Analytical Methods Used in the Total Diet Study
CFSAN/Office of Analytics and Outreach
The Total Diet Study (TDS) currently uses various methods to analyze foods and beverages for analytes in the following categories:
- toxic and nutrient chemical elements
- pesticides
- industrial chemicals
- radionuclides
We (FDA) update the methods for the analyses as the science and laboratory equipment evolve, and the methods undergo evaluation and testing before being implemented. Analytical Methods (PDF, 106 KB) describes the methods used to detect and measure each analyte. In 2014, we updated the methods of measuring elements in foods. The newer methods can detect and differentiate the elements at lower levels. For a detailed explanation of these changes, please read 2014 Elements Methods Changes (PDF, 100 KB).
TDS Methods for Toxic and Nutrient Elements
Multi-element ICP-AES Method for Food
- Elemental Analysis Method (EAM) 4.4 – Inductively Coupled Plasma-Atomic Emission Spectrometric Determination of Elements in Food Using Microwave Assisted Digestion
Multi-element ICP-MS Method for Food
- EAM 4.7 – Inductively Coupled Plasma-Mass Spectrometric Determination of Arsenic, Cadmium, Chromium, Lead, Mercury, and Other Elements in Food Using Microwave Assisted Digestion
Multi-element ICP-MS Method for Bottled Drinking Water
- EAM 4.12 – Draft Method for Analysis of Bottled water for 18 Elements by ICPMS
Arsenic Speciation HPLC-ICP-MS Method for Juice
- EAM 4.10 – High Performance Liquid Chromatography-Inductively Coupled Plasma-Mass Spectrometric Determination of Four Arsenic Species in Fruit Juice
Colorimetric Iodine Method
- KAN-LAB-MET.95 – Determination of Iodine in Food
We use multi-element determination methods (EAM 4.4 and EAM 4.7) we developed to reduce the need for many methods comprising multiple digestions and analytical determinations. These methods have improved efficiencies and detection capabilities. The EAM 4.10 method was developed to perform arsenic speciation analysis for juice samples.
TDS Methods for Pesticides and Industrial Chemicals
Extraction Method
- KAN-LAB-PES.53 – Analysis of Pesticides and Industrial Chemicals by the QuEChERS Procedure
Determination Method
- KAN-LAB-PES.67 – Determination of Pesticides and Industrial Chemicals Using the GC-Mass Selective Detector
- KAN-LAB-PES.72 – Determination of Pesticides and Industrial Chemicals by LC-MS/MS Using AB Sciex 4000 and 5500 QTraps
- KAN-LAB-PES.75 – Determination of Pesticides and Industrial Chemicals using Agilent 7000 GC/MS Triple Quad
- KAN-LAB-PES.77 – Analysis of Acid Herbicides
To analyze the large numbers of samples whose pesticide treatment history usually is unknown, we use analytical methods capable of simultaneously determining multiple pesticide residues. These multi-residue methods (MRMs) can determine the majority of the approximately 400 pesticides for which EPA has established tolerance levels, and many others for which tolerance levels are not available. The most commonly used MRMs can also detect many metabolites, impurities, and alteration products of pesticides.
We conduct ongoing research to update our pesticide-monitoring program. This research includes testing the behavior of new or previously untested pesticides through existing analytical methods and developing new methods to improve efficiency and detection capabilities. In recent years, newer extraction procedures and detection techniques have increasingly replaced older methods, allowing for a greater level of pesticide coverage.
TDS Methods for Radionuclides
Strontium-90 (beta emitter)
- WEAC.RN.METHOD 2.0 – Determination of Strontium-90 in Foods by Internal Gas-Flow Proportional Counting
Gamma-ray Emitters
- WEAC.RN.METHOD 3.0 – Determination of Gamma-Ray Emitting Radionuclides in Foods by High-Purity Germanium Spectrometry
For the TDS program, we use a radionuclide analysis approach that captures the radionuclides expected to give the greatest health risk from radiological events. A very broad-based gamma-ray analysis (WEAC.RN.METHOD 3.0) is performed that covers nearly all relevant radionuclides. A separate analysis is conducted for strontium-90 (WEAC.RN.METHOD 2.0), because this can be a significant contributor to mixed-radionuclide events, such as those involving nuclear power reactors, and to radiological dispersal devices (aka "dirty bombs").
These analysis methods are able to detect radioactive contaminants even at trace levels far below those that would be of health concern. Method-development efforts focus on decreasing analysis time (to increase throughput/capacity) and improving laboratory operations (to standardize quality control, minimize production of waste products, etc.).
If you have questions about the Total Diet Study, email [email protected].