By Anonymous on Tuesday, July 6, 2004 - 10:18 pm:
Hi,
We are using an Agilent HPLC 1100 and a DAD detector. Recently we encounter some problems: negative peaks in the chromatograms. It is the same chromatograms that we are getting normally except that everything is "inverted".
The method is as follows:
MP A: 0.05%TFA in H2O
MP B: 0.05%TFA in ACN
Time A(%) B(%)
0 100 0
8 95 5
9 100 0
11 100 0
We have encounter this problem thrice. We tried to use H2O to wash the system and the detector (as advised by the vendor), it works but the problem returns after a while. The method is validated and we did not make any changes to the settings. Can anyone enlighten us on this? Thanks in advance!
By rob burgess on Wednesday, July 7, 2004 - 07:30 am:
Have you got the polarity settings right on your detector? If not its simple to change.
By Anonymous on Wednesday, July 7, 2004 - 05:50 pm:
Hi Rob,
Thanks for your reply. How do we check the polarity settings?
By rob burgess on Thursday, July 8, 2004 - 04:34 am:
We use hand held control modules to control our Agilent systems. Its just then a matter of going to the detector settings and changing there. Consult your user manual if in doubt.