Ion chromatography

At the start of the 1950s, Kraus and Nelson demonstrated the use of many analytical methods for metal ions dependent on their separation of their chloride, fluoride, nitrate or sulfate complexes by anion chromatography.

A groundbreaking method by Small, Stevens and Bauman at Dow Chemical Co. unfolded the creation of the modern ion chromatography.

[14] As a result, a period of extreme competition began within the IC market, with supporters for both suppressed and non-suppressed conductivity detection.

[16] The boom of Ion exchange chromatography primarily began between 1935 and 1950 during World War II and it was through the "Manhattan project" that applications and IC were significantly extended.

They performed ion methods to treat clays with the salts, resulting in the extraction of ammonia in addition to the release of calcium.

[18] Because of the abundant separating columns, elution systems, and detectors available, chromatography has developed into the main method for ion analysis.

Since 1935, ion exchange chromatography rapidly manifested into one of the most heavily leveraged techniques, with its principles often being applied to majority of fields of chemistry, including distillation, adsorption, and filtration.

[22] The stationary phase surface displays ionic functional groups (R-X) that interact with analyte ions of opposite charge.

The concentration of the exchangeable counterions, which competes with the molecules for binding, can be increased, or the pH can be changed to affect the ionic charge of the eluent or the solute.

With increasing ionic strength of the buffer, the salt ions will compete with the desired proteins in order to bind to charged groups on the surface of the medium.

It is not imperative to add the sample in minute volumes as the predetermined conditions for the exchange column have been chosen so that there will be strong interaction between the mobile and stationary phases.

Altering the shapes of the stirred chamber, as well as of the limit buffer, allows for the production of concave, linear, or convex gradients of counterion.

Among the most common immobilized charged groups used are trimethylaminoethyl (TAM), triethylaminoethyl (TEAE), diethyl-2-hydroxypropylaminoethyl (QAE), aminoethyl (AE), diethylaminoethyl (DEAE), sulpho (S), sulphomethyl (SM), sulphopropyl (SP), carboxy (C), and carboxymethyl (CM).

DEAE is an anion exchange matrix that is produced from a positive side group of diethylaminoethyl bound to cellulose or Sephadex.

[27] Agarose gel based medium contain large pores as well but their substitution ability is lower in comparison to dextrans.

[26] Incorporation of high temperature and pressure allows a significant increase in the efficiency of ion chromatography, along with a decrease in time.

In some experiments, the retention times of weak ion exchangers are just long enough to obtain desired data at a high specificity.

This is typically a resin or gel matrix consisting of agarose or cellulose beads with covalently bonded charged functional groups.

It can be used to overcome mass transfer limitations[43] and pressure drop,[44] making it especially advantageous for isolating and purifying viruses, plasmid DNA, and other large macromolecules.

The column is packed with microporous membranes with internal pores which contain adsorptive moieties that can bind the target protein.

Adsorptive membranes are available in a variety of geometries and chemistry which allows them to be used for purification and also fractionation, concentration, and clarification in an efficiency that is 10 fold that of using beads.

A more recent method involved the use of live cells that are attached to a support membrane and are used for identification and clarification of signaling molecules.

These porous particles are also referred to as beads, may be aminated (containing amino groups) or have metal ions in order to have a charge.

This effect comes as a result of two similarly charged particles, one from the resin and one from the solution, failing to distribute properly between the two sides; there is a selective uptake of one ion over another.

This behavior was manipulated to separate lipids, mainly fatty acids from mixtures in to fractions with differing number of double bonds using silver ions.

Ion Exchange Resins(IER) have been widely used especially in medicines due to its high capacity and the uncomplicated system of the separation process.

[citation needed] These isoenzymes include MM, MB, and BB, which all carry out the same function given different amino acid sequences.

From the finding, about 35 out of 71 patients studied suffered from heart attack (myocardial infarction) also contained an abundant amount of the CK-MM and CK-MB isoenzymes.

The most significant development related to ion chromatography are new sample preparation methods; improving the speed and selectivity of analytes separation; lowering of limits of detection and limits of quantification; extending the scope of applications; development of new standard methods; miniaturization and extending the scope of the analysis of a new group of substances.

For example, IC is used to improve stabilities and solubility properties of pharmaceutical active drugs molecules as well as used to detect systems that have higher tolerance for organic solvents.