US3757584A - Diluter for laboratory titration - Google Patents

Diluter for laboratory titration Download PDF

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US3757584A
US3757584A US00233887A US3757584DA US3757584A US 3757584 A US3757584 A US 3757584A US 00233887 A US00233887 A US 00233887A US 3757584D A US3757584D A US 3757584DA US 3757584 A US3757584 A US 3757584A
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diluter
shaft
chamber
axis
formation
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US00233887A
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R Gallant
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Linbro Chemical Co Inc
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Linbro Chemical Co Inc
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    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N1/00Sampling; Preparing specimens for investigation
    • G01N1/28Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
    • G01N1/38Diluting, dispersing or mixing samples

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  • Titration is performed by preparing dilutionsof graduated concentration of the substance that is. to be analysed, and by determining the lowest concentration in which the analysed substance just produces a product that is clearly detectable, by discoloration or precipitation, for example, upon reacting with a particular selected reagent.
  • Modern titration technique involves the use of a titration tray anda diluter, when the tray having rows of cup formationsofwhich those in at least one row are dropwise supplied witha diluent, and the diluter, being in the form of a liquid holding cage at the end of a shaft or stem, is with its cage dipped into a solution to-be-analysed in order .to be charged to its full capacity withsuch solution by capillary action.
  • the .diluter is then dipped with its charged cage into the diluent in a first cup formation in .the tray, and is oscillated therein about the shaft axis in order completely to mix the solution charge with the diluent. Qn then removing the diluter from this cup formation in the tray, its cage will'have been fullycharged with the mixture which is now a dilution of the solution to-be-analysed.
  • the diluter is next dipped ,with its charged cage into the diluent in the next succeeding cup formation in the tray, and is therein oscillated to mix its charge with the diluent, as before. This procedure is repeated in each following cup formation in the tray.
  • An indicator is thereafter introduced dropwise into each of the involved cup formations, and by reference to the reactions which occur, such as discoloration or droplet formation, and .the order in succession of thecup formation in which the reaction is first detectable, theconcentration of the selected substance in the initial solution can be determined.
  • the ring-shaped chamber may, even at minimum outer diameter of the body for desirable good clearance from the customarily quite narrow peripheral :walls-of the cup formations in a tray, be easily kept at an entirely adequate volume and also effective capillary width, by spacing the chamber .from the outer body periphery .by a relatively thin wall, and
  • the liquid in the chamber so near the outer body periphery will, on oscillation of the diluter during its dip into the diluent in a cup formation in a tray,be subjected to optimum centrifugal force which assists the cam formations in operating the liquid holding cage as an effective periodically-reversing pump for most thorough mixing of the liquids involved.
  • . .lt is a further object of the present invention to provide a diluter of this type in which the aforementioned ring chamber in the liquid holding body is further arranged so that on dipping the body into diluent in a cup formation in a tray and oscillating the diluter shaft for the aforementioned pumping performance of the body and ensuing mixing of the liquids, all the liquid in the cup formation at any instant, including that at the very bottom of the cup formation, is within effective pumping reach of the body, thereby to attain most thorough andeven mixing of the liquids involved with a minimum number of pumping pulses and, hence, operational oscillations of the body.
  • the post with the terminating tip not only carries the ring shape of the chamber in the body through theinwardly converging chamber part at the body's dip end, but even forms theIport in the latter into a ring-shaped port so that the same may take up a substantial area portion of the body's dip end and thus be in particularly close proximity to, and hence within quite effective pumping reach of, liquid in the most restricted part of the liquid path to and from the pumping body, i.e., the space between the bodys dip end and the part of the bottomof a cup formation confronting this dip end, yet the width of this ringshaped port maybe kept sufficiently small securely to retain liquid therein, if only bys urface tension, when the body is not oscillated for pumping action.
  • the central tip on the diluter body in bearing against such a bottom of a cup formation, will also accurately center the body in the cup formation for most uniform mixing of the liquids in pumping action of the body. Also, with the tip on the diluter body bearing against the bottom of a cup formation and thereby keeping the bodys dip and spaced from the cup bottom as mentioned, this clip end cannot scratch the cup bottom in oscillation of the body for pumping action.
  • Another object of the present invention is to provide a diluter of this type which is specially fitted for, and particularly effective in displacing and thoroughly and evenly mixing liquids in, cup formations with bottoms of a given section, by shaping the dip end of the diluter body to conform to the section of the bottoms of such cup formations, and arranging the aforementioned tip on the body so that the dip end of the latter will be spaced from the bottom of a cup formation by a uniform and quite narrow gap when the tip bears against the cup bottom.
  • a further object of the present invention is to provide a diluter of this type in which the aforementioned liquid-impelling cam formations in the ring chamber in the body are arranged not only to increase the volume of the ring chamber, but also to increase the force of capillary attraction of liquid into, and of its capillary retention in, the ring chamber without, however, impeding their liquid-impelling function in pumping action of the body.
  • This is achieved by forming these cam formations as grooves in the inner peripheral surface of the ring chamber, with these grooves being equiangularly spaced and equally inclined to the body axis, and being also of identical width of capillary dimension.
  • cam grooves will indeed increase the volume of the ring chamber and also the force of capillary attraction of liquid into, and of the capillary liquid retention in, the ring chamber, as contemplated, yet these cam grooves will, on oscillation of the body for pumping action, exert on the confined liquid in the body axial displacement force components which are quite effective, since they easily overcome the capillary liquid retentivity of the body's interior as weakened as it then is by agitation of the confined liquid due to operational oscillation of the body and also centrifugal force.
  • the diluter shaft has an axial recess in one end, and the body has' a shank which is slidable in the shaft recess and has therein a lost-motion connection with the shaft, and a spring in the shaft recess urges the body stem to that end of the lost-motion connection at which the body is at maximum projection from the shaft.
  • FIG. 1 is a view of a diluter embodying the invention
  • FIG. 2 is a similar view, but partly in section, of the same diluter
  • FIG. 3 is a cross-section through the diluter as taken on the line 33 of FIG. 2;
  • FIGS. 4 and 5 are fragmentary views, partly in section, of diluters of different modifications.
