DE2201654A1 - Multiple micropipette - Google Patents

Description

14.1.1:; / ^

Patent attorney Dipl.-Ing.H. Strohschänk

8 Munich 60 Musäusstrafi 5

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AGA AKTIEBOLAG
Lidingö / Sweden

Multiple micropipette

The present invention relates to an arrangement for pipetting several preferably very small sample quantities from a vessel and transferring the same after measuring each separately together with reagent liquid in separate test tubes or the like.

Within various areas of science there is a need, a variety of analyzes with import, export Probeflüeeigkeit same, although you only have access to a very small sample quantity. It is necessary to have a large number of identical or different sizes, very small but extremely precisely defined , with the lowest possible losses

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• To remove and measure the volume of liquid. For example In infant care, there are often only extremely small amounts of serum available, for example approx. 1 ml, which must be sufficient for 20-30 analyzes.

Other analyzes are carried out in very large numbers, for example 10,000 / day. You are here for cost reasons interested in keeping the amount of sample liquid and reagent required for each individual sample as small as possible keep. This also requires very small but extremely precise liquid volumes. The same applies to radioactive ones Samples where you want to keep the sample amount and thereby the radioactivity low. Furthermore, one is interested in limit the time required to take, measure and transfer each individual sample.

It has already been proposed to form a Vierwegenc.hn a round disc provided with channels opening onto two pitch circles, the one between two also round disks provided with channels lying on the pitch circles mentioned (Swedish Auslegeschrift 339 624). By turning the middle disk, the channels are alternately connected to one another according to a certain system brought to measure sample liquid in a pipette and reagent liquid in a measuring burette and the sample liquid by rinsing the reagent liquid into a vessel.

With this type of pipetting, as well as with conventional pipetting, in particular small amounts, these can be made from different Reasons fluctuate. The accuracy depends on the one hand on the design and quality of the pipette and on the other hand also how the pipette is operated. Furthermore, hoses, couplings and tubes etc. of the pipetting device each cause errors to arise. However, it is in first and foremost the suction tube corresponding to the pipette tip, that can be the cause of the largest volume measurement errors.

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In the case of the smallest measurement volumes, which are becoming more and more common, i.e. for example 5 to 15 μΙ », the generated errors can be downright catastrophic and make up a few tenths of the total amount. A drop at the end of one Einsaaughröhrehens, which is designed inappropriately, can fluctuate between 0 and 5 μΐ. Even if you have all the tricks has taken to eliminate this source of error, there is still a source of error in the small "lens" that is attached to the The suction end of the tube is seated and can vary between convex and concave. This fluctuation alone can be up to 1 μΐ turn off.

The above-mentioned known device is therefore not suitable for reliably measuring small volumes within the μΙ ranges can be used.

Furthermore, it has already been proposed to use a channel located between two plug valves as a measuring volume during pipetting and to use exact measuring of a certain amount of liquid. This sample amount is obtained by inserting an or several fixed duct pieces adjustable between the two plug valves.

This known device leads to a substantial improvement in terms of accuracy. However, it still has certain disadvantages which the present invention is intended to overcome. Thus, for example, for each individual sample taking a relatively large amount of sample liquid in relation to the sample volume is lost, which is passed unused into a drain. Furthermore, only one sample can be taken at a time, which is why the known device works relatively slowly. Also can with vigorous sucking any air zv / een valve housing and valve bodies are sucked and reach the measuring channel, thereby influencing drs Llessergebnis. In the event of a leak between the valve body and valve housing, freezing liquid or reagent liquid can also escape from the arrangement and contaminate the same.

