The ideal chromatographic peak has a Gaussian profile, which occurs if the solute’s partition coefficient, KD, between the stationary phase and mobile phase KD = [S]s/[S]m is independent of the solute’s concentration. If this […]
The goal of chromatography is to separate a mixture into a series of chromatographic peaks, each representing a single component of the mixture. The resolution between two chromatographic peaks, RAB, is a […]
A solute’s chromatographic peak may be characterized in many ways, two of which are shown in this figure. Retention time, tr, is the time between when we inject the sample injection and […]
The most common method for bringing the stationary phase and the mobile phases into contact is to hold the stationary phase within a column and to pass the mobile phase through the […]
In chromatography, a separation occurs because there is a difference in the equilibrium partitioning of solutes between the mobile phase and the stationary phase. Equilibrium partitioning, however, is not the only basis […]
As illustrated below, in chromatography we pass a sample-free phase, which we call the mobile phase, over a second sample-free stationary phase that remains fixed in space. We inject or place the […]
Shown here is an illustration outlining the progress of a traditional liquid–liquid extraction (LLE) using two identical extractions of a single sample with fresh portions of the extractant. The numbers give the […]
Voltammetry is a particularly attractive technique for the analysis of samples containing two or more analytes. Provided that the analytes behave independently, the voltammogram of a multicomponent mixture is a summation of […]
In amperometry we apply a constant potential to the working electrode and measure current as a function of time. Because we do not vary the potential, amperometry does not result in a […]
In a cyclic voltammetry experiment, scanning the potential in both directions provides with the opportunity to explore the electrochemical behavior of species generated at the electrode. This is a distinct advantage of […]
In cyclic voltammetry (CV) we scan the potential in both the cathodic and anodic directions. The illustration below shows a typical potential-excitation signal (a) in which we first scan the potential to […]
As illustrated here, anodic stripping voltammetry (ASV) consists of two steps. The first step is a controlled potential electrolysis in which we hold the working electrode—usually a hanging mercury drop or a […]
