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R9 Laboratory SOP 530
ANALYSIS OF ANIONS BY ION CHROMATOGRAPHY
Summary
This method is applicable for drinking, ground, surface, and saline water, domestic and industrial wastes and solids leached with reagent water.
This method applies to the determination of the inorganic anions fluoride, chloride, nitrite, bromide, nitrate, ortho-phosphate and sulfate by Method 300.0.
The reporting limit (RL) is 0.10 mg/L for fluoride, nitrate (reported as mg/L N) and nitrite (reported as mg/L N), and 1.0 mg/L for chloride, bromide, ortho-phosphate (reported as mg/L P) and sulfate.
A small volume of sample is injected onto and passed through a series of ion-exchange columns. The anions of interest are separated on the basis of their relative affinities to a low capacity, strongly basic anion exchanger. The separated anions are directed into a strongly acidic cation suppressor exchanger where they are converted to their highly conductive acid forms. The carbonate and bicarbonate eluent is converted to weakly conductive carbonic acid. The separated anions in their acid forms are detected by electrical conductivity and are qualitatively determined on the basis of retention time as compared to the standards. Quantitation is based on peak areas and a cubic calibration curve is used to determine concentrations in environmental samples.