WO1991002919A1

WO1991002919A1 - Snap cap reaction column

Info

Publication number: WO1991002919A1
Application number: PCT/US1990/004567
Authority: WO
Inventors: Jeff D. Williams; Eric S. Nordman; Rodger D. Toliver
Original assignee: Applied Biosystems, Inc.
Priority date: 1989-08-15
Filing date: 1990-08-13
Publication date: 1991-03-07

Abstract

A reaction column for holding a sample support and delivering chemicals and reagents during chemical reactions has end caps (25) with molded snap details (27, 28, 41) that engage snap details (29, 30) on nipples (35) of a central body (23). The end caps, when snapped in place, urge surfaces of the caps and the body together forming liquid-tight seals, and also hold filter elements (31) in place defining the reaction chamber. The end caps are provided with connections to attach fluid tubings.

Description

SNAP CAP REACTION COLUMN

Field of the Invention

The present invention is in the area of apparatus for performing chemical processes, and has particular application in DNA synthesis and purification.

Background of the Invention

In DNA synthesis and purification the procedures employed often involve a large number of steps, and DNA related chemistry is a rapidly growing technology. Accordingly, apparatus for performing, and particularly for automating such procedures is commercially important. Synthesis and purification columns have been developed in which a sample of material, typically on a sample support, may be confined in a reaction chamber, where the sample may be exposed in a desired sequence to various chemicals and reagents to accomplish desired reaction, such as synthesis or purification. The reaction chamber in such a column typically is connected to fluid passages through suitable filters.

Fig. 1 is a partial cutaway view of a popular column of the kind described above, manufactured and sold by Applied Biosystems Incorporated of Foster City, California and, in similar form, by several other manufacturers of biochemical equipment. The column is shown partially assembled and partially disassembled to better illustrate the nature of the elements and how the elements are assembled to make a column with a reaction chamber.

Body 11 is a tubing that, when assembled with the other elements, provides a reaction chamber 13. There are two end caps 15 that fit into bores in the body and press against two filter membranes 17. One of the end caps and one of the filter membranes is shown assembled to body 11, held in place by a crimp cap 19. In a completely assembled column, the other filter and end cap is similarly assembled to the body, held in place by a second crimp cap. The body and end caps are typically injection molded from a high molecular weight polymer, and the filter membranes are typically mechanically punched or laser cut from sheets of porous fluorocarbon with a thickness of about .013 mm. (about .005 inches). The pores of the filter membrane are smaller than the solid support sample, typically about 20 to 30 microns in diameter.

A filter membrane is placed against a shoulder of body 11, one on each side to form reaction chamber 13, and the end caps are inserted, trapping the filter membranes against the shoulders and the end of the end caps. There are two aluminum crimp caps 19 to hold the two end caps in place and to provide pressure in the assembly to urge the end caps against the filter membranes, holding the membranes in place and providing a seal for liquid integrity. One of the crimp caps is shown assembled and crimped at edge 21, and the other is shown not assembled.

Since the introduction of the crimp type column shown by Fig. 1 there has been an increase in demand for synthesis and purification columns. As a result, several companies are now competitively marketing synthesis and purification columns of this general type, and the cost of manufacture and assembly has become critical as a competitive issue.

There are problems with the crimp type column. For example, the thin fluorocarbon membrane is flexible and therefore difficult to handle in automated assembly. Moreover, manufacturing, placing and crimping the crimp caps is expensive and time consuming, and it appears impossible to perform non-destructive testing for seal integrity. In addition, the crimp-type column does not provide a ready disassembly for procedures where a sample support must be recovered after processing.

What is clearly needed is a new synthesis and purification column with a liquid seal separate from the filters, filters that are less expensive and easier to handle in automated assembly, and an assembly that lends itself to ease of placement and recovery of sample supports. The column design should also allow for 100 percent, non-destructive, automated testing for integrity and reliability. Summary of the Invention

A reaction column is provided with two caps and a body that snap together with two filter elements to form a reaction chamber between the filter elements. The snap components are a part of the body and the caps. The caps are configured for attaching fluid tubings to the reaction column. In a preferred embodiment a liquid-tight seal is formed between the body and the caps by tapered nipples on the body and tapered bores in the caps, such that the surfaces are urged together forming the seal as the parts are snapped together. The surface-to-surface seal is independent of the presence of the filter elements, but the filter elements are held in place in the preferred embodiment by the ends of the tapered nipples of the body. The column provided has fewer parts than previous columns, needing no crimp caps for holding the assembly together. The parts are more easily handled by automated feeding and placing equipment, including the filter elements, and the column can be easily connected to tubings to check reliability and seal integrity. In a preferred mode, the column is bi-directional.

