Probem with VWD. Please help me!

[le duy]

I have a LC agilent 1100 system. I have just reinstalled chemstation software. But after finishing installation, the system do not work properly. The UV peak of the same sample is short than before about 10 folds. So I can not detect the small amount of interest subtance like before. What should I do??????

[LCbob]

The reinstallation of chemstation should not cause sensitivity issues. Check you have inputted the method conditions correctly, especially the inj volume and the wavelength.

[le duy]

I have inputted the same method and the same wavelength 215nm. What can cause sensitivity issues?

[bisnettrj2]

Are you using an external integrator? If so, check that the voltage in the 'Analog Output Range' under the 'Control' menu of the VWD module matches what you had originally - if your are using an external integrator, your detector setting may have reverted to 0.1 volts instead of 1 volt, hence the 10-fold decrease in signal intensity.

[le duy]

I have reverted the detector setting to 1 volt but nothing happen, the signal is still low.

[Parham]

Hi
You must check your UV Lamp Life and it's numbers of Ignitions.
when your HPLC is Online,in Diagnosis Tab(the last tab in left-down corner of chemstation) you can see in shematic in uv update parameter.
Probebly your problem is due to the Low Intensity of Uv Lamp.
Good luck .

[carls]

Is the peak area also ~10 fold lower?

[Uros]

Try changing the slit size and frequency

[bisnettrj2]

There is no slit width adjustment on the 1100 VWD, and sampling frequency shouldn't have that much to do with a 10x decrease in peak height (unless you had an astounding increase in baseline 'fuzziness' due to extreme oversampling and were looking at a very small peak in the first place).. Did you ensure that your lamp type is defined correctly? The VWD allows for the installation of the G1314-60100 or the 2140-0590 lamps, and perhaps you have a different lamp type installed than is currently specified?