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-A-

According to the present invention, this is done using a multiple micropipette eliminated in the form of several valve plates arranged next to or on top of one another, the alternately stationary or are rotatable about the longitudinal axis of the valve plate stack. Each individual valve plate has a measuring channel known measurement volume. The measuring channels of the various valve plates can be the same or different from one another have large volume. In addition, each valve plate is provided with an inlet and an outlet connection, each of which via channels provided in said valve plate in or out of connection with certain rotational positions of the valve plate can be brought with the associated measuring channels of the adjacent valve plate. Furthermore, the measuring channels all valve plates are brought into connection with one another in a different rotational position. In the latter position all quantities to be measured are sucked in simultaneously through one and the same pipette suction tube, with the Flushing out the valve passages only about the same amount of liquid is consumed as in the aforementioned known arrangement for sampling a single sample, which means that sample liquid is saved by the device according to the invention will. You also save time, as all volumes are sucked in practically at the same time. After changing the rotatable valve plates with respect to the stationary valve plates provided, the different samples are each for itself from the corresponding valve plates into separate reaction vessels with a predetermined amount of reagent liquid each rinsed out with an associated reagent pipette.

The concentration of sample and reagent liquid is then very constant within a sample series, since they - if the device is designed correctly - only depends on the size of the drop of reagent liquid that is released after each Pipetting and rinsing remain attached to the reagent pipette, but only an extremely small percentage of the total Represents amount of reagent. The sample amount that is in this drop

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Reagent liquid is contained can rightly be regarded as completely neglected.

The amount of sample remaining in the sampling tube with the associated hose can either be there until the next sample is taken remain or pressed back into the sample liquid container without the risk of contamination and, if necessary, again be used.

If you want to save sample liquid, you can rinse the suction tube inside and outside and blow dry with air, before the next sample is sucked in, the contamination also decreasing at the same time. This can of course ' can also be reduced by sucking in larger sample quantities, if such are available.

The valve plate can also be provided with two or more measuring channels and associated reagent channels. A additional channel with negative pressure, which runs through all valve plates, can be useful to between these to keep it clean and to compensate for the negative pressure in the sample measuring channel while the sample liquid is being sucked into the same. The top valve plate can serve as a valve for a sample suction pump, which therefore does not require a separate valve. The lowermost valve plate can be used as a valve both for pushing back sample into the sample aspiration tube as well as can be used for rinsing and ventilating the same.

Further characteristics of the invention as well as further developments thereof emerge from the patent claims and the following description of an exemplary embodiment of the invention with reference to the accompanying drawings. Show in a schematic way
1 shows a longitudinal section through a multiple micropipette according to the invention in the suction position,

2 shows a corresponding partial section on a larger scale, in the lower part in the suction position and in the upper part in the emptying position and
Fig. 3 is a perspective view of two normally adjacent, but here pulled apart

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Valve plates of a multiple micropipette according to the invention.

The sample liquid P from which samples are taken is located in a test tube 1 according to FIG. 1. The aspiration tube 2 of the multiple micropipette is connected to the The lower opening is placed in the test tube and immersed below the surface of the sample liquid. The suction tube 2 is attached to the lower end disk 3 of a stack of valve disks 4 and 5 arranged one above the other. Of the The stack is closed at the top by an upper end plate 6. The end disk 3 and 6 and valve disks 5 are stationary, while the valve disks 4 have a common axis of rotation are connected, which is actuated by a rotating mechanism 8, not shown in detail.

In the lower end plate 3, a suction channel 9 is provided, which with the suction tube 2 of the pipette through the measuring channel 10 of the valve disk 4 lying above the end disk 3 can be connected. This measuring channel 10 is to a certain extent Rotary position with the measuring channels 10 of the remaining valve disks 4, 5 and with a suction connection 11 of the upper end disk 6 tied together. A suction pump, not shown in detail, is connected to said suction connection 11, for example in FIG In the form of a piston pump that draws in a predeterminable, adjustable volume with each piston stroke, which is slightly larger than the total volume of all measuring channels 10 of the intake channel 9 and the Suction tube 2 is. This ensures that the sampling takes place with very little loss. At the Sucking in the sample liquid, the first part of the sucked-in liquid column rinses the suction tube 2, the suction channel 9 and the measuring channels 10, reaches the suction connection 11 and is diverted from there.

