Determination of ammonia in exhaled breath by flow injection analysis with electrochemical detection

Abstract

Flow injection analysis with electrochemical detection (FIA-ECD) using a-tocopheol (a-TOH) as a reagent was developed for determining ammonia in exhaled breath. An ethanol-water (4:1, v/v) mixture containing 3 mM a-TOH and 50mM NaCI was used as the carrier solution. The FIA response at +0.70V vs. Ag/AgCI in the flow cell was linear overa range of the ammonia concentration from 0.11 to 1.1ppmv (r = 0.999, n = 7). The lower limit of detection for ammonia was 130pg (S/N = 3), and the relative standard deviation (RSD) was 2.1% (17ng, n = 10). The collected exhaled breath in a Tediar® bag was mixed with water containing NaCl to dissolve ammonia in exhaled breath, and then it was diluted with ethanol containing a-TOH to the same composition of the carrier solution to be injected into the FIA-ECD. The present FIA-ECD method required simple sample preparation and was applied to the determination of ammonia in exhaled breath from a healthy human and gerbils. © The Electrochemical Society of Japan All rights reserved.