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- Posts: 7
- Joined: Wed Feb 04, 2015 2:08 pm
Hello Everyone,
I am using a Waters UPLC for amino acid analysis with FLR detector. The middle peaks (between 3.5 and 6 min) started coming out after 4.5 min and now all "smooshed" together instead of equally spaced peaks. The peaks are stills separate enough to make out the individual amino acid but some can run together at the base. The peaks before 3 min and after 6 are coming out at the right times and look excellent.
I started seeing the problem every 10 samples or so while the majority of the sample came out correctly. Then my buffers ran low and I've made new buffers. The problem was then every sample. I made the buffers again. It worked for a few samples and then stopped (i would get the smooshed together middle peaks again).
The Waters trouble shooting guide suggested the column stabilizer. I fiddle around with it and standard came out correctly, then next standard did not and it hasn't worked since.
I've been checking flow rates through the entire BSM and can't seem to find where the flow is not correct.
After 3 min the Eluent B (ACN) starts to increase from 2% to 5 min 7% and the pressure increases a bit. At 5 minutes when most of the peaks come out (1 right after the next) the pressure increases again. Of course i'm not sure what the pressure should look like on a correct standard anymore.
So i don't know what to check anymore. Can anyone suggest anything?
thank you
I am using a Waters UPLC for amino acid analysis with FLR detector. The middle peaks (between 3.5 and 6 min) started coming out after 4.5 min and now all "smooshed" together instead of equally spaced peaks. The peaks are stills separate enough to make out the individual amino acid but some can run together at the base. The peaks before 3 min and after 6 are coming out at the right times and look excellent.
I started seeing the problem every 10 samples or so while the majority of the sample came out correctly. Then my buffers ran low and I've made new buffers. The problem was then every sample. I made the buffers again. It worked for a few samples and then stopped (i would get the smooshed together middle peaks again).
The Waters trouble shooting guide suggested the column stabilizer. I fiddle around with it and standard came out correctly, then next standard did not and it hasn't worked since.
I've been checking flow rates through the entire BSM and can't seem to find where the flow is not correct.
After 3 min the Eluent B (ACN) starts to increase from 2% to 5 min 7% and the pressure increases a bit. At 5 minutes when most of the peaks come out (1 right after the next) the pressure increases again. Of course i'm not sure what the pressure should look like on a correct standard anymore.
So i don't know what to check anymore. Can anyone suggest anything?
thank you
