DIFFERENTIAL CAPTURING DEVICE AND DIFFERENTIAL MEASUREMENT METHOD

PROBLEM TO BE SOLVED: To accurately and simply correct an error based on the leak into the capturing device of a target substance at the time of circulation and storage before capturing, and/or an error based on the aging effect of a capturing reagent used in the capturing device when measuring the density of a trace of the target substance in a gas by capturing a sample gas. SOLUTION: A pair of capturing devices are prepared in coupled state for circulation and storage with their gas capturing holes connected and communicated. While a sample gas is captured with one of the capturing devices, the densities of the target substances in the gases of both the capturing devices are measured and the difference between the two measuring values is obtained as the density of the target substance.