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Record: 88

Category: Column Selection
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Question
This customer is at Ohio State and they are looking for an IC system to isolate formate (concentration from ppm up to about 5%) and acetate (concentration above 5%) from sulfate/phosphate/bromate. The other ions they are not interested in also have concentrations above 5%.

Answer
As you mentioned, KC-811 is one option. And with a conductivity detector, the high concentration can be a good thing, as shown in the link below (actually now I’m bit worried if the concentration is too low for CD to detect..).
http://www.shodex.com/english/dc030821.html
Inorganic anions will not be retained, so they will be eluted earlier. The application shown uses two KC-811, but I think one column should work.

Another comments & options are:

SO4- may be retained strongly on I-524, so this column is not recommended.
http://www.shodex.com/english/dc070203.html

NI-424
If non-suppressor mode is preferred, NI-424 will be a better choice.
Again, with conductivity detector, high concentration can be injected.
http://www.shodex.com/japanese/dc070617.html

SI-52 4E with suppressed conductivity.
I’m sorry I don’t have information in English, but using 3.6mM Na2CO3 as a mobile phase at 45oC, formic and acetic acids can be separated.
With 0.8ml/min flow rate, they elute around 6 and 7.5 min, while phosphate, sulfate, and bicarbonate elute at much later time (run time ~36min).
If concentrations of both formic and acetic acids are high, there will be a possibility of them overlapping, so this method will not be my best recommendation, when quantification of those two are the main purpose.

 
 
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