Flow splitter for gas chromatography systems

An analytical instrument assembly comprising:

• a gas chromatograph including:
• a primary column configured to receive a sample mixture including a sample and a first portion of a carrier gas;
• and
• a flow splitter coupled to the primary column and configured to receive an eluate;
• a mass spectrometer coupled to the flow splitter via a first restrictor;
• a flame ionization detector coupled to the flow splitter via a second restrictor;
• and
• a pneumatic control module coupled to the flow splitter and configured to:
• deliver a second portion of the carrier gas to the flow splitter, the flow splitter being configured to split the eluate and deliver at least a first portion of the eluate to the mass spectrometer through the first restrictor and at least a second portion of the eluate to the flame ionization detector through the second restrictor at a first split ratio;
• and
• deliver one of (i) a makeup flow including a third portion of the carrier gas to the flow splitter or (ii) an exhaust flow out of the flow splitter, wherein the pneumatic control module is configured to regulate the pressure within the flow splitter to thereby maintain the first split ratio.