Suppressors are needed when performing trace analysis of anions in the low ppm range (mg/L) using conductivity detection. The purpose of the suppressor is to enhance signal-to-noise ratio by increasing sensitivity and reducing the background. The suppressor accomplish this by removing eluent cations and replacing them with hydronium ions (protons), thereby neutralizing the eluent. The suppressor is thus connected downstream of the separation column, before the detector.
To obtain optimum conditions for the suppressor an automatic regenerator is used. Xenoic® XAMS regenerated by Xenoic® ASUREX constitutes a powerful chemical suppression system without any need to prepare regeneration solutions on a regular basis. The external regeneration cartridge holds enough protons for months of unattended operation of the Xenoic® XAMS.
The strongly basic eluents typically used in suppressed ion chromatography are not always compatible with chromatographic equipment constructed from stainless steel. This may affect lifetime of columns, suppressors and equipment since metal ions may continuously leak into the eluent stream. One solution to this issue is to use instruments where the pump heads and flow lines are constructed from poly(etheretherketone), PEEK. Another approach, that works well with carbonate eluents where pH is in the range 11-12, is to passivate all metal surfaces in contact with the eluent and replace majority of the tubing to PEEK. Hydroxide eluents do often have a pH 12-13, which is too high for many stainless steel-based instruments.