Chromatography Forum

Can someone please tell me what the Detector Bunch rate means? And the Noise Monitor? I have a Varian 9050 UV detector. I cannot figure out what these mean and what would happen if I raise or lower the numbers. I am working with Glyphosate products and the base line is not steady. There is a lot of noise or something and I cannot get a decent baseline to effectively calculate a glyphosate peak. I wondered if these would have an effect.

I am not familar with your instrument, but the bunching factor is often simply an accumulation of data points. When you sum up 10 data points, the noise is reduced by about a factor of 3. It also makes your peak a bit wider, but this is not a problem if there is plenty of space between your analyte and other peaks.

Ok, that helps. There is only one peak, as I am only running the std at the moment, but the eluent is a weak buffer solution. I have added a small amount of ACN, but I cannot add too much. Also, the detector is 195 nm for this particular peak. I wondered if this is the main problem and what I can do to help the situation.

You would have to check with Varian re "Noise Monitor". As Uwe indicated, the "bunching" factor amounts to averaging a number of readings. How effective this will be depends on the kind of noise you are seeing. It is most effective with "short-term noise", which is fast, jittery noise. If your problem is "long-term noise" (comparable in time scale to your peak), then it won't help (if you bunch enough measurements to average out your noise, you will also average out your peaks!).

Best suggestion is to to experiment with the settings and see what happens.