The U.S. Food and Drug Administration's (FDA) mission to maintain a safe food supply is met in part by monitoring food and related products for both toxic and nutritional elements. The FDA collects and analyzes food and other materials (foodware, vitamins, supplements, etc.) from commercial channels of trade to determine whether those materials are in compliance with applicable regulations. The analytical data gathered through these monitoring activities are also used for evaluating the extent and significance of these analytes in the food supply.
3.3 (2) What is the difference between an empirical formula and a molecular formula? 3.3(2) An empirical formula gives the relative (reduced) number of atoms of each element in a compound, whereas a molecular formula gives the actual number of atoms of each element in a molecule of a compound. View Lab Report - 2.3.3.3 Lab - Building a Simple Network from CIS 192 at University of the Fraser Valley. Lab - Building a Simple Network Topology Addressing Table Device Interface IP Address Subnet. If you didn’t know the lab experiment, you might not have any idea that the individual sentences had anything to do with each other. On the other hand, the start of a good conclusion paragraph might look like: “In the Response of Circuit Elements lab, we determined the. Jul 18, 2019 Fix any of the following: aria-label attribute does not exist or is empty aria-labelledby attribute does not exist, references elements that do not exist or references elements that are empty Form element does not have an implicit (wrapped) Form element does not have an explicit Element has no title attribute or the title.
FDA laboratories perform these sample analyses using sound analytical practices and methodology which are documented in the Elemental Analysis Manual for Food and Related Products (EAM). This resource serves as a reference, for analysts at the FDA and around the world, providing not only general analytical information and procedures and detailed laboratory methods, but also helpful notes from analysts' experiences using these methods.
The content of the EAM is peer-reviewed on an on-going basis and endorsed by an Elemental Analysis Steering Committee, which is composed of FDA laboratory scientists in the Center for Food Safety and Applied Nutrition (CFSAN) and the Office of Regulatory Affairs (ORA). The analytical methods (in Section 4) have been successfully evaluated via at least a single-laboratory validation and are based on analytical procedures previously published in peer-reviewed scientific journals. For some of these methods, detailed proficiency information, obtained via multilaboratory studies, is also available and presented in appendices to the methods.
The EAM is not an exact representation of procedures used at FDA laboratories. Additional procedures (not in the EAM) may be used and some of the included methods are no longer used. Additional methods are drawn from the Official Methods of Analysis of AOAC INTERNATIONAL. In addition, compliance programs issued by FDA may require specifically-tailored methods not published elsewhere and FDA field laboratories use a separate Laboratory Manual that provides guidance on primary laboratory functions. New methods and procedures are also developed as needed to respond to emergencies. Methods included in the EAM but no longer used at FDA are retained because they are still considered current, relevant for other laboratories, and acceptable for use.
The EAM is only available from this website. A history of the EAM with access to past versions of its content is available from the EAM History and Archive section.
Please send any comments or contributions to [email protected].
The mention of specific items of equipment and chemicals by brand name or the supplying of manufacturer's names and addresses do not constitute endorsement of a product or source by the United States Government.
If you are citing an EAM method or section, it is important to include the revision number, because methods are subject to review and improvement. Although you should follow the Author’s Instructions for your specific publisher, here is a sample citation for an EAM method:
Inductively Coupled Plasma-Mass Spectrometric Determination of Arsenic, Cadmium, Chromium, Lead, Mercury, and Other Elements in Food Using Microwave Assisted Digestion; Official Methods of Analysis of AOAC INTERNATIONAL[U.S. Food and Drug Administration, Internet]; Section 4.7, Version 1.1, 2015. Available from: http://www.fda.gov/EAM (Accessed December 31, 2015).
Table of Contents1. Regulatory Considerations
1.1 Program Areas (under development)
1.1.1 Chemical Contaminants
1.1.2 Food Labeling and Nutrition 1.1.3 Food Ingredients and Packaging
1.2 Regulatory Operations (Capar) (PDF, 333KB)
1.2.1 Regulatory Procedures Manual
1.2.2 Compliance Policy Guides manual 1.2.3 Compliance Program Guidance Manual 1.2.4 ORA Laboratory Manual 2. Sample Preparation
2.1 Food Edible Portion (Various) (PDF, 61KB)
2.1.1 General Procedures
2.2.2 Degasification of Carbonated Beverages
2.2 Food Homogenization (Mindak, Jacobs, Capar, Cunningham) (PDF, 214KB)
2.2.1 Laboratory Homogenization Equipment
2.2.2 Homogenization Procedures 2.2.2.1 General Procedures 2.2.2.2 Candy Procedures 2.2.2.3 Pills, Capsules, Supplements, etc.
