US 3649218 A
Disclosed is a diluting method and apparatus which pumps a metered volume of a diluent into a conduit system, one portion of which includes a metered capillary tube bypass, into which is separately drawn concentrate. Once the system portions are filled with diluent and concentrate, a metered pumping of diluent forces diluent through the capillary bypass and forces the concentrate to mix with the diluent. The volume of mixed dilution thereby forced from the system equals the volume of the metered diluent. The structural arrangement includes valves which coact to obviate the need for between dilution rinsing of the system.
Description (OCR text may contain errors)
137-13, 09. 396499218 SF? '8 I v v r gi/e 1 Umted States Patent  3,649,218
Pontigny 1 Mar. 14, 1972  METHOD FOR PREPARING METERED 3,085,717 4/1963 Anscherlik ..23/270.5 X LIQUID SAMPLE DILUTIONS 3,152,117 10/1964 Eijsberg ..23/271 X 3,166,096 l/1965 Lang ..23/272.8 Inventor: Jatlques Polmgny, Mommmency, 3,199,956 8/1965 Ferrari .....23/267 C France 3,334,018 8/1967 Smythe... ..23/230 B 3 367 849 2/1968 Blaedel ..23/230 B E  Asslgnee flaleah Fla 3,486,859 12/1969 Gremer ..23/230 B  Filed: May 7, 1969 FOREIGN PATENTS OR APPLICATIONS  Appl. No.: 822,488
89,931 1957 Denmark ..23/272.7 807,852 1937 France ..23/267 C  Foreign Application Priority Data 1 Primary Examiner-Norman Yudkoff May 8, 1968 France ..150945 Assistant Examiner s J Emery 521 11s. Cl. ..23/309, 231267 c, 23/272.7, Cass 23/258.5, 23/253 A, 23/259 A Tl T  Int. Cl. ..B01d 11/04, BOld 59/36  BS C  Field of Search ..23/230 A, 230 B, 230 M, 253 A, D s osed is a diluting method and apparatus which pumps a 23/267 C, 267 E, 271, 272.8, 272.7, 272.6, 309, metered volume of a diluent into a conduit system, one por- 312 A, 2585 tion of which includes a metered capillary tube bypass, into which is separately drawn concentrate. Once the system por- 5 References Cited tions are filled with diluent and concentrate, a metered pumping of diluent forces diluent through the capillary bypass and UNITED STATES PATENTS forces the concentrate to mix with the diluent. The volume of mixed dilution thereby forced from the system equals the Toronto volume f the metered diluentstructural arrangement 6 322 cludes valves which coact to obviate the need for between d'l t' 'ns'n fth te 2,984,250 5/1961 Foster ...23/272.8 In on n i g o e sys m 3,052,525 9/ 1962 Vogelmann ..23/272.8 5 Claims, 1 Drawing Figure 7; a M 1; j
PAIENTEUMAR 14 I972 Invemor JACQUES A. PONTIGNY ATTYS.
METHOD FOR PREPARING METERED LIQUID SAMPLE DILUTIONS BACKGROUND OF THE INVENTION This invention is directed to method and apparatus for preparing precise, high ratio dilutions of fluids, and is especially well adapted for biological processing of micro quantities of a concentrate or sample in the absence of intersample contamination and intermediate system rinsings.
Diluting operations are common to laboratories, scientific, industrial and medical. When dilutions are prepared manually, their precision depends on the skill of the operator in charge of this tedious and long work. Consequently, the use of automatic diluting apparatus has been contemplated and employed for sometime. Those known up to the present time employ complicated and costly mechanisms, such as suction or pressure pumps, a complicated valve system and other delicate means. These apparatus are therefore fragile and poorly adapted to mass diluting operations, as for example, in the case of hematology in which the counting of white corpuscles requires a first dilution followed by a second dilution for counting the red corpuscles with respect to a very large number of specimens.
Additionally, prior diluting apparatus and methods have the drawback of drawing inthe liquid to be diluted and discharging the diluted mixture through the same passage. In order to avoid pollution of a specimen by traces of the preceding mixture, it was necessary to carry out intermediate, often long, rinsings and to provide the necessary structure and control apparatus for this purpose, which further complicated the apparatus.
Of specific interest to the present invention is the preparation of dilutions for particle counting and analysis, primarily by apparatus known and sold throughout the world under the trademark Coulter Counter" and disclosed, for example, in
SUMMARY OF THE INVENTION The invention remedies the prior art drawbacks and its object is to provide an automatic, simple, reliable and precise diluting method and apparatus which is easily and rapidly employed and avoids the aforementioned pollution.
The diluting apparatus according to the invention provides a first tubular element having an inlet for the diluent and an outlet for the diluted liquid, a pumping device located at said inlet for circulating a metered volume of diluent in the first element, a second tubular element for the sample to be diluted including a capillary zone of given capacity, means for filling the zone with sample, conduits interconnecting the first and second tubular elements at the ends of the zone, so that the zone forms a fluid bypass and means for preventing the diluent from entering the zone when the sample is introduced therein.
Further advantages and features of the invention will appear from the ensuing description.
BRIEF DESCRIPTION OF THE DRAWING The single FIGURE is a diagrammatic side elevation view, partly in section, of one embodiment of a diluting apparatus according to the invention.