  • the reference numeral 10 designates a diluter having as its major components a shaft 12 with an axis x, and a liquid holding body 14 at one end of and coaxial with the shaft 12.
  • the body 14 which in this instance has an axial stem 16 for its mount on the shaft 12, is preferably formed in two parts 18 and 20, of which part 18 is a plug formation on the end of the stem 16, and part 20 is a cap.
  • the cap 20 which is cup-like in shape, has an annular rim 30 and a bottom wall 32 with a central, preferably circular, aperture 34.
  • the cap 20 is with the top end of its rim 30 fittedly received by the cylindrical plug formation 24 and is firmly secured thereto as by local staking at 36, for example, with the cap 20 being, furthermore, accurately located axially on the plug 18 be resting with its rim top on an annular shoulder 38 on the plug.
  • the rim 30 of the cap 20 surrounds the peripheral surface 40 of the cylindrical plug formation 26 and is uniformly spaced therefrom by a capillary gap 42, while the cap bottom 32 overlaps the end 28 of the cylindrical plug formation 26 and is unformly spaced therefrom by a capillary gap 44.
  • the plug 18 and surrounding cap 20 thus form a capillary chamber 46 which at 48 is ring-shaped about the axis x over the axial extent of the peripheral wall 40 of the cylindrical plug formation 26, and at 50 converges inwardly toward the axis x between the plug end 28 and the cap bottom 32.
  • the chamber 46 is closed to the outside except at axially spaced ports, of which one is the aperture 34 in the cap bottom 32 and the remaining ports 52, in this instance four, are provided in the cap rim 30 within the axial extent of the cylindrical plug formation 26.
  • the plug end 23 is also provided with an axial post extension 54 which projects through the port 34 in the cap bottom 32 to the outside thereof and there terminates in a preferably rounded bearing tip 56.
  • the post extension 54 thus forms the post 34 in the cap bottom 32, and also the inwardly converging part 50 of the capillary chamber 46, ring-shaped about the axis 1:.
  • the ports 34 and 52 are preferably of sufficiently restricted area to retain liquid at least by surface tension in order to avoid any loss of liquid from the body 14 in certain phases of operation of the diluter involving transfer of the liquid-charged body from one cup formation to a next cup formation in a titration tray.
  • Operation of the diluter also involves mixing of a liquid charge in its body with liquid in a cup formation in a tray into which the body is dipped.
  • the body 14 is provided with cam means inclined to the axis x and exposed to the capillary chamber 46 for impellin g liquid therein on oscillating the body about its axis.
  • These cam means are in the preferred form of grooves 60 of capillary width in the cylindrical plug formation 26 which preferably are equiangularly spaced, extend at the same inclination to the axis x, and are coextensive over their extent axially of the body 12.
  • There are preferably four of these cam grooves 60 in keeping with the provision of the exemplary four ports 52 in the cap rim 30.
  • the present diluter is also specially fitted for cup formations c with standard cone-shaped bottoms b in titration trays (FIG. 1).
  • These cone-shaped bottoms b of cup formations c in a titration tray have a given angle A, and the cap bottom 32 of the liquid holding body 14 of the diluter is formed frusto-conical to conform to the cone-shaped bottom b of a cup formation 0.
  • the tip end 56 of the post extension 54 on the cylindrical plug formation 26 is brought to bear against the cone-shaped bottom b of the cup formation, whereby the body 14 becomes also centered on the apex a of this bottom, with this tip end'56 being so spaced from the frusto-conical cap bottom 32 thatthe latter will then be spaced from the cone-shaped bottom b of the cup formation by a uniform gap g which is quite narrow, being in the order of a few thousandths of an inch, but nevertheless sufficient to avoid scratching of the bottom b of the cup formation by the cap bottom 32 of the body 14 on operationally oscillating the latter about its axis.
  • the stem 16 of the liquid holding body 14 has in its mount in the shaft 12 a limited lost-motion connection with this shaft.
  • the body stem 16 is slidably received in an axial recess 62 in the shaft 12 (FIG.
  • the lost-motion connection is in this instance provided by a transverse groove 64 in the stem 16 and a crosspin 66 in the shaft 12 which extends through the groove 64, with the groove 64 having opposite walls 68 and '70 of a given spacing, and the crosspin 66 being of smaller diameter than the spacing of the groove walls 68 and 70.
  • a preloaded spring 72 in the shaft recess 62 normally urges the body stem 16 to one end of its lost-motion connection with the shaft 12 at which the groove wall 68 bears against the crosspin 66 and the body 14 is at its maximum projection from the shaft 12.
  • the body 14 In operation of the diluter for a given titration procedure, the body 14 is first dipped into a solution to-be analysesd and its chamber 46 is thereby charged to its full capacity with solution by capillary action, with even the ports 34 and 52 being then charged with solution.
  • the chamber 46 is, by its restricted width, designed to exert on the solution relatively strong capillary forces which not only assure quick charging of this chamber to its full capacity with solution, but also exhibit relatively strong retentivity of the solution charge in the chamber 46 so that none of the charge will be lost in operational transfer of the diluter body'l4 into a cup formation in a tray.
  • the diluter is with its body dipped into diluent in a starting cup formation c in a tray (FIG. I with the cup formation being characteris tically small so that the diluent charge therein, usually one or two drops, more or less fills the bottom b of the cup formation prior to dipping the diluter body 14 thereinto.
  • the diluter body On dipping the diluter body into the diluent in the cup formation 0, diluent will be displaced by the body 14 sufficiently to raise the level of the diluent to within reach of the body ports 52.
  • the diluter is then oscillated-at its shaft 12 about its axis x for pumping action of the body 14 and ensuing mixing of its charge with the diluent in the cup formation 0.
  • various forces such as hydrostatic pressure and centrifugal force, for example, to which the charge in the capillary chamber 46 is subjected, has a tendency to, and will, force at least some of the charge out of this chamber, but it is the cam grooves 60 in the body, with the assistance of these forces, that impart to the body.
  • 14 a pumping action sufficiently powerful to overcome the capillary retentivity of the charge in the chamber 46.
