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848

Ammonium - Distillation Method

By Special Request

Summary

This method involves the quantitation of ammonium (NH4-N) in water and waste water. Samples are pH adjusted to pH >9.5, steam distilled into dilute sulfuric acid and analyzed by flow injection analysis (FIA). Ammonium concentration is determined by FIA using the color reaction of NH4 with salicylate, nitroprusside and hypochlorite in an alkaline phosphate buffer. The absorbance of the reaction product is measured at 660 nm. The method has a detection limit of approximately 0.5 mg/L and is generally reproducible within 8%.

Sample amount requested:  at least 250 mL
Samples should be frozen or refrigerated until delivered to the lab. Acidification with sulfuric acid to pH < 2 can be used as a preservative.
Questions concerning limited sample size can be answered by the UC Davis Analytical Laboratory.

U.S EPA, 1999. Method 1690, Ammonia-N in Water and Biosolids by Automated Colorimetry with Preliminary Distillation.

Switala, K. 1999. Determination of Ammonia by Flow Injection analysis. QuikChem Method 10-107-06-1-A. Lachat Instruments, Milwaukee, WI.