Gradient elution in HPLC is a technique where the composition of the mobile phase changes during the separation to improve the resolution of compounds.
How It Works
- In HPLC, the mobile phase can be a mixture of solvents (e.g., water and acetonitrile).
- In isocratic elution, the solvent composition stays constant throughout the run.
- In gradient elution, the proportion of solvents changes gradually over time.
- For example, the mobile phase may start mostly water and gradually increase the organic solvent (acetonitrile) content.
- This helps compounds with different polarities elute more efficiently.
Advantages of Gradient Elution
- Better separation of complex mixtures
- Compounds that would take too long to elute under isocratic conditions can come out faster.
- Shorter analysis time
- Gradient elution speeds up the elution of strongly retained compounds.
- Improved peak shapes
- Reduces broadening of peaks for late-eluting compounds.
- Increased sensitivity
- Peaks are sharper and easier to detect.
In simple words:
Gradient elution is when the strength of the solvent changes during the HPLC run.
This helps separate compounds better, faster, and with clearer peaks, especially in complex mixtures.