Suppressor Systems in Anion-Exchange Chromatography

A suppressor system is used for the sensitive detection of ions via their electrical conductance. Its function is to chemically reduce the background conductivity of the electrolyte used as eluent before it enters the conductivity cell. Therefore, the suppressor system may be regarded as part of the detection system. 

As the result of the suppressor reaction, strongly conducting mineral acids in the presence of weakly dissociated carbonic acid enter the conductivity cell and are thus easily be detected. 

The advantage of the suppressor technique is its higher sensitivity. In addition, the specificity of the method is also increased, since the chemical modification of eluent and sample in the suppressor system converts the conductivity detector from a bulk property detector into a solute specific detector [52]. Thus, exchanging eluent and sample cations with protons means that only the sample anions to be analyzed are detected by the conductivity detector and appear in the resulting chromatogram. 

Recently, membrane-based suppressor systems are increasingly used in addition to conventional suppressor columns. The characteristic properties of the various suppressor devices are discussed below. 

The regeneration of conventional suppressor columns is usually carried out for about 15 minutes using sulfuric acid at a concentration of c = 0.5 mol/L with a flow rate of 4 mL/min. Subsequently, the system is flushed with de-ionized water for some minutes and then it is conditioned with eluent again. 

Resin — SO3H 3- NaCl Resin — SOsNa -H HCl Resin — SO3H -H NaBr - Resin — SOsNa -H HBr 

Similarly, sodium chloride and sodium bromide are converted into their 

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Suppressor Systems in Anion Exchange Chromatography 2HjO" + V2O2 (g) + 2e (70)... 

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