An example embodiment of the valve disks is shown in more detail in FIG. 3, in which a stationary and a rotatable valve disc is shown. It is of course not necessary that the valve disk referred to as "stationary" really stands still, but what matters is that the valve disks 4 and 5 are rotatable in relation to one another.

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Each .Ventilscheibe 4, 5 is according to the drawing figures mentioned provided with a measuring channel 10. Of course, more than just one measuring channel can be used in each Valve disc are provided. Such measuring channels can functionally be arranged in parallel or in series. With a parallel arrangement of the three measuring channels, for example, in each individual Y-valve disk, three different Sample liquids with one and the same according to the invention As many samples can be aspirated simultaneously with multiple micropipettes as with three multiple micropipettes with the corresponding Number of valve slices but only one measuring channel in each valve slice. With functional series connection of the measuring channels can take three times as many samples with a multiple micropipette per sample than with a multiple micropipette with only can be taken from one measuring channel per valve slice. In the latter case one also achieves the advantage that the Beginning of the sucked-in liquid column to rinse out all Measurement and suction channels are used, which results in very good economic efficiency, which is the lowest possible Losses concerns.

In addition to the measuring channels, the valve disks 4 and 5 are each provided with two angled channels 12 and 13. The part of these channels running parallel to the longitudinal axis of the valve disk also opens out at the end faces of the valve disks the same peripheral distance from the center as the measuring channel 10. The radially extending part of said angled Channels open out on the circumference of the valve disc, where suitable connection devices are provided. The lower angled Channel is denoted by 13 and for supplying a measured amount of reagent from a reagent burette, not shown, or the like. intended for the valve disc below. The upper with 12 designated angled channel is for emptying the Measuring channel, 10 of the valve disk located above, and for rinsing it out with reagent liquid, which via the connection 13 is supplied. In the drawing this is indicated by an arrow pointing inwards and R (= reagent) or

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with an arrow pointing outwards and the name P + R (=. Sample and reagent) denotes. The upper end disk 6 shows such a channel 13 and the lower end disk such a channel 12.

From Fig. 3 there is also a modification of the embodiment of the measuring channel 10. In addition to the possibility of setting the volume of the measuring channel by selecting the channel diameter accordingly to determine, its length can also be selected differently. This option is available for practical reasons with a straight measuring channel however limited. In addition, once the volume has been selected, it can no longer be changed, apart from the fact that it is a matter of course can drill out the canal. According to a further development of the invention, which in the upper valve disk in 3, it is therefore proposed to attach the measuring channel 10 partially outside the valve disk. The measuring channel 10 is divided into two sub-channels 102 and 103, which extend outward from the end faces of the valve disk lead on their circumference and are connected to one another outside the valve disc. This can be done either through a permanent Connection take place, whereby one can achieve larger measurement volumes than the dimensions of the valve disc otherwise allow were, or by exchangeable connecting parts 101, whereby one achieves the further advantage that the left volume of the measuring channel can be changed in a simple manner and thus adapted to various current needs. It is also possible in this way to have partial channels of different valve disks with one another or with fixedly arranged ones To connect measuring volumes or arrangements of any kind. In the exemplary embodiment according to FIG. 3, the measuring channels 102 are and 103 provided with small connecting tubes on the circumference of the valve disk 5. On top of these tubes is a piece of tubing 101 made of plastic or rubber pushed on as a connecting part. The hose piece can easily be compared to another with a larger one or shorter. Instead of a piece of tubing, other IJoss volumes can also be connected will. The entire measurement volume consists of the duct parts

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102 and 103 and the partial volumes of any connecting tubes so / ie the partial volume of the connecting part in the assembled State.

The above-described versions of the measuring channels can be used with one or more valve disks and with both stationary ones as well as rotatable valve disks are used.

