Chromatographic Enandoseparation—methods and applications, 2nd edition

Chromatographic Enandoseparation—methods and applications, 2nd edition

1400 BOOKREVIEWS techniques (the chapter on phenols is all chromatography) is curious in that there is no apparent logic to it. Some of the techniqu...

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1400

BOOKREVIEWS

techniques (the chapter on phenols is all chromatography) is curious in that there is no apparent logic to it. Some of the techniques selected are in the mainstream of modem analytical chemistry whilst others are highly specialised and are likely to be of very little or no interest to many potential readers. Given the two-volume nature of the work, it might have been more prudent, and commercially adroit, to have grouped mainstream techniques in volume one and the more peripheral ones in volume two. The scope of the latter is as yet unknown but there are certainly many more widely-used techniques that could and should be covered. Inevitably one must compare this book with the established and more detailed volumes on instrumental analysis several of which are up-dated frequently and are generally available in relatively cheap student editions. However, the attraction (but possibly the weakness) of this book is that it includes more diverse and esoteric techniques. It is not a book for the individual but will provide libraries with useful and reasonably up-to-date introductory material and a source of references to more detailed information. D. KEALEY

The Important Peak Iodex of the Rq&try of Mass Spectral Data: Volumes l-3. F. W. MCLAFFERTYand D. B. STAUFFER, Wiley-Interscience, New York, 1991. Pages: viii + 1352 (Volume 1), 1353-2708 (Volume 2) and 27094057 (Volume 3). E576.50. This three-volume Index is derived from the “Registry of Mass Spectral Data”, published in 1989, which contains spectra of over 115,000 different compounds of established structure. With the proliferation of combined GC/MS and LC/MS instrumentation, reliable mass spectral data can now be routinely obtained on individual components of complex mixtures, without the need for isolation of the compounds themselves. This has generated an urgent need to identify the types of compounds which give rise to peaks at the masses found in the spectrum of a compound of unknown structure. Computer searching of MS databases does provide an efficient method for the matching of mass spectra, and recent advances have reduced costs in this area, but additional aids to interpretation are still required. One such adjunct is the widely used “Eight Peak Index” (RSC, 1983), which lists the most abundant peaks by m/z value. In this new Index, the peaks listed are chosen on the basis of their statistical importance, rather than just their abundance, according to a probability-based matching system. This more sophisticated system affords greater reliability in the matching of peaks for two main reasons (i) it eliminates all the commonly occurring low m/z peaks (which are usually the most abundant and the most infuriating) from the analysis, and (ii) it allows attention to be focussed upon those peaks which are of the greatest value in identifying an unknown compound. These innovations allow the number of possible structures to be narrowed down dramatically when higher m/z peaks are considered. The probability of occurrence of ions in the Registry database has been tabulated in terms of the “uniqueness value” (“U”) used in the probability based matching algorithm, U representing the log base 2 value for the probability that a reference will contain a peak of this m/z value of > 1% abundance. The “importance” rating of each peak for this Index is based upon the sum of the uniqueness and abundance values (U + A), thereby allowing ions of low to moderate abundance in the upper m/z range of a mass spectrum to be rated as highly as a base peak of low m/z value. As an aid, a one-line summary of approximate U and A values appears at the bottom of each page of the Index. The Index has been found to be extremely useful in identifying aroma volatiles from various sources by GC/MS headspace analysis. The rating system provides a mechanism for allowing for the differences between mass spectra obtained with different instruments and conditions, particularly as abundance variability can sometimes be considerable. Of course it is not possible to identify new compounds using this Index, but its novel features ensure that existing compounds in the molecular weight range of an unknown can rapidly be identified and eliminated from consideration. Each of these three volumes weighs no less than 51b 50~. Although the published price may seem high, it represents a rare bargain, for they are worth their weight in gold. A. B. TURNER

CbromatograpbicEnantioseparatio~etbods f55.00.

and applications, 2nd edition: S. ALLENMARK, Ellis Horwood, 1991. Pages 282.

The second edition of this book appears three years after the first. The original work was well received (for a review by J. L. Wardell see Talunta, 1989,36, No. 4) and the rapidly advancing field of chiral chromatography has provided the reason for this new edition. If you are new to this area of separation science and wish a good introductory text which also covers some recent work then this book is highly mommended. If you are an experienced practitioner in chromatography and have already purchased the first edition do you also buy this edition? If you wish to keep up to date then the answer must be “yes”. However, a comparison with the first edition may be of interest. The topics covered are essentially the same as in the first edition (the chapters have identical headings) but have been updated where necessary by reference to more recent literature. The most obvious difference between editions is the inclusion of additional experimental procedures for the synthesis of chiral sorbents. In particular, several techniques used for the binding of chiral selectors to silica are now presented. Chapter 10 on “future trends” is also of interest as the newly developed diode-laser-based micropolarimetric detectors (a “future trend” in the first edition) is now mentioned

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as a commercial reality. Chapter 10 also contains new details of computer-aided optimization of mobile-phase systems. Overall the book length has increased from 224 to 282 pages, some new exercises (without answers) have been added and references are now quoted up to 1991. P. J. Cox