Peak Capacity n

The peak capacity, n, of a single-column chromatographic system generating N theoretical plates is given by ... 

Figure 8.4 Schematic diagram of the peak capacity (n ) of a 2-D planar chromatograpliic system (i) the number of squares represents the number of compounds wliich can theoretically be separated.

General applications While capillary separation methods produce peak capacities, n, numbered in hundreds, many real-world mixtures (e.g. in the petroleum industry) require values of 104. This can only... 

It is obvious that n independent molecular properties require -dimensional methods for accurate (independent) characterization of all parameters. Additionally, the separation efficiency of any single separation method is limited by the efficiency and selectivity of this separation mode (i.e., the plate count N of the column and the phase system selected). Adding more columns will not overcome the need to identify more components in a complex sample, due to the limitation of peak capacities, n. The corresponding peak capacity... 

The efficiency of a separating system is best demonstrated by its peak capacity. This shows how many components can be separated in theory within a certain k range as peaks of resolution 1. The number of theoretical plates, N, of the column used must be known, as the isocratic peak capacity, n, is proportional to its square root ... 

We now note that peak capacity n- Is defined as being the maximum number of observed peaks which can theoretically be packed Into a chromatogram or a specified portion of a chromatogram. 

Figure 2.21. Chromatogram illustrating the concept of peak capacity (n), which is the maximum number of peaks that can be accommodated in a chromatogram with a resolution of one. Diagram courtesy of Waters Corporation.

Rgure 1 (A) Peak capacity (n expressed for a single GC column. (B) Peak capacity expressed for a multidimensional GC analysis, with a first-dimension GC column (n ) and one heartcut event to a second-dimension GC column capacity (rtic). Total capacity nt+rric. (C) Peak capacity expressed for a comprehensive two-dimensional GC analysis where each dimension has capacity and ntc, respectively. Total capacity nt x mt. 

Giddings and Davis [55] have shown that, for complex mixtures, analyte retention data tend to reflect a Poisson distribution. This result permits a simple calculation of the probability of finding a certain number of singlets, doublets, and higher-order multiplets in the course of analyzing a mixture of m components on a column with a peak capacity n. If the ratio mhi is not small, the probability is low. This confirms that there is little chance of separating a complex mixture on the first phase selected [56]. Method development is a long and onerous process because the probability of random success is low. 

The peak capacity n ) is a measure of the number of compounds that can be... 

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