FI70806C - FOERFARANDE OCH ANORDNING FOER UTSPAEDNING AV VAETSKEPROV - Google Patents

Description

70306

This invention relates to a method and apparatus for transferring or accurately diluting liquids. The invention is used e.g. in photometers and Muorometre ir.rä.

5 In the field of clinical chemistry, and in particular microbiology, there are many assays that require the processing of large numbers of samples. It is still very common for sample and reagent transfers to occur one at a time. However, devices have been developed (e.g., a multi-channel 10 Finnpipette '' -) that can transfer multiple samples or reagent doses simultaneously. Achieving sufficient speed and accuracy when transferring and diluting samples simultaneously remains a major challenge. Particularly in the pipetting of small volumes of microliters in the order of 15 liters, the accuracy is limited by the fact that the point of rupture of the liquid column when liquid removal or suction is interrupted cannot be accurately predicted, i.e. the size of the liquid tip at the tip of the pipette is random.

U.S. Pat. No. 2,980,512 discloses a flow-through colorimeter in which a sample is introduced down the tube into a seed and in which a portion of the sample flowing through the cuvette is returned to the inlet tube through a return tube which joins its wall. However, the instrument is not applicable to high-precision dilutions and transfers of individual samples.

It is an object of the present invention to provide an accurate, automatic dilution method and apparatus for liquid samples, especially small liquid samples.

The method of the present invention is characterized in that one or more downwardly opening side channels are used which join the downwardly opening main channel above this tip. The tips of the main and side tubes are. ^ nested so that the tip of the inner (i.e. side channel) tube is located higher than the tip of the outer (i.e. main channel-35 van) tube, i.e. when the outer tube contains liquid the tip of the inner tube is in question. in the liquid. j

The method according to the invention makes it possible to prepare several different dilutions of f I ', 7 O G O 6 c from the same sample in a rapid and precise sequence. When dosing 1 teaspoon according to the invention, a standard deviation of less than 1% is achieved.

The invention and its applications will be described in more detail: the following with reference to the accompanying drawings, in which Figure 1 is a flow diagram of a device according to the invention and Figure 2 shows a coaxial arrangement of main and side channel tubes at the tip of a liquid dispenser.

In the example presented here, a serial dilution is performed in which the main channel 1 contains water and the side channel 2 a sample. Depending on the required dilution ratios, the channels can be divided differently. The liquids used can also be chosen arbitrarily, often e.g. a reagent is used instead of water.

The operation is started by filling both channels 1 and 2 and their connecting channel 3 with water. This can be done either by pumping water with a hose pump U from the tank 5 or from the water vessel 6 with the guide bricks 7 and 8 simultaneously or alternately with the open 20 and the piston 9 in its extreme position down. A sample of the sample container 10 is then drawn into the side channel by closing valves 7 and 8 and pulling the piston 9 backwards. A larger amount of sample is aspirated than is required in the dilution series because the top of the aspirated sample is diluted due to water in the common portion of the chickens and adhering to the sidewall walls. When the piston 9 is stopped, the valve 7 is opened and water is pumped out so much that the common part of the channels becomes clean of the sample. In this case, the sample column breaks at the tip 11 of the side channel exactly and repeatedly. The diluted sample is delivered to the dilution vessel 12 as follows: valve 7 is kept open and valve 8 is closed. The hose pump 4 starts to pump water into the dilution vessel 12. Simultaneously or shortly thereafter, the piston 9 pushes the sample into the common part of the channels 35, from where it enters the dilution vessel 12 with the water, while mixing well. The desired dilution ratio is obtained by selecting the ratio of the bumping rates and / or the length of the pumping cycles as appropriate. The piston 9 is stopped, and when the common part of the channels has been cleaned again, the hose pump is also stopped. Immediately thereafter, the dilution tip can be moved above the new dilution stage 9 or the new dilution vessel below the dispensing tip and the new dilution can be performed at the same or different dilution ratio.

A particular advantage of the method according to the invention is the improvement of the dosing accuracy of the sample, because the solution of the sample column takes place in a tip which is surrounded on all sides by a liquid. This avoids the harmful tip phenomena, which are e.g. the unpredictable convexity or concavity of the sample surface inside the tip, the splashing of the sample on the outer surface of the tip and the consequent deficiency, and any mixing with any subsequent sample. The sample spilled on the outer surface of the tip surrounding the air can be removed by mechanical cleaning or liquid rinsing, but in this case it is not possible to accurately predict the amount of sample to be lost inside the tip during cleaning. 20 Also, if washing liquid has adhered to the outer surface of the tip during washing, this dilutes the sample locally from the very point where the sample is sucked into the tip after washing.

