US3494508A - Fractionator - Google Patents

Description

Feb. 10, 1970 v P. s. HOEFER 1 7 3,494,508

- FRACTIONATOR Filed May 10, 19 8 INVENTOR.

Peter S Hoefer 73 BY w N 2 k Attorneys United States Patent 3,494,508 FRACTIONATOR Peter Stanton Hoefer, 2609 California St., San Francisco, Calif. 94115 Filed May 10, 1968, Ser. No. 728,216 Int. Cl. B67b 7/24; B04b 9/12 US. Cl. 222--82 8 Claims ABSTRACT OF THE DISCLOSURE A fractionator for the removal of gradient layers from preparative ultra-centrifuge tubes. The tube is retained by a structure including a bottom plate with three upwardly extending posts upon which spacer rings are slid. These provide abutments for adaptor rings into which the centrifuge tube is set. A rubber cap with a dome shaped surface seals the top of the centrifuge tube and is held against the tube by a hold-down tube which extends through a twist-lock top plate fastened to the upwardly extending posts. A knurled knob fastens the hold-down tube to maintain pressure on the centrifuge tube. The bottom of the centrifuge tube rests on a rubber washer which covers an aperture through the bottom plate. The washer and tube bottom are pierced by a needle in a chuck assembly as it is threaded into the bottom plate. The centrifuge tube may be drained by gravity downwardly or a dense liquid pumped into the bottom through the needle to cause upward flow through the hold-down tube.

BACKGROUND OF THE INVENTION The present invention is directed to a fractionator for the removal of gradient layers from preparative ultracentrifuge tubes.

In the field of removing gradient layers from ultracentrifuge tubes present devices are inadequate in that separate units are necessary for different size centrifuge tubes. Moreover, the construction of the units vary depending on whether the layers are to be drawn out of the top of the tube (termed upward flow) or from the bottom of the tube (termed downward fiow). Prior art devices, moreover, have involved, complex and time consuming adjustments.

OBJECTS AND SUMMARY OF INVENTION It is therefore a general object of the invention to provide an improved fractionator for the removal of gradient layers from preparative ultra-centrifuge tubes.

It is another object of this invention to provide a fractionator of the above type which is usable with tubes of many different sizes.

It is another object of the invention to provide a fractionator of the above type which is suitable for both upward and downward flow.

It is another object of the invention to provide a fractionator which is simple in operation.

In accordance with the above objects there is provided a fractionator for the removal of gradient layers from preparative ultra-centrifuge tubes which includes a bottom plate having an apertured center portion adapted to receiving one of the tubes. A plurality of support posts extend upwardly from the bottom plate and define a cylindrical volume having a predetermined diameter. Spacer means are provided which are adapted to be slid over the posts and provide abutments. A plurality of adaptor rings having an outer diameter substantially equal to the predetermined diameter of the cylindrical volume and an inner diameter equal to the tube diameter rest on the abutments provided by the spacer means. Finally, means are provided which are adapted to hold down the tube 3,494,508 Patented Feb. 10, 1970 against the center portion including a cap for sealing the tube, a top plate afiixed to the posts and a rigid tube extending through the top plate into contact with the sealing cap along with means for fixedly securing the rigid tube to the top plate.

BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a perspective view of a fractionator embodying the present invention;

FIGURE 2 is a cross-sectional view in exploded format taken substantially along the line 22 of FIGURE 1; and

FIGURE 3 is a cross-sectional view taken substantially along the line 33 of FIGURE 1.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Referring now to FIGURE 1, a bottom plate 11 is provided with a recessed center portion 12 having an inset rubber washer 13. A centrifuge tube 14 which is to be fractionated has its bottom resting upon the rubber washer. Bottom plate 11 also has a central aperture below the rubber washer 13 which will be discussed below.

