title: An ammonia-sensing air gap microelectrode.
abstract: An ammonia-sensing air gap microelectrode has been designed on the basis of a neutral carrier pH-sensing inner electrode. This electrode has a tip diameter of 2 to 5 microns, has a simple design, is easy to fabricate, and has a long shelf life. Its response to ammonium is linear in the range 3 x 10(-5) to 10(-2) M and its response time (95%) is 10 to 15 s. The electrode was converted to a microsensor for urea by immobilization of urease within its tip. The linear response to urea ranged from 3 x 10(-4) to 10(-2) M and the response time was 15 to 20 s.
authors.affiliation: Department of Physiology, University of Pennsylvania, Philadelphia 19104.
authors.forename: Y L
authors.initials: YL
authors.lastname: Ma
authors.forename: L
authors.initials: L
authors.lastname: Cleemann
mesh_terms: D000641:Ammonia / Q000032:analysis*; D004563:Electrochemistry / Q000295:instrumentation; D004800:Enzymes, Immobilized; D008839:Microelectrodes; D014510:Urease / Q000378:metabolism
chemical_list: D004800:Enzymes, Immobilized; D000641:Ammonia; D014510:Urease