US 4,300,393 AGranted

Sample introduction apparatus for gas chromatographic analysis using packed or capillary bore open tubular columns and method of testing

OwnerStanley D. Stearnsinventor

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Abstract

The illustrated and preferred embodiment of the present invention is a sample delivery system for packed or open tubular column gas chromatographic apparatus. The apparatus comprises a sample injection valve constructed and arranged to utilize multiple ports wherein a gaseous or liquid sample is injected through a syringe into an injection port, the valve being heated to volatilize the sample which is then temporarily stored in a sample storage loop. The valve apparatus rotates to connect the sample storage loop with an inlet conduit delivering the sample and sweep gas to an exponential dilution flask (EDF). The flask provides an output which delivers a diluted portion of sample with the extent of dilution controlled as a function of time through a second valve assembly. The second valve assembly is switched with a timer to deliver a portion of the sample flow and sweep gas to a capillary bore gas chromatographic apparatus. The first valve may also be used independently as an off-line, septumless inlet for use with packed columns without the dilution stage.

Claims18

Dependent claims

A sample injection valve having a relatively fixed stator and a movable rotor having a plurality of ports in the stator, the ports comprising a syringe injection port, a sample loop storage connecting port, a second sample storage loop connecting port, a dilution gas introduction port, a back pressure vent port and an outlet port, there being three internal passages within said rotor means which are selectively moved to connect with pairs of said ports and wherein said sample injection port is adapted to receive a syringe for injection a sample thereinto and further wherein said stator and rotor are made of a material which can be elevated to a temperature sufficient to convert the injected sample into a gas by heating thereof wherein the injected sample gas is then received and stored in the sample injection loop;

wherein said syringe injection port terminates at a relatively small offset volume and serially connects with one of the internal passages within said rotor;
a source of a dilution gas which is introduced through the dilution gas port and is conducted by one of the internal passages to fill the sample loop connected to the sample loop ports;
wherein said sample injection valve is switched to communicate said sample injection storage loop with said syringe injection port prior to insertion of a syringe such that the sample injection port is filled from the internal passage towards the exterior by the dilution gas;
wherein the sample from the syringe is a liquid which liquid is heated by the sample injection valve on delivery from the syringe to vaportize and flow into the sample storage loop in a gaseous state;
and
wherein said sample storage loop is sized to receive the entirety of the vaporized sample.

3 more elements

Dependencies are inferred from the claim text.