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- Posts: 1
- Joined: Thu Dec 02, 2021 5:43 pm
Below is an example run (50-100% ACN, 28min) with the following parameters:
A: H2O, 0.1%TFA B: ACN, 0.1%TFA
C18 or C8 column, 4.6x100mm
flow: 1mL/min.
T A B
0 90 10
1 50 50
12 0 100
20 0 100
21 90 10
28 90 10
https://imgur.com/a/tFqO7T5
-There are no obvious pressure spikes that co-occur with the peaks in the spectrum. The pressure profile itself is quite consistent; a sawtooth pattern with a maximum delta of ~35.
-The issue is also present when using methanol, but to a lesser degree.
-Varying the flow rate only changes the spacing between peaks and when the first peak 'elutes'
I assume the issue is something like a bad pump seal, but I am just trying to make sure before we shell out the money for an expensive repair kit. It could also be an issue in the gradient proportioning valve, but I don't know how to distinguish between that and a high-pressure pump issue. I do not think this is a contamination issue. The peaks are far too regular and consistently eluting. Their absorbance intensity shows no decrease across runs.
Things I have tried:
-Remaking solvents fresh daily, from multiple different HPLC-grade solvent containers. No change.
-Flushing the entire system with IPA. No change.
-Switching lines. Normally we use lines A and B. I switched to C and D and saw a very minor improvement, but the issue was still there.
-No injection. No change
-No column. Inconclusive, we didn't have the correct fitting to create sufficient backpressure.
Any help would be appreciated!