Correctness of results.

[n-cute]

Hello,

I have question about control of your results. I mean, what do you do in everyday analysis to confirm correctness of it e.g CRS on level in the middle of calibration curve and...? What else?

[tom jupille]

I'm not quite sure how to interpret the word "correctness", but I suspect most labs would use some form of control charting (run check standards regularly to confirm 100% recovery).

[rolpe]

Hi,

1. add some standard to a part of your sample and make a run.
If your detected peak gets bigger you have got the right Peak. If you have samples with many peaks (plant extracts etc.) this can help you identify the right peak.

2. look at the symmetry of your Peak. Is it good ? If the symmetry is not good this could be a hint that there is more than one substance in your peak.

3. if you have an DAD you can look at the spectrum or the 3D-Plot of the peak in your sample, compare it with the standards spectrum. Is it the same ?

4. Change to an alternative wavelength and repeat your run (standards and sample). Do you get the same result ?

5. Increase for example your flow (1,0 to 1,5 ml/min) and/or decrease your column temperature (5-10°C). This will result in an increase of your selectivity. Run Standard and sample and check if you get the same result. You can sometimes see in your chromatogram that there were impurities under your peak.
I once made this with an method for Arnica planta tota, and discovered by changing temperature and flow in the above way, that there were three more Peaks hiding under my "good looking" peak.

Hope I can help you with this.

Best Regards
Rolpe