US3564925A

US3564925A - Sample injector for a high pressure liquid chromatograph

Info

Publication number: US3564925A
Application number: US850925A
Authority: US
Inventors: Hubert N Divelbiss; Billy E Goostree
Original assignee: Varian Associates Inc
Current assignee: Varian Medical Systems Inc
Priority date: 1969-08-18
Filing date: 1969-08-18
Publication date: 1971-02-23
Anticipated expiration: 1988-02-23
Also published as: GB1301180A; DE2040835A1

Abstract

A SAMPLE INJECTOR FOR A HIGH PRESSURE LIQUID CHROMATOGRAPH IS DISCLOSED. THE INJECTOR INCLUDES A HOUSING COUPLED TO THE END OF THE CHROMATOGRAPHIC COLUMN. THE HOUSING INCLUDES AN INJECTOR PASSAGEWAY ALIGNED WITH THE COLUMN AND THROUGH WHICH A HYPODERMIC SYRINGE IS INSERTED FOR INJECTING SAMPLE MATERIAL INTO THE HEAD OF THE COLUMN. A BLOCKING PLATE IS PIVOTABLE INTO POSITION FOR

BLOCKING THE SAMPLE INJECTOR PASSAGEWAY, AFTER INJECTION OF THE SAMPLE, AND IS SEALED TO THE HOUSING BY MEANS OF A DEFORMABLE SEALING RING. A SCREW, WITH INTERNAL PASSAGEWAY, IS PROVIDED FOR PRESSING THE PLATE INTO SEALING ENGAGEMENT WITH THE RING AFTER INSERTION OF THE SAMPLE.

Description

Feb. 23, 1971 v 5s EI'AL 3,564,925

SAMPLE INJECTOR FOR A HIGH PRESSURE LIQUID CHROMATOGRAPH Filed Aug. 18, 1969 INVENTORS HUBERT N.DIVELBISS BILLY E. GOOSTREE AT RNEY United States Patent 3,564,925 SAMPLE INJECTOR FOR A HIGH PRESSURE LIQUID CHROMATOGRAPH Hubert N. Divelbiss, Napa, and Billy E. Goostree, Pleasant Hill, Calif., assignors to Varian Associates, Palo Alto, Calif., a corporation of California Filed Aug. 18, 1969, Ser. No. 850,925 Int. Cl. G0ln 1/10 US. Cl. 73-422 Claims ABSTRACT OF THE DISCLOSURE A sample injector for a high pressure liquid chromatograph is disclosed. The injector includes a housing coupled to the end of the chromatographic column. The housing includes an injector passageway aligned with the column and through which a hypodermic syringe is inserted for injecting sample material into the head of the column. A blocking plate is pivotable into position for blocking the sample injector passageway, after injection of the sample, and is sealed to the housing by means of a deformable sealing ring. A screw, with internal passageway, is provided for pressing the plate into sealing engagement with the ring after insertion of the sample.

Heretofore, liquid chromatographs have had sample injectors wherein a relatively thick rubber diaphragm sealed off a port in the injector housing. The sample was injected by pushing a hypodermic syringe containing the sample material to be injected through the diaphragm. After insertion of the sample into the head of the chromatographic column, the hypodermic syringe is withdrawn from the diaphragm. Such diaphragms, after perforation by the hypodermic syringe, were capable of withstanding only about 1,000 p.s.i.g. of liquid pressure exerted at the head of the column before leakage was encountered through the perforations produced by insertion of hypodermic syringe. It is desirable to provide a sample injection system for relatively high pressure liquid chromatographs which will permit the chromatograph to operate with pressure heads on the column substantially in excess of 1,000 p.s.i.g., such as from 1,000 to 20,000 p.s.i.g. without encountering leakage of the carrier fluid from the sample injector system.

SUMMARY OF THE PRESENT INVENTION The principal object of the present invention is the provision of an improved sample injector for a high pressure liquid chromatograph.

One feature of the present invention is the provision in a sample injector housing of a passageway communicating with the head of the chromatographic column for insertion of a hypodermic syringe, such injector housing including a movable blocking member to be moved into position for blocking the sample injection passageway after injection of the sample, such blocking member being sealed in fluid tight relation to the housing by means of a deformable sealing member encircling the sample introduction passageway with means for pressing the blocking member into sealing engagement with the sealing member to provide a relatively high pressure fluid tight closure of the passageway.

