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Analyzing anions and cations in polar organic solvents

IC-man
Involved Contributor II
Involved Contributor II

I have been analyzing anions and cations in Organic polar solvents (DMF, NMP, DMAC) .   I usually do a 1:10 dilution.  The max % after dilution is  7%. Most of the time the amount is around around 2%.  I inject 25uL, ICS 6000, A(c)DRS 600,  AS19 4um, CS 12a, flow 1.00min, KOH or MSA, conductivity.  I have found the non-polar solvents trapped in these solvents are the true headache( mecl2, TCE etc....    I  filter through c18 SPE always.  This only removes the nonpolar solvents.  Believe it or not I don't see major problems.   How do the polar organic solvents cause problems in the IC system above.  I know alcohols are bad for suppressor.  I am planning on changing over to exterior water with pump.  Also, I have been informed the caps are for secondary filtration only with an As/DV autosampler.  Any tips?  

Thanks, 

3 REPLIES 3

GeorgeTFS
Community Manager
Community Manager

Hello @IC-man, Thank you for your patience as we try to get you some feedback. @The_Ion_Lady will get back with you. Best regards.  

The_Ion_Lady
Team TFS
Team TFS

@IC-man , Going to external water definitely helps when it involves organic solvents (whether it's polar or non-polar), this will help up to about 40% organics. If it's higher then best to go to Chemical Suppression. 

There are other ways to trap organic with OnGuards or InGuard traps or maybe just a guard column like the IonPac NG1:

https://assets.thermofisher.com/TFS-Assets/CMD/manuals/Man-031688-IC-OnGuard-II-Cartridges-Man031688...

https://assets.thermofisher.com/TFS-Assets/CMD/manuals/84276-Man-065345-01-INGUARD-Dec09.pdf

https://assets.thermofisher.com/TFS-Assets/CMD/Specification-Sheets/ps-70526-concentrator-column-ps7...

For the AS-DV caps with the standard filters are only 20µm so you may need offline finer filters instead, but there are a range of Guardcaps that have built-in resins in such as HRP that removes surfactants and other hydrophobic matrix:

https://assets.thermofisher.com/TFS-Assets/CMD/manuals/Man-065705-Guardcap-H-Vial-Caps-Man065705-EN....

 

Have a look and see what is the best approach for your sample matrix.

 

Have you seen my Dr Yan Liu's Teach me in 10, talking about sample prep in IC? https://www.technologynetworks.com/analysis/videos/simple-and-effective-sample-preparation-technique...

Good-luck!

 

 

IC-man
Involved Contributor II
Involved Contributor II

thanks for video.

1)  knowing the amount of metal and or non polar organics is my concern with caps.  The caps are easier but when in doubt use the on guard 2.5 cc , much higher capacity.  Unfortunately,  I inject simultaneously( cations and anions).  I use the entire 5 mL. I could plug the cation portion then inject 2.5 mL.  If the metal is below 100ppm I probably would be safe using the caps.  Is this a correct assumption?

2) how does injecting 25 uL of 5% DMAC or DMF affect the suppressor.  I know recycle mode is not recommended.  

I am so happy to have you guys!!!!

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