DE1698240B2 - Device for carrying out laboratory analyzes with a large number of test tubes arranged on a carrier - Google Patents

Description

The invention relates to a device for performing laboratory analyzes with a plurality of Test tubes arranged on a carrier, which are stepped by the distance between two test tubes are movable forward, and with at least one in the path of the test tubes vertically arranged syringe, which can be moved pneumatically, synchronously with the stepping mechanism and vertically is.

A device for carrying out laboratory analyzes is already known, in which syringe-like Devices for supplying the liquid media to be examined with a pneumatic Control piston and test tubes arranged on supports are provided. The porters are one Stepping drive exposed, the step of which corresponds to the distance between the test tubes, so that these are passed under the syringes, the pneumatic control of the syringes with that of the Stepping control is synchronized (U.S. Patents 3,193,358, 3,193,359).

In this known device, the rinsing is carried out by the liquid that is to be analyzed Liquid is mixed in. The liquid delivered by a first pump is used to feed the a second pump to convey liquid withdrawn. This series promotion of two different Liquids makes a complicated distribution valve necessary. In addition, the liquids are mixed as they are drawn off by pumping. this leads to to the fact that the desired dilution is not guaranteed with certainty. Besides, that's mixing disadvantageous in the lines or pumps when a substance reacts chemically or Separates substances. For when such a previous reaction sets in, it is a precisely proportioned one Cannot be added to the individual test tubes. Also, if there is an impurity between the test tubes of the different rows should be absolutely excluded, this as a result the inadequate flushing effect is possible, as a Mixing of rinsing liquid with liquid to be analyzed can occur.

The object on which the invention is based is therefore to provide a device of the initially described type described, with which dilutions are made successively for the analysis without contamination occurring between the different treated rows, d. H. that the functions of dilution and flushing are clearly separated from one another, however can be executed simultaneously and by the same controller.

In the device of the type described at the outset, this task is achieved by two further syringes solved, which are arranged vertically on a carrier with respect to the direction of movement of the test tubes can be pivoted so that with every row of test tubes one of the Syringes in a test tube and the other immersed in a cleaning container and that at the next Test tube row with each feed step one of the syringes into a cleaning container and the immersing others in a test tube.

This device has the advantage that for drawing off and transferring the liquid Rinsing and pulling up to the test tubes are done separately. In addition, the device can easily adapted to different programs.

Zv / square is due to the pneumatic control of the immersed in the test tubes Syringe for the first test tube e'n suction stroke and for the following test tubes in a row each a delivery and a suction stroke are provided.

The pneumatic pump control of the syringes advantageously has an additional pump phase for the syringe to be rinsed, to keep it in the upper position and before moving the syringes to empty while in the syringe to carry out the dilution the last dilution aspirated substance is located after switching the syringes during the implementation the dilutions of the next row of test tubes in the cleaning container should be emptied.

The invention is explained in more detail, for example, with reference to the drawings; it shows

3 4

Fig. 1 is a perspective view of the upper stores and reaching under the table 1 in a

Part of the machine, direction acting coupling member 18, for example

F i g. 2 a partial view of the machine with the instruction with the idler gear wedged on, which is able to

drive control of the test tube carrier, the axis 17 in the only one in the drawing

2a shows a detailed view of the test tube carrier, 5 to be taken along in the direction indicated by the arrow £

F i g. 3 is a partial side view of the illustration according to (FIGS. 2 and 8) and its leading part fixed with it

F i g. 2, a driver arm 20 is connected, which via a

F i g. 4 is a plan view of a drive rod 21 with the crank pin 22 in a drerrichtung one of the standing plate 23 carrying the test tubes is connected. The latter becomes beKorbes according to Fig. 1, ίο lovely, continuously with the interposition of a

F i g. 5 is a view according to the arrow V in an electric motor driven by a drive

F i g. 4, belt transmission 25 is connected to the plate,

F i g. 6 shows a partial view along the line VI-VI in the axis of rotation 26 of which a row of control cams C is shown

Fig. 4, the role of which will be seen below

FIG. 7 is a detailed view corresponding to FIG.
Arrow III in FIG. 4, The rotary motion of the motor is so turned into a

8 schematically shows the control of the machine. Alternative movement of the driver arm 20

The in F i g. The machine shown in the figure forms the plate 23 with each half turn

upper part a holding table 1 for the reagent in the direction of arrow E , the idler wheel 18

