Identifying if a compound polarity?.... moblie compostion

[seamoro]

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

[grzesiek]

pKa's quite helpful

[Vlad Orlovsky]

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

[tom jupille]

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.