Precise droplet injection for calibrating a gas chromatography instrument

Abstract

A method and apparatus for calibrating a gas chromatography instrument by forcefully shooting a measured droplet which securely passes through a confined passageway without direct intervention of human hands into the entry throat of the instrument so as to avoid contaminating the apparatus or impairing the accuracy of the instrument.

1 . In the art of calibrating a gas chromatography instrument that has an inlet throat for receiving a gas whose characteristics are to be analyzed, the method of:
 generating a droplet of a known substance and which has known chemical constituents;   shooting the droplet through an accurate trajectory that is essentially coaxial to the inlet throat of the instrument so as to assure that neither the droplet nor the instrument will become contaminated in that process; and   then comparing a reading from the instrument with the known constituents of the droplet.   
     
     
         2 . The method of  claim 1  in which the droplet is forcefully shot through a pulse valve. 
     
     
         3 . The method of  claim 1  in which the droplet is generated by a droplet generator, and a flexible boot is utilized to align the droplet generator with the inlet throat of the instrument. 
     
     
         4 . The method of  claim 1  in which the gas chromatography instrument is of the type that displays a closed-figure polar diagram representing the constituents of a vapor received in the throat of the machine, thus enabling an operator to establish by pattern recognition that the calibration of the instrument is correct. 
     
     
         5 . The method of  claim 4  wherein the droplet is generated by a droplet generator, a flexible boot is utilized to align the droplet generator with the inlet throat of the instrument, and the droplet is forcefully shot from a pulse valve in the droplet generator into the throat of the instrument. 
     
     
         6 . The method of  claim 5  utilizing an apparatus wherein both the droplet generator and the flexible boot are very small and are incorporated into a single apparatus that may be conveniently held in one hand. 
     
     
         7 . An instrument system for precisely analyzing and measuring the chemical constituents of a vapor, comprising:
 a gas chromatography machine having a housing and an entry throat projecting outward from the housing for receiving a sample of vapor to be analyzed, the machine also having an electronic screen and being adapted to display on the electronic screen a closed-figure polar diagram representing the constituents of a vapor sample received in the throat of the machine;   an electronically controlled metering and injection apparatus for producing a droplet of a desired liquid to be injected into the entry throat for the purpose of calibrating the machine;   a flexible boot cooperatively attached to the metering and injection apparatus and selectively attachable to the inlet throat of the gas chromatography machine for providing a confined passageway within which the droplet may securely pass without contamination or error; and   the metering and injection apparatus being adapted to shoot the droplet through the flexible boot into the inlet throat without intervention of human hands, whereby an accurate vapor image on the screen enables the operator by pattern recognition to determine that the calibration of the instrument was correct.   
     
     
         8 . A gas chromatography instrument and a test apparatus
 for calibrating it, comprising, in combination:   the gas chromatography instrument having a flat face within which a cylindrical central opening is formed, and an elongated inlet throat extending from that opening in coaxial relation thereto;   the test apparatus being contained in a hand held housing, having an electronically controlled droplet generator contained within the housing and a pulse valve that extends from the housing, the pulse valve having a rigid cylindrical outer wall;   the pulse valve also having a droplet outlet tube which extends forward from one end thereof in concentric relation to its rigid outer wall, and a pair of wires extending from the other end of the pulse valve for connection to and activation from the droplet generator; and   a rigid housing for temporarily aligning the pulse valve with the throat of the gas chromatograph when a test droplet is to be injected into the throat of the instrument, the rigid housing having an internal space for slidably receiving the pulse valve in a predetermined position relative thereto;   the rigid housing also having a forwardly projecting circumferential rim portion that interfits in a predetermined relation with the cylindrical central opening in the face of the instrument with the droplet tube projecting forward.   
     
     
         9 . The apparatus of  claim 8  which further includes a soft cylindrical flexible boot for supporting the rigid pulse valve housing in adjustable relation to the housing of the hand held test apparatus when alignment with the gas chromatograph is being established for purpose of injecting a test droplet.