Objective 5 pertaining to the analysis of toxic elements in foods. Additionally, a gas chromatograph – triple quadrupole mass spectrometry (GC-MS/MS) instrument was recently upgraded in the lab to achieve state-of-the-art sensitivity for the detection of pesticides and other contaminants in foods. Furthermore, a robotic liquid autosampler was installed with this same instrument, including new software, which enables high-throughput analysis of >200 targeted chemicals in <13 min for each sample including automated cleanup. These powerful analytical tools have been used to develop automated streamlined high-throughput analytical methods, which also entail reliable data processing for hundreds of pesticides, veterinary drugs, and environmental and other contaminants with minimal human review and manual corrections. Improved analytical methods developed by the ARS scientists have already been transferred to USDA Food Safety and Inspection Service (FSIS), and similar technology transfer activities of this research project will continue with FSIS and other stakeholders as the even more efficient, sensitive, and accurate methods with wider scope are being developed and validated.


4. Accomplishments
1. Evaluation and use of more reliable and efficient data processing for chemical analysis by chromatography. As analytical technologies and techniques have improved, sample throughput in chromatography has become limited by data processing of large generated data sets. Human review and manual corrections of integrated chromatographic peaks has been standard practice for decades, but this is no longer possible in high-throughput applications involving many targeted chemicals. ARS researchers at Wyndmoor, Pennsylvania empirically applied and evaluated a simple automated summation chromatographic peak integration approach for pesticide residue monitoring, which obviates the need for time-consuming human review and manual reintegrations. Improved results were achieved using summation integration in a much more efficient and reliable approach, which is applicable to chromatographic analysis in many fields of investigation. This simple, reliable, and automatic data handling approach for chromatography has been transferred to monitoring labs in the USDA-Food Safety and Inspection Service, and it is expected to be more widely implemented in the future.

2. Validation and transfer of an analytical method for veterinary drug residues in liquid and powdered eggs. The USDA-Food Safety and Inspection Service (FSIS) is responsible for monitoring the safety of liquid and powdered egg products, including analysis of veterinary drug residues to assure that regulatory tolerances are not exceeded. However, FSIS lacked a validated analytical method that could be used to determine the presence of the veterinary drug residues. At the request of FSIS, ARS researchers at Wyndmoor, Pennsylvania extended and validated their analytical method for food animal tissues to egg products. The results met FSIS validation criteria for >150 drug residues in the samples, and the method was transferred to FSIS for routine use in their monitoring laboratories.

3. Development of a cold-finger digestion system for speciation analysis of mercury (Hg) in fish. Traditional open-vessel sample digestion for metals analysis suffers from loss of relatively volatile elements, such as Hg. Closed-vessel microwave-aided digestion (MAD) partially overcomes this problem, but the expensive Teflon vessels compatible for microwave ovens can only accommodate a limited number of samples. To avoid MAD and Teflon vessels altogether, ARS researchers at Wyndmoor, Pennsylvania designed a cold-finger digestion system using 16 mm diameter x 150 mm tall Pyrex culture tubes placed in block heater. A temperature gradient in the tube headspace enables solvent reflux and condensation, thus minimizing analyte loss. The new approach and protocol obviates the need for additional chemical separation prior to analysis, saves thousands of dollars in equipment and supplies, and increases sample throughput, while still maintaining good analytical performance.

4. Development of an analytical technique for rapid determination of antimicrobial resistance of aminoglycoside antibiotics. Microbial resistance to antibiotic drugs, such as aminoglycosides, is a major health concern worldwide, and more efficient and effective methods of analysis are needed to monitor and study resistance. ARS researchers at Wyndmoor, Pennsylvania initiated development of a new method of detection by introducing into host bacteria plasmid encoding enzymes that modify aminoglycosides through acetylation and phosphorylation. After exposing the bacteria to aqueous aminoglycoside solution, mass spectrometric analysis revealed biomarkers useful for rapid detection of the resistant strain. In-house devised software was then used for rapid quantification of the biomarkers. This type of instrument-based approach using mass spectrometry possesses advantages over traditional microbiological methods, including complementary value.

