PESTICIDE NALY TICAL MANUAL VOLUME Multiresidue methods F△ Z.S. Department of Health and Human Services Public Health Service Food and Drug administration
MANUAL VOLUME I: Multiresidue Methods U.S. Department of Health and Human Services • Public Health Service Food and Drug Administration PESTICIDE ANALY TICAL RAPE D MT ENT OF HEALTH & HUMAN SERVICES . USA
Pesticide Analytical Manual Vol I PESTICIDE ANALYTICAL MANUAL VOLUME I 3rd edition 1994 Revised, September, 1996 Revised. October. 1997 Revised. October 1999 EDITORIAL STAFF Carolyn M. Makovi, Editor Bernadette M. Mcmahon. Editor emerita EDITORIAL BOARD Marion Clower, ]r, Ph D Charles H. Parfitt, Jr. JohnJ O Rangers, Jr, Ph D Ronald R. roy Richard Schmitt. Ph. D. ePA TECHNICAL ADVISORS Jerry E Froberg Marvin L Hopper Fred r. Krick Ronald G. Luchtefeld Milton a. Luke MANAGING EDITORS Management Methods Branch Office of the Associate Commissioner for Management and Operatic Design and Format: R.O. w. Sciences, Inc. under contract to U.S. Food and drug administration The mention of specific items of equipment and chemicals by brand name or the supplying of manufacturers names and addresses do not constitute endorsement of a product or source by the United States Government. Form FDA 2905a(6
Pesticide Analytical Manual Vol. I Transmittal No. 2000-1 (10/1999) Form FDA 2905a (6/92) PESTICIDE ANALYTICAL MANUAL VOLUME I 3rd Edition, 1994 Revised, September, 1996 Revised, October, 1997 Revised, October 1999 EDITORIAL STAFF Carolyn M. Makovi, Editor Bernadette M. McMahon, Editor Emerita EDITORIAL BOARD Marion Clower, Jr., Ph.D. Charles H. Parfitt, Jr. John J. O’Rangers, Jr., Ph.D. Ronald R. Roy Richard Schmitt, Ph.D., EPA TECHNICAL ADVISORS Jerry E. Froberg Marvin L. Hopper Fred R. Krick Ronald G. Luchtefeld Milton A. Luke MANAGING EDITORS Management Methods Branch Office of the Associate Commissioner for Management and Operations Design and Format: R.O.W. Sciences, Inc. under contract to U.S. Food and Drug Administration The mention of specific items of equipment and chemicals by brand name or the supplying of manufacturers’ names and addresses do not constitute endorsement of a product or source by the United States Government
Pesticide Analytical Manual Vol. I TABLE OF CONTENTS PESTICIDE ANALYTICAL MANUAL VOLUME I TABLE OF CONTENTS Introduction to pam Preface to pam i 3rd edition Guide to use of pami Chapter l Regulatory Operations 102 Preparation of Analytical Samples 103 Method Application in Regulatory analy 104 Analytical Results 105 Analytical Limits of Quantitation Chapter 2 General Analytical Operations and Information 201 Percentage Fat, Water, and Sugars in Foods 202 Basic Analytical Techniques 203 Equipment and Procedures for Comminuting 204 Special Reagent Preparation 206 Quality Assurance/Quality Control 207 Laboratory Safety 208 Hazardous Waste Disposal Chapter 3 Multiclass Multiresidue Methods 801 General Information 302 Method I for Nonfatty Foods 303 Method II for Nonfatty Foods 304 Method for Fatty Foods Chapter 4 Selective Multiresidue Methods 0l Method for N-Methylcarbamates 402 Method for Acids and phenols 403 Method for Phenylurea Herbicides 404 Method for benzimidazoles
Pesticide Analytical Manual Vol. I TABLE OF CONTENTS iii Transmittal No. 94-1 (1/94) Form FDA 2905a (6/92) PESTICIDE ANALYTICAL MANUAL VOLUME I TABLE OF CONTENTS Introduction to PAM Preface to PAM I 3rd edition Guide to Use of PAM I Chapter 1 Regulatory Operations 101 Regulatory Policy 102 Preparation of Analytical Samples 103 Method Application in Regulatory Analysis 104 Analytical Results 105 Analytical Limits of Quantitation Chapter 2 General Analytical Operations and Information 201 Percentage Fat, Water, and Sugars in Foods 202 Basic Analytical Techniques 203 Equipment and Procedures for Comminuting 204 Special Reagent Preparation 205 Reference Standards 206 Quality Assurance/Quality Control 207 Laboratory Safety 208 Hazardous Waste Disposal Chapter 3 Multiclass Multiresidue Methods 301 General Information 302 Method I for Nonfatty Foods 303 Method II for Nonfatty Foods 304 Method for Fatty Foods Chapter 4 Selective Multiresidue Methods 401 Method for N-Methylcarbamates 402 Method for Acids and Phenols 403 Method for Phenylurea Herbicides 404 Method for Benzimidazoles
TABLE OF CONTENTS Pesticide Analytical Manual Vol I Chapter 5 Gas Liquid Chromatography 01 General Information 502 Columns 503 Detectors 504 Quantitation 05 Bibliography Chapter 6 High Performance Liquid Chromatography 601 General Information 602 Columns 603 Mobile Phase Selection, Preparation, and Delivery 604 Injection Systems 605 Detectors 606 Residue Identification and Quantitation 607 Quality Assurance and Troubleshooting 608 Bibliography Appendix I PESTDATA Appendix II Protocols and Reporting Forms for Testing Chemicals Through PAM multiresidue methods Index to PAM I Methods, by Chemicals Tested for Recovery Index to Names used for Chemicals in Pami Index to CAS Registry Numbers for Chemicals in PAM I Index to Subjects Transmittal No. 94-1(1/94] Form FDA 2905a(6/92]
