A method for the determination of volatile ammonia in air, using a nitrogen-cooled trap and fluorometric detection

A quick, cheap, and accurate method for the determination of ammonia in air is described. Ammonia and water vapor are trapped simultaneously in a gas sampling tube cooled in liquid nitrogen. Subsequently ammonia is derivatize d with o-phthaldialdehyde and determined using fluorescence detection. The detection limit of ammonia in a gaseous sample is about 1 nmol per liter of gas. The recovery, using a calibration gas of 6.00 ppm ammonia in nitrogen , is 102.9 +/- 6.4%. Examples are presented in which this method is used fo r the determination of ammonia in environmental air and in expired air duri ng exhaustive exercise of a human subject. It is suggested that this method can be used for the determination of volatile ammonia and other compounds in air during environmental and biological monitoring and in research. (C) 2001 Academic Press.