problems coupling anti-GST

Hi, I'm trying to use the GE healthcare GST capture kit with a CM5 chip

The kit has anti-GST and immobilisation buffer and I'm trying to NHS-EDC couple the anti-GST to the chip
The kit estimated I should be getting 7500 RU bound. This allows me to then couple about 500 RU of GST-fusion to this to then bind to my analyte

Problem is, I can see a really big peak when I flow the anti-GST over - around +30000 RU
But most of this doesn't leaving me with about 500RU on the chip.

Not sure what the problem is, I've tried lower flow rate and high [] of the anti-GST


Machine is a biacore 3000

A peak of >30.000 RU indicates that there is air injected instead of liquid, or somehow there is a high salt/glycerol concentration in the injected liquid.
I would say: check the injection system.

To check this, try injecting flowbuffer: it should give a minor baseline displacement of max 5-10 RU.

Arnoud