chromatography signal is lower than the detector???

[tiger]

We have a HP1050 (from Agilent) and SEDEX 75 detetor. The problem is: the signal from computer chromatography is always about 100 times lower than the number from detector screen. For example, i ran a biodiesel sample, at 5 minutes, a peak showed up, the signal from the detector screen went up to 266 mv, however, the peak from the chromatography was only about 3 mv. Can someone give me some suggestions? Thanks a lot!!
BTW: we use Agilent 35900E Dual channel interface

[tom jupille]

I would guess that one is set to 1V full scale, and the other is set to 10mV full scale. As long as the A/D converter is set appropriately, it shouldn't matter.

[tiger]

Hey Tom. Thanks for your reply. In our chemstation, we set up ADC signal as below:
Unit:mV
Units/Volt=1000
I just changed "Units/Volt" to 10, even worse after running the sample. No peak showing up. What do you mean "A/D converter"? How can i access that and set up properly? Thank you very much for your suggestions and this is very important to us.

I would guess that one is set to 1V full scale, and the other is set to 10mV full scale. As long as the A/D converter is set appropriately, it shouldn't matter.

[tom jupille]

I don't have any experience with the 1050 . Hopefully someone else will chime in with more details.

[lcguy1]

Looks like the Sedex 75 has 3 outputs, a 0-1V, a 0-10mV, and digital RS232 port. It sounds like you have it hooked to the 0-10mV. Usually, the detector output to the computer is 0-1V. Just make sure it is hooked and configured correctly.