Volumetric pumping apparatus and method for supplying fluids to sheath stream flow cells

• US 4,695,431 A
• Filed: 08/16/1985
• Issued: 09/22/1987
• Est. Priority Date: 08/16/1982
• Status: Expired due to Term

• Current Assignee: Technicon Instruments Corporation
• Original Assignee: Technicon Instruments Corporation
• Inventors: Farrell, Gregory A.
• Primary Examiner(s): Richman, Barry S.
• Assistant Examiner(s): Gzybowski, Michael S.
• Application Number:
  US06/766,671
• Time in Patent Office: 767 Days
• Field of Search: 417/404, 417/267, 417/268, 422/55, 422/63, 422/81, 422/82, 436/50, 436/52-55, 73/863.01, 73/863.02, 73/863.03, 73/863.83, 73/864.12, 73/864.21, 73/864.22, 73/864.81, 137/2, 137/3, 137/10, 137/93, 137/571, 356/246
• US Class Current: 422/81
• CPC Class Codes: G01N 35/1095 for supplying the samples to flow-through analysers for a specific analyser see relevant groups, e.g. under G01N15/00, G01N21/00, G01N27/00, G01N30/00, H01J49/00
• CPC Class Codes: Y10T 436/117497 with a continuously flowing sample or carrier stream

Abstract

Apparatus and method are provided for the precisely controlled and coordinated supply of sample and sheath stream fluids to a sheath stream flow cell, and comprise the use of positive displacement differential pumping means which are operable to insure consistent sample and sheath stream fluid diameters, velocity and volume flow conditions within the flow cell, thereby maximizing the accuracy and reproducibility of successive analyses.

Claims

1. In an apparatus for establishing a precisely controlled sheath stream flow of first and second fluids from respective sources thereof through a sheath stream flow cell having an inlet and an outlet, the improvements comprising, means for pumping a controlled volume of said first fluid from said (a) source thereof to said flow cell inlet, means integral and cooperating with said first fluid pumping means for aspirating a controlled volume of said second fluid from said (a) source thereof to said flow cell inlet, and means integral and cooperating with said first fluid pumping means and second fluid aspirating means for withdrawing by aspiration at a controlled rate from the outlet of said flow cell a volume of mixed first and second fluids equal to the sum of the volumes the first and second fluids introduced into said flow cell while said first and second fluids are being pumped and aspirated, respectively, into said flow cell inlet by said first fluid pumping means and said second fluid aspirating means.

2. In an apparatus as in claim 1 wherein the improvements further comprise means to detect characteristics of one of said fluids as it is flowed through said sheath stream flow cell, and means operatively associated with said integral fluid pumping and aspirating means and operable to control the operation of said detecting means in response to the operation of said integral fluid pumping and aspirating means.

3. In an apparatus as in claim 1 wherein the improvements further comprise, the means for pumping said first fluid comprises means for pumping a sheath stream liquid and the aspirating means comprises means for aspirating a sample liquid.

4. In an apparatus as in claim 1 wherein the improvements further comprise said first fluid pumping means, second fluid aspirating means and means for withdrawing said mixed first and second fluids comprising an integral differential pump cooperating with respective sources of said first and second fluids and the inlet and outlet of said flow cell.

5. In an apparatus as in claim 1 wherein the improvements further comprise said first fluid pumping means, second fluid aspirating means and means for withdrawing by aspiration said mixed first and second fluids cooperate as means for withdrawing said mixed first and second fluids at a flow rate equivalent to the sum of the flow rates at which said first fluid is pumped and said second fluid is aspirated.

6. In an apparatus as in claim 5 wherein the improvements further comprise, means operatively associated with said first fluid pumping means, second fluid aspirating means and means for withdrawing by aspiration said mixed first and second fluids to drive the same at a substantially constant rate.

7. In an apparatus as in claim 5 wherein the improvements further comprise, the first fluid pumping means is means for pumping a sheath stream liquid, and the second fluid aspirating means comprises means for aspirating a sample liquid for analysis in said sheath stream flow cell.

8. In an apparatus for establishing a precisely controlled sheath stream flow of first and second fluids from respective sources thereof through a sheath stream flow cell having an inlet and an outlet, the improvements comprising, means for pumping a controlled volume of said first fluid from said source thereof to said sheath stream flow cell inlet, means integral and cooperating with said first fluid pumping means for aspirating a controlled volume of said second fluid from said source thereof to said sheath stream flow cell inlet, and means integral and cooperating with said first fluid pumping means and said second fluid aspirating means for withdrawing at a controlled rate from said sheath stream flow cell outlet a volume of mixed first and second fluids equal to the sum of the volumes said first and second fluids introduced into said sheath stream flow cell while said first and second fluids are being pumped and aspirated, respectively, into said sheath stream flow cell inlet by said first fluid pumping means and said second fluid aspirating means;

said first fluid pumping means, said second fluid aspirating means, and said means for withdrawing said mixed first and second fluids, respectively comprising an integral differential pump cooperating with said sources of said first and second fluids and the inlet and outlet of said sheath stream flow cell;

said differential pump being a double acting piston pump comprising a pump cylinder, a pump piston reciprocatable therein and dividing said pump cylinder into first and second pumping chambers, with the first of said pumping chambers comprising said means to pump the first of said fluids therefrom to said sheath stream flow cell inlet, and the second of said pumping chambers comprising said means to aspirate said second fluid to said sheath stream flow cell inlet and to withdraw the first and second of said fluids through said sheath stream flow cell outlet into said second pumping chamber.

