Patent ID: 7819946
Filing Date: 2010-10-26
Classification: G01N

Abstract:
1. A method comprising: collecting a first sample absorption data set for a first sample of a gas mixture that comprises a reactive gas at a reactive gas concentration and a first background composition that contributes spectral interference that hampers direct spectroscopic measurement of the reactive gas concentration in the gas mixture, the collecting comprising passing light from a scannable laser source operating in a scan range through the first sample, the scan range comprising a target wavelength; determining a first measured concentration of the reactive gas in the first sample, the determining of the first measured concentration comprising: selecting whether to use the first background absorption data set or a second background absorption data set to determine a second measured concentration of the reactive gas in a second sample of the gas mixture based on whether a correlation of the first background absorption data set to the first background composition is within a pre-defined tolerance; and determining the second measured concentration by generating a second differential absorption spectrum by adjusting the second sample absorption data set using either the first background absorption data set or the second background absorption data set, and converting the second differential absorption spectrum to the second measured concentration of the reactive gas in the gas mixture using the calibration data.