Unusual sensorgram : dissociation below baseline

Hi,

I am struggling with the recent experiments because of unusual sensorgram pattern.

I would appreciate if SPR users could give me advice so that this problem can be resolved successfully.




First of all, I used ProteOn XPR36 and GLC chip which is designed to use ligand capturing by amine coupling method.I have experimented exactly the same way as before, but I get other results.




My problem is that dissociation sensorgram droped below baseline and also final baseline was not recovered to zero.

I think this result may be influenced by analyte concentration because high analyte concentration show more significant difference in sensorgram.

I used serial dilution with running buffer, so running buffer can be another factor for this problem.

In addition, if analyte was flowed over and over on GLC chip, dissociation sensorgram and final baseline were less significant than first time. I think something is saturated on the chip, but I don't know exactly.





In this forum, I found someone who asked about similar problems (Title : Dissociation below baseline).

I think my problem is similar with his problem, but there was no clear solution for this.



If you any idea or solution to this problem,
I would really appreciate your advice.

Thanks for reading.