Patent ID: 8206311

Claim:
A method for treating an analyzer for detecting gaseous nitric oxide levels in human exhalation so that said analyzer will produce reproducible results upon analyzing a succession of samples of exhaled breath, said method comprising: purging a nitric oxide sensor of the analyzer with filtered atmospheric air that is substantially NO x -free between analyses, the purging including: drawing atmospheric air through a NO x -filter of the analyzer to filter the atmospheric air of NO x and establish a purge gas; and passing the purge gas through a measurement cell containing the sensor; wherein the sensor includes: (i) a protein that binds nitric oxide contained in exhaled breath and that undergoes an optically detectable change upon so binding, said protein immobilized in a porous inert matrix at a protein concentration that together with said matrix porosity causes exhaled breath containing 200 ppb or less of nitric oxide to produce said optically detectable change, and (ii) a desiccant that maintains a controlled moisture level in said matrix without affecting the ability of the analyzer to differentiate between samples containing different nitric oxide levels.