9. In an apparatus as in claim 8 wherein the improvements further comprise, said pump piston comprises opposed piston faces of different effective areas, with the effective area of the piston face for said first pumping chamber being less than the effective area of the piston face for said second pumping chamber, and said second pumping chamber having a greater pumping capacity than the first of said pumping chambers.

10. In an apparatus as in claim 8 wherein the improvements further comprise, said first and second pumping chambers cooperate as means for withdrawing said mixed first and second fluids at a flow rate equivalent to the sum of the flow rates at which said first fluid is pumped and said second fluid is aspirated.

11. In an apparatus as in claim 10 the improvements further comprising, means operatively associated with said differential pump to drive said pump piston at a substantially constant linear velocity.

12. In an apparatus as in claim 11 the improvements further comprising, detecting means operatively associated with said sheath stream flow cell to detect predetermined characteristics of one of said fluids as the same is flowed through said sheath flow cell, and means operatively associated with said pump piston to control the operation of said detecting means in response to the operation of said pump piston.

13. In an apparatus for the positively controlled and coordinated supply of a sheath liquid and a sample liquid from respective sheath liquid and sample liquid sources to sheath stream flow cell analysis means which include a sheath stream flow cell having inlet means and outlet means, the improvements comprising, differential pump means operatively associated with said sheath stream flow cell inlet and outlet means and with the respective sheath liquid and sample liquid sources, said differential pump means being operable to pump said sheath liquid from its source to said sheath stream flow cell inlet means for flow through said sheath stream flow cell, said differential pump means being further operable to concomitantly aspirate said sample liquid from its source through said sheath stream flow cell inlet and outlet means, and said sheath liquid from said sheath stream flow cell outlet means, for concomitant coordinated flow of said sheath and sample liquids through said sheath stream flow cell.

14. In an apparatus as in claim 13 wherein the improvements further comprise, said differential pump means comprise a double acting piston pump which includes a pump cylinder and a pump piston reciprocatable therein and dividing said pump cylinder into first and second, positive displacement pumping chambers, with the first of said pumping chambers being operable to pump said sheath liquid therefrom to said sheath stream flow cell inlet means, and the second of said pumping chambers being operable to concomitantly aspirate said sheath liquid and said sample liquid through said sheath stream flow cell inlet and outlet means into said second pumping chamber.

15. In an apparatus as in claim 13 wherein the improvements further comprise, said sheath liquid source is essentially at ambient pressure.

16. An apparatus as in claim 13 wherein the improvements further comprise, said sample liquid source is essentially at ambient pressure.

17. In an apparatus as in claim 13 wherein the improvements further comprise, a source of a sheath stream flow cell wash liquid, and means connecting said wash liquid source to said sample liquid source for flow of said wash liquid to the latter following the aspiration of said sample liquid from said sample liquid source whereby, said wash liquid may be aspirated from said sample liquid source through said sheath stream flow cell by said differential pump means following the aspiration of said sample liquid therethrough.

18. In an apparatus as in claim 13 wherein the improvements further comprise, said sample liquid source is open to ambient air whereby, ambient air may be aspirated through said sample liquid source and said sheath stream flow cell by said differential pump means following the aspiration of said sample liquid therethrough.

19. In an apparatus as in claim 13 wherein the improvements further comprise, said sheath stream flow cell analysis means further comprise detecting means operatively associated with said sheath stream flow cell and operable to detect predetermined characteristics of said sample liquid as the same is flowed through said sheath stream flow cell, and wherein the improvements further comprise, control means for controlling said detecting means being operatively associated with said differential pump means and operable to control the operation of said detecting means in accordance with the operation of said differential pump means.

20. In an apparatus as in claim 19 improvements further comprise, said differential pump comprises a pump cylinder, a pump piston reciprocatable therewithin, and piston rod means connected to said pump piston and including a piston rod portion which extends without said pump cylinder, said detecting means control means comprising means operatively associated with said piston rod portion and said detecting means and operable to control the operation of said detecting means.

21. In a sheath stream flow cell analysis apparatus for the analysis of sample liquids, the improvements comprising, a source of a sheath liquid, a source of a sample liquid, a sheath stream flow cell having inlet means and outlet means, and a differential pump means operatively associated with said sheath stream flow cell inlet and outlet means and with the respective sources of said sheath liquid and said sample liquid, said differential pump means being operable to pump said sheath liquid from its source to said sheath stream flow cell inlet means for flow through said sheath stream flow cell, said differential pump means being further operable to concomitantly aspirate said sample liquid from its source through said sheath stream flow cell inlet and outlet means, and said sheath liquid from said sheath stream flow cell outlet means, for concomitant coordinated flow of said sheath and sample liquids through said sheath stream flow cell.

22. In an apparatus as in claim 21 wherein the improvements further comprise, said differential pump means comprise a double acting piston pump which includes a pump cylinder and a pump piston reciprocatable therein and dividing said pump cylinder into first and second, positive displacement pumping chambers, with the first of said pumping chambers being operable to pump said sheath liquid therefrom to said sheath stream flow cell inlet means, and the second of said pumping chambers being operable to concomitantly aspirate said sheath liquid and said sample liquid through said sheath stream flow cell inlet and outlet means into said second pumping chamber.