Extending upwardly from bottom plate 11 are three vertical posts 16 on which are slid aluminum spacer tubes 17. The top portion 17a of these spacer tubes provide abutments on which adaptor rings 19 rest. Each adaptor ring has an outer diameter which is determined by the diameter of the cylindrical volume encompassed by posts 16 and an inner diameter determined by the diameter of the particular centrifuge tube which is to be fractionated. Thus, different size tubes may be accommodated by varying the inner diameter of adaptor rings 19 and centrifuge tubes of different lengths may be accommodated by varying the number of spacers 17 and adaptor rings 19 used. For example, if a longer tube is to be used an additional set of spacers 17 and adaptor rings 19 would be added. Conversely, if a shorter tube is used the lower-most adaptor ring might be placed directly against bottom plate 11 and only one set of spacers 17 used.

Tube 14 is retained against the rubber washer 13 by hold-down means which include a silicone rubber sealing cap 21, a rigid tube 22, and a twist-lock top plate 23. As shown in greater detail in FIGURE 3, the cap 21 has a conical or dome shaped undersurface 24 which mates with the top of tube 14 to provide an air and liquid tight seal. A center aperture 26 of cap 21 communicates with tube 22 which is inset into recessed portion 27 of cap 21. This also provides an air tight seal between rigid tube 22 and cap 21. Top plate 23 is secured to posts 16 by a twisting type action. Plate 23 is placed on the posts through its oversize holes 28 and then rotated into locking abutment with undersize holes 29 in the plate with respect to corresponding grooves in the posts 16.

Rigid hold-down tube 22 is fixedly secured to top plate 23 to provide for pressure by cap 21 against the tube 14. Pressure is first applied to tube 22 and then it is secured to the top plate by a knurled knob 31 which extends through the plate into contact with tube 22.

A horizontal rod 32 is afiixed to bottom plate 11 to serve as a support arm for use with standard laboratory apparatus.

In order to either draw liquid out of the tube 14 from the bottom to provide a downward flow or to create an upward pressure in the tube for upward fiow through tube 22, means are provided for penetrating the centrifuge tube with a needle 33.

In general, and referring to FIGURE 2 as well as FIGURE 1, needle 33 is inserted into a needle holding chuck assembly generally indicated at 34 which allows the needle to protrude from the chuck assembly a predetermined amount. The chuck assembly is then screwed into a center aperture 36 of bottom plate 11 to cause the needle to penetrate rubber washer 13 and the bottom of tube 14 to reach the indicated layers of liquid 37 in the ultra-centrifuge tube.

More specifically, chuck assembly 34 includes a knurled nut 38 having a threaded receptacle portion 39. A sleeve 41 with deformable jaws 42 is fitted into receptacle 39 with jaws 42 abuting against the end of the receptacle. A main chuck knob 43 includes exteriorly threaded sleeve 44 which is affixed to main knob 43 by a lock washer 46. An exterior threaded portion 47 of sleeve 44 mates with the interior threads of aperture 36. Portion 47 includes an internal cam surface 48 which wedges against the jaws 42 to hold needle 33. Threaded portion 47 allows the chuck assembly 34 to be screwed into aperture 36 so that needle 33 penetrates rubber washer 13 and the bottom of tube 14.

OPERATION To provide a downward flow (that is, taking the gradient layers out of the bottom of tube 14) an ultra-centrifuge tube containing gradient layers is placed in the apparatus with the spacers and adaptor rings. The cap normally used for centrifugation is removed and the silicone rubber cap 21 placed on the tube. The twist-lock cap 23 is then placed over the posts and twisted. Hold-down tube 22 is placed through the hole in the twist-lock cap and seated in the recess 27 of the sealing cap 21. Downward presure is applied to hold-down tube 22 and the knurled knob 31 on top plate 23 is tightened. This holds tube 14 in place and creates an air and liquid tight seal at the rim of the centrifuge tube. A leak-proof seal is also created at the bottom of the centrifuge tube in relation to rubber washer 13.

