Method of selectively measuring the concentration of those gaseous and/or liquid substances in gases and/or liquids which absorb radiation ranging from IR to UV, and device for carrying out the method

摘要

The invention relates to a method of selectively measuring the concentration of those gaseous and/or liquid substances in gases and/or liquids which absorb radiation ranging from IR to UV by means of the transmission procedure. The intensity, assigned to the substances li1...lin-1, of a beam periodically interrupted by means of filters Fi1...Fin-1 in test components Mi1...Min-1 is measured, each test component Mi being made up of a test signal and a dark signal. The object of the invention is to improve the process photometer of the type mentioned at the outset in such a way that a simultaneous measurement of the concentration of a plurality of substances is made possible. The object is achieved in that a value which is proportional to the measured value of the respective preceding test signal of the test component Mi-1 is subtracted from the measured value of the test signal of the test component Mi, and a value which is proportional to the measured value of the respective preceding test signal of the component Mi-1 is subtracted from the measured value of the dark signal of the measured component Mi, and in that the cross sensitivity which arises as a result of a spectral overlap of the absorption bands of the various gaseous or liquid components is compensated for analytically.