Fixed Ammonium Determination: Quantitative Method Using Fusion Decomposition
William L. Campbell, Ann E. Sturdivant
A method was developed for determination of fixed ammonium (NH+4) content using a small volume of sample. After removing the exchangeable (surface) NH+4 from the clay-rich sediment samples by distillation, fusion decomposition was used to isolate the fixed (lattice) NH+4 from the samples.
Fusion decomposition takes place in a closed system, breaking down the silicate minerals at a temperature of approximately 500°C. Sodium hydroxide (NaOH) is used as a flux. Ammonium liberated from the sample during fusion decomposition is trapped in a dilute solution of hydrochloric acid (HCl). The NH+4 content of the trap solution was quantitatively determined using a Dionex 2000i ion chromatograph with an electrical conductivity detector and a CSl sulfonated polyvinyl benzene resin column.
AAPG Search and Discovery Article #91024©1989 AAPG Pacific Section, May 10-12, 1989, Palm Springs, California.