By Sean on Monday, September 20, 1999 - 05:31 pm:
When we say that an analyte is neutral or ionized
what do we mean by that-at a particular pH or in general? And supposing a compound is given to us and nothing is known about its ionization,how do we determine that?
By lisa on Wednesday, September 22, 1999 - 02:28 pm:
When speaking of an analyte being neutral or ionized, there needs to be a reference to pH. If you know the pK of the compound and the basic structure (functional group(s)), the compound will be in form HA if pH is pK by at least 2 units. If the pH is within two units of the pK in either direction (generally speaking), your chromatography will be AWFUL--the peak will go up sharply, then broaden, then come down eventually.
By AHackman on Friday, September 24, 1999 - 08:55 am:
Sean,
For more information on analyte ionization, see the following:
www.alltechweb.com
Promotional literature
Alltech Brochures
HPLC
333 Separation Science Today
page 8.
For a more detailed explanation on ionic samples, pH, buffers, etc., see chapter 7 of:
Practical HPLC Method Development, 2nd ed, Lloyd R. Syder, et al.
Excellent book!
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