GC028 Van Deemter Plots

Plots depicting the Height plate (H, usually in mm) versus the linear velocity (u, typically in cm/s) are called Van Deemter plots. In such a picture, the three terms of the Golay equation are plotted. In the equation for H, one of the terms is multiplied by u and another is multiplied by it. This leads to the presence of a minimum in the curve for H, an optimal point of velocity which provides the highest efficiency and smallest plate height. Chromatographers manipulate the Van Deemter equation to get the best performance while minimizing the analysis time. The CM term is the most important contribution as the velocity increases. Plots are used to calculate H, and the van Deemter equation is rarely used to achieve this.

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