Method for the dilution of liquid samples

• US 4,610,170 A
• Filed: 11/02/1984
• Issued: 09/09/1986
• Est. Priority Date: 11/30/1983
• Status: Expired due to Fees

• Current Assignee: Labsystems Oy (Thermo Fisher Scientific Incorporated)
• Original Assignee: Labsystems Oy (Thermo Fisher Scientific Incorporated)
• Inventors: Ekholm, Pertti, Kaukanen, Esko
• Primary Examiner(s): Levy, Stewart J.
• Assistant Examiner(s): Noland, Tom
• Application Number:
  US06/667,819
• Time in Patent Office: 676 Days
• Field of Search: 73/864.12, 73/864.22, 73/863, 73/864, 73/864.34, 73/864.35, 73/864.73, 73/864.74, 73/864.11, 73/864.13, 73/864.15, 436/179
• US Class Current: 73/864.22
• CPC Class Codes: G01N 1/38 Diluting, dispersing or mixing samples
• CPC Class Codes: Y10T 436/25625 Dilution

Abstract

Method for the precise dilution of a liquid sample, in which diluting agent is pumped through a main channel (1) open at its lower tip and, at the same time, sample is pumped through a side channel (2), whose lower tip (11) opens into the main channel. The invention can be used e.g. in photometers.

Claims

1. A method for diluting a sample of liquid comprising the steps of:

accumulating diluent in a diluent conduit so that the interior of said conduit is substantially filled with liquid;

said diluent conduit having a downwardly directed opening at the lower portion thereof,

suctioning a sample into a sample tube whose tip is coaxially aligned with said diluent conduit and arranged concentrically therein;

said tip being arranged at a level above said downwardly directed opening of said diluent conduit,

pumping a predetermined amount of diluent out of said conduit through said downwardly directed opening, and substantially simultaneously with said step of pumping diluent through said downwardly directed opening of said diluent conduit, displacing a predetermined amount of sample out of said sample tube into the stream of diluent issuing through said downwardly directed opening;

said tip of said sample tube having an opening in spaced facing relation with said downwardly directed opening;

whereby the stream of diluent being pumped through said sample conduit promotes mixing of sample and diluent and flows about the periphery of said opening of said sample tube to prevent accumulation of sample thereabout.

2. The method according to claim 1, wherein said diluent conduit is filled with liquid by suctioning diluent from a reservoir thereof through said downwardly directed opening.

3. The method according to claim 1, wherein said diluent conduit is filled with liquid by pumping diluent into said conduit from the upper portion thereof.

4. The method according to claim 1, further comprising the step of suctioning a bubble of gas or liquid which does not mix or react with either the diluent or sample into the sample tube before said step of suctioning the sample.

5. A method for diluting a sample of liquid comprising the steps of:

providing a diluent conduit with diluent through a filling channel provided with first valve means until said conduit is substantially filled with liquid;

said diluent conduit having at its lowermost portion a dispensing tip including a first downwardly directed opening;

contemporaneously with the step of providing said diluent conduit with diluent, filling a sample tube with diluent through a connecting channel communicating said diluent conduit and said sample tube until said diluent accumulates in said sample tube to the level of pump means disposed at the upper portion of said sample tube;

said connecting channel being provided with second valve means whereby liquid is directed to said sample tube and diluent conduit in accordance with manipulation of said first and second valve means, said sample tube having a tip coaxially aligned with said diluent conduit and arranged concentrically therein at a level above said downwardly directed opening of said diluent conduit,

closing said first and second valve means to preclude flow in said connecting and filling channels and, by way of said pump means, suctioning sample into said sample tube;

pumping diluent out of said diluent conduit for flow through said first downwardly directed opening; and

substantially simultaneously with said step of pumping diluent through said downwardly directed opening of said diluent conduit,

displacing sample out of said sample tube into the stream of diluent issuing through said downwardly directed opening,

said tip of said sample tube having a second downwardly directed opening in spaced facing relation with said downwardly directed opening of said diluent conduit so that sample displaced from said sample tube is directed theretoward,

whereby the stream of diluent being pumped through said diluent conduit promotes mixing of sample and diluent and flows about the periphery of said opening of said sample tube to prevent accumulation of sample thereabout.

6. The method according to claim 5, further comprising the step of suctioning a bubble of gas or liquid which does not mix or react with either the sample or diluent prior to said step of suctioning said sample.

7. In an apparatus for diluting liquid samples, the combination comprising a diluent conduit having a first downwardly directed opening at the lowermost portion thereof, means for pumping diluent to said conduit, a sample tube with a second downwardly directed opening concentrically arranged within said conduit so that said second downwardly directed opening is located above said first downwardly directed opening, means for supplying diluent to said sample tube and suctioning means operable to suction liquid sample sequentially through said first and second downwardly directed openings in a sample drawing step and to displace sample out of said sample tube and said diluent conduit sequentially through said second and first downwardly directed openings in a sample dispensing step which promotes mixing of said sample with said diluent and whereby said diluent flows about the periphery of said sample tube to prevent the accumulation of liquid sample thereabout.

8. The combination according to claim 7, further comprising a connecting channel communicating said sample tube with said diluent conduit provided with first valve means and wherein said means for pumping liquid diluent to said diluent conduit includes a filling channel provided with second valve means.

9. The combination according to claim 8 wherein said suctioning means includes a piston mounted in said sample tube for translation therein having a lower extreme position of translation at a point where said connecting channel joins said sample tube.

10. The combination according to claim 7, wherein the lowermost tip of said diluent conduit is in the shape of a truncated cone.

11. The combination according to claim 7, wherein the lower tip of said sample tube having said second downwardly directed opening is cylindrical.