Books
"A picture says more than a thousand words"
Pitfalls and Errors of HPLC in Pictures Veronika R. Meyer Hüthig GmbH Postfach 10 28 69 D-69018 Heidelberg, Germany 1997, 168 pp., $31.75
Inis is a giant of a little book on HPLC The author packs more concise, usable knowledge into the 168 pages of this volume than what is in most textbooks twice its size. Chromatographic knowledge is—in a sense—picture-based, and the chromatographic world has long been needing a book written in the same concise language, namely a picture book of HPLC. Meyer has delivered a well-organized, concise, yet in-depth volume. This is the kind of book that working chromatographers will want to keep in the stack at the front of their desks, along with the phone book, their old analytical textbook, and perhaps their old organic and physical chemistry texts. They will use it that much. The author works from the viewpoint of showing pictures of common problems of separations that do not work, rather than showing examples of things that do work. This is a powerful approach, and it is one that unfortunately is missing from many texts in this and other areas. Showing chromatographic problems, usually in the form of both good and bad separations in the same picture, instantly helps the working scientist understand and recognize what is wrong with his or her particular separation. 544 A
Most chemists have a firm grasp of what they are trying to do when developing or running a separation. They really don't need a textbook telling them how things should be done theoretically. Instead, they need clear, concise help when they find things do not work as they had hoped. In these cases, the author's quoted graffiti "1 wort = 1 millibild (a picture eays more ehan a thousand words)" is apropos. As I perused the book, I was reminded of problems I encounter at the bench and of things that I had perhaps forgotten when trying to solve a particular problem. As a daiiy working guidebook and as a training guide for newer chromatographers this book is superb The text is divided into three sections. Part I, "Fundamentals", gives a bird's eye view of basic chromatographic theory, including definitions of the most commonly used terms, such as "efficiency", "capacity factors", and "resolution". It also includes very useful sketches of reduced plate heights and velocity, separation peak capacity, and statistical probability of peak overlap. Other topics include propagation of errors, ruggedness, linearity, and noise. Obviously, one does not find full mathematical treatments of all these subjects in 49 pages. However, recalling from my academic days that most students slept through the other 200 of theoretical material I think most will find this approach refreshing Meyer keeps a lively witty prose throughout making for fun reading Part II, "Pitfalls and Sources of Error", covers many of the most common problems in HPLC. Problems with mobile-phase mixing, pH reagent purity, system peaks, peak distortion, peak tailing, and column selectivity are presented, just to mention a few. Many instrumental-related artifacts or errors are likewise covered, including the role of flow errors on peak areas and heights, wavelength-related problems, ex-
Analytical Chemistry News & Features, August 1, 1998
cessive noise, and instrument leaks. Problems with poor resolution and quantitation of trace peaks eluting either before or after the major peak are also presented and discussed, including the wide misuse of a simple correlation coefficient as the sole measure of linearity when determining a calibration curve. The author shows an excellent example of inherently nonlinear data producing a correlation coefficient of 0.999 and re-enforces the need to examine the residuals of the regressed data to make a final judgment regarding linearity. She accomplishes in two pages what statistical books cannot to do in 200 namely to remind analysts to look at their data and not just the equations or the results Part III, "Strategies", is shorter but just as powerful. Issues discussed here include column testing, wavelength accuracy, and internal standards. Regarding quantitation, the point is made that, although precision may be acceptable, accuracy peaks that are to be quantitated must be baseline resolved. Hints for good quantitation in purity assays are covered, including "high/ low" chromatography. The book ends with brief summaries of method validation and quality-assurance procedures subjects that unfortunately cannot easily be reduced to one-DUffe summaries. Given this the author might better have covered this entire area with ci sinsrle sentence namely the old adage of "Say what you do and do what you say" as the basic principles of standard operating procedures and indeed of quality assurance The index of the book is good and is not extensively cross-referenced. However, in a straightforward book such as this, information can still be easily found. The book makes no attempt to extensively cite the primary literature. References are generally limited to a single reference of the source of the figure used, or to unpublished applications either by the author or others. However, this does not detract from