DESCRIPTION OF A PREFERRED EMBODIMENT A first tubular element 1, through which the diluent and dilution flows, and a second tubular element 2 through which flows the sample or concentrate to be diluted, for example blood, comprise the two major flow portions of the apparatus. Both of these elements can be of a rigid material such as glass.
Located at an inlet 3 of the tubular element 1 is a metering pump comprising a cylinder 4, a piston 5 retained in its lower position by a return spring 6, a cam 7, and a motor 8, for driving the cam to urge the piston 5 toward the top of the cylinder. This pump is coupled to a source of diluent (not shown) by way of a conduit 9 having a vertical section in which a ball valve 10 is placed. Thus, upon each cycle of the pump, a given amount of diluent is fed into the tubular element 1.
Intermediate the ends of the tubular element 1 is a vertical branch 11, at the ends of which are two capillary conduits 12 and 13. Between the two conduits 12 and 13, the branch 11 has a region of reduced diameter or a constriction 14. A ball valve 15 is disposed in the branch 11 between the two conduits12 and 13.
Two other ball valves 16 and 17 are respectively located in the element 1 upstream and downstream of the branch 11. The element 1 terminates in an outlet 18 which can empty into a dilution receiving vessel 19.
The tubular element 2 has a capillary zone 20, of given capacity, the ends of which are connected to the two conduits 12 and 13. The element 2 is fed with sample, such as blood, from a source 21 located at one of its ends 22. An aspirator or equivalent device 23 is provided at the other end 24. The second tubular element 2 also includes shutofi' valves 25 near its ends.
The apparatus operates in the following manner.
Initially, the tubular element 1 and the conduits 12, 13 are filled with diluent and the tubular element 2 with concentrate sample. The valves 25 are closed and the piston 5 is in its lower position.
Then the cam 7 urges the piston 5 to its upper position and this delivers a given amount of diluent to the element 1. This amount of diluent displaces an equal amount of diluent already contained in the element 1 and the latter amount flows partly through the branch 11 and, owing to the constriction 14, partly through the bypass consisting of the conduit 13, the zone 20 and the conduit 12.
Since the zone 20 is capillary, the small amount of sample it initially contained is completely urged along as soon as the diluent starts to arrive in this zone 20. The mixture thus formed of a given amount of diluent and the amount of sample contained in the zone 20 drops into the vessel 19. The dilution is thus effected. To achieve a 1 to 500 red blood count dilution for use by a Coulter Counter, the capillary zone 20 could have a 40 microliter volume, and the cylinder 4 would then have a 20.04 milliliter volume; such that each precise dilution would have the volume of 20.04 milliliters, of which 40 microliters is the blood sample.
Thereafter, the cam 7 withdraws, the piston 5 is returned to its lower position by the spring 6, and diluent enters the cylinder 4. The valves 25 are then opened and blood sample is again drawn from the source 21 into the tubular element 2. The blood sample fills this element 2, and in particular the zone 20, the excess blood from the previous drawing off being pushed along by the supply of new blood and discharged to waste by way of the aspirator 23.
When the zone 20 is filled with blood, the valves 25 are again closed and the starting position is obtained.
From the foregoing, it will be seen that only the tubular element 2 comes in contact with and receives the sequence of concentrated samples with each sample purging the former from the capillary zone 20. Also, the tubular element 1, upstream of the ball valve 15, only comes into contact with the diluent. Additionally, because of the constriction 14 and the relatively small capacity of the zone 20 compared to the volume of diluent, the initial influx of diluent will flush out the capillary zone 20 past the ball valve 17, so that by the time that the entire metered volume of diluent has moved past that point, the entire tubular element 1, all the way to the outlet 18 will have been flushed clean of any residue of the blood sample. Hence, interdilution and intersample contamination has been prevented without the need for any rinse cycles.
It should be apparent to those skilled in the art that synchronism of the pump, valve means 25 and the aspirator 23 can be achieved to cause the method and apparatus to be fully automatic.
Additionally, the volume of the cylinder 4 can, be adjustable, depending upon the lowest position of the piston 5. Likewise, the volume of the capillary zone 20 can be varied by making the zone an interchangeable element; whereby, substitution of different zone elements of different volume can be accomplished.
What is claimed and sought to be protected by United States Letters Patent is:
l. A method for sequentially preparing precise uncontaminated liquid dilutions from liquid sample concentrate, each sequence comprising the steps of:
filling a first conduit with diluent,
filling a second capillary conduit with liquid sample, a metered portion of the second conduit forming a liquid bypass of the first conduit,
forcing a metered volume of liquid diluent into and through the first conduit, diverting a portion of said liquid diluent from the first conduit and causing it to pass through the metered portion of said second conduit and carry therewith a metered volume of liquid sample into the flowing diluent in the first conduit,
obtaining from the first conduit a volume of dilution equal to the metered volume of liquid diluent and including substantially all of the liquid sample in the metered portion of the second conduit, and
flushing the metered portion of said second conduit with liquid diluent to clean the same of any residue of said liquid sample.
2. A method according to claim 1 in which aspirating is employed in said step of filling the second conduit.
3. A method according to claim 1 in which cyclic pumping is employed in said step of forcing the metered volume of diluent.
4. A method according to claim 1 in which said first conduit comprises a tubular element.
5. A method according to claim 4 in which constricting the first tubular element just downstream of the entrance to the bypass is employed in said step of diverting and causing a portion of the liquid diluent to pass through the bypass.