Patent ID: 8360974

Claim:
A diagnostic method for high sensitivity detection of component concentrations in human gas emissions comprising: (a) collecting a gas sample in a gas cell, wherein the gas sample may contain a specified component being associated with a plurality of fundamental absorption peak frequencies, and wherein the gas sample contains a plurality of other components; (b) passing, at distinct and different times, a tunable optical radiation beam at a first frequency and at a second frequency through the gas cell (1) when the gas cell contains a reference sample having a known concentration of the specified component and (2) when the gas cell contains the gas sample, wherein the first frequency corresponds to one of the fundamental absorption peak frequencies and wherein the second frequency is used to measure any background absorptions caused by the plurality of other components; (c) measuring, after each passing of the tunable optical radiation beam through the gas cell, an optoacoustic signal in the gas cell detected by an acoustic microphone and a power measurement of the tunable optical radiation beam; and (d) determining a concentration of the specified component in the gas sample using the optoacoustic signals and the power measurements obtained from the passing of the tunable optical radiation beam at the first frequency and at the second frequency through the gas cell.