Glaser 2, on which syringes 51 to 55 are used, 20 of the drive pulley 16 of the drive belt 9 takes with it,

the one via a transport path 3 for the reagent while it is in the other half-turn of the plate

Glaser lie, which here in separate rows does not have any entraining effect. To prevent

to 5 are arranged on plates of the carrier 4, which means that in this last passive phase the

are intended to successively on the transport remaining friction of the idler wheel the drive belt

to be led away. The plates 4 are leading to the rear 25, is as a backstop on the

on the transport route, starting from a feed axis 17, a ratchet wheel 27 is provided with the one

rungskorb 5, out, which is designed so that it interacts pawl 28, which completely the rotary

takes up a certain number and their presence is opposite to the axis 17 in one direction

one after the other at the entry of this path, the direction E is blocked and the standstill position

represents, while at their exit they step at a same 30 renation of the so entrained drive belt

Pick-up basket 6 can be supplied. by step, d. H. the positioning of the reagent

To this end, everyone is guaranteed to have the baskets, as described below,

will be shown, a drive control that is intended to ensure that the step equals the interval between

is too determined to move across path 3 see two test tubes one and the same

and in the direction of arrows A and R, depending on the row. At the same time, cams C describe

to the. how the plates 4 passed on this way a rotation with each movement step of the rea-

will. The plates are gradually placed on this glass, including the downtime.

Taken away as will be shown, and while another row of control cams A is on one

by a controller, the step of which is provided to the inter-axis 30 parallel to the axis 26 and

vall between the test tubes. * o connected to this via a reduction gear 31

The transport path 3 consists on its basis of the is such that the axis 30 before a rotation

Grooved rollers 7 designed to guide the lower of each row of five test tubes, i.e.

Section of the plates 4 to be included. It consists of all six steps, which are to be considered

laterally on the one hand from rolls 8 with a vertical axis that the rows of test tubes through a

and on the other hand from a driver drive belt 9 45 interval of two steps differ,
for the plates that have driver tips 10 for this

ways that are intended to be used with the drilling analytical methods, at the same time media

11 to cooperate in the plates 4. Feed these tips into the test tubes and

10 and boreholes 11 are to be diluted in the same manner, whereby the

arranged in such a way that they are at the same level 50 the former function through the syringes S1, S2 and 53

are located when the corresponding plate 4 is secured, which is almost on the vertical of one of the

the transport route 3 is located. Holding points of the test tubes is arranged, and

Each plate has the upper part, from which the second is made by the syringes 53 and 54

Path 3 should appear, incisions 12, which is ensured lengthways, their special assembly continues

of the profile of the test tubes and which will be discussed below.

two rows of incisions 13 opposite each other. Each of the solid syringes S1, 52, 55 comprises one

and have graduated in height, the so injected syringe body 32, in which s'ch a piston 33 moves,

Are directed that they have retaining rings 14 for the reagent, which also has a piston in a body of a

record glasses, which is slotted at 14 a and pneumatic cylinder 34 forms the with the

14 ft, so that it is resiliently assembled into 60 syringe barrels, the de-

_{the incisions are detected and} labeled vertically in the pronounced cylinder with F ₁ , V y V. , savings 13 (FIG. 2 a) are locked. Each cylinder arrangement is single acting, that is,

The drive belt 9 is of the type with internal locking and runs around a loose roller 15 and pushes a cam 33 into the suction position and a control drive pulley 16, the discontinuously driven 65 chamber 36, which is provided with an electric valve ■ will. Line for compressed air distribution is connected.

The drive mechanism of the drive pulley 16 Each syringe body is otherwise under intermediate

comprises a suction flap valve 38 and a circuit on the axis 17 of this block disk

4 1 IQ

Feed line with a storage vessel for a medium, the toothed drive belt 9, which is at an angle in front of the chin, which means that the syringe S _{1 is} connected to the cams, the plates only through

Syringes S and S ₄ are like the other one- _i0 VoSS ^ J ^ JIrSÄ ^ Ä

pzen S and S ₄ are like the others a _i0 VoSS ^ J

multiple working cylinder arrangements assigned to row A I

denoted by K and V; about ⁸ addition, 'execution FRMM two _t

but these cylinder arrangements on a carrier that is preferred by l

IS ⁸ "'· to ^{which great appraisals are given} " ™ ^L «« ΛΑ

receives whose piston rod 48 carries a finger 49, 'this M ₅ bes SS U, h ^de " ^Betricbsz y ^k ' ^lls

in a slot 50 in a fixed de- with the carrier carrying vS? '"■ · ς ^{e" ts} P ™ Hencl the

