US3233785A

US3233785A - Rinsing pipette

Info

Publication number: US3233785A
Application number: US223469A
Authority: US
Inventors: Burke Robert Charles
Original assignee: Dade Reagents Inc
Current assignee: Dade Reagents Inc
Priority date: 1962-09-13
Filing date: 1962-09-13
Publication date: 1966-02-08
Anticipated expiration: 1983-02-08

Description

Feb. 8, 1966 R. c. BURKE RINSING PIPETTE Filed sept. 13, 1982 United States Patent Ofifice Patented Feb. 8, 1966 3,233,785 RINSING PIPETTE Robert Charles Burke, Miami, Fla., assignor to Dazle Reageuts, Inc., Miami, Fla., a corporation of Florida Filed Sept. 13, 1962, Ser. No. 223,469 2 Claims. (Cl. 222-158) This invention relates to a rinsing pipette, and more specifically, to a pipette adapted to be used in drawing a measured quantity of liquid and thereafter mixing the same with a diluent. The pipette of the present invention is particularly useful in the field of analytieal chemistry where a final solution is to be prepa-red with all of the liquid first drawn and -contained within the pipette.

A principal object of the present invention is to provide a squeeze rinse pipette which -is capable of self-filling by reason o'f capillary attraction. Another object is to provide a pipette which is much easier and faster to use in mixing .and rinsing than a conventional pipette equipped with a mouth tube. A further object is to provide a pipette which is suitable for use in diluting blood 1specimens and which may be used Without the dangers attending the use of conventional mouth tube pipettes of contaminating either the technician, as where a part of the solution enters the technicianl's mouth during drawing or mixing, or of contaminating the speCimen, as where moisture or 'bacteria are |carried from the technicians mouth to the speci'men.

Other objects will appear from the specification and drawings in which:

FIGURE 1 is a side elevational view 'of a rinsing pipette embodying the present invention;

FIGURE 2 is a side elevational view in reduced scale illustrating the step of drawing a test sample into the pipette;

FIGURE 3 is a broken side elevational view illustrating a pipette containing a measured amount of the specimen liquid prior to a rinsing or mixing step;

FIGURE 4 is a broken elevational view illustrating the discharge of the specimen during a |rinsing operation;

FIGURE 5 is a broken elevational view taken partly in section and showing the intake of the diluted speci- Inen during the rinsing operation.

In the embodirnent of |the invention illustrated in the drawings, the numeral generally designates a rinsing pipette consisting essentially of a glass body 11 and a resilient bulb or cap 12 formed from rubber or any other suitable material. The glass body is elongated and is provided with an upper portion 13 and a lower portion 14. The reduced lower portion 'of the tubular body is provided with a longitudinally-extending vcapillary passage 15 and the enlarged upper portion 11 has a longitudinally-extending chamber 16 which communicates at its lower end with the upper end of the capillary pasf sage 15, as shown in FIGURES 1 and 3-5.

The capillary passage 15 -is of the same length "x as lower section 14 and is of predetermined and preselected volume. The particular volume of the capillary passage for any given pipette will depend upon the pipette's intended use, the material o-r materials intended to flow into the passage, and the desired position of the pipette during filling. For example, a capillary passage having a capacity of 50 cubic millimeters is generally considered a practical size limit for use in drawing blood samples, although the capacity may be as much as 100 cubic 'millime'ters if considerable tipping of the pipette can be tolerated du-ring a filling and measuring step. Normally, a capacity of .001 to 0.1 milliliter (l to 100 'cubic millimeters) is considered to vbe a practical size range.

At its free lower end, the pipette 'is provided with 'a tapered point 17. In the illustration given, the conical surface of the point tapers at an angle of approximately 30 degrees with 'respect to the pipette's longitudinal axis, although other angles of taper might be used.

The capacity of the chamber 16 of the pipette's upper section may be varied considerably and is limited only by Practical considerations and the intended use of the pipette. At its upper end, the pipe'tte is provided with a pair of integral and axially-spaced annula-

r Shoulders

18 and 19 which define an annular recess 20 therebetween. This recess receives and sealingly contacts the inwardly directed end flange or lip 21 of bulb 12, the bulb being stretched slightly .about the end of the pipette so that the tension of the material from which the bulb is formed will tend to maintain the parts in air-tight sealing contact.

As shown in FIGURE 1, the bulb is provided with a single small hole 22 which extends through the wall of the 'bulb and normally places the chamber 16 in com- |munication with the outside. In the illustration given, the hole is located in the side wall of the bulb intermediate the upper and lower ends thereof. While other locations for the hole may be provided, it has been found that this location is particularly desira'ble in facilitating mauipulation and operation of the pipette.

In the use of the pipette, a doctor, nurse or other technician grasps the device as shown lin FIGURE 2 and, without squeezing bulb 12, places the tip of the pipette into a drop 'or body 23 of `bloo-d or other liquid to be collect'ed. The liquid flows upwardly into the capillary passage 15 by vcapillary att'raction and automatically stops fiowing when its concave meniscus 24 has reached the upper limits of the capillary passage (FIGURE 3). Since the chamber 16 of the upper section is substantially wider than the capillary passage, the forces of capillary attraction are not sufiiciently strong to elevate the liquid level above the indicated point. This is particularly important in providing a rinsing pipette since t'here is no danger o'f a possible wet-ting of the walls of chamber 16 with blood or other liquid during the sample-taking step; if such wetting occurred, the amount of blood re- 'tained 'by the pipette would be uncertain and the accuracy of the test would be directly afected.

