Examples retention time, troubleshooting

We divided this section into two major subsections peak-shape problems and retention-time problems. The last section then covers problems that do not fit into the first two categories, such as pressure problems. This structure should allow you to quickly move to the chapter that covers the problem that you are trying to solve. In the section of peak-shape problems, example chromatograms should also help to point you to the most appropriate section. While this structure is good for rapid troubleshooting, it also makes repetition unavoidable. Therefore, we would like to remind the reader that this part of the book is not designed to be read as a consecutive text. 

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