  • cam grooves 60 will, on oscillation of the body 14, exert on the confined charge in the latter axial displacement force components which are quite effective, since they easily overcome the capillary liquid retentivity of the bodys interior as weakened as it then is by agitation of the confined charge due to operational oscillation of the body and also centrifugal force.
  • the pumping action of the oscillating body 14 is, therefore, relatively powerful, and is also periodicallyreversing, resulting in circulation of the liquids involved back and forth through the chamber 46 and ports 34 and 52 and ensuing most thorough mixing of these liquids.
  • the pumping action of the oscillating body 14 results in mixing of the liquids involved not only most thoroughly, as described, but also quite evenly throughout including at the very bottom b of the cup formation 0.
  • the bottom end 28 of the plug 18 is preferably also formed frustoconical to keep the capillary width of the inwardly converging chamber part 50 uniform and preferably the same as that of the cylindrical chamber part 48.
  • the cam grooves 60 in the cylindrical plug formation 26 extend over the greater part of the axial extent of the peripheral surface 40 thereof, these cam formations preferably extend also into the frusto-conical plug end 28 as at 60' (FIG. 2) for optimum pumping action of the body 14 in operational oscillation.
  • the ports 52 are located within the axial extent of the cam grooves 60 in the peripheral surface 40 of the cylindrical plug formation 26, and are preferably slightly below the upper ends of these cam grooves.
  • the shaft, plug and cap parts 12, 18 and 20 of the diluter may be of any suitable metal, and they are preferably of stainless steel. Further, among these parts, the shaft 12 and the plug 18 with its stem 16 are preferably simple and inexpensive parts made and finished in screwmachines, while the cap 20 is preferably a part which is drawn to shape and then simply punched or drilled for the provision of the ports 34 and 52. The assembly of these parts is quite simple and inexpensive, merely requiring sliding of the cap part 20 over the plug part 18 and locally staking the former to the latter, inserting the spring 72 and plug stem 16 into the axial recess 62 in the shaft part 12, and driving the crosspin 66 into the shaft 12.
  • the actual diluter is, of course, much smaller than shown.
  • an indication of the actual size of a diluter of highly satifactory performance in use with cup formations of accustomed size in a titration tray with the outside diameter of the cap part 20 of this diluter being about 0.170 inch, and its other dimensions being in about the same proportion thereto as appears in the drawings which show the diluter at a fairly true, but greatly enlarged, scale.
  • FIG. 4 shows a modified diluter 10 that is in all respects like the described diluter 10 of FIGS. 1 to 3, except that its liquid holding body 14' is specially fitted for cup formations c with semi-spherical or so called round bottoms b in a tray.
  • the bottom 32' of the body cap 20' is formed part-spherical in conformity with the round bottom b of the cup formation, and the bearing tip 56' on the body plug 18', when seated on the bottom b' of the cup formation, holds the bottom end 32 of the diluter body 14' spaced from the round bottom of the cup formation by the uniform and quite narrow gap g.
  • FIG' shows another modified diluter which differs from the diluters l0 and 10' by being specially fitted for cup formations c" with flat bottoms b" in a tray.
  • the bottom 32" of the body cap 20 is formed flat, and the bearing tip 56" on the body plug 18", when seated on the bottom b" of the cup formation, holds the bottom end 32" of the diluter body 14' spaced from the flat bottom of the cup formation by the uniform and quite narrow gap g".
  • a diluter providing a shaft, a cylindrical body, having a longitudinal axis, at one end of and coaxial with said shaft, with said body having a ring-shaped chamber of capillary width about said body axis, and axially spaced ports providing sole communication between said chamber and the outside of said body, and cam means in said body inclined to said body axis and exposed to said chamber for impelling liquid therein on oscillation of said body about is axis.
  • cam means are angularly spaced grooves of capillary width in said inner peripheral surface of said main chamber section, with said grooves being inclined to said body axis.
  • a diluter providing a shaft with an axis; a plug at one end of said shaft having upper and lower cylindrical formations coaxial with said shaft and being of larger and smaller diameters, respectively, of which said upper formation is next to said shaft and said lower formation projects from said upper formation and terminates in an end; and a cup-like cap having a cylindrical rim and a bottom with a central aperture, of which said rim is fitted and secured to said upper cylindrical plug formation and surrounds said lower cylindrical plug formation at uniform capillary spacing therefrom, and said bottom overlaps said end of said lower cylindrical plug formation and is uniformily spaced therefrom by a capillary gap, with said lower cylindrical plug formation and cap forming a capillary chamber, said cap rim having within the axial extent of said lower cylindrical plug formation angularly spaced apertures which, together with said aperture in said cap bottom provide sole communication between said chamber and the outside thereof, and said lower cylindrical plug formation having a peripheral surface with angularly spaced grooves therein of capillary width and inclined to said shaft axis

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Abstract

A diluter having a shaft, and a liquid holding body at one end of and coaxial with the shaft, of which the body has a ringshaped chamber of capillary width about its axis, and axially spaced ports providing sole communication between the chamber and the outside, and cam means in the body inclined to the body axis and exposed to the chamber for impelling liquid therein on oscillating the body about its axis.

Description

atem
Gallant Sept. 11, 1973 [54] DILUTER FOR LABORATORY THTRA'HKON 3,276,847 10/ 1966 Duff et al. 73/4254 P X Inventor: Reginald R. Ga a isto Co 3,627,276 12/1971 Gllford 259/50 [73] Assignee: Linbro Chemical C0., Inc New FOREIGN PATENTS OR APPLICATIONS Haven, Conn' 1,448,191 11/1968 Germany 73/4254 P [22] Filed: 1972 Primary ExaminerWilliam 1. Price [21] Appl. No.: 233,887 Assistant Examiner-Philip R. Coe
AttorneyWalter Spruegel [52] US. Cl. 73/425.4 P, 23/292,225599/l408l, [57] ABSTRACT 51 rm. Cl. G01n 1/10, BOlf 3/08 A dilute having a Shaft, and a "quid hdding [58] Field of Search 259/48, 49 50 51 one end of and coaxial with the shaft, of which the body 259/53, 75, 76, 77 10]; 73/4254 p has a ring-shaped chamber of capillary width about its axis, and axially spaced ports providing sole communi- 5 References Cited cation between the chamber and the outside, and cam UNITED STATES PATENTS means in the body inclined to the body axis and exposed to the chamber for impelling liquid therein on gi g )2 oscillating the body about its axis. 312521331 5/1966 Lancaster..........,......::.... 73/4 25.4 P 20 Claims, 5 Drawing Figures Patented Sept. 11, 1973 I 3,757,584
INVENTOR DllLUTER FOR LABORATORY TITRATION This invention relates to laboratory titration equipment in general, and to dilutersfor laboratory titration in particular.
