MALDI-TOF Mass Spectrometry of Synthetic Polymers. By Harald Pasch (Deutsches KunststoffInstitut, Darmstadt, Germany) and Wolfgang Schrepp (BASF AG, Ludwigshafen, Germany). Springer-Verlag: Berlin, Heidelberg, New York. 2003. xviii + 298 pp. $89.95. ISBN 3-540-44259-6. This book offers a summary of the fundamentals and the technical aspects of the matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) of synthetic polymers as well as detailed experimental procedures. All major applications of MALDI-TOF in polymer analysis, including determination of molar mass and analysis of functional groups and copolymers, are presented, and useful information about instrumentation, selection of matrices, and experimental conditions is provided. The first chapter of the book is a short general discussion of the interest in characterizing molar mass and how to calculate it and has an overview of some nonmass spectrometric techniques for the characterization. Chapter 2 gives a brief description of mass spectrometric instrumentation, including ionization techniques, analyzer types, and detectors used in MS. Fundamentals of MALDI-TOF MS, including ionization mechanisms of MALDI, matrices, and sample preparation, interpretation of the MALDI spectra of polymers and other experimental parameters, such as influence of cationizing agents and laser power on the mass spectra, are reviewed in Chapter 3. The focus then turns to identification of polymers using MALDI-TOF MS (Chapter 4), determination of molar mass (Chapter 5), and analysis of complex polymers (Chapter 6). In Chapter 7, the authors describe the advantages of using preseparation techniques, such as size-exclusion chromatography (SEC) or multidimensional chromatography and their coupling, with MALDITOF MS, and they discuss future developments in Chapter 8. Matrix-assisted laser desorption ionization-time-of-flight mass spectrometry has recently gained wide popularity in analysis of polymers because of its high sensitivity and capability of detecting ions at high mass. MALDI is routinely used for measuring molar mass, identifying structures, and characterizing the end groups of polymers. However, accurate measurement of molar masses requires that the MALDI process be quantitative and independent of the size of the polymer chain. Understanding the mechanism of ionization in MALDI and the sources of efficiency for the process is therefore essential to the quantitative application of MALDI to the analysis of polymers, and an entire chapter of the book is devoted to this subject. Nonetheless, because the process of ionization in MALDI is still not completely understood, the reader necessarily is left without a clear understanding of the process. Another important factor that affects identification and measurement of the molar mass of polymers is the characteristics of the mass spectrometer used. Different mass analyzers, such as the TOF-MS and Fourier transform ion cyclotron resonance mass spectrometers, are discussed in the chapters on mass spectrometric instrumentation and the fundamentals of MALDI10.1021/ja033564m CCC: $25.00 © 2003 American Chemical Society
TOF MS. Regrettably, the new TOF-TOF MS is only mentioned briefly in the chapter on future developments. This technique, which was introduced two years ago, can provide high resolution, high mass accuracy, high mass range, MS/MS capability, and high throughput all in one instrument. Because understanding of the mechanism of ionization for MALDI remains incomplete, acquiring such spectra still heavily depends on the preparation of samples. For this reason, the bulk of the book is devoted to detailed experimental procedures for obtaining high-quality MALDI spectra for different synthetic polymers. Excellent tables are provided, summarizing what matrix/solvent combination to use for each polymer. Most of the experimental procedures that are provided are from the authors’ own labs, however, and little attention is given to resources available on the Internet. The utility of the book would have been enhanced by the inclusion of online resources and databases for more up-to-date procedures. One such resource is the National Institute of Standards and Technology (NIST) Materials Science & Engineering Laboratory - Polymers Division (http://polymers.msel.nist.gov/maldirecipes/). This database consists of methods for MALDI on a wide variety of synthetic polymers. Other on-line resources include Web sites of the MALDI-TOF manufacturers, especially those that deal with analysis of polymers. Whereas the molar mass values of polymers with low polydispersity when measured by MALDI MS are in qualitative agreement with those obtained from other conventional methods, MALDI mass spectra from polydisperse polymers indicate that high-mass components are generally underrepresented with respect to lower mass oligomer peaks. This problem can be overcome by combining MALDI with chromatography, a topic that is addressed in Chapter 7. In general, the book is well written and provides comprehensive information toward practical and established MALDITOF MS of synthetic polymers. Other newly developed areas, such as the analysis of nanoparticles, are only mentioned in passing, however. Nonetheless, the book is recommended reading for practitioners in this field. Mehdi Moini, UniVersity of Texas at Austin JA033564M 10.1021/ja033564m
