CA2093481A1

CA2093481A1 - Processing station for carrying out fluorescence polarization measurements in an analyzer

Info

Publication number: CA2093481A1
Application number: CA002093481A
Authority: CA
Inventors: Gottlieb Schacher
Original assignee: F Hoffmann La Roche AG
Current assignee: F Hoffmann La Roche AG
Priority date: 1992-04-30
Filing date: 1993-04-06
Publication date: 1993-10-31
Also published as: EP0567892A1; EP0567892B1; JP2601780Y2; DE59309444D1; US5496519A; JPH0634643A; JPH09247U; US5384094A

Abstract

Abstract A processing station for making a fluorescence polarization measurement on a sample in a cell under examination in a device for chemical and biochemical analysis, the analytical device containing a conveyor for conveying cells. In order to make fluorescence polarization measurements outside the conveyor, the processing station is characterized in that is is separated from the conveyor and in that it contains the following means: a measuring device for making fluorescence polarization measurements on a sample in a cell, and an automatically controlled change-over and positioning device for removing individual cells from the conveyor, transferring a removed cell to a measuring position in the measuring device, and returning the cell to its original position on the conveyor after the measurement.

Description

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The invention relates to a processing station for making a fluorescence polarization measurement on a sample in a cell under examination in a device for chemical and biochemical analysis, the analytical device containing a conveyor for conveying cells.
Automatic analytical devices usually operate on the following principle: samples for analysis or parts of samples are placed in containers and then subjected to a series of processing steps such as adding (pipetting) reagents, mixing or incubation, and measurements of the reactions which have taken place are made a number of times lo during processing and~or once at the end of processin~. The usual procedure is as follows: the containers holdin~ the samples for analysis are placed in a fixed sequence on a conveyor and travel through various processing stations, or in the case of batch processirlg, as is usual in the case of centrifugal analytical devices, all sample containers are placed on a carrier (rotor) and subjected practically simultaneously to the processing steps and measurements. Analytical systems operating on these principles give good service in large clinics and analytical centers where large numbers of samples have to be processed .
In view, however, of the variety of possible analyses today and the medical requirements on clinical chemistry, particularly in immunological investigations, it has been found that the automatic analyzers conventionally used hitherto for throughput of large quantities of samples are insufficiently flexible to provide analytical profiles (full random access) specifically adapted to individual patients or clinical pictures, while still being able to handle a large number of samples from patients. In addition to photometric extinction rneasurements on mixtures of samples and reagents under investigation, another aim is to make fluorescence polarization measurements on the mixtures in the same analytical device.
In general terms, therefore, the aim of the invention is to provide an analytical system which meets these requirements in that a large number of analytical samples can be processed with very great Ve / 17.02.93 2~93~

flexibility with regard to the analytical profile obtained from the individual sample. More particularly, the aim is to provide a processing station for an aforementioned analytical system and suitable for making fluorescence polarization measurements.
According to the invention, ~his aim is achieved by means of a processing station of the type mentioned at the beginning of this description, the processing station being characteri~ed in that it is separated from the conveyor and in that it contains the following means:
lo a) a rneasuring device for making fluorescence polarization measurements on a sample in a cell, and b~ an automatically controlled change-over and positioning device for removing individual cells from the conveyor, transferring a removed cell to a measuring position in the measuring device, and returning the cell to its original position on the conveyor after the measure ment.
Preferably, the change-over and positioning device contains the following means: a pivo~able hood for screening the cell from outside light during the fluorescence polarizatioIl measurement and means for controlling the motion of the movable components of the change-over and positioning device and for pivoting the hood.
In a preferred embodiment, the change-over and positioning clevice contains means for optionally removing a cell from two different positions on the conveyor for transferring a removed cell to a measuring position in the measuring device, and for returning the cell to its original position on the conveyor after the measurement.
The processing station according to the invention is preferably used in an analytical device described in detail in European Patent Application No. 92105903.9 entitled "An analytical apparatus".
R~ference is hereby made to this description.
An embodiment of the processing device according to the invention will now be described with reference to the accompanying drawings in which:

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Fig. 1 shows a processing station in perspective representation at the time when a measurement cell is gripped and taken from the rotor magazine;
Fig. 2 shows the processing station in Fig. 1 with the cell in the measuring position, i.e. in the position for making a fluor-escence polariza~ion measuremen~;
Fig. 3 is a plan view of the processing station in Fig. 1, in a neutral starting position;
fig. 4 is a plan view of ~he processing statlon in Fig. 1 in a o gripping position relative to the optional position A in the rotor magazine;
Fig. 5 is a plan view of the processing station in Fig. 2, in which a cell is brought into the measuring position in the measuring device;
Fig. 6 is a plan view of the processing station in Fig. l in a gripper position relative to the optional position B in the rotor magazine;
Fig. 7 is a side view of a processing station, partly in section, corresponding to arrow VII in Fig. 4;
Fig. 8 is a side view, partly in section, of the processing station corresponding to arrow VIII in Fig. 5, and Fig. 9 diagrammatically shows the construction of a measuring device for making a fluorescence polarization measurement on a sample in a cell.
A processing station 3 according to the invention will now be described. The processing station is for making a fluorescence polarization measurement on a sample in a cell 2 under examination in a device for chemical and biochemical analysis.
The analytical device contains a circular rotor magazine t, shown in part in Figs. 1, 2, 7 and 8. The rotor magazine serves as a conveyor for conveying cells to various individual processing stations disposed around the rotor magazine in the analytical device. The rotor " ~

2~93~1 magazine can be moved through exact angular steps in both directions of rotation by a drive (not shown in the accompanying drawings3.
The flanges 2a of the cells 2 are held by leaf springs 5 on the peripheral edge 4 of the rotor. magazine l and in defined optional 5 positions at angles of 360/n degrees, where n denotes the total number of optional positions. The rotor magazine 1 is mounted for rotation around an a~is 6 and is driven e.g. by a computer-controlled stepping motor (not shown), so that each optional position in the rotor magazine l can be obtained relative to a processing station 3 10 according to the invention for making fluorescence polarization measurements.
The cells 2 are held on the outer edge of the rotor magazine, i.e.
they have a flange 2a on their top surface which rests on a flat annular surface at right angles to the a3is of rotation of the rotor 15 magazine, one of their wall surfaces abuts the substantially cylindrical outer surface of the rotor magazine, and the cells are also held by resilient tongues on the leaf springs 5, which project radially over the cell and are associated with each cell position, and which for this purpose are formed on their underside with a projection (not shown) 20 which engages in a recess in the cell flange 2a. The resilient holder holds the cells sufficiently firmly to prevent them falling out when the magazine rotates. The resilient holder also enables the cells to be easily removed or inserted manually or by a mechanical gripping m echanis m .
A detailed description of the rotor magazine and operation thereof is given in European Patent Application No.92105902.8 entitled "A conveyor for an analytical apparatus". Reference is hereby made to this description.
The cells 2, the contents of which is e.g. subjected to a fluorescence polarization measurement, are brought by the rotor magazine I into the range of action of the processing station 3, which is used to grip one of the cells, move the gripped cell into the measuring position, and return ~he cell to the rotor magazine after the measure ment.
The processing station 3 is disposed in an exactly defined position relative to the rotor magazine.