After a sample has been taken, the technician wipes od the end of the tip 17 and then flushes the sample into a measured quantity of Water or other liquid 25 contained within tube 26. The discharge of blood from the capillary tube is easily accomplished by simply closing oif the opening or hole 22 with a finger and then squeezing the resilient bulb, thereby expelling the contents of the pipette as represented by arrows 27 in FIGURE 4. Thorough mixing of the diluent and blood is achieved by drawing the diluted sample back into chamber 16 of the pipette and well above the upper limits of capillary passage 15' (FIG- URE 5), and then, in the manner already described, expelling the contents of the pipette back into the test tube. This rinsing action -is repeated until the sample is unifor'mly diluted; ordinarily, three or four rinsing steps are sufficient. Since the capacity of chamber 16 exceeds the Volume of the diluted sample, there is no danger that the pipette will become over-filled or that liquid will pass upwardly into bulb 12.

In drawing liquid from the test tube upwardly into the pipette, a technician merely permits the squeezed bulb to return to its normal condition while at the same time holding a finger over port or opening 22 so that air cannot fiow therethrough. As a result, the resiliency of the bulb, as it expands into a tension-relieving conditon, lowers the pressure within chamber 16 and permits the liquid from the tes tube to surge upwardly into the chamber.

While in the foregoing I have disclosed an embodiment of the present invention in considerable detail fo-r purposes of illustration, it will be understood by those skilled in the art that many of these details may 'be varied Without departing from the spirit and scope of the invention.

I claim:

1. A rinsing pipette comprising a transparent tube having an upper rinsing section and a lower sample-receiving section, said lower sample-receiving section having a tapered lower end and having a narrow bore capillary passa-ge of uniform cross section extending therethrough, said capillary passage being of a predetermined volumetric capacity within the range of .001 to 0.1 milliliter and being fillable under forces of capillary attraction When said tapered end is inserted into a 'body of liquid to be sampled, said upper rinsing section having an enlarged Chamber of substantially greater diameter and volume than said capillary passage and communicating with said passage, said chamber and passage meeting along a line defining the automatic limit line for the intake of liquid into said passage by capillary attraction, whereby, said passage may be completely filled with a liquid sample of predeterminedvolume simply by inserting the lower end of said pipette into a body of liquid, and a collapsible bulb mounted at the upper end of said tube and com- References Cited by the Examiner UNITED STATES PATENTS 528,470 10/ 1894 Fletcher 222-158 672,207 4/ 1901 Dunn. 2,656,070 10/1953 Linder 222-420 X 2,809,773 10/1957 Bender 22-158 LOUIS I. DEMBO, Primary Examner.

RAPHAEL M. LUPO, Examner.

Claims

1. A RINSING PIPETTE COMPRISING A TRANSPARENT TUBE HAVING AN UPPER RINSING SECTION AND A LOWER SAMPLE-RECEIVING SECTION, SAID LOWER SAMPLE-RECEIVING SECTION HAVING A TAPERED LOWER END AND HAVING A NARROW BORE CAPILLARY PASSAGE OF UNIFORM CROSS SECTION EXTENDING THERETHROUGH, SAID CAPILLARY PASSAGE BEING OF A PREDETERMINED VOLUMETRIC CAPACITY WITHIN THE RANGE OF .001 TO 0.1 MILLILITER AND BEING FILLABLE UNDER FORCES OF CAPILLARY ATTRACTION WHEN SAID TAPERED END IS INSERTED INTO A BODY OF LIQUID TO BE SAMPLED, SAID UPPER RINSING SECTION HAVING AN ENLARGED CHAMBER OF SUBSTANTIALLY GREATER DIAMETER AND VOLUME THAN SAID CAPILLARY PASSAGE AND COMMUNICATION WITH SAID PASSAGE, SAID CHAMBER AND PASSAGE MEETING ALONG A LINE DEFINING THE AUTOMATIC LIMIT LINE FOR THE INTAKE OF LIQUID INTO SAID PASSAGE BY CAPILLARY ATTRACTION, WHEREBY, SAID PASSAGE MAY BE COMPLETELY FILLED WITH A LIQUID SAMPLE OF PREDETERMINED VOLUME SIMPLY BY INSERTING THE LOWER END OF SAID PIPETTE INTO A BODY OF LIQUID, AND A COLLAPSIBLE BULB MOUNTED AT THE UPPER END OF SAID TUBE AND COMMUNICATING WITH SAID CHAMBER, SAID BULB HAVING AN OPENING IN THE WALL THEREOF AND BEING ADAPTED TO BE SQUEEZED AND RELEASED FOR RINSING SAID CAPILLARY PASSAGE WITH A SAMPLE-DILUTING SOLUTION AND FOR THOROUGHLY MIXING A SAMPLE WITH SAID SOLUTION.