Book Review

Spot Test Analysis 2nd Edition by E. Jungreis Wiley Interscience, 1997, 377 pages, Vol. 141 in the Chemical Analysis series of monographs on analytical chemistry and its application. Series Editor J. D. Winefordner. ISBN 0-472-12412-5. The book covers a wide range of applications of spot and screening tests in areas such as clinical, forensic, geochemical, environmental (air pollution, water quality, residues in plants and soils) and food adulteration. The aim of all of these tests is to provide a rapid, qualitative or semiquantitative, result with the minimum of cost and fuss, and often in the field rather than the lab. The book opens with a brief description of the history of the spot test, outlining the various ways in which they have been used. This is following by another brief chapter on the techniques used in this type of work, ranging from simple colorimetric reactions, tests with papers impregnated with reagents etc., precipitations; up to more sophisticated (at least in terms of the technology employed to produce the test kit!) immunoassay systems. The chapters that follow are devoted to the various application areas outlined above and provide short descriptions of a very large number of tests, covering a diverse range of anaIytes. The bulk of the method descriptions are very short, usually of the order of half a page or less. As someone who hasn't done a spot test for a very long time, I would feel a little uncomfortable about trying to perform many of the tests without consulting the original scientific or manufacturer's literature. However, whilst the descriptions of the tests are short there is sufficient detail to get a good idea of what each method involves. Some of the methods sound very exciting to perform. For example, I was entranced at the idea of attempting the spot test for sulphur (in explosives) involving the formation of mercuric sulphide. The sample, dissolved in carbon disulphide is shaken with mercury, and the black mercuric sulphide collects on the surface of the metal. Further confirmation of the presence of sulphur can be obtained by removing the bulk of the solvent, taking the mercury and

heating it on a watch glass to remove remaining carbon disulphide, and then covering with a solution of the iodineazide reagent. A foam of bubbles of nitrogen indicates the presence of free sulphur. Marvelous chemistry (and it certainly takes you back), but I shudder think what our safety committee would say about a proposal to perform that one on a routine basis ! One of the nice things about the book is that there is a fair amount of explanation of the underlying chemistry, backed up with clear structures and equations. However, these represent the only illustrations. If there is a book that could really benefit from some good quality colour photographs of typical results, this is it. Given the colourful nature of many of the spot tests described such illustrations would be a nice addition, and greatly enhance the value of the book. A minor irritation is the use of both normality and molarity. It is bad enough to see 0.1 N HCL or NaOH when the term is used consistently, however, when N and M are used interchangeably, on the same page and sometimes for the same reagent it becomes a little tiresome, especially when you have to spend time explaining what it means to a young person who was only taught about M and not N! The work appears to be well referenced, although there are few to the recent literature (possibly reflecting a mature field) and there is a fairly comprehensive 17 page index. To anyone like myself, used to dealing mainly with quantitative instrumental analysis in a well equipped laboratory, spot tests like those described here seem to hark back to a different era in analysis. However, a lot of these tests are performed, often under difficult conditions and it is always worth examining different approaches and methodologies. After all some of the chemistry described may afford opportunities for adaptation to applications elsewhere (I have not found any to my own work yet but I ' m still looking!). As an introduction to spot tests this seems a very reasonable, and reasonably priced, place to start. I. D. Wilson

Chromatographia Vol. 46, No. 11/12, December 1997

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