the usefulness of the book, which makes no pretense at being a comprehensive research tome. This book is designed for tight, efficient transmission of critical knowledge, the kind that a chemist needs to rapidly solve a problem on the spot and continue with the project. The book works wonderfully for that purpose. This book is refreshing in its seeming simplicity, yet is more powerful than it appears. The author covers an amazing breadth of problems and gives sufficient discussion of the underlying principles for the reader to understand why the problem is occurring and how to solve it. I believe this text should be on the bench of every scientist who uses HPLC and wants to produce better separations and more reliable data, which is to say, all of us. Reviewed by Richard Hartwick, PharmAssist Analytical Laboratory
Marrying LC and electroanalysis Pulsed, Electrochemical Detection
Pulsed Electrochemical Detection in High-Performance Liquid Chromatography William R. LaCourse John Wiley & Sons 605 Third Ave. New York, NY 10158 1997, 324 pp., $59.95
Over the past 10 to 15 years, the enalytical chemistry community has seen a rapid
growth in the use of HPLC with pulsed electrochemical detection (PED). PED has extended the capabilities of HPLC to directly separate and quantitate carbohydrates, alcohols, amino acids, peptides, and proteins. This book contains timely, detailed information about PED-based measurements. The book is essentially composed of three sections. The first chapters are an overview of electroanalytical methods. In general, these chapters are best suited for the beginning student or for individuals who are less familiar with electrochemical techniques. The contents of these chapters, written for nonelectrochemists, lay the foundation for understanding HPLCPED. The second group of chapters concentrates on the theory and mechanisms underlying HPLC-PED methods. These very useful chapters include cyclic voltammetry data for some chemical reactions that occur at electrode surfaces under PED conditions as well as concepts behind various pulse waveforms for the detection of carbohydrates, alcohols, and amino acids. These chapters are primarily of interest to the advanced chemistry student or the professional with a background in electrochemistry. The final chapters of the book are devoted to applications of PED for the separation and quantitation of various compounds. Also included are chapters on HPLC-PFD ontimization and some of the potential nrohlems associated with electrochemical measurements. Finally, the book contains two appendices. Appendix A includes ASYST scientific software (version 4.0) for controlling PED measurements with a custom HPLC-PED system. Considering the unique nature of this system, the software is of limited value. Appendix B contains a compiiation of tables containing published applications, which should be very useful to a number of scientists. In general, the references cited in the tables and text are up-to-date and should be very helpful to a variety of inves-
tigators who are interested in HPLC-PED methods. One shortcoming of this book is that it contains no description of the currently available instrumentation for HPLC-PED. Numerous commercially available instruments are capable of performing such measurements. The inclusion of a discussion on the features of PED instrumentation would have been useful, so that future users of PED-based methods could more easily assemble their own systems. In summary, this book is a good compilation of chapters containing the theory of PED and actual applications of this growing technology. This book should be of interest to a wide variety of scientists who are interested in using PED coupled with HPLC. It will likely contribute to a further increase in the use of HPLC-PED methods. Reviewed by Greg A. Gerhardt, University of Colorado Health Sciences Center BOOK RECEIVED A Practical Guide to Graphite Furnace Atomic Absorption Spectrometry David J. Butcher and Joseph Sneddon John Wiley & Sons 605 Third Ave. New York, NY 10158 1998, 250 pp.. $69.95
Up-to-date coverage of nearly all aspects of graphite furnace atomic absorption spectrometry (GFAAS) is provided in this book. It opens with an introduction to GFAAS theory, nomenclature, and analytical methods, followed by a discussion of practical applications. Sections on sample preparation and introduction, calibration, avoidance of interference problems, method development, and commercial instrumentation are included.
Analytical Chemistry News & Features, August 1, 1998 545 A
