New potentiometric gas-gap sensor

A new gas-gap sensor for the determination of ammonia on the base of a pH-m etric electrode is described. It has been established that the equality of the ionic strength and temperature of the sample and the electrode solution is no longer necessary. This allows to reduce the limit of detection for a mmonia to 5x10(-10) M, to vary the measurable ammonia concentration range f rom 1x10(-9)-1x10(-5) M up to 1x10(-7)-1x10(-3) M and to reduce the respons e time to several minutes. (C) 1999 Elsevier Science B.V. All rights reserv ed.