Continues increase of RU in flowcell 2 ?

Dear Arnoud,
This is SA chip. FC 2 was treated with biotinylated peptide(flowrate 5 Micro lit, for 3 mins, obtained 525 RU immobilised peptide.)
After I’ve started sensogram with running buffer at the flow rate of 30 and 60 micro litre per min. In both cases I observe continuous increase in the flow cell 2.

I suspect something in the buffer slowly accumulating on the peptide surface than uncoated fc’s. ?

What should be done at this stage to rectify the experiment?

Buffer consists of 25mM Tris, 140mM NaCl, 3mM KCl, 1mM EDTA, 0.05% of NP40 at PH 7.5.

Hi,
It seems to level out in the end.
My first thought is to leave out the NP40, or change it for Tween-20.

Arnoud

Thank you for the suggestion Arnoud.
What would be the probable technical reason behind this?. What properties of tween and NP-40 makes these differences in the sensogram?

Hi,

My point was that NP-40 and Tween-20 are from a different type of detergents. Tween-20 is a slight gentler detergent with a very low CMC.

I found this website ( www.labome.com/method/Detergents-Triton-...een-20-and-More.html ) with a very comprehensive explanation of detergents.

Kind regards
Arnoud