Troubleshooting: Too little suppressing current for KOH eluent.

[5kyul]

Hello team,

I need your insights on the recent incident we had on our IC. What happened was that one of our analysts set a wrong suppressor current (50mA) for a sequence using 35mM KOH as eluent (recommended is 87-141 mA). IC system was exposed to such condition for about 19 hours which caused serious damage on the cell and/or suppressor. What found to be even worse is that our suppressor is configured to recycle outlet stream from cell, i.e. alkaline solution had been fed to regeneration system, and that the cell and suppressor was stored in alkaline solution for at least 3 days. 

We have been replaced the cell and suppressor now to put the instrument back in service but I am investigating what exactly would have caused such damage and if there is any way to revive the affected parts (like if DI water flushing would work?). Please share your thoughts, thank you very much.

[The_Ion_Lady · Accepted solution]

@5kyul , what happens with electrolytic suppression when you under power it, is that the electrolysis doe not complete 100% so will cause contaminates inside the suppressor. Better way to rescue your suppressor is to do a "kick-start" Section 5.2.1 Suppressor Chemical Regeneration Steps which is detailed in the suppressor manual  (https://tools.thermofisher.com/content/sfs/manuals/Man-031956-IC-Dionex-ERS-Suppressor-Man031956-EN....). Then flush with 50mM eluent (with the right suppressor current). 

Yes, if you were using a very old suppressor (such as ASRS 300) on a very old IC system, then you may increase the current slightly higher. This comes from the old days of analog where the suppressor currents were controlled by an analog box that flicks from 50mA, 100mA...etc. Nowadays, we are digitalized so use what the software says 😊.

Your CD cell has obviously had lots of contaminates going through it with high base so the background is probably very high. It will take time to flush and clean unless the flashing didn't work and the electrodes in the cell are damaged. 

Good-luck!

[GeorgeTFS]

Hello @5kyul.  I am bringing in @The_Ion_Lady our resident guru in IC. I'm hoping she can help you. 

[IC-man]

hello 5kyul, 

The low current would have depleted the membrane.  running a rehydration step could have worked to revive the suppressor.   I was advised to run current above the recommended amount for an hour.  Do you normally run exterior source? I believe in your case this would be around 180mA.  If the suppressor was older then replacing it might be your best bet.  What type of suppressor do you have?   Ion Lady will help you. 

[5kyul]

Hello IC-man,

Thank you for your reply. I am not sure what you meant by 'exterior source'. My guess is that you meant an external water source for regeneration or an external power source. If it is the former case we are recycling the outlet stream from the conductivity cell; i.e. AutoSuppression Recycle Mode Operation, which is one of my major concern since the alkaline solution had been fed on the regeneration side of suppressor during the incident. If you meant the latter we are using the internal power source from ICS 2100. Our suppressor is the Dionex AERS (4mm) and I believe the model number is 500. I will check the exact model number when I get back to the office, but I know for sure that the suppressor has been operated for only 3 months. Thanks again for your advice.

[The_Ion_Lady]

@IC-man , excellent job!.

Running above normal suppressor current is only OK short term as it can burn out the electrodes inside the suppressor. 

[The_Ion_Lady · Accepted solution]

@5kyul , what happens with electrolytic suppression when you under power it, is that the electrolysis doe not complete 100% so will cause contaminates inside the suppressor. Better way to rescue your suppressor is to do a "kick-start" Section 5.2.1 Suppressor Chemical Regeneration Steps which is detailed in the suppressor manual  (https://tools.thermofisher.com/content/sfs/manuals/Man-031956-IC-Dionex-ERS-Suppressor-Man031956-EN....). Then flush with 50mM eluent (with the right suppressor current). 

Yes, if you were using a very old suppressor (such as ASRS 300) on a very old IC system, then you may increase the current slightly higher. This comes from the old days of analog where the suppressor currents were controlled by an analog box that flicks from 50mA, 100mA...etc. Nowadays, we are digitalized so use what the software says 😊.

Your CD cell has obviously had lots of contaminates going through it with high base so the background is probably very high. It will take time to flush and clean unless the flashing didn't work and the electrodes in the cell are damaged. 

Good-luck!

[5kyul]

Thank you so much for your reply with such details! 😁 It helps me a lot to understand and investigate the incident. Thanks!!!

[IC-man · Accepted solution]

This is what I have used from the manual.  This is the electrolytic regeneration( attached). I do think Ion Lady is correct with the kick start. Disconnect line from cell in from detector and run the suppressor eluent out to reagent in(have to use an adapter ).  Pump water for 20 minutes at 1.00mL.min.  make sure not to turn the suppressor on for this period. All of this is in the manual that Ion Lady provided.  I am learning so always confirm with the professionals.