TABLE OF CONTENTS Pesticide Analytical Manual Vol. I Transmittal No. 94-1 (1/94) iv Form FDA 2905a (6/92) Chapter 5 Gas Liquid Chromatography 501 General Information 502 Columns 503 Detectors 504 Quantitation 505 Bibliography Chapter 6 High Performance Liquid Chromatography 601 General Information 602 Columns 603 Mobile Phase Selection, Preparation, and Delivery 604 Injection Systems 605 Detectors 606 Residue Identification and Quantitation 607 Quality Assurance and Troubleshooting 608 Bibliography Appendix I PESTDATA Appendix II Protocols and Reporting Forms for Testing Chemicals Through PAM Multiresidue Methods Index to PAM I Methods, by Chemicals Tested for Recovery Index to Names Used for Chemicals in PAM I Index to CAS Registry Numbers for Chemicals in PAM I Index to Subjects
Pesticide Analytical Manual Vol. I INTRODUCTION PESTICIDE ANALYTICAL MANUAL INTRODUCTION The Food and Drug Administration(FDA) is responsible under the Federal Food Drug, and Cosmetic Act for enforcing tolerances established by the environmental Protection Agency(EPA) for amounts of pesticide residues that may legally re- main on food(including animal feed). In meeting this responsibility, FDA collects and analyzes food from commercial channels of trade for determining compliance with EPA tolerances. The residue data gathered under this regulatory monitoring program are also used for evaluating the extent and significance of pesticide residues in the food supply The Pesticide Analytical Manual(PAM) is published by FDA as a repository of the analytical methods used in FDA laboratories to examine food for pesticide resi- dues for regulatory purposes. The manual is organized according to the scope of the analytical methods Volume i contains multiresidue methods (MRMs) that are used by FDa on a routine basis, because of their efficiency and broad applicability especially for analyzing foods of unknown pesticide treatment his- Volume ii contains methods designed for the analysis of commodities for resi- dues of only a single compound (although some methods are ca- pable of determining several related compounds). These methods are most often used when the likely residue is known to the chemist and/or when the residue of interest cannot be determined by com- mon mrms PAM is designed to be used by analysts experienced in trace residue analysis. All of the techniques employed are subject to potential interferences from reagents apparatus, containers, contaminated air supply, and handling by personnel. The experienced analyst is alert for these possibilities and recognizes the need to con- firm results by other techniques that measure different chemical or physical prop erties of the analyte Expe particular application by a trial of the method that includes examination of re- editors invite analysts to report results of their experiences with PAM methode agent and sample blanks and measurement of the recovery of added analyte. the Revisions Starting with transmittal 96-1(9/96), revisions of PAM I have been issued in two ways (1) changes in most manual sections will be distributed as hard(paper)copies, with symbols or marking lines that have been changed, and(2)updates to the tables 140CFR180.101(c) Form FDA 2905a(6/92)
Transmittal No. 98-1 (10/97) Form FDA 2905a (6/92) v Pesticide Analytical Manual Vol. I PESTICIDE ANALYTICAL MANUAL INTRODUCTION The Food and Drug Administration (FDA) is responsible under the Federal Food, Drug, and Cosmetic Act for enforcing tolerances established by the Environmental Protection Agency (EPA) for amounts of pesticide residues that may legally remain on food (including animal feed). In meeting this responsibility, FDA collects and analyzes food from commercial channels of trade for determining compliance with EPA tolerances. The residue data gathered under this regulatory monitoring program are also used for evaluating the extent and significance of pesticide residues in the food supply. The Pesticide Analytical Manual (PAM) is published by FDA as a repository of the analytical methods used in FDA laboratories to examine food for pesticide residues for regulatory purposes.1 The manual is organized according to the scope of the analytical methods: Volume␣ I contains multiresidue methods (MRMs) that are used by FDA on a routine basis, because of their efficiency and broad applicability, especially for analyzing foods of unknown pesticide treatment history. Volume II contains methods designed for the analysis of commodities for residues of only a single compound (although some methods are capable of determining several related compounds). These methods are most often used when the likely residue is known to the chemist and/or when the residue of interest cannot be determined by common MRMs. PAM is designed to be used by analysts experienced in trace residue analysis. All of the techniques