hplc-MS contamination

[hplcnewuser1]

Hi I am running a peptide on hplc/ms and keep getting this contaminant on MS that is 135m/z appart ex: 1332, 1197.... also 1376, 1241....
What could this polymer be/
thanks for any help.

[JMB]

I think that we need a little more information with this, namely...

1) what is the mobile phase ?
2) is this a synthetic peptide ?
3) are these m/z values [M+H] or sequence ions

JMB

[hfredricks]

check out this paper,
Keller, B.O.; Sui, J.; Young, A.B.; Whittal, R.M. Interferences and contaminants encountered in modern mass spectrometry.
Analytica Chimica Acta (Review/tutorial, Special Issue on Mass Spectrometry), 2008.
The supplementry data excel file is a must-have for contamination issues - it says 135 is "NaCF3CO2, sodium trifluoroacetate clusters" valid in wither pos or neg mode.




[quote="hplcnewuser1"]Hi I am running a peptide on hplc/ms and keep getting this contaminant on MS that is 135m/z appart ex: 1332, 1197.... also 1376, 1241....
What could this polymer be/
thanks for any help.[/quote]

[lmh]

NaTFA is 136, not 135 I think???

[sav]

It's just peptides. May be

Check n+ (n = 2 - 3) and MSMS (isCID or CID).

[BostonFSE]

135 repeating in positive mode = Sodium trifluoroacetate clusters
clean the source
on occasion, spraying the source with methanol over night 0.1 ml/min flow can help reduce contamination

this paper was cited by another user and the xls is awesome to have for MS contam issues.