Chromatography Forum

Hello,

I was wondering if anyone had any experience using a membrane suppressor with the PRP-X110S column? I'm using a 4 mM parahydroxybenzoic acid, 5 mM NaOH, and 0.1 mM sodium thiocyanate eluent in 2.5% MeOH, but am trying to figure out the appropriate regenerant.

I'm using a Dionex AMMS 300 suppressor, which states that the dynamic concentration through the suppressor for eluents such as NaOH and HCO3/CO3, is to multiply the normality of the mobile phase by 7 to figure out the dynamic normality of your regenerant.

The only thing is, those eluents are all bases, while the PRP-X110 column has an acid within the eluent, which I'm guessing can't be suppressed. So would the normality of my eluent by 5 mN NaOH and the 0.1 mN thiocyanate and ignore the parahydroxybenzoic acid as it is an acid already?

Any help would be greatly appreciated,

Thanks,
Vick

Dear vockhead

In your eluent the parahydroxibenzoic acid is titrated by NaOH. Your eluent composition is (inorganic part):

4 mmol/L sodium parahydroxibenzoate
1 mmol/L sodium hydroxide
0.1 mmol/L sodium thiocyanate

This makes up to 5.1 mmol/L sodium which has to be suppressed. The anions are only of interest as after suppression the dissozation of the respective conjugated acids add to the background conductivity.

Hello Markus,

You were dead on, thanks for your help.