46 connected tab engages. Wriiht Uhh ^Veterina [- ^p . ^erumdia gno ^s t> k nach

This assignment of the two syringes S ₃ and S ₄ * ₅ rmd f WoIT``Jn? "* ^b f - ^Ktth ? ^Application B

serves to use these syringes alternatively hand 'in da first rea ^ y ^them . ™ of ^the _r ^se . ^{rum TOn}

such that one of them, which is placed vertically to the transport ^Rea 8 ^enz glass each row cingc-

portweg 3 is arranged, serves to successively thus besit? ™ H ^ ™ u- λ ο ■

Dilutions between the test tubes and f £ S "? ™" ^S P ^{nts f} ° ¥ ^ndc

make the same series by adding medium from 30 phyrioShesK "in ^E J? ^fuh . ^run f _t ^Vo " ⁰ ^ ^ccm

taken from a test tube or from a test tube rdheStze 2F-Th "^ f" "

glass is added (vertical movement and corresponds phvsio oeisrhe, Qr, ^{P, Einfuhrun} g ^{of 0} - ^'sc - ^m

speaking maneuver ^ of the syringe), while the an- 'SSS? ™ Tf ^ "^ ¹ » ·,

particular syringe is then brought to a washing in the VenvendC to F _n "Ϊ ¹ ™ r abwechscln-

pool to immerse 51, such that the Vertäu- ₃₅ from the first R _P, a ^En, f ^tnahm ° ^{of '5 cc} serum

The syringes S ₃ and S _{4 are} updated with every change ΐηΐ ^ _Μ Αί; 2? ϊ ^ ^

the row of test tubes by swiveling their from the next! Kl T ^Re , ^a S ^e " ^z f ^las "

common carrier 46 is made. Here erzeuTteTverHii ^ ^ ^{8 8 Will} "° ^{'5 CCm the}

The cylinder arrangement V ₁ is there via a line Send Z ? third ΐ ^ Τ ° Τ ^{βη And anSch! ie} "

52 with a single-acting electric valve £, ver 40 e second from the Λ ^ ⁸⁶ "? ⁶ ^ ^from P ^e g ^just · ^So i ' ^cht

bound. that with from a common line 53 and vo _n / v7erfen in H r " _f ^daS Γ ^ ^Rea S ^enz - ^Ias

originating compressed air is applied, whereby these remain 0 sTcmm every £ i *% v ™ ^ l ™ "V

Line with the source, not shown, and with passage unTei de ΤΔ test tubes after

the other electrical to be analyzed £ _n ^ Γ " ⁸⁸ ?" ⁰ ! ' ^WHERE ^

valves is connected. _{4S we} d ,, ήπ ^? /, ™ ^{more and more} diluted

The cylinder ^ is with one with a simple 0.5 cc £, A ν Ι ^ ΓΖΤ ^ ί ™ ¹ / ^ ^{8 1} P "

acting electrovalve E " provided Leitune 54 wash basin ςι ι- ^Verdunnun g finished, de im

connected The cylinder v \ is over i Liti 55 S? ^ ¹ " ¹ '" ¹⁰ " ^{will be} » ^ hdem the

irkenden electro valve E " provided Leitune 54 wash basin ςι ι- g,

tied together. The cylinder v \ is about a Leituni 55 Sp? set S and <T ^ ¹ " ¹ '" ¹⁰ " ^become '» ^ hdem the

with a single-acting solenoid valve E, narrowing the Lh ^V f ^rtau ' ^{cht are} ' ^{around the Verdiin} -

bound; the cylinder E ₄ is lead via a line 56 with 50 (the Snritam «R h, Tf ^{? r} t 1" ^

connected to a single-acting solenoid valve E ₄ ; before the renewed vS ^ ^P ". ^{en in the sink} d Zlid F i over i Li * ^ SS ^ SSf ^ ** ***""? ^

connected to a single-acting solenoid valve E ₄ ; before the renewed vS ^ ^P ". ^{enim Wasc} the cylinder F ₅ is connected via a line 5 * to a w ^ SS ^ SSf ^ ** ***" ** "? ^ single-acting electrovalve E ₅ ; the Smtee? ^ » IYn f * ^Steuerun 8 ^e n required).

