Patent Document ID: 9625373
Application ID: 11885212
Patent Flag: 1

Claim One:
1. A chemical analysis method for determining the concentration of at least one gaseous component of interest in a sample gas, comprising the steps of: (a) directing light from a tunable diode laser through an inert gas contained in a sample cell over a selected range of n wavelengths to a light detector to produce a range of baseline signals I 0 n from the light detector, the inert gas being essentially transparent over the selected range of n wavelengths; (b) digitizing the range of baseline signals I 0 n from the light detector; (c) storing the digitized baseline signals I 0 n in a digital computer; (d) directing light from the tunable diode laser through the sample gas contained in the sample cell over the selected range of n wavelengths to the light detector to produce a range of sample signals I S n from the light detector; (e) digitizing the range of sample signals I S n from the light detector; (f) storing the digitized sample signals I S n in a digital computer; (g) calculating a spectrum I(n) in the digital computer according to the equation I(n)=(I 0 n−I S n)/I 0 n; (h) producing a signal from the computer indicative of the concentration of each gaseous component of interest by using spectra of a known concentration of the component of interest in the inert gas stored digitally in the computer, the spectrum of step (g) and a multivariate regression algorithm programmed in the computer, wherein the gaseous components of interest are acetylene and methylacetylene and the sample gas comprises ethylene and methylacetylene from an ethylene cracker hydrogenator, and wherein the pressure in the sample cell is about 100 torr.