employed are subject to potential interferences from reagents, apparatus, containers, contaminated air supply, and handling by personnel. The experienced analyst is alert for these possibilities and recognizes the need to confirm results by other techniques that measure different chemical or physical properties of the analyte. Experienced residue analysts are aware that no report of validation in another laboratory can substitute for verification that the method does indeed work in the analyst’s own laboratory. The analyst should verify method performance in each particular application by a trial of the method that includes examination of reagent and sample blanks and measurement of the recovery of added analyte. The editors invite analysts to report results of their experiences with PAM methods. Revisions Starting with transmittal 96-1 (9/96), revisions of PAM I have been issued in two ways: (1) changes in most manual sections will be distributed as hard (paper) copies, with symbols or marking lines that have been changed, and (2) updates to the tables 1 40 CFR 180.101 (c) INTRODUCTION
Pesticide Analytical Manual Vol I in Chapters 3 and 4, Appendix I, and the indices to methods, names, and CAS Registry numbers will be issued only via Internet. No hard copies will be distributed for the latter updated sections, but updates will be available more frequently than in the past. As chapter tables of contents are revised, they will include the date on which each section within the chapter was transmitted; dates associated with those sections distributed only electronically will reflect the most recent version at the time the table of contents issued Internet Access to pami files PAM I is now available via Internet as Adobe Acrobat"portable document format (pdf) files. Pdf format permits the user to read and print the document from any computer using appropriate free software. ToobtainacopyofPamIfilesgototheWorldWideWebsiteat:http:/ vmcfsan.fda. gov/-frf/ pamil. html. The resulting page describes PAM and provides links to currently available files. Follow the instructions for downloading Adobe Acrobat Reader is required to view and print pdf files Download a copy of this freesoftwarefromadobe'swebSiteathttp://www.adobe.com/acrobat/readstep.html Alink to thatsite is provided on the PAMI page. Choose the version of Acrobat Reader appropriate to your own computer system Transmit N4: 905a16/9?1
Pesticide Analytical Manual Vol. I vi Transmittal No. 98-1 (10/97) Form FDA 2905a (6/92) in Chapters 3 and 4, Appendix I, and the indices to methods, names, and CAS Registry numbers will be issued only via Internet. No hard copies will be distributed for the latter updated sections, but updates will be available more frequently than in the past. As chapter tables of contents are revised, they will include the date on which each section within the chapter was transmitted; dates associated with those sections distributed only electronically will reflect the most recent version at the time the table of contents issued. Internet Access to PAM I Files PAM I is now available via Internet as Adobe Acrobat “portable document format” (pdf) files. Pdf format permits the user to read and print the document from any computer using appropriate free software. To obtain a copy of PAM I files, go to the World Wide Web site at: http:// vm.cfsan.fda.gov/~frf/pami1.html. The resulting page describes PAM and provides links to currently available files. Follow the instructions for downloading. Adobe Acrobat Reader is required to view and print pdf files. Download a copy of this free software from Adobe’s web site at http://www.adobe.com/acrobat/readstep.html. A link to that site is provided on the PAM I page. Choose the version of Acrobat Reader appropriate to your own computer system
Pesticide Analytical Manual Vol. I PREFACE PREFACE TO PAM/3RD EDITION The third edition of PAM I follows by the publication of th e secor edition. During that period, 29 revisions were made, reflecting new or revised methods, new technologies, and periodic updates of tables describing the capabili ties of PAM I methods Preparation of PAM I 3rd edition was motivated by three major deficiencies in the oft-revised 2nd edition: outdated material, obsolete or ganization of methods, and lack of consistent style Changes in multiresidue methods(MRMs)over the past 26 years have been sig- nificant. Among the most notable changes are those related to instrumental deter- minative techniques. Capillary columns and improved detectors have enhanced GLC applications; HPLC, with its various operating modes, has extended multiresidue capabilities to pesticides not amenable to GlC determination; and mass spectrometry, in the form of compact, automated instruments readily com- bined with GLC, has replaced many cumbersome, less sensitive, and less definitive techniques. PAM I 3rd edition attempts to provide a more up-to-date picture of the status of instrumentation