Chromatography Forum

I try to assay the Guanidine hydrochloride in sample with EDTA.
The EDTA eluted with guanidine in 20 mM MSA on AccQTAg Waters C18 3.9 x 150 mm, 4 µm column, 1 ml/min.
Detection in UV, 190 nm but not good partition between both.

What's the most best analysis for assay guanidine sample with EDTA ?

Here is a method for analysis of guanidine. Guanidine will retain by combination of RP (week interaction) and cation exchang. EDTA will not retain by cation-exchange as well as guanidine due to the presence of 4 carboxylic acids (slightly off void on this column). If you go with 150 mm column you will retain guanidine for 12 minutes. You can use MSA or sulfuric acid for UV. Our method was for ELSD and UV:

http://www.sielc.com/compound_049.html

Thanks a lot !!!

But what's the molarity or concentration of MeCN in gradient ?
I have a liquid stock solution of MeCN 1 M

Mobile phase : MeCN/H2O/TFA in 25/75/0.05 %

Kurian,

In our method there is no gradient. It is isocratic run with acetonitrile/water/TFA=25/75/0.05.(250 ml ACN, 750 ml of water and 0.5 ml of TFA). You can use other buffers/acids (ammonium acetate or formate, phosphoric acid, sulfuric acid, etc.). In case on phosphoric and sulfuric acids you need to use UV detection. You can adjust retention by changing amount of the buffer (acid) in the mobile phase.