2.3 Digestion and Separation (Mindak, Cheng, Capar) (PDF, 24KB)
2.3.1 Microwave Digestion (general applications)
2.3.2 References to Procedures in Various Methods 2.3.2.1 Leaching Cadmium and Lead from Ceramicware 2.3.2.2 Mercury Separation in Seafood 2.3.2.3 Arsenic Speciation in Rice
2.4 Contamination Control (Mindak, Capar) (PDF, 356KB)
2.4.1 Environmental
2.4.2 Laboratory Ware 3. General Analytical Operations and Information
3.1 Safety (Mindak) (PDF, 344KB)
3.2 Terminology (Cunningham, Mindak, Capar) (PDF, 413KB)
3.2.1 Figures of Merit
3.2.2 Samples and Sample Solutions 3.2.3 Standard Solutions 3.2.4 QC/QA Materials and Solutions
3.3 Uncertainty (Cunningham) (PDF, 555KB)
3.3.1 Types of Uncertainty
3.3.2 Sampling Uncertainty and Nonhomogeneity 3.3.3 Determining Analytical Uncertainty 3.3.4 Uncertainty on a Report of Analysis (under development) 3.3.5 Uncertainty and Method Development - Example for Method 4.4
3.4 Special Calculations (Cunningham, Capar, and Mindak) (Version 3.0; PDF, 202KB)
3.4.1 Fortification Recovery
3.4.2 Other Recovery 3.4.3 Dilution Factor 3.4.4 Converting Units 3.4.5 Percent Difference 3.4.6 Mass Correction Factor (MCF) 3.4.7 References
3.5 Reference Materials (Cunningham, Capar) (PDF, 468KB)
3.5.1 Reference Material Use For Quality Control
3.5.2 In-house Reference Material Development 3.5.2.1 Selection 3.5.2.2 Analytical 3.5.2.3 Random Error and Homogeneity 3.5.2.4 Uncertainties 3.5.2.5 Instructions 3.5.3 Reference Material Re-verification 3.5.4 Reference Material Sources 3.5.5 In-house Reference Material Certificates 3.5.5.1 FDA Cocoa Powder (CP)
3.6 Performance (Mindak, Cheng, Hight, Capar) (PDF, 567KB)
3.6.1 Instrument Performance
3.6.1.1 Graphite Furnace Atomic Absorption Spectrometer 3.6.1.2 Cold Vapor Atomic Absorption Spectrometer 3.6.1.3 Inductively Coupled Plasma-Atomic Emission Spectrometer 3.6.1.4 Inductively Coupled Plasma-Mass Spectrometer 3.6.2 Method Performance
3.7 Typical Element Concentrations (Capar, Cunningham) (PDF, 70KB)
4. Analytical Methods
4.1 Flame Atomic Absorption Spectrometric Determination of Lead and Cadmium Extracted from Ceramic Foodware (version 1.1; No longer used at FDA but sill an acceptable method. Available in 'EAM archive - Methods (current)” Zip, 1.4MB) (Hight)
4.2 Graphite Furnace Atomic Absorption Spectrometric Determination of Lead and Cadmium Extracted from Ceramic Foodware (version 1.2; No longer used at FDA but sill an acceptable method. Available in 'EAM archive - Methods (current)” Zip, 1.4MB) (Hight)
4.3 Graphite Furnace Atomic Absorption Spectrometric Determination of Cadmium and Lead in Food Using Microwave Assisted Digestion (version 1.2; No longer used at FDA but sill an acceptable method. Available in 'EAM archive - Methods (current)” Zip, 1.4MB) (Mindak, Cheng)
4.3A Appendix A – Supplemental Information on In-house Method Validation (Mindak, Cunningham)
4.3B Appendix B – Supplemental Information on Interlaboratory Trial (Mindak)
4.4 Inductively Coupled Plasma-Atomic Emission Spectrometric Determination of Elements in Food Using Microwave Assisted Digestion (version 1.1; PDF, 1.4MB) (Dolan, Mindak)
4.4A Appendix A – Supplemental Information on In-house Method Validation (Mindak, Capar)
4.5 Cold Vapor Atomic Absorption Spectrometric Determination of Total Mercury in Seafood Using Microwave Assisted Digestion (version 1.0; No longer used at FDA but sill an acceptable method. Available in 'EAM archive - Methods (current)” Zip, 1.4MB) (Hight, Cheng)
4.5A Appendix A – Supplemental Information on In-house Method Validation (Cheng)
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4.5B Appendix B – Supplemental Information on Method Performance (Cheng)
4.6 Inductively Coupled Plasma-Atomic Emission Spectrometric Determination of Cadmium and Lead Extracted from Ceramic Foodware (version 0.2; PDF, 150KB) (Cheng)
4.7 Inductively Coupled Plasma-Mass Spectrometric Determination of Arsenic, Cadmium, Chromium, Lead, Mercury, and Other Elements in Food Using Microwave Assisted Digestion (version 1.1; PDF, 938KB) (Gray, Mindak, Cheng)
4.8 High Pressure Liquid Chromatographic-Inductively Coupled Plasma-Mass Spectrometric Determination of Methylmercury and Total Mercury in Seafood (version 1.0; PDF, 179KB) (Cheng, Hight)