Cylinder V _B is connected via two lines 58 and 59 to test tubes einSeSLn ^ ^{AntigeD ίΠ eachS deF} a double-acting electrovalve E. 55 The α, κΗ, ια 1 1 χτ

the cylinder K ₇ ⁿ connected to the lines 60 ⁶ and 61 'eleSrisdiS fr _"t ^{g of} N °? ^k» C and ^ and a double-acting solenoid valve E ₁ composite ™ 2a22 £? ™ äÄ ^{_I,. m S} ^ ^ travel the

The cams C and A are used to control elek- gS ^ and ^ Hm H "^" ^ ^ ' ^iSt * " ^F ' ^g - ⁸ Irish contacts that make up the aforementioned electrovalve? XkSi ₀ Z · [ 5 ^ΕΓ 2, ^3υ1 ^^ ^{εη m combine tiles} and thus the syringes as a function of the pre-machine.

thrust of the carrier plate 4 of the test tubes on Zunärf ^ t ™ ί λ α

3em transport route 3 and as a function of the Mischlings- SteuerschaltkreSn Zw ^. ^{n proven} , ⁿ ' ^{that in the} Md dilution program of the media, the all-electric S ^^ T ^ntlle _l ' ?? ^ie ? ^nc cozy tube rows in common press. genzgläseralatte amLSSn ? ■ J "! ^? ^ ^Ά * Λ ™ '

The wedging between the 6 ₅ gabewS3 vSLK ?? Τ ^{4 dl} ^ ^{on the} . ^About "3etriebszyklus of the syringes and the reagent lower Teü Ie? Fat ί ⁶ ^ ^{'that 5-f samme} _i ⁿ ^ strengths angsweise ensured making sure end ^{with the} däser bearing panels 4 cams contacts nmfewL *. This ^ by the fact that the ^^^ * ^^

·? ■ · ■

1119

is arranged, a presence contact 61 which is arranged below the dilution _{syringe S 1} or S ₄ and a presence contact 62 below the syringe S ₅ . The mode of operation of this machine, which begins with the entry of a glass carrier plate 4 into the transport path 3, the friction belt 9 of which is set in motion by the fact that the motor 24 is supplied with electricity, is as follows:

The attachment or wedging of the cams C • nd of the detected plate 4 is ensured, as explained, in that the tips 10 mature into the bores 11 {, the plate 4 actuating the presence contact 0 when the first row of test tubes is under injection S ₁ and 5th, appears.

After the syringes that can be seen in FIG. 1, one sees first of all the cylinder F ₁ and thus the electrotentil E ₁ must be actuated so that the syringe S ₁ , 5 cm delivers physiological serum into the second test tube. This is achieved by cams C ₁ and / I ₁ , the cam C ₁ cooperating with an electrical contact 65, the input of which is connected to a pole of a power source 66 and the output of which is connected to the input of the electrical contacts 67, 68 and 69 . The other pole of the power source is connected to the solenoid valves and to relay 72.

The output of the contact 67 actuated by the cam A _{1 is} connected to the solenoid valve E 1 via the contact 60.

For the syringe S ₁ , when the presence contact 60 is closed, the cam A _{ serves to confirm the control of the solenoid valve E ₁ during four steps out of six of the cycle corresponding to the passage of the last four test tubes in each row under the syringe S ₁ to give, while the cam C ₁ rotates once per step, which serves to ensure that the _{control pulse coming into effect on the electrovalve E 1 is given} at a fraction of the half-turn of this cam corresponding to the standstill phase of the test tubes marked at each switching step.

For the syringe S, which is then actuated, the cam A ₂ , when the presence contact 60 is closed, is used to give the control validity signal for your fllektrovcntil E., during the fraction of the desired steps, which is the which corresponds to the standstill of the first test tube in each row under the syringe S., while the cam C ₁ gives the control pulse coming into effect on the electrovalve E.

In the case of the syringe S ₅ , which is arranged in the end region of the transport path 3, it is first necessary for the test tube carrier plate to actuate the presence contact 62 so that the solenoid valve E. can be actuated via the contacts 65 and 69.

The cam A. is used to validate the control of the electrovalve E ₅ during the five steps of the cycle corresponding to the passage of the five test tubes in each row under the syringe; The cam C ₁ serves to deliver the control impulse that takes effect on this solenoid valve at every step (if the position of the syringes and test tubes according to Fig. 2 is taken into account, you can see that the cam A. must be adapted so that it can deliver a control confirmation signal one step before that output by cam A _1).