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As shown more particularly in Figs. 1 and 2, the processing station 3 contains a device 33 for making fluorescence polarization measurements on a sample in a cell 2, and a change-over and positioning device for removing individual cells 2 from the rotor 5 magazine 1, transferring a removed cell to a measuring position in the measuring device 33, and returning the cell to its original position on the rotor magazine after the measurement.
The change-over and positioning device is constructed as follows:
A gripper 7, via a slide 8, co-operates with a guide track 11 on a lo swivel arm 9, so that the tongs 13 of the gripping device 7 are horizontally and longitudinally guided radially relative to the axis of rotation 6 of the rotor magazine 1.
The tongs 13 are disposed on a holding arm 12 projectirlg from the slide 8 and grip in a plane which coincides with the plane in which 5 the cells 2 are conveyed in the rotor magazine 1. rhe tongs 13 ca:n therefore be moved and brought into enga~ement with the cells 2 radially relative to the axis 6.
A gripper control shaft 15 is mounted in bearing blocks 14 on the arm 12 and a movable gripping means 16 in the form of a rocker is 20 non-rotatably connected to one end of shaft 15. The end of means 16 near the rotor has a downwardly extending lug 17 for positive engagement in as recess 2b ~see Fig. 3) in a flange 2a on the cell. l'he end of the gripping means 16 remote from the rotor bears on arm 12 via a compression spring 18 so that the gripping means is moved in 25 the closing direction and presses the flange 2a against a bearing table 19 integrally formed on the arm 12. The previously described device, if suitably actuated, can reliably grip a cell 2, remove it from the magazine l, transfer it to a measuring position in the measuring plane, and return it to the magazine 1.
The gripping motion of the means 16 is brought about by cams 22a, 22b disposed on the surface of a control disc 21, and is transmitted to the shaf~ 15 by a runner 23 and a swivel crank arm 24.
~he swivel arm 9, via an ex~ension arm 26 comprising a guide roller 25, is movable in a control groove 27 formed underneath the 2B93~81 control disc 21, around an axis 28 coinciding with the axis of rotation 6 of the rotor magazine 1, so that when the control disc 21 suitably rotates, the arm is movable from a neutral position (Fig. 3) in one or the other direction into substantially three angular positions, i.e.:
1. Tongs 13 radially in line with cell 2 in optional position A (Fig.
4) of the rotor magazine 1.
2. Tongs 13 in the measuring plane (Fig. 5) or 3. Tongs 13 radially in line with cell 2 in the optional position B
(Fig. 63 of the rotor maga~ine 1.
For example, the angle through which the arm 9 pivots from the optional position A or B to the measuring plane can in each case be 360/n degrees, i.e. the complete angle through which the arrn 9 pivots from A to B will be 2 x 360/n degrees.
A control groove 29 in the top surface of the control disc 21 brings about radial motion of the tongs 13 in the direction of the a~is 3 so as ~o grip a cell 2 from the optional position A or B or radially return it, or for removing a cell 2 from the rotor magazirle 1 and transferring it to a measuring position in the measuring device 33 or moving it in the opposite direction when returniIlg the cell Z to the rotor magaæine 1. The slide 8 of the gripping device 7 is operatively connected to the control groove 29 via a pin 31 and a guide roller 32.
The gripping device 7, considered radially relative to the rotor a~is 6, can move from a neutral position (Fig. 3 ) into two other positions irrespective of the direction of motion of the control disc 21, i.e.:
1. A position near the rotor (Figs. 4, 6 and 7) for gripping or transferring a cell 2 .îrom the rotor magazine 1 and 2. A position remote from the rotor (measuring position); Figs. 5 and 8.
The control disc 21 is rotatably mounted on a shaft secured to a baseplate 34, so that the extension arm 26 of the lever 9 is disposed between the baseplate 34 and the control disc 21, and the guide roll 25 can engage in the control groove 27. The baseplate 34 is adjustably secured to the base 36 of the casing, for accurately positioning the gripping device 7 relative to the rotor magazine 1 (Figs. 7 and 8). The 2~3481 motor (not shown), via a toothed wheel 37 and a toothed belt 38, drives the control disc 21, which has corresponding teeth 39 on its outer periphery (Figs. 1 and 2). The rotation of the control disc is controlled and monitored by computer.
The previously-described components of the change-over and positioning device function and co-opera~e as follows:
Since the control grooves 27, 29 are formed Oll a eommon control disc 21 and are ~hus driven in synchronism by a computer-controller stepping motor (not shown), the pivoting motion of the arm 9 lo overlaps the linear motion of the gripping device 7, such rnotion being radial relative to the axis 6, so that the total motion is as follows:
When the gripping device 7 is in a neutral position as per Fig. 3, the guide rollers 25, 32 of the swivel arm 9 and the gripping device 7 engage in corresponding portions 27a, 29a of the catns on the control discs 27, 29.
As soon as the rotor magazine 1 has stopped in a suitable position, a cell 2 can be taken from the optional position A or B by suitably rotatlng the control disc 21.
When $he control disc 21 rotates anticlockwise, the arm 9, controlled by portion 27b of the control groove 27, first pivots 360/n degrees clockwise and remains there (portion 27c of cam 27) in ~ront of the optional position A of magazine 1 or in front of the cell 2 there.
The gripping device 7 is then moved towards the rotor l by the portion 29a of the cam 29, via the slide 8 or guide roller 32.
Meanwhile, the roller 23 of the tongs-opening mechanism 15, 24 runs against a control cam 22a permanently disposed on disc 21 and opens the tongs 13. If the tongs 13 are in the gripping position, the cam 22a or the compression spring 18 closes the tongs 13. Portion 29c of cam 29 now moves the tongs 13 baclc or removes the cell 2 from the rotor 1 (Fig. 4). When cell 2 has been removed from rotor l, the guide roller 25 of the swivel arm 9 reaches portion 27d of cam 27 and pivots arm 9 through 360/n degrees anticlockwise and remains there (portion 27e of 27).
As soon as the tongs 13 have reached an end position remote from the rotor (the control roller 32 is in portion 29d of cam 29), the ~, ..