4.9 Portable Hand Held X-Ray Fluorescence Determination of Toxic Elements (under development)
4.10 High Performance Liquid Chromatography-Inductively Coupled Plasma-Mass Spectrometric Determination of Four Arsenic Species in Fruit Juice (version 1.0; PDF, 407KB) (Various)
4.11 Arsenic Speciation in Rice and Rice Products Using High Performance Liquid Chromatography-Inductively Coupled Plasma-Mass Spectrometric Determination (version 1.0; PDF, 292KB) (Various)
4.12 Inductively Coupled Plasma - Mass Spectrometric Determination of 18 Elements in Bottled Water (under development)
4.13 Inductively Coupled Plasma - Mass Spectrometric Determination of Iodine in Food Using Tetramethyl Ammonium Hydroxide Extraction (version 1.0; PDF, 595KB) (Todorov, Gray)
Glossary (PDF: 174KB)
Multidimensional Arrays
A multidimensional array in MATLAB® is an array with more than two dimensions. In a matrix, the two dimensions are represented by rows and columns.
Each element is defined by two subscripts, the row index and the column index. Multidimensional arrays are an extension of 2-D matrices and use additional subscripts for indexing. A 3-D array, for example, uses three subscripts. The first two are just like a matrix, but the third dimension represents pages or sheets of elements.
Creating Multidimensional Arrays
You can create a multidimensional array by creating a 2-D matrix first, and then extending it. For example, first define a 3-by-3 matrix as the first page in a 3-D array.
Now add a second page. To do this, assign another 3-by-3 matrix to the index value 2 in the third dimension. The syntax
A(:,:,2) uses a colon in the first and second dimensions to include all rows and all columns from the right-hand side of the assignment.
The
cat function can be a useful tool for building multidimensional arrays. For example, create a new 3-D array B by concatenating A with a third page. The first argument indicates which dimension to concatenate along.
Another way to quickly expand a multidimensional array is by assigning a single element to an entire page. For example, add a fourth page to
B that contains all zeros.
Accessing Elements
To access elements in a multidimensional array, use integer subscripts just as you would for vectors and matrices. For example, find the 1,2,2 element of
A , which is in the first row, second column, and second page of A .
Use the index vector
[1 3] in the second dimension to access only the first and last columns of each page of A .
To find the second and third rows of each page, use the colon operator to create your index vector.
Manipulating Arrays
Elements of multidimensional arrays can be moved around in many ways, similar to vectors and matrices.
reshape , permute , and squeeze are useful functions for rearranging elements. Consider a 3-D array with two pages.
Elements Lab 3.3.2 Software
Reshaping a multidimensional array can be useful for performing certain operations or visualizing the data. Use the
reshape function to rearrange the elements of the 3-D array into a 6-by-5 matrix.
reshape operates columnwise, creating the new matrix by taking consecutive elements down each column of A , starting with the first page then moving to the second page.
Elements Lab 3.3.2 Training
Permutations are used to rearrange the order of the dimensions of an array. Consider a 3-D array
M .
Use the
permute function to interchange row and column subscripts on each page by specifying the order of dimensions in the second argument. The original rows of M are now columns, and the columns are now rows.
Similarly, interchange row and page subscripts of
M .
When working with multidimensional arrays, you might encounter one that has an unnecessary dimension of length 1. The
squeeze function performs another type of manipulation that eliminates dimensions of length 1. For example, use the repmat function to create a 2-by-3-by-1-by-4 array whose elements are each 5, and whose third dimension has length 1.
Use the
squeeze function to remove the third dimension, resulting in a 3-D array.
Elements Lab 3.3.2 OnlineRelated TopicsComments are closed.
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