Chromatography Forum

I am being asked to develop methods for more complicated mixture of analytes and know that I have to consider pH, solvent class, ionic strength, temperature, and column phase and interactions of all of these.

In a current (simple?) project on a neutral analyte in a cream, the matrix components (placebo) behave very differently than the analyte. The target analyte and degradants follow linear addititive effects for solvent and are reasonably predictable. The cream matrix has multiple peaks, with the major one wandering from the front of the chromatogram to the last eluting peak, depending on the mixture of solvents used and temperature, so I know at least the major placebo peak has at least a strong solvent class interaction between MeOH and ACN and probably a temperature component. I have four analytes of interest here and we tend to find mixtures that put the placebo peak on top of one of the four rather than between them.

This seems a good time to really use some DOE software and the company does not have any. Who has used DOE for chromatography and can recommend a user-friendly software package that will help? My next project is neutrals and basics with similar placebos, again at least four target compounds and again expecting interactions between multiple chromatographic parameters.

I leave this open to all suggestions and comments about strengths and weaknesses of anything anyone has used, including the built-in packages the vendors provide.

Thanks in advance for your opinions.

On this forum, you will find plenty of info on Lloyd Snyder's DryLab. Freestanding versions are available from the Molnar Institute in Berlin, or you can also get a copy that interacts with your chromatograms if you use Waters software.

It appears from your description that one of your matrix peaks has a much larger molecular weight than the other analytes. This is potentially the reason why it is wiggling around so much, compared to the other peaks.

We have used the StatEase program for some of our DOE procedures. The software is very capable of manipulating multiple variables at once, but is not incredibly user friendly. Having a strong grasp on interpreting statistics really helps with this program.

Hi Rick -

I've used the Waters software to good effect. It's no panacea, but it's good for boosting efficiency in a methods development setting. It's not inexpensive, but I've found it to be useful to both roughing out a method overnight and in fine tuning parameters. To use it in conjunction with acquisition software (automated method development), you're restricted to PDA data, and it obviously only works with RP method development.

If I can help further, please feel free to drop a line.

BTW, you're not at EL, are you? I'm just down the road a bit in Stony Brook...