The syringes S ₃ and S ₄ actuated by the cylinder arrangements F ₃ , F ₄ , V ₆ and V ₁ have special control circuits for the electric valve E _{0 of} the cylinder for lowering and lifting the syringes F ₆ , for the electric valves E ₁ and E _{4 of} the Pump cylinder F., and F ₄ and for the electric valve E. of the cylinder to swap the syringes.

ίο Raising and lowering of these syringes S _a and S ₄ must be carried out five times in each work cycle, since the dilution syringe must work in all test tubes. The control circuit of the solenoid valve E ₆ goes past a cam A ₃ , which

with a contact 70 for the confirmation signal for a duration of five steps of the cycle interacts, the contact 70 on the one hand irit the power source and on the other hand with the input a control contact for lifting and lowering 71 is connected.

This has two outputs, which are each connected to two solenoids of the double-acting electrovalve E ₁ , whereby the alternating supply of one or the other output depends on the interaction of the actuating arm of this contact with a cam C ₀ , which occurs once for each Step rotates and through this contact emits a control pulse that causes a lowering, which is slightly smaller than the half turn corresponding to the standstill of the test tubes, the rest of the rotation corresponds to a stroke control pulse.

However, this circuit only works under the condition that an initial lowering is only possible when both armatures corresponding to the presence contact 61 are brought into the closed position. The _{solenoid valves E 1} and E _{4 of} the control of the pump cylinders F. and F ₄ must be controlled differently, depending on whether the corresponding syringe is in the dilution or washing phase. Then, the Verdünnungssprii is ^- e at the end of the working cycle of a series of 0.5 ^{cm: i} lifted the last diluted liquid. For the sake of simplicity, these 0.5 cm ^:! discharged into the sink 51, which is provided with a continuous water circulation. The syringe in the washing phase contains 0.5 cm ^{11 of} rinsing water towards the end of its work cycle, which is emptied into the sink before the syringes for the next row are exchanged again.

From this it follows that the syringe in the washing process is then actuated six times per work cycle, by interchanging the syringes during the process of the first cycle of each test tube row, while the dilution syringe is only pumped five times per work cycle or cycle. These different controls for solenoid valves E ₃ and E ₄ are first introduced by means of a relay 72 comprising two reversing armatures built into the circuit of these solenoid valves, the energization of these relays being dependent on a contact 73 which indicates the position of the syringes and is actuated, for example, by the actuating arm 19, while the syringe S ₃ is in dilution

position (see Fig. 8). '

_{A cam C 3 driven} by one revolution at each step is used to deliver pump control pulses in cooperation with a

«W9524 / 176

119

electrical contact 75, namely two pulses per cam rotation, so that there is a double pumping effect (most favorable dilution and most favorable washing), these pulses being emitted during the half rotation of the cam, which corresponds to the standstill of the test tubes. These pulses from contact 75 are direct For example, placed on the finger or the armature L _{1 of} the contact 61 and the armature L _{2 of} the relay 72 to the Eiektroventil E ₃ or E ₄ , depending on whether the syringe S ₃ or S ₄ is being washed, such that the Washing process takes place six times per cycle as previously indicated.

Since the dilution syringe may only be actuated five times per cycle, as indicated, the _{pump pulses generated by the cam C 3} , which originate from the contact 75, are also applied to a contact 76, which is mechanically connected to the contact 70 and through the Cam A _{3 is} actuated, which, as already mentioned, only allows five pulses of the cycle to exist as effective. These effective impulses then reach the electrovalve E ₃ or E ₄ , depending on whether the syringe S ₃ or S ₄ carries out the dilution, namely through the armature D _{1 of} the presence contact 61 and through the armature D _{2 of} the relay 72.

Finally, the control valve E _{1 of} the cylinder V. for the exchange of the syringes is here simply operated with the interposition of an "electrical contact 77, which is subjected to the action of a cam A , which rotates once per cycle, which is so adapted and applied, that at the beginning of the feed movement of the first step of each cycle it supplies the conact 77 with a control pulse of the electrovalve E _{7, so that the reversal at the end of the first step?} has taken place. This pulse is given alternately to one or the other of the solenoids of the electrovalve E. as a function of the position of a reversing armature P _{1 of} the relay 72 and also via the armature P _{n of} the presence contact 61.

