The basic principle of the Timberline Ammonia Analyzer is to combine sample with caustic (nominal 10%) and transport the mixture via gas entrainment on the outside of a hydrophobic membrane. The ammonia gas generated in the high pH environment migrates through the membrane and is reabsorbed by a dilute buffer solution on the inside of the membrane. The ammonia content is then qualitatively measured in a conductivity cell. This procedure is comparable to the classic ammonia procedure where sample + caustic is distilled and the ammonia is caught in a dilute acid trap.