Information about chemstation
Posted: Mon Jan 26, 2009 5:59 pm
by shahis77
I am new to chemstation but I have a good experience on waters empower software .My question is when I am injecting samples on waters system and quantify them using empower software then I am finding the values of my Control samples exactly what is expected but when i quantify them using chemstation software then the values of MQC and HQC are coming out to be same but LQC value is different why this is happening .....and when I calculate the concentrations on excel sheet then all the values are going out in linear cal but are coming out ok in power cal.
I am not able to find the problem can anybosy help me why this is happening
Posted: Tue Jan 27, 2009 5:22 pm
by lmh
I'm assuming LC-Chemstation. I would guess that your peaks are being integrated differently between the two software packages. Big peaks are easy to integrate, so the higher level injections will come out very similar, but the low level peaks are difficult to integrate, and may have bad baselines using default integration parameters. In Chemstation, for instance, selecting the advanced or classic baseline can make a big difference if there are nearby or improperly separated peaks.
You could try using Chemstation's autointegrate on a low-level standard to improve its integration. But I would recommend studying what it is doing, checking that you approve of the baselines it is drawing, and learning what options the integrator offers.
Depending on detector noise, it may also be worth considering using the signal smoothing in the signal details page. The closer the noise level gets to the signal level, the more danger there is that the start of the peak will be triggered by a bit of noise.