strong noise in analyte peaks
Posted: Tue Jul 06, 2010 10:00 am
Hello,
we are having problems with the peak shape of our analyte in ESI negative mode. The technicians of the supplier of the MS/MS don`t have any remaining idea.
We analyzed nucleotides and used 50 mM NH4HCO3 pH 10 (adjusted with NH4OH (p.a.)). Eluent B is MeCN(MS-grade)/acetone (for contaminants). After a few weeks we became the problem, that the peaks of the nucleotides became a zigzag-line. Other parameters measured in negative mode now show a similar peak shape.
We run a standard with a second MS/MS, not used for the nucleotides before, but had the same peak shape.
So we changed the eluent to NH4Ac (without NH4OH) und MeCN (MS-grade) but nothing changed.
We don't have any problems in positive mode.
Does anybody have an idea about this problem?
Thanks!!
we are having problems with the peak shape of our analyte in ESI negative mode. The technicians of the supplier of the MS/MS don`t have any remaining idea.
We analyzed nucleotides and used 50 mM NH4HCO3 pH 10 (adjusted with NH4OH (p.a.)). Eluent B is MeCN(MS-grade)/acetone (for contaminants). After a few weeks we became the problem, that the peaks of the nucleotides became a zigzag-line. Other parameters measured in negative mode now show a similar peak shape.
We run a standard with a second MS/MS, not used for the nucleotides before, but had the same peak shape.
So we changed the eluent to NH4Ac (without NH4OH) und MeCN (MS-grade) but nothing changed.
We don't have any problems in positive mode.
Does anybody have an idea about this problem?
Thanks!!