Purnells resolution equation

What are the best ways to optimize separations One way to answer this question is to consider a popular form of the resolution equation that is originally attributed to Purnell.1... 

Equation (16) was first developed by Purnell [3] in 1959 and is extremely important. It can be used to calculate the efficiency required to separate a given pair of solutes from the capacity factor of the first eluted peak and their separation ratio. It is particularly important in the theory and practice of column design. In the particular derivation given here, the resolution is referenced to (Ra) the capacity ratio of the first... 

Since typical biological mixtures are exceedingly complex, adequate chromatographic resolution is imperative for both identification and quantitation purposes. Improved resolution is feasible through either increasing the column efficiency (number of theoretical plates), or phase selectivity. Alternatively, a combination of both can be practiced. The number of theoretical plates, required for adequate resolution of two adjacent peaks (98% separation of the peak areas) is related to the column selectivity (relative retention, a) and to the capacity ratio, k, according to the well-known equation derived by Purnell [70] ... 

Resolution between peaks is dependent on the retention characteristics of each component (k), the ability of the stationary phase to selectively retain the components (a) and the overall efficiency of the column (N). The equation derived below was first developed by Purnell in 1959 to accurately relate the degree of separation attainable in a GC column in terms of the separating capability and efficiency [13-15],... 

In practical GC, it is important that the number of theoretical plates required (Nreq) in order to provide a desired resolution (Rs) for a given pair of components (defined by a and k) can be calculated. This can be achieved by using the Purnell equation (eqn [1]) ... 

The equation reflecting the relationship of the resolution (separation criterion) and equilibrium and kinetic characteristics of the chromatogreiphic process was derived by Purnell cind is widely used in analytical practice [72, 73] ... 

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