High pressure sample injection apparatus and method

An injector for a liquid chromatograph for injecting a sample liquid into a high-pressure stream of carrier liquid, said injector comprising:

• a. structure defining a reservoir for the sample liquid,
• b. structure defining a dispensing chamber for receiving a measured volume of the sample liquid from said reservoir,
• c. structure defining a flow path for the high-pressure stream of carrier liquid,
• d. control structure means interposed between said dispensing chamber and said flow path for substantially preventing liquid flow from said flow path to said dispensing chamber, and for enabling liquid flow from said dispensing chamber to said flow path only when the pressure of said measured volume of sample liquid in said dispensing chamber is at least equal to the pressure of said high pressure stream of carrier liquid, and
• e. displacement means for limiting the volume of sample liquid receivable in said dispensing chamber and for imparting to the sample liquid in said dispensing chamber a pressure at least equal to the pressure of said high-pressure stream of carrier liquid.