EP0960326A1

EP0960326A1 - Individual septum capped microtube and method

Info

Publication number: EP0960326A1
Application number: EP98900612A
Authority: EP
Inventors: Graham Clough
Original assignee: RTS Thurnall PLC
Current assignee: RTS Thurnall PLC
Priority date: 1997-02-15
Filing date: 1998-01-15
Publication date: 1999-12-01
Also published as: WO1998036260A1; GB9703185D0

Abstract

A method of preparing a sample including providing a microtube (1), closing the microtube (1) with a self-sealing septum cap (2) and injecting a liquid sample through the septum cap using a hollow needle. The method may be performed using automated or robotic laboratory equipment.

Description

INDIVIDUAL SEPTUM CAPPED MICROTUBE AND METHOD

The present invention relates to the preparation and storage of

compounds and particularly although not exclusively to the preparation and

storage of solubilised compounds used in the pharmaceutical and agrochemical

industries.

Research into new pharmaceuticals, often termed "drug discovery " ,

involves the preparation, storage and analysis of large numbers of compounds .

The compounds may also be mixed and matched in an attempt to identify

pharmacologically active compounds. This so called high throughput screening

is carried out as far as is practicable using robotic equipment.

In an existing arrangement compounds under test are stored in

microtubes which, in turn, are mounted in blocks. One current industry

standard block has a footprint of 1 27.5mm by 85.5 mm and accommodates 96

microtubes on a 9mm pitch. It is desirable to make microtubes as small as

possible. This increases the number of different compounds that can be tested

and enables less solvent to be used per microtube which leads to a significant

cost saving.

Microtubes may either be stored open ended or sealed. At present

microtubes are sealed using plastic mats or strips of joined plastic caps that can

be pressed into the open end of microtubes. The existing method of sealing microtubes has a number of disadvantages. To allow for the individual handling of microtubes it is

necessary for the mat or strip of caps to be cut, this is inconvenient. Also,

when a mat is removed to allow access to the microtubes a new mat must be

used when it is desired to re-seal these tubes. Again, this is inconvenient and

also leads to increased costs. Further, by far the greatest disadvantage with

existing methods of microtube sealing and handling is that the contents of a

sealed microtube cannot be accessed without some manual intervention . The

contents of a sealed microtube cannot be accessed without removal of the cap

and the cap cannot be removed and replaced using automated laboratory

equipment. Cap removal and replacement must therefore be carried out by

laboratory staff. This method is tedious, costly in terms of labour, and

increases the possibility of error.

It is an object of the present invention to provide an alternative method

of preparing compound samples in microtubes and an alternative sealing

arrangement which addresses and overcomes or at least mitigates some or all

of the abovementioned problems.

According to a first aspect of the present invention there is provided a

method of preparing a sample comprising the steps of:-

providing a microtube having an opening therein; providing a self sealing pierceable closure for said microtube;

inserting said closure member into the opening of said microtube to seal the microtube;

inserting a hollow needle through said closure into said microtube;

injecting a liquid into said microtube through said hollow needle;

withdrawing said hollow needle from said closure member, to allow said

closure member to seal said microtube.

The microtube is preferably a standard microtube suitable for handling

with automated laboratory equipment.

The above method is particularly suited for the preparation of a liquid

sample for storage under environmentally controlled conditions for example

under freezing conditions or stored under an inert gas.

The closure may be fitted to the microtube manually, or preferably by

using automated equipment possibly including robotic equipment. The closure

preferably comprises a septum cap, insertable at the open end of the microtube.

The cap is preferably produced from a self-sealing material which is pierceable

by a hollow needle and on withdrawal of the needle re-seals the microtube. The closure preferably provides a sufficient seal after being pierced at least 50 and

more preferably at least 1 00 times. The closure may be produced from a

silicone based material.

The closure preferably provides sufficient integrity for the long term

storage of compounds even after repeated access has been made to the

contents of the microtube through the closure.

The liquid sample may be a solution, the solvent of which may comprise

DMSO (Dimethyl Sulfoxide).

The hollow needle preferably includes two unconnected conduits for fluid,

to allow a liquid to be injected into or withdrawn from the microtube and for the

air or gas inside the microtube displaced by the liquid to escape through the

needle or likewise to allow air or gas to flow into the microtube to fill space

vacated by a liquid. The needle is preferably of coaxial construction .

Alternatively the closure member may be pierced by more than one

hollow needle simultaneously, to achieve a similar effect.

The method of preparing a sample may include the further step of

injecting an inert gas into the microtube to enable a sample to be prepared and

stored under an inert gas. Typically a liquid sample would be injected into the

microtube, the air in the microtube being displaced through the second conduit through the coaxial needle. When the desired amount of liquid has been injected then a quantity of inert gas is injected into the liquid sample to displace

any remaining air. The needle may then be withdrawn leaving a sample stored

under an inert gas. Alternatively an inert gas may be injected before the liquid

sample.

