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CN with IC
Posted: Mon Mar 30, 2020 9:06 pm
by georgi
Hi, I need help to solve the problem of free cyanide determination by ion chromatography. The eluent is a solution of Naoh-100mmol/l and EDTA -0.01mmol/l. As can be seen from the picture, no peak appears when testing a real sample, while at a standard peak it is clearly visible even at low concentrations. If anyone has encountered such a problem I would be glad to share the experience.
Thanks in advance.
https://dox.abv.bg/download?id=d80e53372a#%20
https://dox.abv.bg/download?id=21b483218c#%20
Re: CN with IC
Posted: Tue Mar 31, 2020 6:07 am
by Markus Laeubli, Metrohm
Dear Georgi
What is the real sample?
Be aware that only free cyanide is determined. If bound cyanide is in the sample this cannot be determined.
Re: CN with IC
Posted: Tue Mar 31, 2020 10:23 am
by georgi
Dr. Markus Laeubli,
The sample is tap water and another sample is river water. In both cases I do not know what cyanide is present in the sample. What I'm looking for are free cyanides, not related cyanides. What puzzles me and I don't understand is this baseline breakdown / assuming there are no cyanides in the sample. And it should not be because it is drinking water./
Re: CN with IC
Posted: Tue Mar 31, 2020 11:23 am
by Markus Laeubli, Metrohm
Dear Georgi
I assume the the additional "peak" is a matrix disturbance.
I will check with my colleague which actually works with amperometric detection. and come back to cou later.
Best regards
Markus
Re: CN with IC
Posted: Tue Mar 31, 2020 11:31 am
by Markus Laeubli, Metrohm
I assume that you are using one of our instruments.
Would it be possible to send me the exported determination files.
to
markus.laeubli@metrohm.com
Best regards
Markus
Re: CN with IC
Posted: Tue Mar 31, 2020 12:08 pm
by Markus Laeubli, Metrohm
A fast check on your side would be to spike the water asmple with cyanide to check whether you can recognize a cyanide peak in water.
Re: CN with IC
Posted: Tue Mar 31, 2020 1:23 pm
by georgi
I also made a spike to this water. The peak is divided into two symmetries. I'll send you the chromatograms later. Thank you.
Re: CN with IC
Posted: Wed Apr 01, 2020 11:30 am
by Markus Laeubli, Metrohm
Dear Georgi
We had a look to the commatrograms and our final comment (after our internal discussions) are: the baseline disturbance most probably comes from the matrix, e.g. carbonates, meatals etc.
One possibility to lower the the effect could be the use of a longer column (more capacity and more separation).
The other possibility (which we recommend) is applying a distillation step as requested in e.g. ASTM D2036 - 09 (2015), DIN 38405-13.
Best regards
Markus
Re: CN with IC
Posted: Wed Apr 01, 2020 11:38 am
by georgi
Dear mr. Laeubli,
Thanks a lot. I'll try distillation and write about the effect.
Thanks for your time.
Be healthy.
Greetings