Automated sampler-injector apparatus and method for sampling a quantity of sample and testing portions of said quantity

• US 4,836,038 A
• Filed: 03/18/1988
• Issued: 06/06/1989
• Est. Priority Date: 03/18/1988
• Status: Expired due to Fees

• Current Assignee: Einar D.N. Baldwyn
• Original Assignee: Aim Instruments Ltd.
• Inventors: Baldwyn, Einar D. N.
• Primary Examiner(s): Tokar, Michael J.
• Assistant Examiner(s): Raevis, Robert R.
• Application Number:
  US07/169,876
• Time in Patent Office: 445 Days
• Field of Search: 73/863.01, 73/863.72, 73/863.73, 73/864.21, 73/864.22, 73/864.23, 73/864.24, 73/864.25, 73/864.81, 73/864.83 , 73/864.84, 73/864.85, 422/64, 422/67, 422/70
• US Class Current: 73/864.21
• CPC Class Codes: G01N 2030/207 with metering cavity, e.g. sample loop
• CPC Class Codes: G01N 30/24 Automatic injection systems
• CPC Class Codes: G01N 35/1097 characterised by the valves valves in general F16K

Abstract

An automated sampler-injector apparatus and method of sampling, for taking samples from multiple sources and repetitively injecting small portions of a quantity sampled from a single source into a liquid chromatograph column for analysis. The apparatus comprises a syringe and injector tube forming a syringe loop for drawing a quantity of sample from a sample container. A carousel for positioning a selected sample container beneath the syringe loop is provided, and an injector valve having a sample loop therein is further provided for receiving portions of a quantity of sample from the syringe loop and retaining such portion in the sample loop and further transferring the portion of sample from the sample loop into a liquid chromatograph for analysis. The method comprises a procedure for utilizing the apparatus so as to repetitively inject portions of the sampled quantity into the valve, switching the valve from a load position to an inject position to inject the portion of sample into the liquid chromatograph, and repeating the process until the quantity of sample contained in the syringe loop is exhausted.

Claims

1. An automated sample-injector apparatus for use with a liquid chromatograph column, comprising:

(a) a carousel means which holds and retains therein a plurality of sample containers;

(b) syringe means connected by tubing means to an injector tube to form a syringe-loop;

(c) means for positioning a selected one of the sample containers immediately beneath the injector tube;

(d) means for lowering the injector tube into the selected sample container and withdrawing a quantity of sample therefrom into said syringe-loop, and for raising the injector tube from with the sample container;

(e) means for positioning the carousel means to allow direct insertion of the injector tube into a multi-port injector valve having a tube-receiving passage therein;

(f) means for operating the syringe means to inject a portion of the sampled quantity from the syringe-loop into the injector valve when the injector tube is positioned in the tube-receiving passage, and further into a sample loop connected at both its ends to the injector valve; and

(g) means for switching the valve by rotating one portion of the valve and keeping another portion of the valve containing the tube-receiving passage stationary to switch the sample loop from being in fluid communication with the tube-receiving passage to being connected at one end thereof to a supply of pressurized solvent, and at the other end thereof to a liquid chromatograph column;

wherein the pressurized solvent flushes the portion of sample contained in the sample loop and injects it into the liquid chromatograph column for analysis.

2. The automated sample-injector apparatus as claimed in claim 1, further comprising means for supplying solvent to said tubing means and injector tube to purge said tubing means, injector tube, and sample loop of residual sample, comprising:

a wash reservoir for containing a solvent;

pump means to force said solvent into and through said tubing means; and

valve means to allow addition of said solvent to said tubing means when said injector tube is in said tube-receiving passage and said sample loop is in fluid communication with said tube-receiving passage.

3. The automated sample-injector apparatus as claimed in claim 2 wherein said wash reservoir is a sealed container and said pump means is an air pump operatively connected to said wash reservoir to inject a quantity of air into said reservoir to pressurize the solvent located therein and to force said solvent into said tubing means.

4. The automated sampler-injector apparatus as claimed in claim 2 wherein said carousel is a substantially circular disc having an axis of rotation perpendicular to the plane of the disc and passing through its centre, said disc having a plurality of orifices parallel to said axis and located along a common radii about the periphery of said disc for holding and retaining said plurality of sample containers, and having at least one aperture passing in a straight line through the thickness of said disc.

5. An automated sample-injector apparatus for use with a liquid chromatograph column, comprising:

I. carousel means adapted to hold a plurality of sample containers in a substantially horizontal plane, having at one location thereon an aperture;

II. means for removing a quantity of sample from one of said sample containers, and injecting a portion of said quantity directly into a multi-port injection valve means, comprising;

(a) an elongate, hollow injector tube having a substantially flat tip lying in a plane perpendicular to the axis of said tube;

(b) means for rotating said carousel means to allow positioning of a selected one of said sample containers vertically beneath said injector tube and to allow positioning of said aperture vertically beneath said injector tube;

(c) means for lowering said injector tube from an original position to a first position and for raising said injector tube back to said first position and for lowering to a second position within a tube-receiving passage in said injector valve means;

