Forum :: why signal always jumped on one fc

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TOPIC: why signal always jumped on one fc

why signal always jumped on one fc 12 Sep 2006 02:00 #1

Hi, all

The signal on Fc1 always jumped up about 7-60 RU abruptly during the injection time while signals on other flow cells were smooth (the sensorgrams I had used were Fc2-1 or Fc1-2-3-4 with different sensor chips). The signals could jumped down during the dissociation time soon. It troubled me very much to obtain the data for I have to repeat experiments. I have had a signal quality check and its OK.

Whats the reason for these results? The IFC, pump, opto-interface or my samples? What should I do?


why signal always jumped on one fc 12 Sep 2006 02:00 #2

To have an idea,

When running normal flow everything is ok, no signal jumps. Then you inject and immediately the signal in flow cell 1 jumps or after a while. Ending the injection results in no jump. Correct?

My first idea is to suspect the IFC. When you see it with several chips, something could be in the groove which makes up the flowwcell after docking a sensorchip.

But look again carefully at the systemcheck curves. Are there strange shift in the signal?


signal jump 12 Sep 2006 02:00 #3

Thank Arnoud very much!
The signal didnt jump immediately after injection. In fact, it always happened during the injection process (for example, jump at 3min after injection -total injection time is 4min). The reverse jump occurred some time after the injection was finished. Now, Im also worried about the IFC for its expensive price which was replced for 5 months. This phenomenon had ever happened last year which was due to the difference in temperature I think. The temperature of machine was 25C while room temperature was 16C. When I changed the room temperature it became OK.
If theres problem with the IFC , what shall I do? Superclean, unclogging? Ill have a system check recently.


signal jump 12 Sep 2006 02:00 #4

I don't think the temperature has any influence because the injected liquid has to travel all the IFC and is at the right temperature when ariving at the sensorspot.

Which kind of injection do you use? BigInject can cause problems in a Biacore 2000/3000 due to a software flaw. It will inject air instead of liquid.
You must have lots more liquid in your vial to use this option.

A problem in your IFC is best checked with the system check. When done you have to determin if the valves are not working properly or there is a blockage.
When valves are not working you have to replace the IFC. When working regularly you should (let) replace the IFC every six months.


signal jump 12 Sep 2006 02:00 #5

The system check result showed that the Fc1-2-3-4 clip was -370 which was marked as check! Others were OK. I didn't use BigInject. It seemed the IFC was not very good.