Liquid purification or separation – With repair or assembling means
Reexamination Certificate
1999-11-24
2001-11-13
Reifsnyder, David A. (Department: 1723)
Liquid purification or separation
With repair or assembling means
C210S416100, C210S455000, C210S470000, C210S808000, C422S105000, C422S105000, C422S105000, C436S177000
Reexamination Certificate
active
06315902
ABSTRACT:
The invention relates to a device for selectively filtering liquid samples in compartments comprising inlet and outlet openings of a carrier body under reduced pressure and vacuum drying drops present in the area of the outlet openings of the compartments. Furthermore, the invention relates to the uses of the device in the purifying of biopolymers, especially nucleic acids.
In molecular biology, in the analysis of samples, carrier bodies called microtitration plates are used comprising a plurality of compartments arranged two-dimensionally in lines and rows. These compartments are provided with inlet openings towards the upper side of the carrier body and comprise outlet openings on the lower side of the carrier body. In the compartments, there are filter bodies in the shape of frits or membranes provided to bond the substances of the liquid samples to be analyzed.
The sample liquids to be analyzed are introduced into the individual compartments of a carrier body (microtitration plates), if required after being processed. By applying a low pressure to the outlet openings of the compartments, it is provided that the sample liquids flow through the filter bodies of the compartments. In this process, the components to be analyzed and other components of the sample liquid get caught in the filter bodies. In order to obtain the components of interest of the liquid sample, the components which are not required have to be washed out of the filter bodies. For this purpose, wash buffers of various concentrations are pipetted into the compartments. By means of these wash buffers, a part of the components not of interest of the sample liquids is released form the filter bodies. By means of an elution buffer, the component of interest of the sample liquids is then washed out of the filter bodies. The pipetting and the flowing process of the wash buffers, the elution buffer and the sample liquids occur in a pipetting machine, which is computer controlled. These pipetting machines are provided with a vacuum chamber comprising an opening whereon the carrier bodies are substantially gastightly fitted to draw out the sample liquids or the wash buffers through the filter body. A device of the type described above is described in DE-A-41 07 262. In the filtration under reduced pressure, it always occurs that remaining liquids stay on the outlet openings of the compartments in the form of drops. Before the step of elution takes place, it has to be provided that these liquid drops have been removed. For the quantities to be analyzed occasionally are rather small so that a mixture with remaining liquid can lead to faulty results. What is more, components of the sample liquid which are not to be analyzed are present in the liquid drops, thus also adulterating the result of the analysis. In prior art, the carrier bodies, respectively microtitration plates, are dropped several times on a support having an absorbent material so that the liquid drops are virtually shaken off. However, this process cannot be integrated in the case of an automatic process, as in the case of a pipetting machine.
It is the object of the present invention to provide a device by means of which remaining liquid drops on the outlet opening of the compartments of the carrier bodies can be removed automatically and without manual interaction after a filtration process under reduced pressure has taken place.
To achieve this object, the invention proposes a device for selectively filtering liquid samples in compartments comprising inlet and outlet openings of a carrier body under reduced pressure and drying drops of the sample liquid present in the area of the outlet openings of the compartments, the device comprising:
a chamber comprising an interior space limited by a top wall, a bottom wall and lateral walls connecting them,
the top wall comprising an opening with an opening edge whereon a closing lid or the carrier body can selectively be put in a substantially gastight manner by means of outlet openings directed towards the interior space of the chamber,
one of the lateral walls being formed as an access lateral wall which can be opened and closed substantially gastightly for introducing the carrier body into the interior space of the chamber, and
the bottom wall comprising a drain for liquid exiting from the outlet openings of the compartments of the carrier body, and
a vacuum pump with a suction conduit terminating in the interior space of the chamber for producing a first low pressure for drawing liquid samples through the outlet openings of the compartments with the carrier body being placed on the opening edge of the top wall and the access lateral wall of the chamber being closed and for producing a second low pressure higher than the first low pressure for drying drops of liquid samples still present on the outlet openings of the compartments with the carrier body being located in the interior space of the chamber and the lid being placed on the opening edge of the top wall as well as the access lateral wall of the chamber being closed.
The device according to the invention is provided with a low pressure chamber comprising a top wall, a bottom wall and lateral walls connecting them. One of the lateral walls is formed as an access lateral wall and can be opened and closed so that it is possible to introduce a compartment carrier body (subsequently called microtitration plate) via this lateral wall into the interior space of the chamber. Furthermore, the chamber comprises an opening in the top wall thereof being closable by means of a lid. As an alternative to the lid, a microtitration plate can also be placed onto the opening so that the chamber can then be used for filtering the sample liquid of the compartments under reduced pressure. The chamber comprises a drain in the bottom wall so that the flowing liquids can be drained.
The low pressure in the interior space of the chamber is produced by a vacuum pump connected to the interior space of the chamber by means of a suction conduit. By means of this vacuum pump, a first and a second low pressure can be produced alternatively in the interior space of the chamber. The first low pressure is required to draw in the sample liquid through the outlet opening of the compartments of the microtitration plate. Thus, the first low pressure is used for filtering under reduced pressure. The second low pressure higher than the first low pressure serves to dry sample liquid drops which might be adhering to the outlet openings of the microtitration plate at a vacuum. In the case of vacuum drying, the opening in the top wall of the chamber is closed by means of a lid, while the microtitration plate itself is located in the interior of the chamber. By lowering the pressure in the chamber, the evaporation point of the liquid drops is reduced, whereby they can be removed by evaporation.
By means of the device according to the invention, it is possible to use one and the same low pressure chamber both for filtering and for removing sample liquid drops. The manipulations to be executed on the chamber for this purpose, which are described above, can be put into practice without a problem by means of the gripping device of a pipetting machine so that manual interference is no longer necessary.
In an advantageous development of the invention, it is provided that the chamber comprises a support mounting for receiving the microtitration plate for putting it in the interior space of the chamber. Preferably, this support mounting is located on the interior side of the access lateral wall of the chamber directed towards the interior space, which wall is formed to be movable from the other walls of the chamber or towards them for this purpose. In this context, it is advantageous if the access lateral wall is provided with at least one cam element connected to the access lateral wall. The cam element can be moved by means of a driving device, whereby the access lateral wall is also moved. In this context, the cam element and the access lateral wall work in the manner of an automatic drawer which ca
Collasius Michael
Venschott Oliver-Guido
Birch & Stewart Kolasch & Birch, LLP
Qiagen GmbH
Reifsnyder David A.
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