Chromatography Forum

...which methode do you prefer (for standards and samples) ???



especially LC

If peak shape, signal-to-noise, and resolution are all fine, then I wouldn't want to spend my time manually integrating everything. However, sometimes different autointegration algorithims work better for different types of runs.

Standards-
For GMP work I never perform manual integrations on any standard. The point of having a standard is to be a repeatable reliable source for comparison. If your standards are not consistant throughout the run you should be concerned with either the system going bad or your standard degrading.

Samples-
Hopefully the integration you use for standards matches your samples. However, when facing 100+ samples chances are you will have to manual integrate some of them to make them consistant with the others. For GMP compliance always include the original integration with your updated manual integration along with an expanation as to why you performed the manual integration on this sample.

I fully agree that you should have clearly defined and documented integration methods for your standards (especially for system suitability).

If your method is not reproducable enough to integrate your standards, how can you trust your results?

You should have "suggested" integration methods for each product. Often there will be differences; lot to lot variation or samples from accelerated stability studies, that require modified integration methods. My procedure is to clearly document the revised integration method, then use that method for all replicates of the sample. Sometimes there will be a noisy baseline for one replicate injection that requires "manual intervention" with the integration. A brief memo is included with the assay results to show the revised integration method.

Just a tip - I like to create a screen view on the computer with a "Blow Up" of the integrated chromatogram and the integration table. I then COPY the image on the computer screen by using the "print screen" key and PASTE it into a word document (along with appropriate discrriptions and assay information). This allows me to make a clearly understandable one page memo that I then sign and include with the assay data. I make no claim that this is the official (part 11 compliant) records. The complete assay run is stored by the HPLC software - this is just a brief memo to show the integrated peaks and "integration event table".

Make sure you have good scientific justification for everything and it does not look like you are trying to hide something.

one "problem" is that i have to analyze natural substances ... Food analysis -> e.g. Vitamine B Komplex...

Well , what you all say is quit clear ... If you got clear peaks , no question ... but analyzing food samples its sometimes hard to find the best way... and especially when its hard to extract the components to get a better Chormatogram.

have always to fight against baslinedrift, peakdrift and so on ...