Chromatography Forum

Hello,

I have to evaluate the peak purity of some batches using Chemstation (version B.01.03[204]). Even though I read the manual and the tutorial from the software, there are some questions I couldn't figure out.
1.How do I overlay two spectra from two separate runs (spectra data files)? There is no option to load spectra only signals.
2. For peak purity evaluation, is the word "similarity" the same as "purity factor"? I need to calculate the peak purity ratio and the only number I get is the purity factor and the threshold.
3. For peak purity evaluation, under spectral options, the logarithm parameter reduces the absorbance scale and is useful when the absorbance scale is very large. How much large? over 2 absorbance units? the manual states that for purity calculations the spectral absorbance need to be less than 1absorbance unit.
4.For peak purity evaluation, under spectral options, is the smooth factor (remove spectral noise from low absorbing spectra) the opposite function of the logarithm parameter or not necessarily?
5.For background correction of the peak spectra, which option is better when there are non-baseline separated peaks: manual reference (the operator sets 2 reference spectra with retention times) or automatic background correction?

If someone can answer some of my questions that would be great!

This is very complicated and not something that can be explained in this format. Please consider taking an advanced ChemStation DAD course to learn about the many parameters and settings required to use this tool correctly. Agilent's manuals and HELP section will not provide you with the detailed knowledge you need to use this feature. BTW: Before you use the feature you should have a great deal of experience using ChemStation's Data analysis software (advanced integration tools, spectral and file overlays plus a good understanding of all of the peak purity tools in the menu).

Agilent does not offer one, but we know many scientists whom have taken the one offered by Chiralizer Services in Newtown, PA. Their course teaches the use of the advanced integration and peak purity tools as well as how to obtain a high quality chromatogram in the first place (correct detector settings which 99% of all users do not have set up correctly from the start). This is a complex topic which requires about four to eight hours to go over.

BTW: One quick answer for you: Spectral Overlays from different files. Easy. Load them one at a time on the screen; select overlay format, hold down the control key while clicking on the chosen spectra to overlay and it will overlay as many as you want on the screen.

Thank you for the advise. I got already an Agilent consultant to clear my questions.