Patent ID: 7663098

Claim:
A gas monitoring apparatus comprising: a gas introduction section for introducing a sample gas; an ion source for ionizing a component or components contained in the sample gas; a mass spectrometer for analyzing the ion or ions formed by the ion source for m/z; an operation section for calculating the concentration of diphenylcyanoarsine and/or diphenylchloroarsine contained in the sample gas based on the ion intensity data obtained by the mass spectrometer; and a display section for displaying the result or results obtained in the operation section, wherein said operation section calculates the sum total concentration of diphenylcyanoarsine and diphenylchloroarsine from a signal common to diphenylcyanoarsine and diphenylchloroarsine as obtained in said mass spectrometer, calculates the concentration of diphenylcyanoarsine from a signal specific to diphenylcyanoarsine and calculates the concentration of diphenylchloroarsine from the difference between said sum total concentration and said concentration of diphenylcyanoarsine.