The second module covers HPLC pumps and gradient elutions. It begins by reviewing the most popular mobile phase solvents, including important physical properties such as viscosity and detector compatibility, and mobile phase additives, such as buffer salts. The central topic of the module, however, is the general elution problem of identifying a mobile phase that can separate both strongly retained and weakly retained solutes. A simulator, in which students adjust the mobile phase’s solvent strength in an isocratic separation, nicely illustrates the general elution problem. Although the module introduces the use of a gradient elution as a solution to the general elution problem, the authors miss an opportunity to include a simulator that challenges the student to discover an optimum gradient for a separation. The remainder of the module discusses the need for filtering the sample before injection and the basics of HPLC pumps. These topics, although important, seem out of place in what is an otherwise useful module.

The final two modules cover HPLC columns and detectors, data analysis systems, and method development. The module on columns is very thorough, presenting information on both normal and reverse phase columns and providing examples of typical applications. The module also provides an introduction to ion-exchange chromatography and size-exclusion chromatography. The final module includes short but useful descriptions of the most common HPLC detectors. A brief discussion of method development provides students with an appreciation for the general approach to developing HPLC methods. This module also includes a simulator that allows students to investigate the effect of column efficiency, column selectivity, and retention on chromatographic resolution. Although useful, the simulator feels out of place in this module; it would have been better placed in the first module.

Each module ends with a short quiz of multiple choice or true/false questions that largely test a student’s recall of facts; a few questions require calculations. The quality of the questions is highly variable, with some probing only trivial details. At the end of the quiz the student receives, for each incorrect answer, a suggestion of a page to review; unfortunately, the page to which the student is directed does not always provide a suitable explanation of the question’s answer.

As might be expected of a computer-based learning program, the modules take advantage of animations to enhance the presentation. The most effective animations are those that encourage interaction by the student. For example, an animation on column efficiency includes a slider for controlling peak width; this helps students appreciate that narrower peak widths improve the resolution between two solutes. Most animations, however, do not contribute significantly to the module’s content or effectiveness. The program also includes an audio narration of the text, but the quality of this computer-based narration is disappointing. Finally, the modules include internal links to an extensive glossary and bibliography.

Although the modules are free of errors, the authors often miss the opportunity to clarify topics or to extend a student’s understanding of the material. Two examples illustrate this point. In the first module, when introducing t0 as the “time required to elute a nonretained species,” it would be helpful to clarify this statement by noting that a nonretained solute molecule takes, on average, the same amount of time to pass through the column as the average solvent molecule and, therefore, moves through the column with the same velocity as the mobile phase. In the second module, the authors state that some separations require the use of mobile phase additives, such as a pH buffer; what they fail to do, however, is explain why pH matters or to provide an example of how controlling pH can improve a separation.

The publisher suggests that the modules in this course will be valuable to a student who is new to HPLC or who is seeking a review of HPLC, and to a college instructor who needs materials to supplement his or her course. Although these modules provide an adequate review of HPLC, a novice to the subject will find an introductory analytical chemistry textbook to be of greater use. Given the availability of many freely available Internet resources on HPLC—a search, for example, of the Analytical Sciences Digital Library (accessed Nov 2006) for HPLC yields 53 results—faculty members probably will not find that investing limited financial resources on this program to be worth the price.