I am getting unusual elution profiles. I have been using the feature to create a gradient from TLC and have been loading the sample in the developing solution for TLC. This is always a more polar DS than the initial eluent.
For instance, if my TLC DS is 15% ethyl acetate in hexanes, the gradient might start at 5% ethyl acetate and finish at 40% ethyl acetate. I'm wondering if loading my sample in 15% ethyl acetate (not 5%) could cause issues.
Hello sir you dissolve your sample in low % of ethyl acetate, after loading dry it completely and use slow gradient. Before starting make sure about your column packing.
I use Teledyne Isco systems, but the loading is similar. I suggest, if possible, to use dry loading for best results. If you must use liquid load, use the minimum amount of the strong solvent as possible.
As for the gradient, use the gradient they suggest . I find shallow gradients tend to take longer and produce broad peaks, wasting solvent and increasing drying time. There are times where a shallow gradient is best.
Please see:
For loading techniques:
http://www.isco.com/WebProductFiles/Applications/101/Application_Notes/AN29_Overview_of_Silica_Column_Sample_Loading_Techniques.pdf
http://www.isco.com/WebProductFiles/Applications/101/Application_Notes/AN88_C18_Flash_Column_Loading.pdf
Gradient methods:
http://www.isco.com/WebProductFiles/Applications/101/Application_Notes/AN89_CombiFlash%20Gradient%20Methods.pdf
With some columns, adsorbing on silica may not be the best idea:
http://www.isco.com/WebProductFiles/Applications/101/Application_Notes/AN82_Comparison_of_Solid_Load_Cartridges_and_Reservoir_Type_Columns.pdf
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