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Chromatographic peak resolution is given by = + where t R is the retention time and w b is the peak width at baseline. The bigger the time-difference and/or the smaller the bandwidths, the better the resolution of the compounds.
The Purnell equation is an equation used in analytical chemistry to calculate the resolution R s between two peaks in a chromatogram. [1] [2]= (′ + ′) where R s is the resolution between the two peaks
So what does this mean? It means that to increase resolution of two peaks on a chromatogram, one of the three terms of the equation need to be modified. 1) N can be increased by lengthening the column (least effective, as doubling the column will get a 2 1/2 or 1.44x increase in resolution). 2) Increasing k' also helps.
In chromatography, the area of a peak is proportional to the number of moles (n) times some constant of proportionality (k), Area = k×n. The number of moles of compound is equal to the concentration (molarity, M) times the volume, n = MV. From these equations, the following derivation is made:
The method interpolates peaks between bracketing n-alkanes. The Kovats index of n-alkanes is 100 times their carbon number, e.g. the Kovats index of n-butane is 400. The Kovats index is dimensionless, unlike retention time or retention volume. For isothermal gas chromatography, the Kovats index is given by the equation:
The van Deemter equation is a hyperbolic function that predicts that there is an optimum velocity at which there will be the minimum variance per unit column length and, thence, a maximum efficiency. The van Deemter equation was the result of the first application of rate theory to the chromatography elution process.
A high value for resolution corresponding to good separation of peaks is similar to the convention used with chromatography separations, [13] although it is important to note that the definitions are not the same. [14] High resolution indicating better peak separation is also used in ion mobility spectrometry. [15]
Gas chromatography (GC) is a common type of chromatography used in analytical chemistry for separating and analyzing compounds that can be vaporized without decomposition. Typical uses of GC include testing the purity of a particular substance, or separating the different components of a mixture. [ 1 ]