We developed a bioanalytical LC-MS/MS method and everything is OK, but to determine whether the run time and the organic percent is enough for plasma's effect on column we did a UV detection between 200 to 300 nm wavelength, and found unknown peaks in the bio samples at the 5th min. and 11th min. that not causing any carry over or any effect on the MS method and results, but its interesting to know what peaks those might be! we reduced the run time but the 11th min. peak had no effect on the later injections. Has anyone similar experience ?
PS. extraction method : protein precipitation
column : C18 100 x 2.1
mobile phase 17.5 methanol , 82.5 (0.1%) FA
Dear mr Armoudjian
280 nm wavelength is used when looking for aromatics, as mentioned above, in the specific case proteins, considering that most contain at least a few aromatic amino acids.
I could figure that Plasma's proteins containing tyrosine aid tryptophan side chains adsorbs at around 280 nm, but why they're not causing carry over in later UV injections ?
In case we ignored it, will it effect the column or the results in the primary MS method ?
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