coeluting peaks

SSIMS 2 months ago

Hi,

I am currently encountering coeluted peaks in my chromatographic analysis for two specific analytes following a recent maintenance session. To provide a comprehensive overview, here is a detailed timeline of the actions taken:

- Prep MPA (0.1 % formic acid aq) and MPB (0.05% formic acid aq)

--> ran a blank (MeOH) [Figure 1A] and system stability check of a Continuing Calibration Verification Standard [Figure 1B].The chromatography of this run mirrors our normal results

- Same day: Following the calibration run, the chromatogram reveals RT shifts and coeluted peaks

--> blank (MeOH) [figure 2A] and a calibration level [figure 2B]

- Replace the guard column, ran a blank (MeOH) [figure 3A] and a calibration level [figure 3B]

- Replace guard column and analytical column [Figure 4A]

Any ideas on how I can fix this issue?

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0 Wolney Vasconcelos 1 month ago

Wow, your peaks are super close to each other! Anything minor will affect your chromatogram. Maybe you should search for a better method? Anyways, what impacts the most are flow (are you running a gradient method?), organic concentration (again, gradient method?), temperature and pH. Maybe you could check if your MCGV (gradient valve) is working fine and maybe replace that? it is unlikely, but those are the starting points
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0 Wolney Vasconcelos 1 month ago

Wow, your peaks are super close to each other! Anything minor will affect your chromatogram. Maybe you should search for a better method? Anyways, what impacts the most are flow (are you running a gradient method?), organic concentration (again, gradient method?), temperature and pH. Maybe you could check if your MCGV (gradient valve) is working fine and maybe replace that? it is unlikely, but those are the starting points
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