Without more information on your chromatographic procedure and nature of compound it is difficult to give you good advice. In general, small inner diamater and long column is best for resolution (of two peaks) but if your column is overloaded than you should have chosen a larger diameter.

For better resolution, you should go with 1cm diameter than 4cm but overloading should keep in mind as said by Ines Mulder Kannewischer.

In liquid chromatography, contrary to capillary gas chromatography, the internal diameter of a column has no effect on the efficiency of a separation (provided the mobile phase velocity is adapted). The choice of the correct diameter will depend on the amount you wish to inject at a time. Wider columns can accept higher amounts and volumes, but cost more.

Thank you all.........but can you elaborate more on overloading issues.........

Overloading means injection volume or sample concentration more than column capacity. So injection volume must according to column dimensions.

Hi,

For better resolution lot of different factor play role. Like which type of column you are using. For better resolution column length do play a role in separating different molecules but most imprtant is concentration of your sample. So if you know the concentration of sample and the loading capacity of your column then you dont have to consider the lenth. You can use either column keepin gin mind the concentration and volume of your sample.

If you provide more info then more better suggestion can be given as your question is too general in chromaography.hoping this general info give you some help !

I am using burette as a column and the yield of my compound after soxhlet extraction is 5g.

What is the molecular size of your compuund and wich type of resin you are using. How much amount of material you are loading and what is the binding capacity of your resin. Without these info it very difficult to answer your question !

compounds are terpenoidal, silica gel mesh 60-120 I am using, i have dissolved my compounds approx. 5g in the solvent itself....and then adsorbed them on 5g silica and loaded on the column which had around 40g of silica..now can you suggest something!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Your loading material should be 1/3 of the packing material of the column. Then you get you desired column length.

For this type of purification you can take silica around 20 times of the loading material if you want to have a better reoslution and separation of different constituents. In this column lenth has nothing to do but depend on the resin and loading material amount in better way. so for example i guess for 5 gm compund you use 100 silica or you can adjust loading materail accordingly doing in sequence. Essential Oil Purification

On DAVISIL® Chromatographic Silica Media, may be u can try this gel and if u using same then go ahead and try. Its just a suggestion and not a perfect method i am suggesting. Hope it will help you this in seomways. ! Good Luck !

Yes, 40g silica is enough to separate the compound. Now you can go from low polarity solvent to high polar. Then you will separate it. If you know the nature of your desired compound then go through literature for solvent polarity. After that you should start.

Thank you all for your suggestions.....now i am more confident in proceeding.....thanx a lot!!!!!!!!!!!!!!!!!!!!!!!!!