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USGS · 70015629

Determination of ammonium in a buddingtonite sample by ion-chromatography

P.R. Klock·P. J. Lamothe
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Abstract

An ion-chromatographic method for the direct determination of ammonium, potassium, and sodium in geologic materials is described. Samples are decomposed with a mixture of hydrofluoric and hydrochloric acids in a sealed polycarbonate bottle heated in a microwave oven. The ion-chromatograph separates the cations and determines them by conductivity measurement. The ammonium concentrations thus determined have been verified by use of an ammonia-specific electrode. A total of 32 analyses of ammonium salts by both techniques showed an average error of −4%, with a relative standard deviation (RSD) of 6%. The ammonium concentrations found in a buddingtonite sample had an RSD of 2.2% and their mean agreed with that obtained by the Kjeldahl method. By use of the prescribed dilution of the sample, detection limits of 0.1% can be achieved for all three cations.

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P.R. Klock, P. J. Lamothe. 1986. Determination of ammonium in a buddingtonite sample by ion-chromatography. https://doi.org/10.1016/0039-9140(86)80261-2

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