Theory of Gradient Elution through Ion Exchangers

Analytical chemistry

“…If a sample contains a large number of substances, representing a wide range of distribution ratios, it is advantageous to consider the use of programmed changes in temperature (10), flow ( tration of a reagent (13,14) in order to minimize the time required. However, one should not overlook the fact that there is an interplay, for example, between flow rate of the carrier and rate of temperature change which can, in turn, be optimized.…”

Separation of Phenols by Reversed-Phase Chromatography.

“…Experiments were carried out in both nitric and perchloric acid solutions, and the effect of acid and nitrate concentrations on the observed "instability" constants was examined. Quadrivalent cerium ion forms adducts with many anions such as sulfate (2), chromate (8), nitrate (9), oxalate (S), and hydroxyl (6) in aqueous solution. Highly colored complexes are also formed with aliphatic alcohols, and analytical procedures have been developed for the determination of methanol, ethanol, and ethylene glycol by absorbtion spectrometry (8,4).…”

“…A gradient elution apparatus similar to that used by Schwab, Rieman, and Vaughan was used to obtain separations of more than two phenols (9). Elution curves were recorded using a Uviscan II ultraviolet flow monitor.…”

Automation of Ion Exchange Chromatographic Analysis of Condensed Phosphate Mixtures

“…The progress of a separation is controlled by the proportioning pump because the reservoir, constant-volume mixing chamber, and column are connected in series to the pump. The rapid response of the instrument permits the use of exponential elution gradients (6) which accomplish an analytical separation of condensed phosphate species in a minimum amount of time. A spare poly (vinyl chloride) tube is installed in the proportioning pump to facilitate regeneration and re-equilibration of an "off-stream" column.…”