Progress in the Chemistry of Organic Natural Products, 86. Edited by W. Herz (The Florida State University, Tallahassee), H. Falk (Johannes-KeplerUniversita¨t), and G. W. Kirby (University of Glasgow). Featuring “Monopyrrolic Natural Compounds Including Tetramic Acid Derivatives” by A. Gossauer (University of Fribourg). Springer-Verlag: Wien. 2003. viii + 222 pp. $149.00. ISBN 3-211-83889-9. This volume of the series of monographs on the chemistry of natural products focuses attention on monopyrrole compounds. As such, pyrroles as simple as the various esters of pyrrole J. AM. CHEM. SOC. 2003, 125, 14649
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2-carboxylic acid and as complex as roseophilin are discussed. The author takes liberties with the “pyrrole” designation to include any compound with a nitrogen in the five-membered ring and various tetramic acid derivatives as well. This extra material does not detract from the value of the monograph, however. The organization of the chapters is based on the biological source of the compounds (vertebrates, invertebrates, plants, bacteria, and fungi) rather than on structural diversity. Coverage within the subsections is slightly haphazard: within a family of related compounds, the author has included references to the isolation and structure determination of every member of the family. The coverage of these aspects of the topics is outstanding. In many instances, the discussion also includes references to biosynthetic and synthetic studies, although the coverage of these topics is not comprehensive. For instance, there is no discussion of the synthetic efforts by many research groups to the total synthesis of tetramic acids (admittedly, an area near and dear to my heart). While this nonuniformity of coverage is not a serious flaw, the reader should be aware that the situation exists. The book is technically outstanding. The text is thoroughly referenced including references from 2000 with almost 900 articles cited. Although the coverage may not be complete in every instance, the references provided are those that would serve as the foundation for a comprehensive search of any individual topic or class of compounds. The indices are also excellent and include both author and subject formats. As one has come to expect in the Zechmeister series, the quality of the binding and of the materials used are superb and will withstand the rigors of many years of use. In conclusion, this volume is a recommended reference book for experts in the field of isolation/structure determination or synthesis of natural products. Philip DeShong, UniVersity of Maryland JA0335869 10.1021/ja0335869
Methods in Polyphenol Analysis. Edited by Celestino Santos-Buelga (University of Salamanca) and Gary Williamson (Nestle´ Research Center, Lausanne). Royal Society of Chemistry: Cambridge. 2003. xvi + 384 pp. $199.00. ISBN 0-85404-580-5. This guide to modern methods of polyphenolic analysis presents a wide array of analytical techniques for chemical
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identification of cinnamate derivatives (e.g., flavonoids, catechins, proanthocyanidins, condensed tannins, chalcones, and chlorogenic acid) and is a timely update to Harborne’s classic text Phytochemical Methods (Chapman and Hall: London and New York, 1984). Specialized sample-preparation methods including microwave-assisted, supercritical-fluid, and pressurized-liquid extraction are presented, as are chromatographydetection coupled devices, such as LC-MS, LC-NMR, and LCcoulometric detection. Applications of methods of detection are often accompanied by sample spectra and information about limitations of instrumentation that should make this text useful as both a handbook for the lab bench as well as a primer of underlying concepts of biochemical extraction and spectroscopic detection. Several chapters focus on polyphenolic extraction/ quantification from fruits and vegetables as well as metabolic intermediates from biological tissues. There are also two chapters covering traditional chemical synthesis of flavonoids and enzymatic synthesis of glucosides and glucuronides. In addition, one chapter reviews common chemical motifs of polyphenolic metabolites that confer antioxidant properties and briefly covers methods for generating, studying, and detecting phenoxyl radicals. The book is divided into 16 separately authored chapters with references provided at the end of each. The editors have expertly selected the topics covered so that the chapters have little overlap and at the same time blend to provide a coherent synopsis of contemporary analytical techniques in polyphenolic research. A subject index allows cross-referencing of specific compounds (e.g., luteolin, myricetin, rutin), classes of compounds (e.g., anthocyanins, phenolic acids, procyanidins), organisms (e.g., Arrabidaea chica, Candida albicans, Salix), and fruits (e.g., olive oil, onion, peanut) and contains comprehensive indexing of analytical devices as well. Because of the complex chemical nature of polyphenolic isolation and characterization, this new text on methods in polyphenolic analysis, written in a clear and authoritative style, should be a valuable reference book for upper-division students and researchers in such diverse areas as food chemistry, metabolic profiling, synthesis of natural products, and the tracking of intermediates in biological samples. Paul W. Pare´ , Texas Tech UniVersity JA033571A 10.1021/ja033571a
