Difference Between Isocratic and Gradient Elution

Difference Between Isocratic and Gradient Elution in High Performance chromatography (HPLC).

  • The major difference between gradient elution & isocratic elution is that isocratic elution refers to maintaining a constant concentration in the mobile phase, whereas gradient elution refers to maintaining a variable concentration in the mobile phase.
  • In chromatography, the words isocratic and gradient elution are employed. We utilise a stationary phase, which is a non-moving substance, and a mobile phase, which is a moving substance, during a chromatographic run.
  • The characteristics of the mobile phase are described by isocratic and gradient elution.

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What is Isocratic Elution?

  • In chromatography, isocratic elution denotes to when the mobile phase remains constant in concentration. Throughout the chromatographic process, the mobile phase concentration remains constant.
  • The peak width increases linearly with retention time in the chromatogram throughout this process. The late-eluting peaks for late elution, however, become relatively flat and broad as a result of this. As a result, these broad peaks become difficult to be to identify as peaks.
  • Furthermore, the selectivity of isocratic elution is unaffected by column diameters. This indicates that changes in column dimensions have no effect on selectivity.
  • The length and diameter of the column are taken into account here. As a result, the peaks elute in the same sequence order.

What is Gradient Elution?

  • Gradient elution is a word used in chromatography to describe when the mobile phase concentration varies. In other words, the mobile phase concentration does not have to be constant.
  • In HPLC, for example, a common separation procedure starts with 10% methanol and progressively increases to 90% by gradually increasing the concentration.
  • There are two solvents in the mobile phase: a weak solvent and a strong solvent. The solute elutes slowly in a weak solvent, whereas the solute elutes quickly in a strong solvent.
  • In reverse phase chromatography, the weak solvent is water, while the strong solvent is an organic solvent.
Difference Between Isocratic and Gradient Elution in HPLC
Difference Between Isocratic and Gradient [email protected]

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