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I methods Preparation of PAM I 3rd edition was motivated by three major deficiencies in the oft-revised 2nd edition: outdated material, obsolete or ganization of methods, and lack of consistent style Changes in multiresidue methods(MRMs)over the past 26 years have been sig- nificant.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(6/92Transmittal 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 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. 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 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 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 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, (3) to Chemical Abstracts Service (CAS) Regis￾try 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