currently used in FDA Pesticide laboratories. D dvances in instrumentation, the basic approach to determination of trace level residues has not departed dramatically from that used in the 1960s. Residues are still extracted from the food commodity, isolated from co-extracted materials and determined by instrumental techniques that separate residues from one an- other. While these analytical steps continue to be part of any MRM, methods research, coupled with advances in analytical technologies, has produced mrMs capable of determining a greater number of widely different types of pesticide residues in a single extract, i.e.,"multiclass MRMs. "Research has also produced other MRMs that determine multiple residues of chemically related pesticides, such as N-methylcarbamates; these types of methods are known as"selective MRMs PAM I 2nd edition organized methods according to the chemical class of the targeted residues, an organization that does not conform to modern methodology A major change in the PAM I 3rd edition is its grouping of methods into multiclass MRMs( Chapter 3)and selective MRMs( Chapter 4) Another change in method descriptions accommodates the choices available to the experienced residue analyst. Typically, the residue laboratory chooses from among several validated options within basic methodology; choices are dictated by the particular commodity, available instrumentation, and targeted residues. Thus, PAM I 3rd edition method descriptions consist of individual extraction, cleanup, and determinative step modules, with indications of which combinations are vali- dated. This organization permits easier reference to the precise combination of steps used in an analysis and facilitates sharing particular methods with colleagues Future addition or revision of methods will be simplified by adding or replacin only the necess sections or modules. The numbering system used in Chapter 8 and 4 is explained in the Guide to PAM I Finally, PAM I 3rd edition incorporates a new and consistent design. A new num- bering system is used, in which chapter and subsection numbers avoid the restric- tive 2nd edition decimal system. Pages are numbered within major subsections Four indices are included: (1)to methods applicable for individual residues,(2) to preferred names for pesticides, (8)to Chemical Abstracts Service(CAs)Regis- try Numbers for the chemicals, and (4)to subjects by key word. An introductor Guide to PAM I, on the following pages, explains the organization of chapte FDA 2905a(6/92
Transmittal No. 94-1 (1/94) Form FDA 2905a (6/92) vii Pesticide Analytical Manual Vol. I PREFACE PREFACE TO PAM I 3RD EDITION The third edition of PAM I follows by 26 years the publication of the second edition. During that period, 29 revisions were made, reflecting new or revised methods, new technologies, and periodic updates of tables describing the capabilities of PAM I methods. Preparation of PAM I 3rd edition was motivated by three major deficiencies in the oft-revised 2nd edition: outdated material, obsolete organization of methods, and lack of consistent style. Changes in multiresidue methods (MRMs) over the past 26 years have been significant. Among the most notable changes are those related to instrumental determinative techniques. Capillary columns and improved detectors have enhanced GLC applications; HPLC, with its various operating modes, has extended multiresidue capabilities to pesticides not amenable to GLC determination; and mass spectrometry, in the form of compact, automated instruments readily combined with GLC, has replaced many cumbersome, less sensitive, and less definitive techniques. PAM I 3rd edition attempts to provide a more up-to-date picture of the status of instrumentation currently used in FDA pesticide laboratories. Despite advances in instrumentation, the basic approach to determination of trace level residues has not departed dramatically from that used in the 1960s. Residues are still extracted from the food commodity, isolated from co-extracted materials, and determined by instrumental techniques that separate residues from one another. While these analytical steps continue to be part of any MRM, methods research, coupled with advances in analytical technologies, has produced MRMs capable of determining a greater number of widely different types of pesticide residues in a single extract, i.e., “multiclass MRMs.” Research has also produced other MRMs that determine multiple residues of chemically related pesticides, such as N-methylcarbamates; these types of methods are known as “selective MRMs.” PAM I 2nd edition organized methods according to the chemical class of the targeted residues, an organization that does not conform to modern methodology. A major change in the PAM I 3rd edition is its grouping of methods into multiclass MRMs (Chapter 3) and selective MRMs (Chapter 4). Another change in method descriptions accommodates the choices available to the