Purdue Research Foundation

Tracor, Inc.

Jack B Dixon

Randall C Hall

Burney J Ehrlich

Lawrence G Baldwin

A liquid chromatograph for HPLC utilizes low pressure solvent metering pumps for solvent mixing in series with a high pressure pump driving the column. Solvent mixture is provided at a flow based upon the intake demand of the high pressure pump. Such operation is obtained by the use of flow control apparatus disposed between the solvent metering pumps and the high pressure pump. The flow control apparatus includes a detector cell disposed in the solvent mixture flow path between the metering pumps and the high pressure pump. The cell has an inlet port for receiving an input flow of solvent mixture into the cell from the solvent mixing means, an outlet port for withdrawal of an output flow of solvent mixture by the high pressure pumps, and a reservoir between the inlet and outlet ports for holding a volume of solvent mixture accumulated in an amount dependent upon the relative flow rates of the cell input and output flow. The cell having first and second spaced-apart electrodes in contact with the solvent mixture accumulated in the cell. One of the electrodes receives an applied electrical excitation. The other electrode senses the applied excitation through the accumulated solvent mixture and produces an excitation response functionally related to the volume of accumulated solvent mixture. An electrical control circuit connected to the detector cell and coupled to the pump speed controller responds to the detector excitation response and produces a control input to the pump controller that selectively inhibits and enables operation of the solvent metering pumps as required to meet the intake of the high pressure pump without wastage or excessive loss of compositional response.

Solvent mixing in HPLC using low pressure solvent metering pumps

A detection unit having a solute detector and a transport system with a quartz fiber conveyor is disclosed that is particularly useful for liquid chromatography. The quartz fiber conveyor is a porous belt that is mounted at the periphery of a rotatable disc so that the total effluent to be detected is applied to the belt as it is rotated within a heated housing enclosing the disc. The volatile solvent of the effluent is removed by evaporation within the heated housing to leave the non-volatile organic solute on the quartz fiber conveyor, which solute is then detected by a solute detector such as a flame ionization detector or a stacked flame photometric detector. After detection, the quartz fiber conveyor is cleaned by hydrogen-oxygen flame and is thus made ready for further transport of effluent. Alternate embodiments of a stacked flame photometric detector and top flame jets connected therewith are disclosed, as is a device to fabricate the quartz fiber conveyor.

Detection unit with solute detector and transport system

A flame ionization detector is disclosed that is particularly useful for liquid chromatography. The detector is preferably utilized with a disc transport assembly with flame jets being positioned at opposite sides of the solute-bearing periphery of the disc. Hydrogen and air are injected through the flame jets and coaxial cables are connected to make electrical contact with the flame jets so that a flame ionization response occurs when organic compounds on the disc of the disc transport assembly are combusted in a potential field. When so combusted, a current is caused to flow from the flame jets through the coaxial cable to an electrometer where the current is amplified for display on a strip chart recorder or other output device.

Growing community of inventors

Georgetown, TX, United States of America

Jack B Dixon