| 摘要 |
An isocratic gradient profile is inserted into a gradient profile during a flash chromatographic run when TLC indicates that it will be difficult to separate the component being purified from its closest impurity by a gradient. TLC is utilized to determine at least two retention factors with two significantly different solvent strengths for the same solvent system. The two or more retention factors are used to determine a solvent strength in which the retention factor of a target component and the retention factor of a closest impurity are within 0.8 of each other. The isocratic gradient profile is started when this solvent strength is reached during the gradient chromatographic run. It is ended when the earlier of four events occurs, which are: (1) the end of a second peak if a first peak is detected at an isocratic-gradient profile starting-solvent strength or within a predetermined starting tolerance of the isocratic-gradient profile starting-solvent strength detection; (2) the end of the first peak after the starting tolerance; (3) the detection of a peak during the isocratic gradient profile or isocratic segment run after the regular isocratic time period; or (4) an operator initiated termination of the isocratic gradient profile or isocratic segment run. The gradient profile then resumes and continues to the end of the run.
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