The guidance of the test tube carrier plates upon entry into the transport route 3 and their transfer When exiting, dining and receiving baskets 5 and 6 are conveniently interposed ensured, the respective vertical rollers 80 on their bottom for guidance and spacing of the Have test tube carrier plates. These baskets also have lateral webs 81, which are longitudinally on the basket the axis 82 are articulated and which serve to the plates 4 on the crank during its handling by means Hold handles 83 firmly. From Fig. 1 one recognizes that when a basket is in its position on is brought to the machine, the articulated web 81 is automatically supported on the transport path side is raised, the support taking place against a support provided on the machine.

The entrainment of the baskets 6, 5 in the direction of the arrows A and R is indicated here for each by one in FIGS. 5 to 7 ensured device, which has two driving belts 85, with the plane of the machine table, which is open, are aligned and carry the driving tips 86, which cooperate with bores 87 in the bottom of the basket

ίο and in the extension of which they are arranged, if the basket is gripped between the guides 88 fixed to the machine, the weight of the basket is applied evenly to slide rails 89 on the machine table.

Is taking the drive belts or conveyor belts with you 85 with internal toothing takes place via gears 90 wedged onto a shaft 91, the shaft 91 being a Counter gear 92 which is connected to a gear 94 via a toothed drive belt 93 is, which is keyed on the output shaft 95 of an electromagnetic clutch, which as a whole with 96 is designated. The input shaft 97 of the diesel clutch becomes permanent via an electric motor 98 powered when the machine is in motion

as is located.

For the feed basket 5, the advance of the basket according to the arrow A can also be carried out as a function of a stop contact 99 which is at the entrance of the transfer path

provided under the drive belt of the latter, this contact ensures the excitation of the clutch 96 for bringing the basket forward from cc \\\ moment where no plate 4 ee <vp this is applied. Such a stop contact canoe

can also be used to trigger only the feed ücs basket, combined with a UnU.ι ■ breaker contact, which exercises the standstill of the basket in successive certain positions, z. B. the contact 100, which can be activated by an arm 101 ″ C, which interacts with a toothed Ν <κ! .C; i 102, which acts on the motorvellü ^l! i is wedged. The arm 101 is> verschuv : < '. -Bar at 10 and carries a finger 104, which is pressed in constant storage against the teeth of the cam 102 by c :: ic spring 105, so that at the same time ii! actuation of the contact 100 ensures that the basket is finally shut down with each advance of the first.

An identical device for taking along 'Ic-

The receiving basket is used - the only difference is that the one that triggers the advance of the basket Stop contact at 106 on the machine table in extension of the transport path 3 is arranged in this way is that he goes through each plate 4 at termination

the arrival path at the basket (Fig. 1) can be actuated.

For this purpose 2 sheets of drawings

A 1 1n

Claims (3)

Patent claims: 1. Device for carrying out laboratory analyzes with a plurality of test tubes arranged on a carrier S , which can be moved forward by a stepping mechanism by the distance between two test tubes, and with at least one syringe arranged vertically in the path of the test tubes, which is pneumatically synchronized with the stepping mechanism and is vertically movable, characterized by two further syringes (S ₃ , S ₄ ) which are arranged vertically on a carrier (46) which can be pivoted with respect to the direction of movement of the test tubes (2) so that in a first row of test tubes with each advance step one of the syringes (S ₃ or S ₄ ) is immersed in a test tube (2) and the other (S ₄ or SJ) in a cleaning container (51), and that in the next row of test tubes, one of the syringes ( S ₄ or S ₃ ) is immersed in a cleaning container (51) and the other (S ₃ or S ₄ ) in a reagent bottle (2). 2. Apparatus according to claim 1, characterized in that the pneumatic control of the syringe immersed in the test tubes (S ₃ , S ₄ ) for the first test tube (2) has a suction stroke and for the following test tubes (2) one Row is provided with a discharge and a suction stroke. 3. Apparatus according to claim 1 or 2, including du.-ch characterized in that the pneumatic pump control of the syringes (S ₃ , S ₄ ) has an additional pumping phase for the syringe to be rinsed in order to keep it in the upper position and before the conversion Empty the syringes while the syringe for carrying out the dilution contains the substance sucked off during the last dilution, which after the syringes (S ₃ , S ₄ ) are switched over during the dilution of the next row of test tubes should be emptied into the cleaning container (51). 45