effect of acetonitrile or methanol on analyte response

[danko]

Hi Tomasz,

“Blessed are the die-hard guysâ€

[Tomasz]

danko

I have no free LC for experiments. Besides, I'm in GC lab this month.

Moreover, I know the results without making the experiment just as you know. I just wrote in my firs post what I had observed in my lab. The peak area was not the same and it happend several times.

Regards

[Uwe Neue]

I must support Danko in this argument. 1 + 1 = 2. If this is not observed, then either the 1's are not 1, or there is a third party involved.

Peak area (with concentration proportional detectors such as UV or RI) is independent of retention. Specifically, the peak area is proportional to the injected mass. This can be demonstrated with simple math.

If this is not observed in practice, then something MUST have changed together with the change in retention. A simple case (with a weak change) could be caused by inappropriate integration parameters, where more of the true peak is cut off for the wider peaks. Another possibility (with larger changes) is that the change in retention is associated with a change in pH, which in turn can cause a change in the spectra of the analytes. I am sure that if we think hard enough, we can cook up a few additional possibilities.

[Tomasz]

OK Uwe

You are right. There must be something. However, I had observed higher area for wider peaks - not lower as you sugested. There was no bad integration. Moreover, any cut off for wider peak would give lower peak area - not higher. You must think about some other possible reasons. This argumentation is not good enough - not for me. Maybe I'll do some experiments later (in my free time). I'll take care of a good integration. I'll also use a method using no buffer.

Regards

[Tomasz]

danko wrote a nice motto in one of his posts:

Tradition - good, curiosity - better, creativity - best.

bye

[Uwe Neue]

Take your time.... The laws of nature do not change that rapidly

[Tomasz]