experienced residue analyst. Typically, the residue laboratory chooses from among several validated options within basic methodology; choices are dictated by the particular commodity, available instrumentation, and targeted residues. Thus, PAM I 3rd edition method descriptions consist of individual extraction, cleanup, and determinative step modules, with indications of which combinations are validated. This organization permits easier reference to the precise combination of steps used in an analysis and facilitates sharing particular methods with colleagues. Future addition or revision of methods will be simplified by adding or replacing only the necessary sections or modules. The numbering system used in Chapters 3 and 4 is explained in the Guide to PAM I. Finally, PAM I 3rd edition incorporates a new and consistent design. A new numbering system is used, in which chapter and subsection numbers avoid the restrictive 2nd edition decimal system. Pages are numbered within major subsections. Four indices are included: (1) to methods applicable for individual residues, (2) to preferred names for pesticides, (3) to Chemical Abstracts Service (CAS) Registry Numbers for the chemicals, and (4) to subjects by key word. An introductory Guide to PAM I, on the following pages, explains the organization of chapters
PREFACE Pesticide Analytical Manual Vol I and the most useful path for finding pertinent information within the volume. The user is urged to take advantage of these tools and to offer comments or improvements that would make them more useful. PAM I remains, as always,a loose-leaf volume, designed for continuing update The Editors acknowledge the continuing cooperation and support of the pesticide hemists in FDA District and Regional Laboratories, District Research Centers, and Division of Pesticides and Industrial Chemicals: those who contributed sub stantially to 3rd edition preparation are included as technical advisors on the title page. Many of these advisors drafted or reviewed individual sections of the 3rd edition, and all FDA chemists responded repeatedly to requests for information about the applications of analytical methodology for pesticide residues. The edi tors also acknowledge the preparation of specialized sections by Mark Wirtz(QA, QC and GLC Quantitation by Electronic Integration) and Ann Stack(Safety) numerous editorial reviews performed by Norma Yess, secretarial assistance pro- vided by Joan Duy, and comments on portions of the chapters on GLC and HPLC by Dr Colin Poole. Without the assistance of all these individuals, the 3rd edition would not have been possible, and we are grateful to them ecember Transmit aDa2 951(6/92)
Pesticide Analytical Manual Vol. I viii Transmittal No. 94-1 (1/94) Form FDA 2905a (6/92) PREFACE and the most useful path for finding pertinent information within the volume. The user is urged to take advantage of these tools and to offer comments or improvements that would make them more useful. PAM I remains, as always, a loose-leaf volume, designed for continuing update. The Editors acknowledge the continuing cooperation and support of the pesticide chemists in FDA District and Regional Laboratories, District Research Centers, and Division of Pesticides and Industrial Chemicals; those who contributed substantially to 3rd edition preparation are included as technical advisors on the title page. Many of these advisors drafted or reviewed individual sections of the 3rd edition, and all FDA chemists responded repeatedly to requests for information about the applications of analytical methodology for pesticide residues. The editors also acknowledge the preparation of specialized sections by Mark Wirtz (QA/ QC and GLC Quantitation by Electronic Integration) and Ann Stack (Safety), numerous editorial reviews performed by Norma Yess, secretarial assistance provided by Joan Duy, and comments on portions of the chapters on GLC and HPLC by Dr. Colin Poole. Without the assistance of all these individuals, the 3rd edition would not have been possible, and we are grateful to them. December, 1993
Pesticide Analytical Manual Vol. I GUIDE TO PAM Chapter 2 General Analytical Operations and Information Chapter 3 Chapter 4 Multiclass Selective MRMs MRMs Chapter 5 GLC Chapter 6 HPLC GU∥ DE TO PAN Each chapter in Volume I covers a different topic. Effective use of PAM I requires an understanding of the reasons that specific information is included in the chap- ter in which it appears The user is advised to: (1) become familiar with the information in this manual and where it is located, as explained on pages x-xi;(2)understand how to choose and find appropriate methods, as detailed on pages xii-xiii;(3)review pages xiv xvi for other information about Volume I and comparison to the 2nd edition; and (4)learn to use the indices provided
