Chromatography Forum

If you are given a compound with a known molecular structure...is it possible to work out its polarity through its electronegavity of its atoms? and therefore with the information of its polarity you can better tailor a moblie phase for its retention/eluation? or is there a simplier way to do this? thanks in advance

pKa's quite helpful

The following guide will explain you how to decide on the column and mobile phase, based on the properties of your compound:
http://www.sielc.com/MethodDevelopment_ ... dType.html

here are few tables on mobile phase and column selection:
http://www.sielc.com/MethodDevelopment_Guide.html

Contact me if you have questions

is it possible to work out its polarity through its electronegavity of its atoms?

Yes

and therefore with the information of its polarity you can better tailor a moblie phase for its retention/eluation?

Not really. I agree with the two previous posts that *general* information about your molecule is extremely useful for choosing an initial column and mobile phase, but detailed computation really doesn't add much.

or is there a simplier way to do this?

Yes. Run a full-range gradient on your chosen column (typically 20 minutes for a 150 x 4.6 mm @ 2 mL/min; scale time for other dimensions and flows) and enter the retention times of the first and last peaks into a spreadsheet you can download from the LC Resources web site (http://www.lcresources.com/more_resourc ... hp?f=7&t=8 note that you will have to register on the site before you can access the "Scouting Gradient Spreadsheet"). That will recommend either isocratic or gradient elution and suggest a reasonable initial %B or gradient range.