Titration is performed by preparing dilutionsof graduated concentration of the substance that is. to be analysed, and by determining the lowest concentration in which the analysed substance just produces a product that is clearly detectable, by discoloration or precipitation, for example, upon reacting with a particular selected reagent. Modern titration technique involves the use of a titration tray anda diluter, when the tray having rows of cup formationsofwhich those in at least one row are dropwise supplied witha diluent, and the diluter, being in the form of a liquid holding cage at the end of a shaft or stem, is with its cage dipped into a solution to-be-analysed in order .to be charged to its full capacity withsuch solution by capillary action. The .diluter is then dipped with its charged cage into the diluent in a first cup formation in .the tray, and is oscillated therein about the shaft axis in order completely to mix the solution charge with the diluent. Qn then removing the diluter from this cup formation in the tray, its cage will'have been fullycharged with the mixture which is now a dilution of the solution to-be-analysed. The diluter is next dipped ,with its charged cage into the diluent in the next succeeding cup formation in the tray, and is therein oscillated to mix its charge with the diluent, as before. This procedure is repeated in each following cup formation in the tray. An indicator is thereafter introduced dropwise into each of the involved cup formations, and by reference to the reactions which occur, such as discoloration or droplet formation, and .the order in succession of thecup formation in which the reaction is first detectable, theconcentration of the selected substance in the initial solution can be determined. With the volumes of the liquids involved in titration being exceedingly small, being in the order of a drop or two of diluent in each cup formation in a tray,
' and being, in the case of the solution to-be-analysed,
equal to the capacity of the diluter cage which customarily is a small fraction of a milliliter, it stands to reason that the results obtained in titration will be inaccurate or even grossly false unless the diluter cage will, after each clip, not only hold exactly the same liquid volume, but will also securely retain it during transfer to sueceeding cup formations in a tray, and will also mix its entire charge evenly with the diluent in successive'cup formations. Therefore, in order that the diluter cage may function to meet the various requirements just mentioned, it is imperative that its capillary forces on the liquids involved are comparatively powerful, yet its entire charge must, on oscillation of the diluter shaft, mix with the diluent in each cup formation not only freely but also evenly throughout.
It is among the objects of the present invention to provide a diluter of this type of which the liquid holding cage not only exerts relatively powerful capillary forces on the liquids involved, but is also highly effective in freely and most evenly mixing these liquids throughout in each cup formation in a tray, thereby fully to meet the aforementioned exacting requirements of diluters.
It is another object of the present invention to provide a diluter of this type which has a shaft and a cylindrical body at one ,end of and coaxial with the shaft, of which the body forms the liquid holding cage, and is to this end provided with an internal ring chamber of capillary width throughout which is closed except for axially spaced ports for liquid passage to and from the chamber, with the chamberbeing also provided with cam formations which act as impellers to pulsate liquid from the chamber alternately through the axially Spacedports on oscillating ithe diluter shaft about its axis. With this arrangement, the ring-shaped chamber may, even at minimum outer diameter of the body for desirable good clearance from the customarily quite narrow peripheral :walls-of the cup formations in a tray, be easily kept at an entirely adequate volume and also effective capillary width, by spacing the chamber .from the outer body periphery .by a relatively thin wall, and
the liquid in the chamber so near the outer body periphery will, on oscillation of the diluter during its dip into the diluent in a cup formation in a tray,be subjected to optimum centrifugal force which assists the cam formations in operating the liquid holding cage as an effective periodically-reversing pump for most thorough mixing of the liquids involved.
. .lt is a further object of the present invention to provide a diluter of this type in which the aforementioned ring chamber in the liquid holding body is further arranged so that on dipping the body into diluent in a cup formation in a tray and oscillating the diluter shaft for the aforementioned pumping performance of the body and ensuing mixing of the liquids, all the liquid in the cup formation at any instant, including that at the very bottom of the cup formation, is within effective pumping reach of the body, thereby to attain most thorough andeven mixing of the liquids involved with a minimum number of pumping pulses and, hence, operational oscillations of the body. This is achieved by forming the ring chamber in the body cylindrical over its axial extent, except near the dip end of the body where this chamber converges inwardly toward the body axis and is open to a central aperture in the bodys dip end-which is one of the aforementioned ports in the body, with this inwardly converging chamber part being, moreover, provided with a central post which extends axially therein and to the outside of the bodys dip end through the central aperture therein with clearance therefrom all around, and this post terminating, outside this central aperture but at fairly close spacing therefrom, in a narrow tip with which the diluter is to bear against the bottom of .a cup formation in a tray. In thus bringing this tip to bear against the bottom of a cup formation, the same unfailingly keeps theport in the body's dip end spaced from the cup bottom at the built-in distance which is selected to bring all liquid in the cupvformation, including that at the very bottom of the-latter, within most effective pumping reach of the oscillating body. Moreover, the post with the terminating tip not only carries the ring shape of the chamber in the body through theinwardly converging chamber part at the body's dip end, but even forms theIport in the latter into a ring-shaped port so that the same may take up a substantial area portion of the body's dip end and thus be in particularly close proximity to, and hence within quite effective pumping reach of, liquid in the most restricted part of the liquid path to and from the pumping body, i.e., the space between the bodys dip end and the part of the bottomof a cup formation confronting this dip end, yet the width of this ringshaped port maybe kept sufficiently small securely to retain liquid therein, if only bys urface tension, when the body is not oscillated for pumping action. Further,
with the bottoms of the cup formations in titration traps being mostly V-shaped or round in section, the central tip on the diluter body, in bearing against such a bottom of a cup formation, will also accurately center the body in the cup formation for most uniform mixing of the liquids in pumping action of the body. Also, with the tip on the diluter body bearing against the bottom of a cup formation and thereby keeping the bodys dip and spaced from the cup bottom as mentioned, this clip end cannot scratch the cup bottom in oscillation of the body for pumping action. Last, but not least, with a liquid charge in the ring chamber being completely enclosed and, hence, not exposed to the atmosphere, except at the narrow bottom port and at the few other and similarly narrow ports in the body, the liquid charge will not be subject to evaporation which might conceiv ably lead to a wrong evaluation of a solution being analysed.