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isolated cell 2 is positioned in the measuring position in the measurirlg device 33. The control disc drive is then stopped and the measurement can be made.
After the measurement, the control disc 21 is driven clockwise, so that the cell 2, after the measurement, is returned in the opposite direction to the rotor magazine l or optional position A.
The gripping device 7 then returns to a neutral position and the control disc dri~7e is stopped. While a cell 2 is being brought into the measuring station 33, the rotor magazine can of course continue to o rotate and carry out other operations, but when the cell 2 has been returned to the rotor 1, the previous position must be restored.
If the gripper 33 is to remove a cell 2 from the optional position B, the control disc 21 is moved from the neutral position in the cloclcwise direction. The eontrol roller 25 on the swivel arm 9 now runs in a portion 27f of cam 27 and pivots arm 9 through 360/n degrees anticlockwise and remains in radial alignment with the optional position B (portion 27g of 27). The tongs 13 are radially moved in the direction of the rotor axis 6 by a portion 29e of cam 29.
An additional cam 22b on the control disc controls the movement of tongs 13. The cell 2 is transferred to and from the measuring position 33 as described in the case of the optional position A. Arm 9 is pivoted into the measuring plane via portion 27h of control groove 27 and linear motion into the measuring position is brought about via portion 29f of the control groove 29.
When the previously-described preferred embodiment of the control station 3 is used, an empty cell for a blank measurement, for e~ample, is taken from the optional position A whereas a cell containing a sample for investigation is taken from the optional position B. This saves time during measurement.
In a variant of the previously-described embodiment of the processing station 3, containhlg a simplified version of the change-over and positioning device, the cell 2 is always taken from the same position on the rotor magazine 1. This variant is of use in analytical devices in which the time sequences obviate the need for a facility for taking cells for idle measurements from a different op~ional position from cells containing samples to be measured.

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9 2~1~3~1 A measuring device 33 for making fluorescence and polarization measurements and diagrammatically shown in Figs. 1 and 2 will now be described in detail with reference to Figs. 7, 8 and 9.
Fig. 9 diagrammatically shows the optical arrangement of the 5 measuring device 33. The device comprises a measuring-light source 46, substantially made up of a halogen lamp 63, a lens system 64 and an interference filter 65 for the excitation wavelength. In orcler to monitor the light intensity or to compensate fluctuations in intensity by computer, a beam divider 66 is disposed in the path of the lo measuring light source 46. The beam divider 66 conveys a part of the measuring-light beam to a photodiode 67 which delivers signals for additional processing. The measuring-light bearn travels through a cell 2 and excites its contents. The light emitted by a sample contained in a cell 2 during a fluorescence-polarization measurement is supplied 15 via a lens system 68 and an interference filter 71 to a photomultiplier 51 which delivers a corresponding measurement signal. A polarizer 69 disposed in the path of the light emitted by the sample and drivable by a motor (not shown) can make t~,vo different measurements, i.e. at polarization angles of 0 or 90.
As shown in Figs. 1, 2, 7 and 8, the measuring-light source 46 is disposed in a casing 45 and the photomultiplier 51 is disposed in a casing 49. As shown in Figs. 7 and 8, the measuring duct 56 of the photomultiplier 51 is closable by a slide 57. When, and only when, the cell 2 is in the measuring position, an opening 58 through the slide is in line with an entry opening 56 in the photomultiplier casing 49. The slide 57 is actuated via an abutment surface 59 on the carriage 8 of the gripper device 7, which can act directly on the slide 57. The closing motion can be brought about e.g. by leaf springs (not shown).
When the slide 57 is closed, the photomultiplier current in darlcness can be measured.
During ~he measurement, the measuring light is supplied horizontally, in the direction towards the rotor-magazine axis 6, through an outlet opening 61 (Fig. ~ ) to a measuring cell 2, which it travels through and exci~es the conten~s thereof, and can leave the measuring chamber through a small opening 62 in the front wall 42 of the hood 41, to avoid in~erfering reflections.