Another feature of the present invention is the same as the preceding feature wherein the blocking member includes a plate pivotably mounted with respect to the housing such that the plate may be pivoted into blocking position for making a seal and pivoted out of blocking position to permit injection of the sample.

Another feature of the present invention is the same as any one or more of the preceding features including the Patented Feb. 23, 1971 provision of a screw threadably mating with a portion of the injector housing and being axially translatable with respect to the sample injection passageway for pressing the blocking member into sealing engagement with the sealing member.

Another feature of the present invention is the same as the preceding feature wherein the screw includes an axially directed passageway in line with the sample injection passageway to permit insertion of the hypodermic syringe through the screw and the passageway in the housing.

Other features and advantages of the present invention become apparent upon a perusal of the following specification taken in connection with the accompanying drawing wherein:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic line diagram, partly in block diagram form, depicting a relatively high pressure liquid chromatograph incorporating features of the present invention,

FIG. 2 is an enlarged sectional view of a portion of the structure of FIG. 1 delineated by line 22,

FIG. 3 is a view of the structure of FIG. 2 taken along line 33 in the direction of the arrows, and

FIG. 4 is a view similar to that of FIG. 3 depicting a pivotable blocking member in the unblocked position.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIG. 1, there is shown a liquid chromatograph 1 incorporating features of the present invention. The chromatograph 1 includes a chromatographic column 2, as of 1 millimeter inside diameter and 3 to 300 feet long, packed with a suitable ion exchange resin in the form of beads having a particle size of approximately 1 micron. A sample injector housing structure 3 is afiixed to the head of the column 2. The injector housing 3 includes an injector passageway 4 through which a hypodermic syringe needle 5 is inserted for injecting a sample of material 6 into the head of the column 2. The injector housing 3 is more fully described below with regard to FIGS. 2-4. A liquid carrier stream is injected through the sample injector housing 3 into the head of the column 2 from a suitable solvent pump 7 at a relatively high pressure as of 1,000 to 20,000 p.s.i.g. Suitable liquid solvents, serving as the carrier liquid, include water, chloroform, ammonium formate and other liquids serving as a solvent for the sample of interest.

The liquid carrier stream carries the dissolved sample material through the column 2 wherein the sample constituents are separated into time displaced peak concentration as the eluted carrier stream exits from the column to an ultraviolet detector 8. The ultraviolet detector 8 includes an ultraviolet lamp 9 which shines ultraviolet radiation through the carrier stream to a photodetector 11. The relative absorption of the ultraviolet light as absorbed by the sample constituents in the carrier stream is detected by photodetector 11 to derive an electrical output corresponding to the peak concentrations of the sample constituents. The detected output signal is fed to an amplifier 12 wherein it is amplified and thence fed to the input of a recorder 13 to produce a chromatogram of the sample material. The chromatogram yields both qualitative and quantitative informtion concerning the sample constituents.

Referring now to FIGS. 2-4, the sample injector 3 of the present invention is shown in greater detail. The sample injector housing 3 includes a rectangular metallic base plate 14, as of stainless steel, having a fluid coupling fitting 15 for attachment to the end of the column 2. The base plate 14 includes a sample injector bore 16 coaxially aligned with the axis of the column 2. A laterally directed bore 17 intersects the injector bore 16 and a second fluid coupling fitting 18 is affixed at the outer end of the bore 17 for connection of bore 17 to the solvent pump 7.

A pivotably mounted blocking plate 19, as of stainless steel, is mounted to the base plate 14 by means of a pivot pin 21. Pivot plate 19 is also axially slideable on the pivot pin 21. The blocking plate 19 is pivotable into a first blocking position, as indicated in FIG. 3, such that the plate 19 extends across and covers over the opening into bore 16.

A cylindrical sealing plug structure 22 is inserted within the upper end of the injector bore 16. The sealing plug structure 22 includes a longitudinally directed bore 23 therethrough to receive a hypodermic syringe needle slideable therethrough for injecting sample material into the head of the column 2. The sealing plug structure is formed in two

parts

24 and 25. The lower cylindrical part 25 includes an outwardly directed flange portion which seats against a shoulder of the bore 16 in sealing engagement therewith. The lower plug member 25 is made of a deformable sealing material such as Teflon or rubber. The upper sealing member 24 is likewise made of a deformable sealing material such as Teflon or rubber and is seated between the lower member 25 and the blocking plate 19.