(d) syringe means operable by an electric motor;

(e) tubing means connecting said syringe means to said injector tube to allow said syringe means when activated by said electric motor to draw a quantity of sample from said sample container into said injector tube and tubing means; and

(f) means to activate said electric motor to cause said syringe means to inject said portion of said quantity through said injector tube directly into said injector valve;

III. said injector valve means adapted to receive said injector tube in said tube-receiving passage and further receive said injected portion of said quantity of sample and transfer said portion to said liquid chromatograph column to be analyzed, comprising;

(a) a non-rotatable first element having said tube-receiving passage extending therethrough along a straight line to a face thereof;

(b) a second element rotatably mounted on said first element and having a face axially adjacent to and in bearing contact with said face on said first element;

(c) rotating means for rotating said face on said second element relative to said face on said first element to switch the injector valve means from a load position to an inject position;

(d) a first port in said second element for connection at one end thereof to one end of a sample loop, said first port at its other end being narrower than the flat tip of the injector tube whereby the flat tip can lie flush against the face of the second element;

(e) a second port in said second element for connection at one end thereof to said other end of said sample loop;

(f) a third port in said second element for connection at one end thereof to a pressurized supply of liquid solvent;

(g) a fourth port in said second element for connection at one end thereof to said liquid chromatograph column;

(h) a fifth port in said second element for connection at one end thereof to a discharge tube;

wherein said second element, when rotated relative to said first element to said load position by said rotating means has said first port aligned with said tube-receiving passage so as to be in fluid communication therewith, said second port in fluid communication through said first element with said fifth port, and said third port in fluid communication through said first element with said fourth port; and

wherein said second element, when rotated relative to said first element to said inject position by said rotating means, has either of said first port or said second port in fluid communication through said first element with said third port, and said other of said first port or said second port in fluid communication through said first element with said fourth port.

6. A method for automatically sampling a quantity of sample and injecting in consecutive sequence portions of said quantity into a liquid chromatograph column for analysis, from each of a plurality of sample containers, comprising the steps of:

(a) positioning a carousel member containing a plurality of sample containers so that a selected one of the sample containers is disposed vertically beneath an injector tube connected by tubing means to a syringe means;

(b) lowering said injector tube from an original position into the selected sample container, and operating said syringe means to draw up a quantity of said sample through said injector tube into said tubing means;

(c) raising said injector tube to its original position, and removing the selected sample container from beneath said injector tube so as to expose a multi-port injector valve vertically beneath said injector tube;

(d) switching said multi-port injector valve so that one end of a sample loop, connected to a first port on a second element of said valve, is aligned and in communication with a tube-receiving passage located in a first element of said valve;

(e) lowering said injector tube into said tube-receiving passage;

(f) operating the syringe means to force a portion of the quantity of sample contained in said tubing means through said injector tube and into said sample loop, said sample loop connected at its said other end to a second port on said second element of said valve;

(g) rotating said second element of said injector valve relative to said first element so that a means for flushing said portion of sample from the sample loop, connected to a third port on said valve, is in fluid communication with one of said ends of said sample loop, and a liquid chromatograph column connected to a fourth port on said second element is in fluid communication with said other of said ends of said sample loop, thereby flushing the sample from the sample loop and into said chromatograph column;

(h) repeating steps (d), (f) and (g) at least once;

(i) raising said injector tube to said original position; and

(j) positioning said carousel member so that a further selected one of the sample containers is disposed vertically beneath said injector tube.

7. The method as claimed in claim 6, step (h) thereof further comprising the step of repeating steps (d), (f) and (g) until the quantity of sample contained in said tubing means is exhausted.

8. The method as claimed in claim 6, further introducing the steps after item thereof;

(h'"'"') switching said multi-port injector valve so that said one end of a sample loop connected to said first port on said second element of said valve, is aligned and in communication with said tube-receiving passage located in said first element of said valve;

(h") opening a valve to allow flow of a solvent into said tube means and through said injector tube, sample loop, and out a discharge tube connected to a fifth port on said injector valve, to thereby purge any residual sample; and

(h"'"'"') closing the valve.

9. The method as claimed in claim 6, said second element of said injector valve having a flat surface axially adjacent and in bearing contact with a flat surface on said first element, said tube-receiving passage extending through said first element to said flat surface thereon, said injector tube having a flat tip lying in a plane perpendicular to the axis of the tube, step (e) of such method further comprising:

lowering said injector tube into said tube receiving passage wherein said flat tip abuts said flat surface on said second element.

10. The method as claimed in claim 6, said carousel member comprising a substantially circular disc having an axis of rotation perpendicular to the plane of the disc and passing through its center, said disc having a plurality of orifices parallel to said axis of rotation and located along a common radii about the periphery of the disc for holding and retaining said plurality of sample containers, and having at least one aperture passing in a straight line through the thickness of the disc, said step of positioning a carousel member comprising rotating said disc so that a selected orifice holding a selected sample container is disposed vertically beneath said injector tube, said step of removing the selected sample container from beneath the injector tube comprising rotating the disc so as to align said aperture vertically beneath said injector tube.