Mechanical gas chromatography injection valves and column multiplexing techniques

A gas chromatography injection valve for controlling the flow of a sample vapor to an outlet comprising:

• a housing having an internal passageway and at least two outlet ports with at least one of said outlet ports for connection to an analytical separation column,
• a shuttle tube linearly displaceable within said housing and having an injection port communicating with said sample vapor,
• actuator means for moving said shuttle within said housing to cause said injection port to be moveable between an injection position with said injection port in registry with one of said outlet ports providing fluid communication therebetween, to a non-injection position with said injection port out of registry with each of said outlet ports,
• inlet means for communicating said housing passageway with a source of a flushing gas, and
• means for controlling the flow of said flushing gas through said housing such that said sample vapor flowing into said housing does not communicate between said injection port and any of said outlet ports when said shuttle is in said non-injection position.

A gas chromatography injection valve for controlling the flow of a supplied fluid to an outlet, comprising:

• a housing having an internal passageway and a first port,
• a plug rotationally displaceable within said housing and having a second port,
• actuator means for rotating said plug within said housing to cause said second port to be moveable between an injection position with said first and second ports in registry providing fluid communication between said ports, to a non-injection position with said ports out of registry,
• inlet means for communicating said housing internal passageway with a source of a flushing gas, and
• means for controlling the flow of said flushing gas through said housing such that said supplied fluid flowing into said housing does not communicate between said first and second ports when said plug is in said non-injection position.

A gas chromatography system for the analysis of an analyte comprising:

• at least two analytical separation columns, said columns exhibiting differing separation characteristics,
• a detector receiving analyte components eluted from each of said columns for sensing the presence of analyte components being eluted,
• a mechanical injection valve for injecting an unseparated sample of said analyte into said columns said injection valve having a housing with an internal passageway and at least two outlet ports communicating with said analytical columns and a moveable shuttle element having an injection port from which said unseparated sample flows and said shuttle element moveable from an injection position wherein said injection port is aligned with one of said outlet ports to a non-injection position in which said injection port is out of registry with each of said outlet ports, and
• controller means for operating said injection valve such that said analyte is sequentially injected into said columns in a timed sequence such that the components of interest are eluted from said columns and sensed by said detector at distinct time intervals.

A gas chromatography injection valve for controlling the flow of a continuously supplied sample vapor to at least one outlet comprising:

• a housing having an internal chamber and at least one outlet port for connection to an analytical separation column, said chamber further defining an elongated bore,
• a shuttle tube linearly displaceable within said housing bore and having a hollow inside passageway and a vapor injection port in the form of an aperture through a wall of said tube,
• actuator means for moving said shuttle tube within said housing bore to cause said injection port to be moveable between an injection position with said injection port and said outlet port in registry providing fluid communication between said ports, and to first and second non-injection positions with said ports out of registry and said non-injection positions corresponding to said injection port on opposite sides of said outlet port along said bore,
• inlet means for communicating said housing chamber with a source of a flushing gas, and
• first and second vent passageways within said housing for permitting leakage of said flushing gas from said housing, said vent passageways positioned adjacent said injection port when said shuttle tube is in said non-injection positions,
• capillary flow restrictors connected to said outlet ports for controlling the flow of said flushing gas from said vent passageways, and
• at least one sealing element within said bore providing a bearing for said shuttle tube and controlling leakage of said flushing gas along said tube.