Because water and the sample are in contact with each other at the tip of the sample tube, diffusion of the sample occurs and vice versa. The effect of diffusion can be minimized by using fast and always equally long operating cycles. Mixing of the upper end of the sample (which was first sucked into the sample channel) and water can be prevented by sucking 30 air bubbles or a small amount of liquid between them that does not mix with or react with either the sample or water.

Another advantage of the method according to the invention is the good mixing result obtained when the sample and water are mixed in the common part of the channels and fall into the dilution vessel. This in many cases makes a separate mixing step unnecessary.

70806

The method of the invention also allows the use of a concentrated reagent, whereby the reagent is taken into the sample channel and diluted as appropriate in the run-out step, to different cuvettes, either by the same or with a gentle dilution.

5 The method also allows the use of two reagents which can only be mixed immediately before use by taking one into the main channel and the other into the side channel.

Claims (7)

A method for diluting a liquid sample, characterized in that the main channel (1) open downwards from the lower tip (13) is filled with the diluent, the side channel (2) is filled with the sample, the lower tip (11) of which opens downwards into the main channel above its lower tip, then pumped diluent from the main channel and at the same time a sample from the side channel. 2. A method according to claim 1, which comprises a -10 method, in which case the medium is used via a specific genome of the pump (4). A method according to claim 1, characterized in that the main channel is filled with a diluent through the lower tip by a suction pump (¾). 3 · For the purposes of patent claim 1, the invention includes an entertainment channel for the genome 15 pump (4) utilizing the entertainment channel. A method according to claim 1, characterized in that the main channel is filled by pumping (4) a diluent through the main channel. A method according to claim 1, characterized in that at the same time as filling the main channel with diluent, the lower part of the side channel is also filled with diluent up to the pump (9) therein by passing the diluent through the connection channel 20 (3) between the main channel and the side channel. the valve (7) above and the valve (8) in the connecting duct and sucking the sample into the side duct by means of said pump therein. 4. A patent according to claim 1, which comprises a passageway for the use of a feeder, the feedstock for which the feedstock has been used as an alternative to the pump (9), the genome of which has been used. 3) in the case of an air duct and a duct, the air ducts and the duct can be connected to a duct valve (7) and in the duct air duct (8) 5. A patent according to claim 4, comprising a combination of a spatula and a spatula, in which a spatula or a spatula is provided, in which case a spatula or a reactor is used. A method according to claim 4, characterized in that when the side channel is filled with a diluent, a gas or liquid bubble is sucked into the side channel which does not mix with or react with the sample or diluent. 6. Arrangements for the transfer of a special offer, which are not included in the special channels (; 13 * are available in the entertainment channel (1) and in the communication channel (2), the special offer (11) are included in the special channels (35) nedre spets. Apparatus for diluting liquid samples, characterized by a main channel (1) open downwards from its lower end (13) and a side channel (2), the lower tip (11) of which opens downwards into the main channel above its lower tip. Apparatus according to claim 6, characterized by a connecting channel (3) connecting the main channel and the side channel, having a valve (8), and a valve (7) in the main channel. 70806 c Apparatus according to claim 6 or 7, characterized by a piston (9) in the side channel, the lower sound position of which is at the same point where the connecting channel joins the side channel. An apparatus according to any one of claims 6 to 8, characterized by a downwardly tapering truncated cone-shaped lower channel tip (13). Apparatus according to one of Claims 6 to 9, characterized by a cylindrical second side channel lower tip (11). 70806 Patent claim 1 »For use in the manufacture of materials, including the manufacture of air filters (13), and for the manufacture of air conditioners (1), for the manufacture of air conditioners (2), Väre nedre spete (11) öppnar sig ned & t i huvudkanalen ovan-för dess nedre spete, varefter lösningsmedlet pumpas frän huvudkanalen och provet veltidigt frän sidokanalen .. 7 · Anordning enligt patentkrav 6, kännetecknad av en huvudkanalen och sidokanalen förenande