The sample injector housing structure 3 includes a second rectangular plate member 27, as of stainless steel, fixedly secured to the lower base plate member 14 via a pair of cap screws 28. A lower surface portion of the second plate 27 is relieved at 29 to accommodate the blocking plate 19. Plate 27 includes a threaded bore 31 coaxially aligned with the sample injector bore 16. A screw 32, as of stainless steel, having a knurled knob portion 33 is threaded into the bore 31. The blocking plate 19 is pressed into sealing engagement with the plug structure 22 by axial translation of the screw 32 toward the plate 19. When the plate 19 is pressed into sealing engagement with the deformable plug structure 22, a fluid tight seal is formed between the upper surface of the cylindrical sealing plug member 24 and between the outer periphery of the upper plug member 24 and the inside surface of the bore 16. In addition, a fluid tight seal is formed between the lower plug 25 and the shoulder portion of the bore 16.

The screw 32 includes a longitudinally directed bore 35 therethrough in axial alignment with bore 23 in the plug structure 22. To inject the sample material into the column 2, the screw 32 is translated in a direction away from the blocking plate 19 thereby removing the sealing presure from the blocking plate 19. Blocking plate 19 is then pivoted to an out of the way position as shown in FIG. 4 to permit the hypodermic syringe to be inserted through aligned

bores

35, 23 and 16 into the head of the chromatographic column 2. A sample is then injected into the head of the column 2'. The syringe is removed and the blocking plate 19 is pivoted back to the position as shown in FIG. 3 and screw 32 is tightened against the plate 19 to form the seal with the plate 19 and plug structure 22. The column 2 is then pressurized by injecting solvent from the solvent pump 7 via passageway 17 and bore 16 to the head of the column 2 at pressures in the range of 1,000 to 20,000 p.s.i.g. and preferably between the range of 1,000 to 5,000 p.s.i.g. The efficiency of column 2 for separation of the various sample constituents is proportional to the pressure of the solvent as applied to the column 2.

A pair of mounting holes 37 are provided in the base plate 14 for mounting the injector housing structure 3 4 to a suitable support chassis or structure, not shown. In addition, an alignment pin 38 is driven through aligned apertures in the upper and lower plates 27 and I14, respectively, to obtain proper alignment of plates -14 and 27.

Since many changes could be made in the above construction and many apparently widely diflierent embodiments of this invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. In a liquid chromatographic apparatus, means forming a chromatographic column for separating sample constituents as carried through said column via a liquid carrier stream under a relatively high pressure, means for introducing sample material to be analyzed into the column for passage through said column, the improvement wherein, said sample introducing means includes a housing structure having a sample introduction passageway therein a liquid communication with said column and through which a sample is injected into said column, a deformable sealing member disposed encircling said sample introduction passageway, movable blocking means for movement to a first position for blocking said sample introduction passageway, means for applying sealing pressure to said blocking means to press said blocking means into sealing engagement with said sealing member to form a relatively high pressure liquid tight seal between said blocking means and said housing to prevent the escape of liquid carrier from said sample introduction passage- Way when blocked and pressurized, and means for selectively releasing the sealing pressure on said blocking means to permit movement of said blocking means to a second position which unblocks said sample introduction passageway to permit injection of the sample.

2. The apparatus of claim 1 wherein said blocking means includes a plate pivotably mounted with respect to said housing.

3. The apparatus of claim 2 wherein said means for applying sealing pressure to said blocking means includes a screw threadably mating with a portion of said housing structure and being axially translatable with respect to the axis of said sample introduction passageway for pressing said pivotable plate against said sealing member.

4. The apparatus of claim 3 wherein said screw is substantially coaxially disposed of said sample introduction passageway and is apertured in axial alignment with said passageway to permit insertion of a sample injection tube through said aperture in said screw.

5. The apparatus of claim P1 wherein said sealing member is cylindrical having a centrally disposed axially directed passageway therethrough defining a portion of said sample introduction passageway, said housng including a bore coaxially aligned with said sample introduction passageway, and said cylindrical sealing member being disposed in said bore in sealing relation with said bore at the periphery of said cylindrical sealing member.

References Cited UNITED STATES PATENTS 3,346,486 10/1967 Winter et al 73--61.1

FOREIGN PATENTS 1,215,748 11/1959 France 73-422 S. CLEMENT SWISHER, Primary Examiner