The microtube is preferably stored in a block. Preferably the method

involves the simultaneous preparation of a plurality of samples.

The method preferably includes the further step of marking the microtube

to identify the sample. The marking is preferably machine readable and is

usefully in the form of a two-dimensional dot code, applied to the microtube

using an ink type jet print head.

The method may also include the step of using a hollow needle to remove

a liquid sample from a microtube. Where a sample is stored under an inert gas

and a quantity of the sample is removed from the microtube, it is preferable that

additional inert gas is injected into the microtube to fill the space vacated by the

liquid sample.

The method of the present invention is particularly suitable for use with

automated stores, and for the preparation of samples for storage in automated

stores, possibly under refrigerated conditions. In one embodiment the method includes additional steps for the

preparation of a liquid for injection into the microtube, including any or all of the

following steps:-

i) placing a dry compound into a vial;

ii) placing a solvent into said vial;

iii) closing said vial using a pierceable closure;

iv) agitating said vial to aid dissolution of the dry compound;

v) passing a hollow needle through said closure into the vial and extracting

the liquid therein through said needle.

The solvent preferably comprises DMSO (Dimethyl Sulfoxide) .

The vial is preferably of greater internal volume than a microtube.

The liquid prepared in the vial may then be injected into microtubes.

The pierceable closure member preferably comprises a septum cap.

Providing a sample in a microtube with a septum cap, by the above method coveys numerous advantages. Particularly, the operation of filling the

microtube with a sample and subsequently removing the sample may be carried

out using automated laboratory equipment, precluding the need for the tedious

manual removal and replacement of caps and associated waste produced when

gaining access to the contents of existing microtube arrangements. Also, as the

septum caps are separate, each microtube remains individually removable from

the block.

Large numbers of microtubes may be conveniently prefilled with suitable

reagents for subsequent experimentation and analysis. The tubes may be

prepared using automated equipment, reducing the cost of labour associated

with existing methods. The filling of microtubes using hollow needles enables

smaller microtubes to be employed, again reducing costs.

According to a second aspect of the present invention there is provided

a microtube assembly comprising a microtube and a self-sealing pierceable

closure for use in the above described method of providing a sample.

The microtube is preferably a conventional microtube and may, for

example, be constructed from glass or a plastics material.

The closure is preferably inserted into the open end of the microtube.

The assembly enables a microtube to be filled with a desired liquid compound using automated laboratory equipment, preferably by the use of a coaxial hollow needle. Subsequently various analysis and mixing of the

samples may also be performed by automated laboratory equipment, gaining

access to the contents of the microtubes through the closure.

In order that the invention may be more clearly understood there are now

described embodiments thereof, by way of example and with reference to the

accompanying drawings in which:-

Figure 1 shows an exploded view of one embodiment of a microtube and

closure;

Figure 2 shows a side elevation of the microtube and closure illustrated

in Figure 1 in exploded form;

Figure 3 shows a side elevation of the microtube of Figure 2 with the

closure inserted;

Figure 4 shows an exploded perspective view of a second embodiment

of a microtube and closure;

Figure 5 shows a side elevation of the microtube and closure of Figure 4;

Figure 6 shows an elevational view of the microtube and closure of Figure 5 with the closure partially inserted into the microtube;

Figure 7 shows the microtube and closure of Figure 6 with the closure

fully inserted into the microtube and the skirt rolled over the top of the

microtube;

Figure 8 shows a perspective view of a partially filled block of

microtubes; and

Figure 9 shows a cross-sectional view of a partially filled microtube of the

embodiment illustrated in Figures 1 to 7.

Referring to Figures 1 to 3 there is shown a standard microtube 1 . The

microtube 1 is formed from a plastics material, resistant to the compounds to

be stored therein, for example the solvent DMSO (Dimethyl Sulfoxide) .

A septum bung or cap 2 having a substantially cylindrical portion 3 and

radially projecting shoulder 5 is also provided. The bung 2 is produced from a

silicone based material arranged to re-seal itself following being pierced with a

needle. The material is resilient and the bung 2 is of appropriate dimensions to

effect an interference fit with the microtube 1 , when inserted as shown in

Figure 3. A two dimensional machine readable dot code 4 is printed onto the

side of the microtube 1 . Referring to Figures 4 to 7 there is shown an alternative microtube 6 and

bung 7. The microtube 6 is formed from a plastics material and includes a

shoulder 8. The open end of the tube is of reduced external diameter compared

to the rest of tube. The bung 7 is produced from a silicone based material

arranged to re-seal itself following being pierced with a needle. The bung 7 includes a cylindrical portion 9 and an integrally formed flexible skirt portion 10.