Brief Description of the Drawings

Fig. 1 is an elevation view of a commercially available reaction column with crimp caps.

Fig. 2 is an elevation view of a reaction column according to a preferred embodiment of the invention.

Fig. 3 is an enlarged view of a body of the column of the preferred embodiment with dimensions.

Fig. 4 is an enlargement of a portion of the body of Fig. 3 showing additional detail of a tapered nipple and snap details.

Fig. 5 is a section view of a snap cap of the column in the preferred embodiment showing dimensions.

Fig. 6 is an enlargement of a portion of the snap cap of Fig. 5 showing additional detail.

Fig. 7 is a section through a filter element of the preferred embodiment, showing dimensions.

Description of the Preferred Embodiments

Fig. 2 is a partially cutaway view of a synthesis and purification column according to a preferred embodiment of the invention. The elements are partly assembled and partly not assembled to better illustrate the arrangement of the elements in the assembly. The column in the preferred embodiment has a body 23, two snap caps 25, and two filter elements 31. The body has a straight through bore 33, and terminates at each end in a tapered nipple 35, each having a ridge portion 29 adjacent to a groove 30.

Each snap cap has a through bore 37 with a shoulder 39, a tapered portion 41, and a groove 27 adjacent to a ridge 28. The filter elements are porous frit material and are rigid enough to be easily handled in assembly. The filter elements are sized to fit in the bore diameter at shoulder 39 of each of the snap caps. A filter element is placed in a snap cap against shoulder 39, and a nipple 35 of the body is pushed into the bore of the snap cap. The end of the nipple presses into the filter element, the tapered nipple fits against tapered portion 41 of the snap cap, forming a liquid-tight seal, and ridge 29 snaps into groove 27 as ridge 28 snaps into groove 30, providing a rigid assembly. With a snap cap installed on each side of a body with two filter elements in place a reaction chamber 43 is formed between the two filter elements. The volume of the reaction chamber may be easily controlled by controlling the length of body 23. Also, although it is not required, in the preferred mode the column and snap caps are symmetric, end-to-end, so that the system is completely bi-directional.

In the preferred embodiment, the snap caps and the body are molded from high molecular weight polymers, such as Tenite 5020 Polyallomer marketed by Eastman Kodak Corporation, which also exhibits contact clarity when wetted with solvent so that the reaction process can be visually monitored. There are other suitable high density and ultra high molecular weight inert polymers that may be used for the body and end caps.

The filter elements in the preferred embodiment are compression molded using high density polyethylene and ultra high molecular weight polyethylene. Filters molded from such materials exhibit a decreased flow resistance which provides better washing efficiency and more homogeneous flow of reagents over the agitated derivatized sample support. (A sample support is not shown in the drawings.) The frits can also be laser cut or mechanically punched from porous sheets of high density polyethylene with pores from 20 to 30 microns in diameter and marketed by Porex Corporation of Fiarburn Georgia.

Figs. 3, 4, 5, and 6 are sections of the body, the tapered snap end of the body, the snap cap and an enlarged portion of the snap cap, to illustrate the approximate dimensions of different parts of these elements in the preferred mode. The dimensions are not meant to be exclusive, as it will be apparent to a person skilled in the art that there may be broad variation in the dimensions within the spirit and scope of the invention.

In Fig. 3, diameter Dl is about 8 mm., diameter D2 is about 7 mm., and the through bore diameter D3 is about 6 mm. Radius Rl is about .23 mm. Angle Al of the tapered end for insertion into a snap cap, is about 12.64 degrees, and angle A2 is about 35 degrees. D4 is the depth of the groove behind ridge 29, and is about .15 mm. in the preferred embodiment. D5 is the width of the land of groove 29, and is about .3 mm. Dimension D6 is about .75 mm. D9 is the length of a tapered end, and is about 3.5 mm. The maximum outside diameter is D8, about 9.5 mm. The length D7 of the center section varies according to the relative volume required in the reaction chamber that results from assembly of the body with filters and end caps. For a 1.5 micro-mol column D7 is about 1.25 mm. For a 3.0 micro-mol column D7 is about 8.9 mm.

