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By Gad on Monday, August 2, 2004 - 07:16 am:
Hi, Friends
I need an urgent help. How do you obtain a smooth baseline in LC/MS? I am using 50:50, acetonitrile:water as a blank, and the baseline shows a constant trend but very broad and very dark as if there are too many peaks very close to each other.
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By paktiyat on Thursday, August 5, 2004 - 01:06 am:
Hello Friends,
Need your help ASAP! I have problem with ghost peaks on a very smooth baseline of a gradient run. After a blank 50% acetonitrile-water injection of 10 uL or 0 uL, the base line shows 2 peaks at the two m/z ratios of the drugs of interest, even on a brand new column. The peaks were gone when a union replaced the column. This problem happened with unknown reason right after the system was pre-validated and ready for a full validation of the 2 drugs of interest, artesunate and dihydroartemisinin. Before the problem occured, the baseline started flat at the beginning of the injection for ~ 4 mins and slowly rised up becoming a plateau in the region where the peaks of interest came out until the end of run (~ 8 min).
When the problem occured, the baseline had less noise, the plateau was gone and the 2 peaks showed up. It looked like the plateau covered up the peaks of interest. We suspect that the change in the baseline is related to electronic problem.
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By Michele on Thursday, August 5, 2004 - 12:06 pm:
It sounds as if your solvents are contaminated. Even as specific as MS is, you can still have unanticipated interference. Try solvents, including water from a different source. I suspect the change in the baseline is probably due to contamination or composition of mobile phase (as B increases, baseline increases, for example) rather than electronic problems.
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By paktiyat on Sunday, August 8, 2004 - 05:45 pm:
Thank you so much, Michele. It really was the water.
We normally stored MilliQ water that was in a different lab in our 20 L container in our lab. The ghost peaks were gone when we used freshly collected water. We were confused by one of the ghost peaks having the same m/z ratio as one of our drug. It was a nice peak and really looked like our drug peak.
Thank you again for your expert advice. We are very grateful to you.
Hi, Friends
I need an urgent help. How do you obtain a smooth baseline in LC/MS? I am using 50:50, acetonitrile:water as a blank, and the baseline shows a constant trend but very broad and very dark as if there are too many peaks very close to each other.
-------------------------------------------------------------------------------------------------------
By paktiyat on Thursday, August 5, 2004 - 01:06 am:
Hello Friends,
Need your help ASAP! I have problem with ghost peaks on a very smooth baseline of a gradient run. After a blank 50% acetonitrile-water injection of 10 uL or 0 uL, the base line shows 2 peaks at the two m/z ratios of the drugs of interest, even on a brand new column. The peaks were gone when a union replaced the column. This problem happened with unknown reason right after the system was pre-validated and ready for a full validation of the 2 drugs of interest, artesunate and dihydroartemisinin. Before the problem occured, the baseline started flat at the beginning of the injection for ~ 4 mins and slowly rised up becoming a plateau in the region where the peaks of interest came out until the end of run (~ 8 min).
When the problem occured, the baseline had less noise, the plateau was gone and the 2 peaks showed up. It looked like the plateau covered up the peaks of interest. We suspect that the change in the baseline is related to electronic problem.
-------------------------------------------------------------------------------------------------------
By Michele on Thursday, August 5, 2004 - 12:06 pm:
It sounds as if your solvents are contaminated. Even as specific as MS is, you can still have unanticipated interference. Try solvents, including water from a different source. I suspect the change in the baseline is probably due to contamination or composition of mobile phase (as B increases, baseline increases, for example) rather than electronic problems.
-------------------------------------------------------------------------------------------------------
By paktiyat on Sunday, August 8, 2004 - 05:45 pm:
Thank you so much, Michele. It really was the water.
We normally stored MilliQ water that was in a different lab in our 20 L container in our lab. The ghost peaks were gone when we used freshly collected water. We were confused by one of the ghost peaks having the same m/z ratio as one of our drug. It was a nice peak and really looked like our drug peak.
Thank you again for your expert advice. We are very grateful to you.
