Metrics of separation performance in chromatography: Part 3: General separation performance of linear solvent strength gradient liquid chromatography

• Equations for peak capacity of an arbitrary segment of a chromatogram are developed.
• Equations for several other metrics of separation performance are developed.
• All equations account for gradient band compression in gradient LC.
• Each metric can be expressed as a function of several alternative parameters.

The separation performance metrics defined in Part 1 of this series are applied to the evaluation of general separation performance of linear solvent strength (LSS) gradient LC. Among the evaluated metrics was the peak capacity of an arbitrary segment of a chromatogram. Also evaluated were the peak width, the separability of two solutes, the utilization of separability, and the speed of analysis—all at an arbitrary point of a chromatogram. The means are provided to express all these metrics as functions of an arbitrary time during LC analysis, as functions of an arbitrary outlet solvent strength changing during the analysis, as functions of parameters of the solutes eluting during the analysis, and as functions of several other factors. The separation performance of gradient LC is compared with the separation performance of temperature-programmed GC evaluated in Part 2.