In Fig. 4, showing the tapered snap end of the body enlarged and in more detail, D10 is about .23 mm., diameter Dll is about 7.2 mm., and R2 is about .076 mm. The other dimensions of Fig. 4 are the same as in Fig. 3.

In Fig. 5, showing a snap cap in section, D12 is about 1.8 mm., D13 is about 3.2 mm., D14 is about 4.75 mm., D15 is about 5.7 mm., D16 is about 6 mm., and the overall length D17 is about 12.8 mm. Diameter D18 is about 5.7 mm., diameter D19 is about 6.9 mm., and overall diameter D20 is about 12.7 mm. Also, diameter D21 is about 6 mm. and diameter D22 is about 10.4 mm. Included angle A3 is about 90 degrees.

Fig. 6 is an enlargement of a portion of Fig. 5 to show additional detail. Diameter D23 is about 7.6 mm. D24 is about .127 mm. Angle A4 is about 45 degrees, angle A5 is about 35 degrees, and angle A6 is about 15 degrees.

Fig. 7 is a section through a porous frit filter element of the preferred embodiment to show dimensions. Diameter D25 is about 7 mm. and width D26 is about 1.6 mm.

It will be apparent to a person with skill in the art that there are many changes that may be made without departing from the spirit and scope of the invention. The materials listed for the preferred embodiment are materials that are suitable and relatively inexpensive for the chosen manufacturing process. There are many other materials that would suit the purpose of making a workable snap cap column. The dimensions detailed for the various elements are dimensions of elements that have been manufactured and tested to snap together with a liquid-tight seal, and that are suitable for existing equipment with which such columns are used. These are not the only dimensions that might be used to produce a useful snap cap column.

It is not required that the snap elements between the body and the end caps be continuous ridges and grooves. There are many other forms that protrusions and depressions might take to accomplish the snap action between the elements. However, in the manufacturing process, providing multiple snap devices for the elements will generally increase the manufacturing complexity and cost. It is recognized, too, that the exact angles for the tapered surfaces where the liquid-tight seal is formed may vary, but the relatively shallow angle (less than about 20 degrees) is generally more effective in producing a liquid-tight seal than a larger angle (greater than 20 degrees).

In the preferred embodiment, the ends of the snap caps away from the reaction chamber are in the form of female luer-type fittings for insertion of flexible liquid lines, but the snap caps need not be limited to fittings of this type. There are many other changes that could be made without departing from the spirit and scope of the invention.

Claims

What is claimed is:

1. A reaction column comprising: a body having a passage therethrough and a first snap means near each end of said body; two filter elements spaced apart in said passage providing a reaction chamber therebetween; and two snap caps connecting to said body, one at each end of said passage, said snap caps for attaching tubings to said reaction column, each of said snap caps having a second snap means for engaging said first snap means on said body.

2. A reaction column as in claim 1 comprising a first sealing surface near each end of said body and a second sealing surface on each of said snap caps, such that with said first and said second snap means engaged said first and said second sealing surfaces are urged together forming a liquid-tight seal > between each said snap cap and said body, said liquid-tight seal being independent of said filter elements.

3. A reaction column as in claim 2 wherein said first sealing surface comprises a tapered nipple substantially concentric with said passage through said body and wherein said second sealing surface comprises a tapered bore of about the same taper angle as said tapered nipple.

4. A reaction column as in claim 1 wherein said first snap means comprises a first ridge adjacent to a first groove and said second snap means comprises a second ridge adjacent to a second groove, such that at engagement, said first ridge snaps into said second groove and said second ridge snaps into said first groove.

5. A reaction column as in claim 1 wherein each of said snap caps comprises a female luer-type fitting at the end opposite the end connecting to said body, said luer-type fitting for attaching tubing to said reaction column.

6. A reaction column as in claim 1 wherein said body has a bore ending in a shoulder from each side, such that one of said filter elements fits in each said bore against said shoulder, and an end of said snap cap on each side presses against said filter element, holding said filter element in place when said first and said second snap means are engaged.

7. A reaction column as in claim 1 wherein said snap caps and said body arranged so that said column is bidirectional.