When aspirating and measuring samples, the disks 4 and 5 are in the mutual position indicated in FIGS. 1 and 3, wherein the measuring channels 10 or their mouths each lie in their extensions. The turning of the rotatable valve discs 4 takes place by the axis of rotation actuated by the rotating mechanism 8 7 - in the present Pig. 3 with a triangular cross-section ■ engages in the central opening 14 of the rotatable valve disks, the cross section corresponding to the cross section of the axis of rotation have, while the axis of rotation runs freely through the somewhat larger central opening 21 of the stationary valve disc 5. The stationary valve disks 5 and, in the present case, the lower and upper end disk 3, 6 are with each other by means of a connecting rail 16, which is also connected to the stationary housing of the rotating mechanism 8, and screws 15 connected. The disk stack 3-6 is compressed by a spring 20.

Another further development of the invention is shown in FIG. The valve discs are on one side in the Area of the mouth of the channels 10, 12 and 13 on the end faces provided with an annular elevation 17 which surrounds the central opening 14 and 21, respectively. That way you achieve better ones Tightness between the valve disks because the contact surface between the valve disks is smaller. See also Fig. 3 This annular elevation 17 is only a few tenths of a millimeter high, so that there is a very narrow space between forms the remaining parts of the valve disks. As shown in Fig. 2 and 3, at the foot of this elevation 17 can be all around extending channel 18 are provided. The grooves 18 of the various valve disks are connected to each other by a Negative pressure channel 19 connected to the upper or lower

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The end plate is guided outwards in the radial direction and is connected to a suction pump (not shown). File the vacuum channel 19 can also be offset by about half a turn from valve disk to valve disk. With this device, it is achieved in an advantageous manner that the negative pressure that occurs when the sample is sucked into the measuring channels cannot lead to air being sucked into the measuring channels. This is achieved partly by the smaller contact surface between the valve disks and the resulting improved density and partly by the fact that the elevations are surrounded by the channel 18 and thus by a negative pressure which can compensate or possibly even outweigh the suction negative pressure in the measuring channels. At the same time, one achieves the advantageous effect that any liquid leaking between the valve disks does not run down the outside of the valve disks and contaminates the device, but that any leakage fluid enters the vacuum channel 19 via the channels 10 and is sucked off by it.

The operation of the device is as follows:.. In the embodiment shown in Figure 1 as well as the lower part of Figure 2 position the sample P is calculated from the test tube 1 through the suction tube 2, the suction channel, the measuring channel 10 and the suction port 9j sucked up, after which the rotatable valve discs 4 can be rotated into the emptying and flushing position shown above in FIG. 2. \ Each measuring channel 10 is connected to the angled channels 12 and 13 of the adjacent valve disks. A predetermined amount of reagent R is fed from a measuring burette through the channel 13 and the sample amount 10 pipetted in the measuring channel 10 is thus rinsed out via the channel 12. This amount of sample leaves the measuring channel 10 and the channel 12 first and is passed into a test tube indicated in FIG. 2, for example. After the sample P, the reagent quantity R follows, which at the same time flushes out the measuring channel 10, the channel 12, etc. Possibly this can be followed by blowing out with air or gas , which results in a fairly complete emptying. Since the reed

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volume is chosen to be significantly larger than the measurement volume, korn, the sample amount that was in the last emptying drop (P η- Ε) included is negligibly low εη / resehen r.orden.

After emptying, the multiple micropipette according to the invention is there immediately for a new sample with the same test flow rate ready. When taking the second sample with the same sample liquid, there may be less liquid to rinse out of the ducts required and the suction can be down to one Height of only a few cm above the uppermost measuring channel 10 can be limited.

