Chromatography Gaussian peak

Distribution Coefficients. Gel-permeation stationary-phase chromatography normally exhibits symmetrical (Gaussian) peaks because the partitioning of the solute between mobile and stationary phases is linear. Criteria more sophisticated than those represented in Figure 8 are seldom used (34). 

Resolution (R) is the measure of the chromatographic separation of two components. Ideally, mixtures should be completely separated, but in many instances spots or peaks will overlap (co-elute). For gas chromatography, where the components are isolated as Gaussian peaks, the resolution is given by ... 

There are many methods used to calculate efficiency. All methods give the same results with ideal, Gaussian peaks. Real chromatography peaks tend to tail on the backside of the peak (away from the injection mark on the... 

Load a small volume of a probe compound (e.g. toluene in reversed-pha.se chromatography). Measure plate count of Gaussian peak. 

Equation 2.38 stems from the relationship giving the variance (in length units), of, of a Gaussian peak obtained in chromatography, imder linear conditions, for a Dirac pulse injection (Figure 2.3a) ... 

Gaussian peak a standard bell-shaped curve based on the mathematical description of a random distribution of, in the case of chromatography, component molecules in a band moving through the column. 

Isotherms plot of distribution ratios K, that is, a plot of concentration of the component in the stationary phase versus concentration in the mobile phase. Isotherms represent the relative attraction of a solute for the stationary and mobile phases, the plot is linear for a symmetrical Gaussian peak, non linear isotherms lead to unsymmetrical peaks, e.g. peak fronting and tailing. Langmuir isotherms describe the equilibrium process in adsorption chromatography, Nernst isotherms relate to partition chromatography. 

Let us consider the impact of this on chromatography by imagining ourselves in three different situations travelling down an HPLC column along with a sample of solute that has just been injected onto the column. As the band-broadening effects described previously start to become obvious, a Gaussian distribution of solute concentrations starts to develop. If there is no effect of concentration on K (a linear sorption isotherm), then all that happens is that the band continues to broaden symmetrically as it travels down the column. A symmetrical Gaussian peak will elute from the column. 

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