When we deal with lack of peak capacity of chromatography columns, we encounter coelution of compounds. Moreover, due to some fluctuations in temperature, flow rate, pressure, matrix effect, stationary phase degradation (particularly in GC) and changes in mobile phase composition (especially in LC), RT shifts are occurred. They are two types of most important challenging problems in chromatographic analysis and sometimes are indistinguishable from each other during signal processing in analysis of complex natural/biological samples from one chromatraphic run to other ones.
Retention time shift occurs in GC due to leaks and Inlet "O" ring damage.
in HPLC it can be due to mostly mobile phase or column stationary phase damage.
For instance:
1)mobile phase pH is not good: coelution takes place
2)Column pressure decreases peak RT Increases.
3)Solvent ratio increases, RT Decreases. buffer ratio increases, RT Increases
To get the exact results, keep following the method accurately .
Regards,
Bujji Reddy Kanchi.
Well trained individuals in method development are your best tool to solve this problem. Retention time drift is usually a result of poor quality methods, poorly maintained equipment and/or a lack of control of environmental factors (e.g. temperature), You must develop rugged methods with resist these effects and result in consistent results for every injection.
I have attached a link to an HPLC article which I think will help you troubleshoot these problems, "HPLC Retention Time Drift, Change, Variability or Poor Reproducibility. Common Reasons for it.". Many of the same principles apply to GC as well.
http://hplctips.blogspot.com/2015/11/hplc-retention-time-drift-change.html
- Badges
- Science topic
- Similar topics
- Engineering
- Electrical Engineering
- Signal Processing