Hi everyone, we are having an issue with our Dionex ICS 5000. We are analysis phenol levels in alcohol samples from different distilleries within the company using HILIC and electrochemical detection (glassy carbon electrode) and gradient elution. We were running our samples very happily on an old Dionex ICS 500 machine, but about a year ago we upgraded to the ICS 5000 and have had issues with peak height in our phenol analysis ever since. Basically our peak heights sequentially drop with each sample we run until no peaks are detected (this only happens with phenols and not with our carbohydrate analysis on the same system but with a different column and eluents). We have tried everything from multiple different cleaning methods for the glassy carbon electrode, changing both the reference and glassy electrodes, changing the detector, buying new reagents, changing the column, and getting thermo involved and nothing has worked. We are now back to using the old ICS 500 as it has never had this issue. Thermo don't seem to have any idea of what could be the cause either. Can anyone help? Many thanks
Dear Angela,
Which operating potential/s and detector temperatures are you using.
Kind regards,
Ade Kujore
Marketing
Cecil Instruments Limited
Milton Technical Centre, Cambridge CB24 6AZ
United Kingdom
email:- [email protected]
telephone:- +44 (0) 1223 420821
fax.:- +44 (0) 1223 420475
web site:- www.cecilinstruments.com
Dear Ade,
For the DX5000 our detector temperature is not set so would just be ambient, and the operating potential is 1.2 v. For the DX 500 we run the detector at 35oC and at a potnetial of 1.2 v.
Many thanks,
kind regards,
Angela
Dear Angela,
At this stage, I would be tempted to run the new electrochemical detector at 35 °C. Is your baseline stable, if it is not, it may be worth decreasing the potential a little.
Kind regards,
Ade
Forgot to say, yes the baseline is stable just the peak height really, drops to zero over about 6 to 8 standard samples.
Thanks again,
Angela
Hi Ade,
We tried running some standards with the detector compartment set to 35oC and also cleaned and sonicated the glassy carbon electrode. The first standard result was perfect, but after that the peak heights dropped off again.
Thanks,
Angela
Dear Michael,
Thanks very much, we will give it a try and see what happens.
Thanks again,
Angela
Hi Angela,
I agree with Michael. Do you have pulsing options on your detector.
Kind regards,
Ade
Hi Ade,
Yes we use integrated amperometry mode for our carbohydrates analysis. We are going to do a run tomorrow with the detector on IA mode and see what happens. We will also try purging the detector.
Many thanks again,
Angela
Hi Ade and Michael,
We tried a cleaning cycle and it didn't work, then it was noticed that the reference electrode setting was changed just as the results started going bad, we changed it back to what it was originally and all seems to be ok now.
Thanks very much for all your help and suggestions.
Best regards,
Angela
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