' Another object of the present invention is to provide a diluter of this type which is specially fitted for, and particularly effective in displacing and thoroughly and evenly mixing liquids in, cup formations with bottoms of a given section, by shaping the dip end of the diluter body to conform to the section of the bottoms of such cup formations, and arranging the aforementioned tip on the body so that the dip end of the latter will be spaced from the bottom of a cup formation by a uniform and quite narrow gap when the tip bears against the cup bottom. Thus, in lowering the diluter body all the way into a cup formation, its dip end will displace all liquid it confronts until it reaches its final position in which it is spaced from the cup bottom by the mentioned uniform and quite narrow gap which affords no pocket whatever along the cup bottom in which liquid would not at all, or only poorly, mix with the liquid remainder in operational pumping action of the body.
A further object of the present invention is to provide a diluter of this type in which the aforementioned liquid-impelling cam formations in the ring chamber in the body are arranged not only to increase the volume of the ring chamber, but also to increase the force of capillary attraction of liquid into, and of its capillary retention in, the ring chamber without, however, impeding their liquid-impelling function in pumping action of the body. This is achieved by forming these cam formations as grooves in the inner peripheral surface of the ring chamber, with these grooves being equiangularly spaced and equally inclined to the body axis, and being also of identical width of capillary dimension. With this arrangement, the cam grooves will indeed increase the volume of the ring chamber and also the force of capillary attraction of liquid into, and of the capillary liquid retention in, the ring chamber, as contemplated, yet these cam grooves will, on oscillation of the body for pumping action, exert on the confined liquid in the body axial displacement force components which are quite effective, since they easily overcome the capillary liquid retentivity of the body's interior as weakened as it then is by agitation of the confined liquid due to operational oscillation of the body and also centrifugal force.
It is another object of the present invention to provide a diluter of this type of which the body has limited axial yieldability on the shaft which is adequate to take up such relative axial motion between shaft and body as may occur after the bodys tip has become seated on the bottom of a cup formation in a tray as, for example,
where titration is undertaken in apparatus in which a row of diluters are with their shafts removably mounted on an overhead support and one or more of their bodies are hardly perceptibly below the level of the remaining bodies, and the bodies are simultaneously projected into aligned cup formations in a tray either by mechanically lowering the diluters or by mechanically raising the tray. To this end, the diluter shaft has an axial recess in one end, and the body has' a shank which is slidable in the shaft recess and has therein a lost-motion connection with the shaft, and a spring in the shaft recess urges the body stem to that end of the lost-motion connection at which the body is at maximum projection from the shaft.
Further objects and advantages will appear to those skilled in the art from the following, considered in conjunction with the accompanying drawings.
In the accompanying drawings, in which certain modes of carrying out the present invention are shown for illustrative purposes:
FIG. 1 is a view of a diluter embodying the invention;
FIG. 2 is a similar view, but partly in section, of the same diluter;
FIG. 3 is a cross-section through the diluter as taken on the line 33 of FIG. 2; and
FIGS. 4 and 5 are fragmentary views, partly in section, of diluters of different modifications.
Referring to the drawings, and more particularly to FIGS. 1 to 3 thereof, the reference numeral 10 designates a diluter having as its major components a shaft 12 with an axis x, and a liquid holding body 14 at one end of and coaxial with the shaft 12.
The body 14, which in this instance has an axial stem 16 for its mount on the shaft 12, is preferably formed in two parts 18 and 20, of which part 18 is a plug formation on the end of the stem 16, and part 20 is a cap. The plug 18, which is joined to the stem 16 by a tapered top 22, is provided with coaxial cylindrical formations 24 and 26, of which the formation 24 is next to the top 22, and the formation 26 projects from the formation 24 and has an end 28, with the cylindrical plug formation 26 being of smaller diameter than the other cylindrical formation 24.
The cap 20, which is cup-like in shape, has an annular rim 30 and a bottom wall 32 with a central, preferably circular, aperture 34. The cap 20 is with the top end of its rim 30 fittedly received by the cylindrical plug formation 24 and is firmly secured thereto as by local staking at 36, for example, with the cap 20 being, furthermore, accurately located axially on the plug 18 be resting with its rim top on an annular shoulder 38 on the plug. The rim 30 of the cap 20 surrounds the peripheral surface 40 of the cylindrical plug formation 26 and is uniformly spaced therefrom by a capillary gap 42, while the cap bottom 32 overlaps the end 28 of the cylindrical plug formation 26 and is unformly spaced therefrom by a capillary gap 44. The plug 18 and surrounding cap 20 thus form a capillary chamber 46 which at 48 is ring-shaped about the axis x over the axial extent of the peripheral wall 40 of the cylindrical plug formation 26, and at 50 converges inwardly toward the axis x between the plug end 28 and the cap bottom 32. The chamber 46 is closed to the outside except at axially spaced ports, of which one is the aperture 34 in the cap bottom 32 and the remaining ports 52, in this instance four, are provided in the cap rim 30 within the axial extent of the cylindrical plug formation 26. The plug end 23 is also provided with an axial post extension 54 which projects through the port 34 in the cap bottom 32 to the outside thereof and there terminates in a preferably rounded bearing tip 56. The post extension 54 thus forms the post 34 in the cap bottom 32, and also the inwardly converging part 50 of the capillary chamber 46, ring-shaped about the axis 1:. With the chamber 46 having capillary attraction to liquid within reach and holding liquid in this chamber by capillary retention, the ports 34 and 52 are preferably of sufficiently restricted area to retain liquid at least by surface tension in order to avoid any loss of liquid from the body 14 in certain phases of operation of the diluter involving transfer of the liquid-charged body from one cup formation to a next cup formation in a titration tray.
