Chromatography Forum

Hello,
We use indirect uv method which show negative peak in our chromatograms while using agilent 1200 HPLC with variable wavelength detector we use option to invert polarity of detector to be positive peak ,our new HPLC instruments thermo ultimate 3000 and vanquish flex (both equiped with pda detector) can't found polarization option to invert it...It make a great problem with our stability studies...
Do any one here know how to invert the polarity of pda detector of thermo ultimate or thermo vanquish operate with chromelon 7.2 ?!

Search in the Instrument Configuration Manager. Use Help in the program.

Search in the Instrument Configuration Manager. Use Help in the program.

This would change the detector response for all analyses, maybe not what the OP wants.
Sorry I don't have CM7.2 here, but the procedure I used in 6.8 should also work here:
Go to the analysis program, add a post-acquisition step. Look for "arithmetic combination of channels" and multiply your UV channel with -1. In CM 6.8 you can select one out of four options for combination of two channels. Then all negative peaks will become positive.
(I hope the post-aquisition module was improved in 7.2. If not, use factor "-1" for channel A and "0" for channel B and select A+B as equation for the desired result.)
Good luck!

Search in the Instrument Configuration Manager. Use Help in the program.

This would change the detector response for all analyses, maybe not what the OP wants.
Sorry I don't have CM7.2 here, but the procedure I used in 6.8 should also work here:
Go to the analysis program, add a post-acquisition step. Look for "arithmetic combination of channels" and multiply your UV channel with -1. In CM 6.8 you can select one out of four options for combination of two channels. Then all negative peaks will become positive.
(I hope the post-aquisition module was improved in 7.2. If not, use factor "-1" for channel A and "0" for channel B and select A+B as equation for the desired result.)
Good luck!

It works like a charm,thanks