Recovery integral absorbance method in the full concentration range to eliminate the interference of background gas

Abstract

At present, gas sensors are extremely susceptible to interference from background gases in the field environment, which leads to greatly reduced accuracy. For this reason, we propose an improved method of recovering integral absorbance (IA) using Y component of first harmonic to achieve accurate prediction of the full range of concentration (not reaching absorption saturation). This approach can eliminate the interference of background gas at a low modulation depth (m < 0.25). When the background gas is pure nitrogen and a mixture of nitrogen and carbon dioxide, the recovery effect of this method on methane is both close to the theoretical value when the background gas is air. The linear fitting coefficients for the methane concentration range of 2000–7000 ppm are all greater than 0.999. The prediction effect is satisfactory regardless of the background gas, with a relative error of less than 1%. In summary, this method has considerable application prospects.