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The light emission, which gives information abou~ the contents of the cell, is measured by a photomultiplier 51 disposed vertically under the cell.
A preferred embodiment of the processing station 3 contains a hood 41 which is mounted îor pivoting through ~0 on the gripper arm l 2 and has a front wall 42, two side walls 43 and a cover wall.
As shown in Figs. l, 3 4, 6 and 7, when the tongs l 3 hold the cell 2 in positions outside the measuring posi~ion in the measuring device 33, the hood 4 I is substantial horizontal, so that the cell 2 is exposed lo and the hood 41 does not interfere wi~h the required transfer processes.
As shown in Figs. 2, 5 and 8, when the tongs l 3 hold the cell in the measuring position in the measuring device 33, the hood 41 is pivoted through 90 and is vertical and surrounds the cell on four sides and co-operates with the wall of the casings 45 and 49 to form a dark chamber which screens the cell from outside light.
In order to control the motion of the hood 41, a~ extension arm 52 is secured to the swivel arm 9 and ends in a control pin 54 which engages in a control groove 53 in hood 41. Pin 54 is at a vertical distance from the axis 55 of hood 4i (Figs. 7, 8). The motion of pin 54 relative to axis 55, i.e. when the carriage 8 moves along the side 11 arm 9 during the motion of the gripping device 7 towards the measuring position, results in a corresponding rotation ~see Figs. 7 and 8) of hood 41, bringing it to the position shown in Figs. 2, 5 and 8.
As can be seen from the previously-described means for controlling the motion of the hood 41, the motion is controlled by the same previously-described means which control the motion of ~he change-over and positioning device.
In the present case, for example, of a fluorescence polari~ation measurement, the cell 2 being measured has to be screened from outside light, i.e. the measurement must be made in a dark chamber.
In the measuring position 33, the cell 2 is kept dark by a hoocl 41 mounted on gripper arm 12 so as to be pivotable through 90, and substantially surrounding the cell 2, during measurement in the 2~g3~8~

measuring device 33, on four sides, i.e. a front wall 42, t~To side walls 43 and a top wall 44.
In the measuring position 33, the tongs 13, the cell 2 and the hood 41 are moved up to the casing 45 of the measuring-light source, 5 so that the casing substantially constitutes the back wall 47 of the dark chamber. The floor 48 of the dark chamber is formed by a part 49 of the photomultiplier casing comprising a measuring channel.
In every position of the tongs 13 outside the measuri~g position 33, the hood 41 is pivoted through 90, so that the cell 2 is exposed 10 and the required conveying processes are not interfered wi~h.

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Claims

1. A processing station for making a fluorescence polarization measurement on a sample in a cell under examination in a device for chemical and biochemical analysis, the analytical device containing a conveyor for conveying cells, the processing station being characterized in that it is separated from the conveyor and in that it contains the following means:
a) a measuring device for making fluorescence polarization measurements on a sample in a cell, and b) an automatically controlled change-over and positioning device for removing individual cells from the conveyor, transferring a removed cell to a measuring position in the measuring device, and returning the cell to its original position on the conveyor after the measurement.

2. A processing station according to claims 1, characterized in that the change-over and positioning device contains the following means: a pivotable hood for screening the cell from outside light during the fluorescence polarization measurement and means for controlling the motion of the movable components of the change-over and positioning device and for pivoting the hood.

3. A processing station according to claim 1, characterized in that the change-over and positioning device contains means for optionally removing a cell from two different positions on the conveyor, for transferring a removed cell to a measuring position in the measuring device and for returning the cell to its original position on the conveyor after the measurement.
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