title: Exhaled nitric oxide: sources of error in offline measurement.
abstract: Delayed offline measurement of exhaled nitric oxide (eNO), although useful in environmental and clinical research, is limited by the instability of stored breath samples. The authors characterized sources of instability with the goal of minimizing them. Breath and other air samples were stored under various conditions, and NO levels were measured repeatedly over 1-7 d. Concentration change rates varied positively with temperature and negatively with initial NO level, thus "stable" levels reflected a balance of NO-adding and NO-removing processes. Storage under refrigeration for a standardized period of time can optimize offline eNO measurement, although samples at room temperature are effectively stable for several hours.
authors.affiliation: Environmental Health Service, Los Amigos Research and Education Institute, Downey, California, USA. linn@hsc.usc.edu
authors.forename: William S
authors.initials: WS
authors.lastname: Linn
authors.forename: Marisela
authors.initials: M
authors.lastname: Avila
authors.forename: Henry
authors.initials: H
authors.lastname: Gong
mesh_terms: D000293:Adolescent; D000328:Adult; D001944:Breath Tests; D002648:Child; D005260:Female; D006801:Humans; D008171:Lung Diseases / Q000175:diagnosis*; D008297:Male; D009569:Nitric Oxide / Q000032:analysis*; D015203:Reproducibility of Results; D013048:Specimen Handling; D013696:Temperature; D013997:Time Factors
chemical_list: D009569:Nitric Oxide