An organometallic compound vaporizing and feeding system includes a carrier gas feed passageway connecting a carrier gas source to a container containing an organometallic compound MO and having a carrier gas mass flow controller, an MO gas passageway connecting the container to an in-line monitor for transporting the MO gas, a sample gas passageway connecting the in-line monitor to a sample inlet of an ICP spectrometer, a standard gas passageway connecting a gas cylinder filled with a calibration standard gas to the sample gas passageway and having a standard gas mass flow controller, and a diluent gas passageway connected to the standard gas passageway for passing a diluent gas for adjusting the concentration of the standard gas and having a diluent gas mass flow controller.