Automatic fluid injector

In apparatus characterized as a fluid injector useful for the measurement and injection of preselected quantities of a fluid specimen into a medium such as an inlet to an analytical instrument which includes the combination of (A) a syringe assembly inclusive of a barrel into which a fluid specimen can be loaded, a needle mounted on an end of the barrel through the bore of which fluid specimen from the barrel can be flowed and overflowed via a dispensing end of the needle, a fluid diversion valve characterized as a tubular body within which the dispensing end of the needle can be positioned for receipt of fluid overflowed from the dispensing end of the needle, an outlet port through which the fluid specimen can be passed, and a tube, one end of which is connected to said outlet port and the other end to a container into which droplets of the fluid specimen are discharged, and means for the displacement of the fluid specimen from said barrel via the dispensing end of the needle into said inlet to the analytical instrument, (B) an injector feed assembly comprised of a probe sub-assembly inclusive of a pair of hollow needles which provide conduit means for the pick up of said fluid specimen and transport of said fluid specimen to the barrel of said syringe, and (C) a magazine for transporting one or more fluid specimen-containing septum sealed vials for pick up by said pair of hollow needles of said probe sub-assembly for delivery to the barrel of said syringe via thrust of the probe through the septum of a vial, pressurizing the contents of the vial by delivery of gas from a source through a first of said hollow needles of said probe sub-assembly to produce flow of fluid specimen from the vial into the second of the pair of hollow needles for transport through the probe sub-assembly to the barrel of the syringe,

• the improvement wherein the combination further includes
• (D) drop counting means communicated with said tube leading from the outlet port of said fluid diversion valve through which fluid specimen overflowing the syringe via the dispensing end of the needle is flowed to the container, for monitoring and counting a preselected number of the drops of the fluid specimen, and means responsive to said drop counting means for interrupting the flow of fluid specimen transported from a vial via the probe sub-assembly to trap said fluid specimen within the barrel of the syringe prior to injection of a measured quantity of the fluid specimen into the inlet of said analytical instrument.