sedex 75

[sepscientologist]

I am using a Sedex 75 with chemstation via the 35900 data acquisition box and having a strange problem. I can see the top
of the peak but at a particular threshold the signal just goes to zero. The top of the peak looks fine though. Anybody have any ideas?

[Gerhard Kratz]

At what wavelength you are messuring? It Looks like there is more than one compound under your Peak.

[tom jupille]

It's an ELSD; wavelength is not involved.

The bit of signal before and after the shift look remarkably flat. Is it possible that the baseline offset is such that the data system/display is seeing a negative voltage in that region?

[sepscientologist]

That's a good suggestion Tom. I know the 35900 doesn't handle negative voltage.
I turned the thing on and was going to measure the analog output but everything
was working perfectly. I should have turned it on/off before. Amazing how often
that will fix things!