DETERMINATION OF INORGANIC ANIONS BY ION

2.1 A small volume of aqueous sample, typically 2 to 3 mL, is injected into an ion chromatograph to flush and fill a constant-volume sample loop. The sample is then injected into a flowing stream of carbonate-bicarbonate eluent. 2.2 The sample is pumped through two different ion exchange columns, then a suppressor device, and into a conductivity detector. The two ion exchange columns, a precolumn or guard column and a separator column, are packed with low-capacity, strongly basic anion exchange resin. Ions are separated into discrete bands based on their affinity for the exchange sites of the resin. The suppressor is an ion exchange-based device that reduces the background conductivity of the eluent to a low or negligible level and also converts the anions in the sample to their more conductive acid forms. The separated anions in their acid forms are measured using an electricalconductivity cell. Anions are identified based on their retention times compared to known standards. Quantitation is accomplished by measuring the peak height or area and comparing it to a calibration curve generated from known standards.