Operation of the diluter also involves mixing of a liquid charge in its body with liquid in a cup formation in a tray into which the body is dipped. To this end, the body 14 is provided with cam means inclined to the axis x and exposed to the capillary chamber 46 for impellin g liquid therein on oscillating the body about its axis. These cam means are in the preferred form of grooves 60 of capillary width in the cylindrical plug formation 26 which preferably are equiangularly spaced, extend at the same inclination to the axis x, and are coextensive over their extent axially of the body 12. There are preferably four of these cam grooves 60 in keeping with the provision of the exemplary four ports 52 in the cap rim 30.
For a reason explained hereinafter, the present diluter is also specially fitted for cup formations c with standard cone-shaped bottoms b in titration trays (FIG. 1). These cone-shaped bottoms b of cup formations c in a titration tray have a given angle A, and the cap bottom 32 of the liquid holding body 14 of the diluter is formed frusto-conical to conform to the cone-shaped bottom b of a cup formation 0. Further, for proper dip of the diluter body 14 into liquid in a cup formation c, the tip end 56 of the post extension 54 on the cylindrical plug formation 26 is brought to bear against the cone-shaped bottom b of the cup formation, whereby the body 14 becomes also centered on the apex a of this bottom, with this tip end'56 being so spaced from the frusto-conical cap bottom 32 thatthe latter will then be spaced from the cone-shaped bottom b of the cup formation by a uniform gap g which is quite narrow, being in the order of a few thousandths of an inch, but nevertheless sufficient to avoid scratching of the bottom b of the cup formation by the cap bottom 32 of the body 14 on operationally oscillating the latter about its axis.
With the liquid holding diluter body 14 being required, for its prescribed dip into liquid in a cup formation c in a tray, to bear with its tip 56 against the bottom b of the cup formation, contact between them, either on lowering the diluter or raising the tray, is preferably cushioned to avoid possible damage to the diluter or tray. To this end, the stem 16 of the liquid holding body 14 has in its mount in the shaft 12 a limited lost-motion connection with this shaft. Thus, the body stem 16 is slidably received in an axial recess 62 in the shaft 12 (FIG. 2), and the lost-motion connection is in this instance provided by a transverse groove 64 in the stem 16 and a crosspin 66 in the shaft 12 which extends through the groove 64, with the groove 64 having opposite walls 68 and '70 of a given spacing, and the crosspin 66 being of smaller diameter than the spacing of the groove walls 68 and 70. A preloaded spring 72 in the shaft recess 62 normally urges the body stem 16 to one end of its lost-motion connection with the shaft 12 at which the groove wall 68 bears against the crosspin 66 and the body 14 is at its maximum projection from the shaft 12. Thus, hard and possibly damaging contact be tween the tip 56 on the diluter body 14 and the bottom b of a cup formation c in a tray is avoided by the yield of the body 14 relative to the shaft 12 which is afforded by the described spring-loaded lost-motion connection.
In operation of the diluter for a given titration procedure, the body 14 is first dipped into a solution to-beanalysed and its chamber 46 is thereby charged to its full capacity with solution by capillary action, with even the ports 34 and 52 being then charged with solution. The chamber 46 is, by its restricted width, designed to exert on the solution relatively strong capillary forces which not only assure quick charging of this chamber to its full capacity with solution, but also exhibit relatively strong retentivity of the solution charge in the chamber 46 so that none of the charge will be lost in operational transfer of the diluter body'l4 into a cup formation in a tray. Having once been charged with solution to-be-analysed, the diluter is with its body dipped into diluent in a starting cup formation c in a tray (FIG. I with the cup formation being characteris tically small so that the diluent charge therein, usually one or two drops, more or less fills the bottom b of the cup formation prior to dipping the diluter body 14 thereinto. On dipping the diluter body into the diluent in the cup formation 0, diluent will be displaced by the body 14 sufficiently to raise the level of the diluent to within reach of the body ports 52. The diluter is then oscillated-at its shaft 12 about its axis x for pumping action of the body 14 and ensuing mixing of its charge with the diluent in the cup formation 0. In thus oscillating the body 12, various forces, such as hydrostatic pressure and centrifugal force, for example, to which the charge in the capillary chamber 46 is subjected, has a tendency to, and will, force at least some of the charge out of this chamber, but it is the cam grooves 60 in the body, with the assistance of these forces, that impart to the body. 14 a pumping action sufficiently powerful to overcome the capillary retentivity of the charge in the chamber 46. Thus, these cam grooves 60 will, on oscillation of the body 14, exert on the confined charge in the latter axial displacement force components which are quite effective, since they easily overcome the capillary liquid retentivity of the bodys interior as weakened as it then is by agitation of the confined charge due to operational oscillation of the body and also centrifugal force. The pumping action of the oscillating body 14 is, therefore, relatively powerful, and is also periodicallyreversing, resulting in circulation of the liquids involved back and forth through the chamber 46 and ports 34 and 52 and ensuing most thorough mixing of these liquids. Moreover, the pumping action of the oscillating body 14 results in mixing of the liquids involved not only most thoroughly, as described, but also quite evenly throughout including at the very bottom b of the cup formation 0. Thus, in lowering the diluter body all the way into the cup formation 0, its dip end, i.e., the bottom 32 of the body cap 20, will displace all the diluent it confronts until it reaches its final disposition on which it is spaced from the bottom b of the cup formation by the uniform and quite narrow gap g which affords no pocket whatever along this cup bottom b in which liquid would not at all, or only poorly, mix with the remaining liquid in operational pumping action of the body.
