| 摘要 |
<p>The present invention relates to a method and an apparatus for determining the concentration of substances in gases. The method employs electromagnetic irradiation and measurement of the transmitted radiation intensity at a wavelength characteristic of the substance to be determined, the gas containing the substance being measured at not less than two different gas pressure values. In order to overcome the disadvantages of conventional methods, which without exception employ reference gases which have to be specially prepared and stocked, and in order, nevertheless, to be able to determine very rapidly and simply the concentration of a substance in a gas with a relatively high precision, the invention proposes that an initial measurement is carried out at an essentially constant first pressure of the gas to be analysed, then the gas pressure is altered and a second measurement is carried out at a second constant gas pressure with an otherwise identical measurement system, and that the concentration of said substance in the gas is determined by calculation or graphically from the ratio of, or the difference between, the intensities measured in these two measurements on the basis of a theoretical relationship between the absorbance and the concentration by volume of the substance concerned. <IMAGE></p> |
