Chromatographic parameters: Transport efficiency-A meaningful alternative to the plate number parameter.

The plate number parameter officially defined in GC and LC as N = (t/σ) (t and σ are peak retention time and standard deviation, respectively, under no-programming conditions) can be substantially smaller than the actual number of plates. Therefore, N does not always represent what its name implies it does, and its interpretation is not clear. This is even more so for the extensions of N to multidimensional separations. N has other shortcomings. Metrics of separation performance of chromatographic analyses (peak resolution, R, peak capacity, n, and others) are not proportional to N. A column transport efficiency, Q = t/σ, is free of the shortcomings of N. Metrics R and n are proportional to Q. Q also has a transparent interpretation - it is the number of σ-wide segments in the time-intervals of certain significance in static and programmable GC and LC analyses. Q also has meaningful extensions to multi-dimensional separations.