Pre-concentration

Hi all,
I'm new to Biacore so any help will be appreciated.
When trying to run the pre-concentration test the sensogram dips down to different levels instead of going up.
I use bog-standard HBS running buffer and IgG 25 ug/ml in Na acetate buffer.
Can anyone please explain?

Hi,

Strange indeed.
Can you tell which type of sensor chip you use?
And what is the buffer of the IgG?

Arnoud

Hi,
Thanks for your reply. I'm using standard GEHealthcare CM-5 chip. I was using a custom program, but then used the wizard for pH scouting all worked as it should.
However, when used 2.5 ug/ml and the wizard it went downwards again
I'm guessing the concentration in the latter was too low...
Thanks again. T