Negative peak on Dionex ICS5000

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4 posts Page 1 of 1
Hello everyone,
I am a PhD student. I am using a HPCAE-PAD to quantify sugars coming from acid hydrolisis of biomass samples. Samples are neutralised to pH ~8 with the same eluent.

I am getting a negative peak at the beginning of each sample run.

The specification of the instrument are:
Dionex ICS50000 equipped with SA10 CarboPac column
Eluent 1mM KOH
Eluent source: EGC-KOH
Eluent flow rate: 1.5mL/min
Temperature: 45 C
Detection: Elettrochemical detection, quadruple waveform
Injection volume: 25uL
Storage solution: 1mM KOH.

I am using a detection method of 12 minutes isocratic.

Hope the information included is enough and I thank in advance anyone that can help.

R
Hi Rosario,

If you see a dip or peak between 1-2 minutes, I'd say it's probably normal. You can see small dips/peaks in figures 1-4 of the Dionex CarboPac SA10 specification sheet (link below). Is it negatively affecting your analysis? Were you always seeing this dip before? Is it present in all injections or only certain ones (e.g., blanks, standards, samples)?

Some useful links...

Dionex CarboPac SA10 Specification Sheet:
https://tools.thermofisher.com/content/sfs/brochures/PS-70870-CarboPac-SA10-PS70870-EN.pdf

Dionex CarboPac SA10 Manual:
https://tools.thermofisher.com/content/sfs/manuals/Man-065384-CarboPac-SA10-Columns-Man065384-EN.pdf

Electrochemical Detection User's Compendium:
http://tools.thermofisher.com/content/sfs/manuals/Man-065340-Electrochemical-Detection-Man065340-EN.pdf
Best regards,

John Guajardo
Senior Product Manager
Thermo Fisher Scientific
Hello John,
Thank you for your help. I was not observing these peaks previously, when I was running samples from enzymatic digestion. They are in all injections and they affect my analysis because they affect my arabinose peak. Should I decrease the flow speed to leavethem behind?

Best wishes,
Rosario
Hi Rosario,

Can you please send me a few of your runs showing the current issue and a few from before the issue started? The raw data from Chromeleon as a cmb(x) file would be best. Please also include the column serial number. I can be reached through email at john.guajardo@thermofisher.com.
Best regards,

John Guajardo
Senior Product Manager
Thermo Fisher Scientific
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