Application of forced-flow liquid chromatography to the determination of iron

Abstract

A liquid chromatograph is described which permits rapid separation of metal ions using strongly acidic eluents. The chromatograph is inexpensive to construct and provides for quick changing of eluents.With this equipment, iron(lll) can be separated from other ions and determined spectrophotometrically in less than 6 minutes. The iron is concentrated on a small anion exchange column and then is stripped from the column with dilute hydrochloric acid. The amount of iron is calculated from the peak height of the elution curve. Virtually all chemical and electrochemical methods for determining small amounts of a metal ion are at times subject to interferences that necessitate a chemical separation. Methods such as atomic spectrometry are very selective but their dependency on excitation conditions and matrix composition necessitates frequent calibration and standardization. A separation or concentration is often carried out in conjunction with flame methods.Ion exchange and partition chromatographic methods for separating metal ions from one another are quantitative and selective. However, most of the published methods are slow, often requiring 30 minutes or more to elute each element from the column. Recently a systematic scheme for 27 elements was published (/). By using samples of 25 to 50 mg and relatively small columns, the average elution time was reduced to around 15-20 minutes per element. Clearly a more rapid way to separate inorganic ions by ion exchange and partition chromatography would be useful.

High pressure liquid chromatography of phenols and metal ions

“…A similar study by Seymour e^ has been done on the elution of iron from an anion exchanger (19). Qualitatively, the results in that study resemble the results shown in Figure 32 with the flow rate of 2 ml/min to 4.5 ml/min in that study corresponding to 1.2 ml/min to 2 ml/min in Figure 32.…”

“…One way of doing this has been described by Seymour, Sickafoose, and Fritz (19) . The eluent was placed in poly ethylene bottles which were encased in steel jackets.…”

“…To take this into consideration let the equilibrium constant be related to standard free energy in the usual way. log = -AG°/2.3RT (19) where R is the gas constant, T is the absolute temperature and O AG^ is the free energy of adsorption. To simplify the dériva-o tion, let -AG^/2.3RT be AE.…”

Principles and Applications of Ion Chromatography

“…One of such possibilities is the application of a photometric detector. It was first used to determine metal ions in 1971 [43]. Photometric detection is based on the light absorption in the visible spectrum and in the ultraviolet range.…”

Rapid separation and determination of heavy metals in hydrochloric acid by forced-flow anion exchange chromatography

“…In an effort to apply these techniques in inorganic analysis, a recent paper describes a rapid and selective method for iron(I II) using a liquid chromatograph and UV de tection [27). Iron(III) is sorbed to a small column of anion exchange resin from 6M hydrochloric acid.…”