5. Optimization of sample processing techniques to determine minimum test sample size for analysis of contaminants in foods. The best way to improve the efficiency in chemical residue analysis of foods is to use the minimum amount of test sample portion that still yields accurate results for the bulk sample. ARS researchers at Wyndmoor, Pennsylvania conducted a study involving 10 food commodities and two types of modern commercial sample processing devices to minimize test portions for analysis of added and incurred pesticide residues in the bulk samples. The results indicated that 5 g test samples processed at room temperature from 1 kg typically meets needs for regulatory analysis. This is half the portion commonly analyzed currently, which means that half the amount of reagents may be used thereby saving costs in the future.

6. Survey for the presence of mercury (Hg) in 38 fish oil supplement samples. Fish consumption is the main pathway of human exposure to inorganic mercury (iHg) and methylmercury (MeHg), and ARS researchers at Wyndmoor, Pennsylvania analyzed for these toxic chemicals in fish oil using a novel differential photochemical vapor generation atomic fluorescence spectrometric (PVG-AFS) method. Average concentrations of iHg and MeHg in the 38 fish oil samples were 0.67 and 1.1 ng/mL, respectively, which is 2-3 orders of magnitude lower than in fish. This study helped provide the fish oil industry insights and guidance for quality control and assurance of their products, and should increase consumer confidence in consumption of fish oil supplements.

7. Evaluation of a new sorbent material for efficient cleanup of complex food samples for the analysis of pesticides and environmental contaminants. Chemical analysis of residual contaminants in highly complex pigmented and fatty foods requires efficient cleanup of the food extracts to remove interfering matrix components. ARS researchers at Wyndmoor, Pennsylvania evaluated a new commercial sorbent, called Verde, which combines fat and pigment removing properties, in fatty and/or pigmented commodities (avocado, pork, salmon, and pork) for analysis of 117 pesticides and environmental contaminants. The new sorbent provided efficient removal of chlorophyll and lipids, which enabled acceptable analysis of nearly all of the selected contaminants at or below regulatory tolerance levels. The new method is fast, efficient, and can be implemented in any laboratory for residual analysis of contaminants in foods.

8. Development of an extraction method for inorganic arsenic in algae. Algae are rich in innocuous arsenosugars but some algae species contain high levels of extremely toxic inorganic arsenic (iAs). ARS researchers at Wyndmoor, Pennsylvania in collaboration with the Institute of Quality Standards and Technology for Agri-Products, Chinese Academy of Agricultural Science, Beijing, China developed an improved effective method of analysis of iAs in algae. The new method eliminated interferences from arsenosugars and other organic arsenicals, achieving quantitative recovery and low detection limit of 3 ng/g for iAs. The method was applied in the analysis of real samples.


Review Publications
Perez Jr, J.J., Watson, D.A., Levis, R.J. 2016. The classification of gunshot residue using laser electrospray mass spectrometry and offline multivariate statistical analysis. Analytical Chemistry. doi: 10.1021/acs.analchem.6b01438.

Han, L., Sapozhnikova, Y.V., Lehotay, S.J. 2016. Method validation for 243 pesticides and environmental contaminants in meats and poultry by tandem mass spectrometry coupled to low-pressure gas chromatography and ultra high-performance liquid chromatography. Food Control. 66:270-282.

Han, L., Sapozhnikova, Y.V., Matarrita, J. 2016. Evaluation of a new carbon/zirconia-based sorbent for the cleanup of food extracts in multiclass analysis of pesticides and environmental contaminants. Journal of Separation Science. 39(23):4592-4602.

Lehotay, S.J. 2017. Utility of the summation chromatographic peak integration function to avoid manual reintegrations in the analysis of targeted analytes. LC GC North America. 35:391-402.

Zhang, Z., Feng, M., Zhu, K., Han, L., Sapozhnikova, Y.V., Lehotay, S.J. 2016. Multiresidue analysis of pesticides in straw roughage by liquid chromatography - tandem mass spectrometry. Journal of Agricultural and Food Chemistry. 64:6091-6099. doi: 10.1021/acs.jafc.5b05981.

Zhang, W., Qi, Y., Qin, D., Liu, J., Mao, X., Chen, G., Wei, C., Qian, Y. 2017. Determination of inorganic arsenic in algae using bromine halogenation and on-line nonpolar solid phase extraction followed by hydride generation atomic flourescence spectrometry. Talanta. 170:152-157.

Anumol, T., Lehotay, S.J., Stevens, J., Zweigenbaum, J. 2017. Comparison of veterinary drug residue results in animal tissues by ultrahigh-performance liquid chromatography coupled to triple quadrupole ... use of a commercial lipid removal product. Analytical and Bioanalytical Chemistry. 409:2639-2653.