By Anonymous on Thursday, May 10, 2001 - 12:11 am:
Hi,
I have to pepare the following mobile phase recipe:
Pot. Dihydrogen phosphate (10mM): Acetonitrile: Triethylamine [ 40:60:0.02]. I have to fix the pH at 6.0 and then add Acetonitrile.
1. Which one of the two acids [hydrochoric acid / phosphoric acid] should I employ? Does it make any difference?
Alternatively, Can the mobile phase be prepared as indicated below:
Go for Dipotassium hydrogen phosphate (dibasic) instead of Potassium Dihyrogen phosphate (monobasic), add triethylamine and adjust the pH to 6.0 using phosphoric acid/HCl and then add acetonitrile?
2. Will both the buffered mobile phase prepared using different salts behave in the same manner? Is there be any flaw in the method of preparation of the buffer?
Thanks for your valuable time.
By Anonymous on Thursday, May 10, 2001 - 06:45 am:
Do your own homework.
By Anonymous on Thursday, May 10, 2001 - 07:21 am:
Why in some methods, amine or diamines are added to mobile phases?
By jclark on Thursday, May 10, 2001 - 08:11 am:
Amines are added to the mobile phase to outcompete basic analytes for the acidic sites on the stationary phase that would result in secondary retention and tailing of basic compounds.
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