The invention is the development of a dual region ionization tube consisting of 2 independent pathways each capable of providing different selective ionization environments. The initial design is a 1-inch metal tube split in half with a thin metal membrane placed down the entire length of the tube. This enables the use of two ionization sources to produce different ion chemistry in each section. Analyte vapor brought to the front of the tube is divided equally into the 2 separate chambers where unique ionization occurs. These 2 regions recombine at the inlet to the commercial mass spectrometer.