Ion suppressor question

Record: 604

Category: Specifications
Product: IC
Sample:

Question
I’ve never seen a suppressor used for cation analysis. I think the reason is that the typical mobile phases for cations don’t have any background conductivity that needs to be suppressed, or maybe the conductivity of the analyte cations is huge compared to what’s in the mobile phase (like HNO3) so it’s not necessary.

Kanna – can you help me with this one? Is my answer correct, or are there other reasons why a suppressor is not used for cations? Glenn works for our distributor in Canada and occasionally has questions about ion chromatography. Thanks for your assistance, as always!

Answer
Often used solvents do not have high conductivity.
Please see table 3-2 on the linked technical note book below.
http://shodex.net/data/downloads/Shodex_Technical_Notebook_4_YS-50.pdf

So suppressor is not necessary for cation chromatography, but if someone is trying to achieve lower detection limit, it will help.
You may compare Fig 4-1 vs. Fig 5-1. The scale is almost same. For some cations (e.g., Mg and Ca) you can see the signal intensity is higher with suppressed method.

 
 
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