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Techniques in Analytical
Chemistry Series. Wiley-Interscience: New York, 1997. 420 pp.
Figs and tables. ISBN 0-471-11914-8. $69.95.
This book, the latest in a series covering
contemporary analytical techniques published by Wiley Interscience, is
the most thorough review of this important
high-performance liquid chromatography (HPLC) detection technique to
date. Although it affords a very thorough background and
introduction to the basic science behind the technique that
could be used for an advanced undergraduate or graduate
studies course, it is written with the chromatographic
practitioner in mind.
Pulsed electrochemical detection (PED) is the
generic name given to a set of electrochemical detector
operating modes in which a pulse program is applied to a
noble-metal working electrode to bring about continuous
electrode surface regeneration, in order to overcome deactivation by
surface fouling. This method of detection in HPLC has
become indispensable in many applications in which the analyte
of interest is weakly absorbing in the UV but does possess
an electroactive polar constituent such as a hydroxyl, amine,
or sulfur-containing group. PED techniques have seen
particular use for the selective and sensitive detection of
carbohydrates and small amine compounds.
Organization of the book is logical and flowing. The
first few chapters introduce the history of the detection
technique and impart the fundamental electrochemical
knowledge necessary for the reader to understand how and why
the technique works the way it does. The second chapter,
Electrochemical Fundamentals, is an especially impressive review
of fundamental electrochemistry, presenting as it does a
selective review of pertinent background information. Rather
than weaving a tortuous path through the entire field of electrochemistry,
LaCourse steers a straight and narrow course
that touches upon only those areas that are important for the
understanding of the PED techniques presented in later
chapters.
With the basic information dealing with
electrochemical science out of the way, the book then reviews the
interface between electrochemistry and high-performance liquid
chromatography. After reviewing amperometric
electrochemical detection and cell design considerations, the author takes
up the topic of using pulsed waveform programs during
detection to overcome the shortfalls of nonpulsed detection. He
explains in detail the mechanistic differences between the three
major modes of detection in PED, namely, (i) direct detection
at oxide-free surfaces, (ii) direct oxide-catalyzed detection,
and (iii) indirect detection at oxide surfaces. From a
fundamental knowledge of the state of the working electrode surface as
a function of potential, LaCourse guides the reader
to an understanding of which mode of detection works best
for what compound.
Turning to the more practical aspects of using PED
in HPLC, the author includes a very useful discussion of
waveform optimization using pulsed voltammetry (PV). In
this technique, parameters such as pulse duration and
potential can be varied in an automated fashion while monitoring
the background-corrected response towards the analyte. As
the author points out, using this technique to optimize
waveform parameters can save the analyst significant amounts of
time, effort, and sample when compared to the more
common practice of recording the magnitude of the detector
response by repeatedly making injections while manually adjusting
the parameter undergoing optimization. Because of the absence
of commercial PV instrumentation, LaCourse includes
details on the instrumental aspects of performing PV
experiments, including an ASYST Scientific Software program for
generating the PV waveforms.
The next portion of the book provides detailed
information on the specific applications of PED, by
compound class, published to date. This section is immensely
informative as a guidepost to those with a specific application in
mind. The last sections of the book deal with instrumental
aspects of PED and the author's perception of where the
technique will go in the future.
In summary, this is an excellent review of pulsed
electrode techniques of detection in HPLC. It is thorough
and well written, serving as an outstanding review of the
theoretical aspects of the technique while simultaneously being
a useful, practical guide for the HPLC practitioner wishing
to make immediate use of the technique.
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