ix Transmittal No. 94-1 (1/94) Form FDA 2905a (6/92) Pesticide Analytical Manual Vol. I GUIDE TO PAM I GUIDE TO PAM I Each chapter in Volume I covers a different topic. Effective use of PAM I requires an understanding of the reasons that specific information is included in the chapter in which it appears. The user is advised to: (1) become familiar with the information in this manual and where it is located, as explained on pages x–xi; (2) understand how to choose and find appropriate methods, as detailed on pages xii–xiii; (3) review pages xiv– xvi for other information about Volume I and comparison to the 2nd edition; and (4) learn to use the indices provided. Chapter 1 Regulatory Operations Chapter 2 General Analytical Operations and Information Chapter 3 Multiclass MRMs Chapter 5 GLC Chapter 4 Selective MRMs Chapter 6 HPLC
GUIDE TO PAM I Pesticide Analytical Manual Vol I Regulatory Operations Chapter l provides information and directions that reflect FDA regu latory policy. PAM I is not the authoritative source for publication of FDA policy, but policy decisions that directly affect the application of Chapter a pesticide analytical methodology are included here as a service to the manual user Chacter s Chapter 2 is a collection of data and directions on ariety of unrelated topics, each of which pro. vides background information needed to perform methods of Chapters 3 and 4 Where information in Chapters I and 2 appears to overlap (e.g, Sec- tions 102, Preparation of Analytical Samples; and Chapter 3 203, Equipment and Procedures for Comminuting) the material in Chapter I reflects the agency policy that must be followed for enforcement of regula tions, and Chapter 2 provides information and hints found useful by FDa pesticide chemists Chapter 3 includes multiclass multiresidue methods(MRMs), those hat are capable of determining pesticide residues of many chemical types. The actual number and identity of the residues determinable by the methods are usually dependent on the number and variety of different determinative steps used to examine the extract. Each method in this chapter is pi s of modules fo the extraction, cleanup, and determinative steps; a complete method is defined as a combination of one or more modules from each step. Complete methods that have been validated in interlaboratory studies, including collaborative studies performed under the aus- pices of AOAC International, are listed; these are sanctioned for use in regulatory analyses. Other combinations of modules must be treated as experimental methodology, additional supporting data for the validity of the analysis are required when such combinations are used in regulatory analyses vo.941(1 2905a(6
Transmittal No. 94-1 (1/94) x Form FDA 2905a (6/92) GUIDE TO PAM I Pesticide Analytical Manual Vol. I Chapter 1 Regulatory Operations Chapter 2 General Analytical Operations and Information Chapter 3 Multiclass MRMs Chapter 5 GLC Chapter 4 Selective MRMs Chapter 6 HPLC Chapter 1 Regulatory Operations Chapter 2 General Analytical Operations and Information Chapter 3 Multiclass MRMs Chapter 5 GLC Chapter 4 Selective MRMs Chapter 6 HPLC Chapter 1 Regulatory Operations Chapter 2 General Analytical Operations and Information Chapter 3 Multiclass MRMs Chapter 5 GLC Chapter 4 Selective MRMs Chapter 6 HPLC Chapter 1 provides information and directions that reflect FDA regulatory policy. PAM I is not the authoritative source for publication of FDA policy, but policy decisions that directly affect the application of pesticide analytical methodology are included here as a service to the manual user. Chapter 3 includes multiclass multiresidue methods (MRMs), those that are capable of determining pesticide residues of many chemical types. The actual number and identity of the residues determinable by the methods are usually dependent on the number and variety of different determinative steps used to examine the extract. Each method in this chapter is presented as a series of modules for the extraction, cleanup, and determinative steps; a complete method is defined as a combination of one or more modules from each step. Complete methods that have been validated in interlaboratory studies, including collaborative studies performed under the auspices of AOAC International, are listed; these are sanctioned for use in regulatory analyses. Other combinations of modules must be treated as experimental methodology; additional supporting data for the validity of the analysis are required when such combinations are used in regulatory analyses. Chapter 2 is a collection of data and directions on a variety of unrelated topics, each of which provides background information needed to perform methods of Chapters 3 and 4. Where information in Chapters 1 and 2 appears to overlap (e.g., Sections 102, Preparation of Analytical Samples; and 203, Equipment and Procedures for Comminuting), the material in Chapter 1 reflects the agency policy that must be followed for enforcement of regulations, and Chapter 2 provides information and hints found useful by FDA pesticide chemists
