Chromatography Forum

Does anyone know of a way to measure Sulfuric Acid/Sulfate Ion by HPLC? Currently I am trying to measure 0-100ppm Sulfate using an Indirect UV method I found on the Hamilton website. It uses a PRPX100 column and uses Hydroxybenzoic Acid in H2O/MeOH, pH 8.9 for a mobile phase. I believe I can see the sulfate ion peak but it is very broad and low levels are hardly distinguishable.

Has anybody used this before or something that works perhaps better than this?

We use a PRPX100 column (100mm x 4.6mm i.d.) but with 4.8 mM KHP HPLC mobile phase (0.97 - 0.99 g KHP into a 1000 ml volumetric flask; mix and dilute to volume with HPLC water, filter through a 0.45u membrane filter). Our peaks are nice shape at about 4 minutes at 1.00 ml/min.

We use conductivity detector for this (I've never tried with UV detector and vacancy chromatography).

here are few methods for analysis of sulfate (the last one us used by two pharma companies). ELS detection with ammonium formate or acetate
http://www.sielc.com/compound_315.html

Contact me if you have question.

[quote="Consumer Products Guy"]We use a PRPX100 column (100mm x 4.6mm i.d.) but with 4.8 mM KHP HPLC mobile phase (0.97 - 0.99 g KHP into a 1000 ml volumetric flask; mix and dilute to volume with HPLC water, filter through a 0.45u membrane filter). Our peaks are nice shape at about 4 minutes at 1.00 ml/min.

We use conductivity detector for this (I've never tried with UV detector and vacancy chromatography).[/quote]

This method sounds similar to the one I am using but with conductivity. Do you have anything else in your samples? Do you do any extractions before shoot on your samples? I ask because I am trying to measure Sulfuric Acid in process samples so there is a lot of other compounds in the sample. So I have to extract an aqueous layer (which should hopefully contain nearly all of the acid) before I run the sample.

How did you set the pH at 8.9

Just mentioned this in another post. I use the same column, 5 mM NaOH, 4 mM p-hydroxybenzoic acid, 0.1 mM NaSCN and 2.5% MeOH as our mobile phase. Haven't had any problems.