In use, the bung 7 is inserted into the microtube 6 and the skirt 10 rolled over

the top of the microtube 6, to provide an enhanced seal. When the skirt 10 is

rolled down the lower edge of the skirt is arranged to lie substantially adjacent

the shoulder 8, as shown in Figure 7.

In both the embodiments illustrated in Figures 1 to 7 the bung serves to

protect the contents of the microtube, particularly from atmospheric

contamination, whilst allowing access to the contents of the microtube by way

of a hollow needle and preferably a coaxial hollow needle to enable the passage

of air or some other gas in or out of the microtube in response to the addition

or extraction of liquid.

Microtubes with pierceable septum bungs are particularly suited to use

with automated laboratory equipment. Referring to Figure 8 microtubes 1 1

with septum bungs 1 2 may be stored in blocks 1 3 for ease of handling in bulk.

For example, for use in high throughput screening. The microtubes are stored

with the bung 1 2 uppermost to facilitate the use of automated laboratory

equipment. The provision of a microtube with a pierceable bung enables the convenient preparation of a large number of samples using automated

equipment. First, the bung 1 2 is inserted into the microtube 1 1 , this may be

done manually or by machine. Then, the microtube 10 with bung 1 2 is placed

into a block 13 along with other microtubes. The microtubes may then be filled

with a desired compound by the use of a hollow needle, preferably a coaxial

needle. The use of a coaxial needle allows air or an inert gas to flow in and out of the microtube in response to the injection or withdrawal of a liquid. This

enables a sample to be prepared under an inert gas. A coaxial needle comprises

an inner and outer hollow needle. The inner needle extends further than the

outer needle so that the inner needle may be extended into a liquid sample

whilst the end of the outer needle remains above the liquid level to enable air

or gas to flow into the region between the inner and outer needles.

Referring to Figure 9 there is shown a cross-section of a microtube 1 4

with a bung 1 5 inserted therein. A hollow coaxial needle 1 6 is shown inserted

through the bung 1 5. A liquid 1 7 has been injected into the microtube through

the needle 1 6. After injection the needle 1 6 may be withdrawn from the bung

1 5 which will then seal the microtube 1 4, protecting its contents 1 7 from, inter

alia, atmospheric contamination.

Subsequent extraction or addition of further liquids or reagents may be

effected by the insertion of further needles through the bung 1 5. The bung is

able to withstand at least 100 piercings before losing its sealing integrity. Liquid for injection into a microtube may be prepared in a vial, of larger

volume than a microtube, also having a septum bung. The required solid

product is placed in the vial along with a solvent and the bung inserted. Alternatively, the solvent may be injected through the bung. The vial is then

agitated to assist dissolution of the solid. The prepared solution is then

withdrawn from the vial by way of a hollow needle and may then be injected

into one or more microtubes.

Microtubes fitted with septum bungs allow liquid products to be

conveniently injected and extracted using hollow needles, possibly by

automated equipment. This leads to savings in labour costs and great sample

containing integrity than with prior art microtubes sealed with conventional caps

or mats.

The above embodiments are described by way of example only, variations

are possible without departing from the invention.

Claims

1 . A method of preparing a sample comprising the steps of:-

providing a microtube having an opening therein;

providing a self sealing pierceable closure for said microtube;

inserting said closure member into the opening of said microtube to seal

the microtube;

inserting a hollow needle through said closure into said microtube;

injecting a liquid into said microtube through said hollow needle;

withdrawing said hollow needle from said closure member, to allow said

closure member to seal said microtube.

2. A method as claimed in claim 1 , wherein said closure comprises a septum

cap.

3. A method as claimed in either claim 1 or 2, wherein said closure member

comprises a silicone based material.

4. A method as claimed in any preceding claim, wherein said hollow needle

is a coaxial needle.

5. A method as claimed in any preceding claim further including the step of

marking the microtube to identify the sample.

6. A method as claimed in claim 5, wherein the microtube is marked with

a two dimensional dot code.

7. A method as claimed in any preceding claim, wherein the step of inserting

the hollow needle through the closure; injecting a liquid into the microtube and

withdrawing the hollow needle are carried out using automated laboratory

equipment.

8. A method as claimed in any preceding claim, wherein the step of inserting

said closure member into the opening of said microtube is carried out using

automated equipment.

9. A method as claimed in any preceding claim including the step of using

a hollow needle to withdraw a sample from the microtube.

10. A method as claimed in any preceding claim including the step of

injecting an inert gas into said microtube through said hollow needle.

1 1 . A microtube assembly comprising a microtube and a self-sealing

pierceable closure for use in the method of providing a sample as claimed in

claim 1 .

1 2. A microtube assembly as claimed in claim 1 1 , wherein said closure

member comprises a septum cap.

13. A microtube assembly as claimed in either claim 10 or 1 1 , wherein said

septum cap comprises a silicone based material.