When optimizing the solvent system only one solvent is varied at a time.
In this optimization step, a small amount of the sample is dissolved in test tubes containing various ratios of the biphasic solvent system and then partitioned between the two phases in a test tube. Both upper and lower phases are then examined by tlc etc. The partitioning results when examined and visualized by TLC to give a good indication of potentially successful CCC solvents. Since we chose the organic phase as the stationary phase ( reverse phase operation of the CCC ) the amount of methanol in the aqueous phase is varied, in order to pull the compounds from the organic phase into the mobile aqueous phase as the amount of methanol increases.

Note : Whilst this technique of tlc/test tube partitioning screening often proves to be accurate in predicting suitable CCC solvents, as we show for this example, it is not universally successful. Researchers should be aware that successful test tube partitioning / tlc does not guarantee successful CCC, plus a lack of resolution by tlc does not mean that this system may not be successful by CCC. Often it is best to do a generic CCC gradient to predict which solvent will be appropriate ( Dr Les Brown, is available to Quattro users / potential purchasers to discuss any CCC applications ).

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