Exponentially modified Gaussian model

The separation efficiency was evaluated using the exponentially modified Gaussian model. With this procedure the peak is characterized by o, the standard deviation of the peak, and r, the exponential modifier. For measurements made in the center of the column, r and a both increased for longer retained compounds. The value of T Increased as the column wall was approached with little change in a. 

Another approach is the characterization of peaks with a well-defined model with limited parameters. Many models are proposed, some representative examples will be deaaib i. Wefl known is the Exponentially Modified Gaussian (EMG) peak, i.e. a Gaussian convoluted with an exponential decay function. Already a few decades ago it was recognized that an instrumental contribution such as an amplifier acting as a first-order low pass system with a time constant, will exponentially modify the... 

Jeansonne, M. S. Foley, J. P. Review of the exponentially modified Gaussian chromatographic peak model since 1983,/. Chromatogr. Sci, 1991, 29, 258-266. 

One empirical model that is widely used for the evaluation of band asymmetry is the exponentially modified Gaussian (EMG) fimction [111-113]. It is the convolution of the unit area Gaussian function and of an exponential decay of unit area. By definition, the convolution of two functions and (f) is the following function... 

For example, a Gaussian peak model is used to derive many fluently used fundamental equations in chromatography (17), but the Gaussian function rarely provides an accurate model for real chromatographic peaks. Convectional effects introduced by the flow cell can cause asymmetry in chromatographic peaks even if a Gaussian profile has been established prior to detection (18). One model diat is well accepted to represent a real chromato phic peak is an exponentially modified Gaussian (EMG) function. The FIA profile is characterized primarily by a dispersion coefficient (19) which offers information about die manifold, but direct information about the peak parameters such as second moment or variance can not be readily obtained. Recently, the EMG was used to describe FIA profiles to obtain the second moment and characterize the peak (20-22). 

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