Next a needle 33 of the proper gauge is procured. For example, a small 20 gauge needle is best for thin-wall cellulose acetate tubes; the large 18 gauge needle is best for the tougher polyalomer tubes. The needle is inserted in the chuck asembly 34 by loosening the small knurled nut 38 in the needle-holding chuck. Of course, the whole assembly has previously been removed from bottom plate 11. The needle 33 is inserted into the chuck until the hole 33a in the needle is about /3 inch above the top of the threaded portion 47. Knurled nut 38 is then tightened.

The entire chuck unit assembly, by use of main knob 43, is threaded into bottom plate 11 until the tube is pierced.

At this time the centrifuge tube may drain either by gravity, since it is open to atmospheric pressure through tube 22, or by applying a small amount of air pressure through tube 22. This air pressure may easily be applied by attaching a rubber tube to hold-down tube 22.

If upward flow is desired, the same steps as above are essentially used in placing the tube 14 in the fractionator. However, a length of polyethylene tubing 50' is first pulled through the aperture 26 in rubber cap 21 until the end of the tubing is flush with the dome-shaped depression 24. The cap 21 is placed on the centrifuge tube and the polyethylene tubing is fed up through rigid tube 22 out through its end. The same procedure is followed thereafter as above.

In order to cause upward flow into the polyethylene tube contained by rigid tube 22 a dense fluid, heavier than any of the fluid already in the centrifuge tube, is

applied through the needle 33 thus displacing the gradient layers upwardly through the dome shaped rubber cap into the polyethylene tubing. This is usually done by using a small peristaltic type pump.

If desired, the depth of penetration of needle 33 into the tube 14 is easily adjusted by initially adjusting the amount the needle protrudes from portion 47. In this manner specific layers that are present in the ultra-centrifuge tubes may be selectively extracted.

Thus, in conclusion the present invention provides an improved fractionator which accommodates different size ultra-centrifuge tubes, is simple in operation, and provides for either upward or downward flow type operation.

I claim:

1. A fractionator for the removal of gradient layers from preparative ultra-centrifuge tubes comprising; a bottom plate having an apertured center portion adapted for receiving one of said tubes, a plurality of support posts upwardly extending from said bottom plate and defining a cylindrical volume having a predetermined diameter, spacer means adapted to be slid over said posts and providing abutments, a plurality of adaptor rings having an outer diameter substantially equal to said predetermined diameter and an inner diameter equal to the tube diameter, said rings resting on said abutments provided by said spacer means, means adapted to hold down said tube against said center portion including a cap for sealing said tube, a top plate afiixed to said posts, a rigid tube extending through said top plate into contact with said sealing cap, and means for fixedly securing said rigid tube to said top plate.

2. A fractionator as in claim 1 in which said cap is composed of resilient material.

3. A fractionator as in claim 2 in which said portion of said cap which contacts said tube is dome shaped.

4. A fractionator as in claim 1 in which said center portion of said bottom plate includes resilient means for receiving said tubes.

5. A fractionator as in claim 1 in which said top plate is aifixed to said posts by a twist-lock type action.

6. A fractionator as in claim 1 together with needle means for penetrating said tube and a chuck assembly for retaining said needle, said chuck assembly being screwed into said aperture of said bottom plate whereby said needle means pierces said tube.

7. A fractionator as in claim 6 together with means included in said chuck assembly for adjusting the depth of penetration into said tube of said needle means.

8. A fractionator as in claim 1 in which said sealing cap includes an aperture for communication between said rigid tube and the interior of a centrifuge tube whereby a pressure head can be applied to liquid in such tube.

References Cited UNITED STATES PATENTS 2,604,261 7/1952 Silverstolpe 233-26 3,081,029 3/1963 Gauslaa 233--26 3,361,343 1/1968 Lerner 23326 3,365,102 1/1968 Castleberry 222-83.5 3,366,278 1/1968 Fobes 222-82 SAMUEL F. COLEMAN, Primary Examiner U .8. Cl. X.R.

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