Chromatography Forum

Hello,
I have a method to analyze Phenylepthrine using HPLC based of the method here:
http://www.phenomenex.com/Application/Detail/3246
The only difference is I'm using a slightly lower flow rate at 0.7mL/min
It works wonderfully for Phenylephrine by itself,but now I am trying to analyze a solution with Phenelyephrine HCl, sodium chloride, sodium bisulfite, and edetate disodium and I have two peaks that are very close to each other.
Any tips on how to get these two peaks to separate better without drastically changing the method? I've already tried altering the flow rate and temperature...
Thanks!

Use a 5 cm Luna column. Eliminate Octanesulfonic Acid (its obsolete) and replace it with 0.05 M Phosphate buffer pH 3.0. Go gradient to tease these peaks apart.

Its apparent this Phenomenex method does not work for your sample matrix.

Thanks for the reply! I have replaced the Octanesulfonic Acid with acetic acid (pH 3.0) do you think the buffer is necessary to desperate or will the gradient surfice?

Gradient. We could only separate Acetaminophen, Phenylephrine, Doxylamine HBr, Diphenhydramine, and Chlorpheniramine HCl using gradient and wavelength shifting.

Would you mind sharing a method?