Should a new sample liquid be used the next time the sample is taken are used, the multiple micropipette can first be brought into the suction position and blown out through the connection 11 are, whereby in the suction channel 9 and suction tube 2 existing liquid is returned to the test tube 1 before the same is removed and replaced with the new test tube will. This achieves an extremely good economic efficiency, as regards the use of the sample liquid, which is particularly important when there is only a very limited sample quantity be available. The sample returned from the suction tube and suction channel does not lead to any contamination of the sample in the test tube 1, since no reagent liquid can get into the suction channel 9 or the suction tube 2.

The uppermost valve disc can also serve as a kind of valve for the pump that feeds the samples into the Mehrfachliikropipette soaks in. There is therefore no need for an additional valve for this pump.

Although the invention has been described in connection with an embodiment thereof, it can nonetheless be arbitrary be modified within the scope of the following claims.

- patent claims -

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Claims (12)

Claims . 1 J multiple micropipette with aspiration tube and measuring section and with a suction device that can be connected to the measuring part, characterized in that that the measuring part is made up of several valve disks (4, 5) is arranged next to or on top of one another and each with at least one measuring channel (10) with a known volume, an inlet connection (13) for reagent or rinsing liquid (R) and an outlet connection (12) for emptying aspirated Sample liquid and associated reagent or rinsing liquid (P + R) are equipped that the measuring part through end plates with suction channels instead of measuring channels and with an inlet or outlet connection (12 or 13) is limited that every second valve slice in proportion is rotatable about a common longitudinal axis to the adjacent valve disks or end disks, whereby the mouths of the measuring channels (10) in the contact plane between adjacent valve disks in or out of connection with one of the Connections (12, 13) of each adjacent valve disk or end disk can be brought. 2. Multiple micropipette according to claim 1, characterized characterized in that the end disks (3, 6) and every second valve disk (5) are stationary, while the others Valve disks (4) are rotatable. 3. Multiple micropipette according to claim 1 or 2, characterized in that every second Valve disc (4) has a central opening (14) with preferably the same cross section as an axis of rotation (7), which through a rotating mechanism (8) can be actuated. 209832/1053 4 · multiple micropipette according to claim 1, 2 or 3 _5, characterized in that every second valve disc (5) by a screw (15) or the like. is connected to a connecting rail (16) and has a central opening (21) with a larger cross-section than the axis of rotation (7). 5 · Multiple micropipette according to one or more of the preceding claims, characterized in that the valve discs (4, 5) at least on one End face a circular increase (17) with a ■ Has inner radius that is smaller and with an outer radius that is greater than the smallest or largest distance between the Openings of the channels (10, 12, 13) on the face mentioned and the center line of the associated valve disc. 6. Multiple micropipette according to claim 5, characterized characterized in that the elevation (17) is surrounded by a channel (18) which is passed through a negative pressure channel (19) is connected to a vacuum source. 7. Multiple micropipette according to one or more of the preceding claims, characterized in that that the measuring channel to at least one individual valve disc (4, 5) two from the end faces of the valve disc the circumference of which comprises guided channel parts (102, 103), as well as that these channel parts with one another outside the valve disc (4, 5) are connected or connectable. 8. Multiple micropipette according to claim 7, characterized in that the channel parts (102, 103) are connected by an interchangeable connector (101) of known volume. 209832/1053 9 · Multiple micropipette according to one or more of the preceding claims, characterized in that that in each valve disc several measuring channels (10, 10 ') and a corresponding number of inlet and outlet channels (12, 13) are arranged. 10. Multiple micropipette according to claim 9> thereby marked that the measuring channels are functional can be coupled in parallel. 11. Multiple micropipette according to claim 9, characterized in that the measuring channels functionally can be coupled in series. 12. Multiple micropipette according to one or more of the The above claims, characterized in that a piston pump is provided for sucking in sample liquid whose suction volume per piston stroke is related to the total volume of the measuring channels (10), the suction channel (9) and the suction tube (2) plus an additional, freely selectable volume for rinsing. 209832/1053 Blank page