F. Dondi et al., FOURIER-ANALYSIS OF MULTICOMPONENT CHROMATOGRAMS - APPLICATION TO EXPERIMENTAL CHROMATOGRAMS, Analytical chemistry, 65(17), 1993, pp. 2209-2222
A complete procedure is presented for quantitative estimation of both
the separation performance and the retention pattern in an experimenta
l multicomponent chromatogram obtained under programmed elution condit
ions. It is shown that, under a conventional good experimental setup,
assuring limited peak width variation (+/-10%) and low peak asymmetry,
the following quantities can be determined: peak capacity, saturation
factor, peak tailing factor, number of single components (SC), and pa
rameters of the SC interdistance distribution. The procedure is based
on the experimental autocovariance function (EACVF) and power spectrum
(EPS) of the experimental chromatogram handled by numerical methods p
reviously presented and validated. What the main features of an experi
mental EACVF plot are and how and where to search for information rela
ted to the retention pattern and SC peak width value contained therein
is also reported, with reference to two typical examples of multicomp
onent capillary gas chromatograms: a chamomile lypophilic extract and
a naphtha sample. The EACVF plots are fitted to four different theoret
ical models of the SC interdistances-exponential, uniform, normal, and
gamma-in order to obtain the best description of the retention patter
n and an evaluation of the SC peak width value. Moreover, the ordered
structure of the chromatogram was identified and analyzed in the EACVF
plot, allowing one to obtain an additional, independent, estimate of
the SC peak width. Similar fittings performed on the EPS plot made it
possible to validate and confirm the EACVF analysis results and, in ad
dition, to detect peak width variations and peak asymmetry effects in
the experimental multicomponent chromatograms. These last SC peak shap
e data were in very good agreement with the peak shape analysis perfor
med with the Edgeworth-Cramer series over well-separated peaks of line
ar hydrocarbons in a reference chromatogram obtained under the same co
nditions.