With the bottom 32 of the body cap 20 being in this instance frustoconical, the bottom end 28 of the plug 18 is preferably also formed frustoconical to keep the capillary width of the inwardly converging chamber part 50 uniform and preferably the same as that of the cylindrical chamber part 48. Also, while the cam grooves 60 in the cylindrical plug formation 26 extend over the greater part of the axial extent of the peripheral surface 40 thereof, these cam formations preferably extend also into the frusto-conical plug end 28 as at 60' (FIG. 2) for optimum pumping action of the body 14 in operational oscillation. Further, and also for most effective pumping action of the oscillating body 14, the ports 52 are located within the axial extent of the cam grooves 60 in the peripheral surface 40 of the cylindrical plug formation 26, and are preferably slightly below the upper ends of these cam grooves.
The shaft, plug and cap parts 12, 18 and 20 of the diluter may be of any suitable metal, and they are preferably of stainless steel. Further, among these parts, the shaft 12 and the plug 18 with its stem 16 are preferably simple and inexpensive parts made and finished in screwmachines, while the cap 20 is preferably a part which is drawn to shape and then simply punched or drilled for the provision of the ports 34 and 52. The assembly of these parts is quite simple and inexpensive, merely requiring sliding of the cap part 20 over the plug part 18 and locally staking the former to the latter, inserting the spring 72 and plug stem 16 into the axial recess 62 in the shaft part 12, and driving the crosspin 66 into the shaft 12.
The actual diluter is, of course, much smaller than shown. In this connection, there is given, by way of example only, an indication of the actual size of a diluter of highly satifactory performance in use with cup formations of accustomed size in a titration tray, with the outside diameter of the cap part 20 of this diluter being about 0.170 inch, and its other dimensions being in about the same proportion thereto as appears in the drawings which show the diluter at a fairly true, but greatly enlarged, scale.
Reference is now had to FIG. 4 which shows a modified diluter 10 that is in all respects like the described diluter 10 of FIGS. 1 to 3, except that its liquid holding body 14' is specially fitted for cup formations c with semi-spherical or so called round bottoms b in a tray. To this end, the bottom 32' of the body cap 20' is formed part-spherical in conformity with the round bottom b of the cup formation, and the bearing tip 56' on the body plug 18', when seated on the bottom b' of the cup formation, holds the bottom end 32 of the diluter body 14' spaced from the round bottom of the cup formation by the uniform and quite narrow gap g.
FIG' shows another modified diluter which differs from the diluters l0 and 10' by being specially fitted for cup formations c" with flat bottoms b" in a tray. To this end, the bottom 32" of the body cap 20 is formed flat, and the bearing tip 56" on the body plug 18", when seated on the bottom b" of the cup formation, holds the bottom end 32" of the diluter body 14' spaced from the flat bottom of the cup formation by the uniform and quite narrow gap g".
What is claimed is:
1. A diluter, providing a shaft, a cylindrical body, having a longitudinal axis, at one end of and coaxial with said shaft, with said body having a ring-shaped chamber of capillary width about said body axis, and axially spaced ports providing sole communication between said chamber and the outside of said body, and cam means in said body inclined to said body axis and exposed to said chamber for impelling liquid therein on oscillation of said body about is axis.
2. A diluter as in claim 1, in which said chamber has spaced inner and outer peripheral surfaces, and said cam means are angularly spaced grooves of capillary width in one of said peripheral chamber surfaces, with said grooves being inclined to said body axis.
3. A diluter as in claim 2, in which said grooves are in said inner peripheral chamber surface.
4. A diluter as in claim 1, in which said body has a free end remote from said shaft, and said chamber has main and end sections, of which said main section is cylindrical about said body axis and has spaced inner and outer peripheral surfaces of given diameters, and said end section is next to said body end and converges from said main section inwardly toward said body axis, with one of said ports being provided in said body end and the remainder of said ports being within the axial extent of said main chamber section.
5. A diluter as in claim 4, in which said one port is centered on said body axis and its cross-sectional dimension is smaller than said given diameter of said inner peripheral chamber surface.
6. A diluter as in claim 5, in which said body has in said end chamber section a coaxial post extending into said one port with clearance therefrom throughout to thereby form said end chamber section and one port ring-shaped about said body axis.
7. A diluter as in claim 6, in which said post extends through said one port to the outside of said body and there terminates in a bearing tip axially spaced from said body end.
8. A diluter as in claim 7, in which said bearing tip is rounded.
9. A diluter as in claim 7, in which said ports are of restricted cross-sectional area for liquid retention by surface tension.
10. A diluter as in claim 7, in which said cam means are angularly spaced grooves of capillary width in said inner peripheral surface of said main chamber section, with said grooves being inclined to said body axis.
11. A diluter as in claim 10, in which said grooves are equiangularly spaced and extend at the same inclination to the body axis, and they are coextensive axially of the body.
12. A diluter as in claim 11, in which said ports other than said one port are within the axial extent of said grooves.
13. A diluter as in claim 7, in which said body end surrounding said one port is frusto-conical.
14. A diluter as in claim 7, in which said body end surrounding said one port is part-spherical.
15. A diluter as in claim 7, in which said body has a coaxial stem, and said shaft has in said one end an axial recess in which said stem is slidable but held against rotation relative to said shaft, and there is further provided an axial lost-motion connection between said stern and shaft, and a spring urging said stem to one end of said lost-motion connection at which said body is at maximum spacing from said one shaft end.
16. A diluter as in claim 15, in which said shaft recess and body stem are cylindrical, said shaft recess has a bottom, and said lost motion connection is formed by a transverse groove with spaced side walls in said stem, and a crosspin in said shaft extending through said recess and groove and being of a diameter smaller than the spacing of said groove walls, with said spring being interposed between said stem and recess bottom, and said crosspin cooperating with said groove in holding said stem against rotation relative to said shaft.
17. A diluter providing a shaft with an axis; a plug at one end of said shaft having upper and lower cylindrical formations coaxial with said shaft and being of larger and smaller diameters, respectively, of which said upper formation is next to said shaft and said lower formation projects from said upper formation and terminates in an end; and a cup-like cap having a cylindrical rim and a bottom with a central aperture, of which said rim is fitted and secured to said upper cylindrical plug formation and surrounds said lower cylindrical plug formation at uniform capillary spacing therefrom, and said bottom overlaps said end of said lower cylindrical plug formation and is uniformily spaced therefrom by a capillary gap, with said lower cylindrical plug formation and cap forming a capillary chamber, said cap rim having within the axial extent of said lower cylindrical plug formation angularly spaced apertures which, together with said aperture in said cap bottom provide sole communication between said chamber and the outside thereof, and said lower cylindrical plug formation having a peripheral surface with angularly spaced grooves therein of capillary width and inclined to said shaft axis for impelling liquid in said chamber on oscillating said shaft about its axis.
