PRP-X110S Suppression

[vockhead]

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

[Markus Laeubli, Metrohm]

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.

[vockhead]

Hello Markus,

You were dead on, thanks for your help.