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- Posts: 1
- Joined: Tue Aug 25, 2015 7:53 pm
Originally, the impression was that the background was the result of LC system contamination until acetonitrile from different brands were examined using direct infusion (directly from solvent bottle with syringe) into the mass spect on the Synapt, Xevo and an ABSciex instrument. The same cluster of ions (m/z 297, 311, 325 and 339) was detected in ES- mode with a separation by 14 Da.
The published lists of common contaminants does not show a match for these ions.
It has been suggested that these may be byproducts of solvent productions that cannot be filtered away at 0.1microns. It has also been indicated that the cluster matches alkylbenzene sulfonate and chloramphenicol which are not used in the preparation of our samples, buffers or solvents .
I have tried different brands and the intensity of the peaks vary from brand to brand while remaining in the chromatogram for data acquired on the Synapt. On other instruments, they are detected by the MS while remaining in the noise level and not evident in the chromatogram.
The main issue is that with some brands/lots of acetonitrile the peaks are well above the noise range thus suppressing the appearance of eluting peaks from the actual sample.
If anyone has seen this issue could you share insight on how it was resolved or what brand of solvent presented the lowest abundance for the cluster?
Thank you