.18. A diluter as in claim 17, in which said end of said lower cylindrical plug formation has an axially projecting post extending with clearance through said aperture in said cap bottom to the outside thereof and there terminating in a bearing tip axially spaced from said cap bottom.
19. A diluter as in claim 18, in which said cap bottom is frustoconical.
20. A diluter as in claim 18, in which said cap bottom is part-spherical.

Claims (20)

1. A diluter, providing a shaft, a cylindrical body, having a longitudinal axis, at one end of and coaxial with said shaft, with said body having a ring-shaped chamber of capillary width about said body axis, and axially spaced ports providing sole communication between said chamber and the outside of said body, and cam means in said body inclined to said body axis and exposed to said chamber for impelling liquid therein on oscillation of said body about is axis.
2. A diluter as in claim 1, in which said chamber has spaced inner and outer peripheral surfaces, and said cam means are angularly spaced grooves of capillary width in one of said peripheral chamber surfaces, with said grooves being inclined to said body axis.
3. A diluter as in claim 2, in which said grooves are in said inner peripheral chamber surface.
4. A diluter as in claim 1, in which said body has a free end remote from said shaft, and said chamber has main and end sections, of which said main section is cylindrical about said body axis and has spaced inner and outer peripheral surfaces of given diameters, and said end section is next to said body end and converges from said main section inwardly toward said body axis, with one of said ports being provided in said body end and the remainder of said ports being within the axial extent of said main chamber section.
5. A diluter as in claim 4, in which said one port is centered on said body axis and its cross-sectional dimension is smaller than said given diameter of said inner peripheral chamber surface.
6. A diluter as in claim 5, in which said body has in said end chamber section a coaxial Post extending into said one port with clearance therefrom throughout to thereby form said end chamber section and one port ring-shaped about said body axis.
7. A diluter as in claim 6, in which said post extends through said one port to the outside of said body and there terminates in a bearing tip axially spaced from said body end.
8. A diluter as in claim 7, in which said bearing tip is rounded.
9. A diluter as in claim 7, in which said ports are of restricted cross-sectional area for liquid retention by surface tension.
10. A diluter as in claim 7, in which said cam means are angularly spaced grooves of capillary width in said inner peripheral surface of said main chamber section, with said grooves being inclined to said body axis.
11. A diluter as in claim 10, in which said grooves are equiangularly spaced and extend at the same inclination to the body axis, and they are coextensive axially of the body.
12. A diluter as in claim 11, in which said ports other than said one port are within the axial extent of said grooves.
13. A diluter as in claim 7, in which said body end surrounding said one port is frusto-conical.
14. A diluter as in claim 7, in which said body end surrounding said one port is part-spherical.
15. A diluter as in claim 7, in which said body has a coaxial stem, and said shaft has in said one end an axial recess in which said stem is slidable but held against rotation relative to said shaft, and there is further provided an axial lost-motion connection between said stem and shaft, and a spring urging said stem to one end of said lost-motion connection at which said body is at maximum spacing from said one shaft end.
16. A diluter as in claim 15, in which said shaft recess and body stem are cylindrical, said shaft recess has a bottom, and said lost motion connection is formed by a transverse groove with spaced side walls in said stem, and a crosspin in said shaft extending through said recess and groove and being of a diameter smaller than the spacing of said groove walls, with said spring being interposed between said stem and recess bottom, and said crosspin cooperating with said groove in holding said stem against rotation relative to said shaft.
17. A diluter providing a shaft with an axis; a plug at one end of said shaft having upper and lower cylindrical formations coaxial with said shaft and being of larger and smaller diameters, respectively, of which said upper formation is next to said shaft and said lower formation projects from said upper formation and terminates in an end; and a cup-like cap having a cylindrical rim and a bottom with a central aperture, of which said rim is fitted and secured to said upper cylindrical plug formation and surrounds said lower cylindrical plug formation at uniform capillary spacing therefrom, and said bottom overlaps said end of said lower cylindrical plug formation and is uniformily spaced therefrom by a capillary gap, with said lower cylindrical plug formation and cap forming a capillary chamber, said cap rim having within the axial extent of said lower cylindrical plug formation angularly spaced apertures which, together with said aperture in said cap bottom provide sole communication between said chamber and the outside thereof, and said lower cylindrical plug formation having a peripheral surface with angularly spaced grooves therein of capillary width and inclined to said shaft axis for impelling liquid in said chamber on oscillating said shaft about its axis.
18. A diluter as in claim 17, in which said end of said lower cylindrical plug formation has an axially projecting post extending with clearance through said aperture in said cap bottom to the outside thereof and there terminating in a bearing tip axially spaced from said cap bottom.
19. A diluter as in claim 18, in which said cap bottom is frustoconical.
20. A diluter as in claim 18, in which said cap bottom is part-spherical.
US00233887A 1972-03-13 1972-03-13 Diluter for laboratory titration Expired - Lifetime US3757584A (en)

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CN111624085A (en) * 2020-07-29 2020-09-04 天津中新科炬生物制药股份有限公司 Sample diluting device and reagent card for detecting novel coronavirus antibody

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US3276847A (en) * 1961-08-31 1966-10-04 Cooke Engineering Company Tubular dropper for micro-titration
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US3191813A (en) * 1962-04-23 1965-06-29 Cooke Engineering Company Laboratory apparatus
US3252331A (en) * 1964-11-23 1966-05-24 Cooke Engineering Company Laboratory apparatus
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CN111624085A (en) * 2020-07-29 2020-09-04 天津中新科炬生物制药股份有限公司 Sample diluting device and reagent card for detecting novel coronavirus antibody

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CA977717A (en) 1975-11-11

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