WO2009141797A2

WO2009141797A2 - Device for the automatic replacement of an instrument for autosamplers

Info

Publication number: WO2009141797A2
Application number: PCT/IB2009/052132
Authority: WO
Inventors: Filippo Degli Esposti; Vittorio Dugheri
Original assignee: Filippo Degli Esposti; Vittorio Dugheri
Priority date: 2008-05-21
Filing date: 2009-05-21
Publication date: 2009-11-26
Also published as: ITFI20080101A1; WO2009141797A3

Abstract

A device for the automatic replacement of an instrument on a robotic autosampler arm ending with an operating head (1 ) moving in three orthogonal directions and co¬ operating with at least one station (3) for the temporary storage of the instrument. The instrument replacement device comprises an attachment plate (4) which can be connected to the head (1 ) of the autosampler arm and an instrument-holder assembly (13) positioned removably on the storage station (3) and provided with hooking means (27a,b;28) for engaging on the attachment plate (4) following a movement of approach of the head (1 ) of the autosampler arm towards the storage station (3), whereby said instrument-holder assembly (13) is disengaged from the storage station (3) and made temporarily integral with the head (1 ). The storage station (3) comprises means (15) for disconnecting the instrument-holder assembly from the head suitable for moving the hooking means (27a,b;28) in relation to the attachment plate (4) to cause their mutual disengagement when said instrument-holder assembly (13) is deposited on the storage station (3).

Description

TITLE

DEVICE FOR THE AUTOMATIC REPLACEMENT OF AN INSTRUMENT FOR

AUTOSAMPLERS

DESCRIPTION Field of the invention

The present invention relates in general to the sector of instruments for chemical analyses and more specifically relates to the equipment for automatic sampling and more particularly a device for the automatic replacement of an instrument in autosampling apparatus. Background art

As is known, an autosampler is an apparatus equipped with a robotised arm enabling automation of the operations of extraction of an analyte (sampling) from a container and of injection into an analysis instrument, for example a gas chromatograph, operations which can be performed with various instruments also according to the type of analysis and equipment used, for example syringes, SPME fibres, dilution tips and other similar instruments that require guiding during the insertion in vials, injectors, washing stations and containers.

The arm of an autosampler is generally provided with a computer controlled

Cartesian movement of translation on three orthogonal axes and ends with a head mounting the instrument selected according to the analysis operation to be performed.

For example, in the case of analyses performed by means of SPME fibres, the head of the arm has a container (holder) for housing the SPME probe formed by a coated melted silica fibre, attached by one of its ends to a connector and inserted slidingly in a protective needle to allow exposure of its opposite end. The connector is removably attached to a piston of the holder and its sliding causes a variable portion of the fibre to be extended out of the needle or to be retracted therein.

In the Italian patent application no. FI2005A000194 in the name of the same Applicants an automatic sampling equipment for solid-phase microextraction (SPME) is disclosed wherein the phase of replacement of the SPME fibres on the robotic arm of the autosampler is also automated thanks to magnetic attachments and to the presence of a workstation whereon the SPME probes transit momentarily after their removal from the collection rack and after injection into the gas chromatograph. Known autosamplers are characterised by a significant working rigidity in the sense that, albeit suitable for moving numerous commonly used instruments in the analysis laboratory, nevertheless once they have been set up for the use of a certain instrument, for example an SPME probe, the use of a different instrument is only possible as a result of an operator intervention. In fact each instrument requires its own instrument container (for example the holder in the case of SPME probes) which is mounted on the head of the autosampler arm. Consequently, once the adaptor or instrument holder has been mounted on the head of the autosampler arm, the latter can handle the relative instrument only. This operating limitation constitutes a serious problem as it prevents continuative use of the autosampler which must necessarily interrupt its activity when, in the absence of the operator, it has ended a cycle of analysis with one instrument and has to start a new cycle with another instrument. The difficulty is such that, in the case of analysis with more complex procedures, wherein several instruments are sequentially used, the presence of an operator who replaces the instruments becomes essential for actual continuity of the analysis. Objects and summary of the Invention

The object of the present invention is to allow automatic replacement of an instrument in a robotic sampler arm for analytical techniques. Another object of the present invention is to provide a device for the automatic replacement of an instrument in robotic autosampler arms which does not require changes to the same robot and which only uses additional mechanical components without providing electromechanical, pneumatic or electronic controls of the same device so as to be able to replace the instruments, also succeeding in limiting the production and management costs.

Another object of the present invention is to provide a device of the type mentioned above which only uses components of a mechanical nature without interfering in any way with the control systems present in the machine whereon the device is installed, consequently appearing to all effects and purposes as a normal accessory to be operated through movements on the three axes only.

A further object of the present invention is to provide a device of the type mentioned above wherein the operations of movement and instrument replacement take place in such a way as to minimise the mechanical stress on the arm and the vibrations which could jeopardise precision thereof.

The device for the automatic replacement of the instrument on a robotic autosampler arm according to the present invention which allows the abovementioned objects to be achieved comprises an attachment plate which can be secured to the head of the autosampler arm and an instrument-holder assembly removably positioned on a storage station and provided with hooking means suitable for engaging on the attachment plate following a movement of approaching of the head of the autosampler arm towards the storage station, so that the instrument-holder assembly is made temporarily integral with said head while it is separated from said station. The storage station also comprises means of unhooking of the instrument- holder assembly from the head suitable for moving the hooking means in relation to the attachment plate in order to cause their reciprocal disengaging when the instrument-holder assembly is deposited on the storage station. According to one aspect of the invention the autosampler arm co-operates with several storage stations, each one intended to hold an instrument-holder assembly dedicated to the movement of a specific instrument. In this way the arm can selectively take out one instrument-holder assembly or another, automatically, i.e. without the operator intervention, according to a predefined programme. According to another aspect of the invention the hooking means comprise hooks extending frontally from the instrument-holder assembly and the attachment plate comprises corresponding engagement seats for said hooks. The engaging between the hooks and the respective seats, to make the instrument-holder assembly temporarily integral with the head of the autosampler arm, and also their disengagement, is driven by the same movements of the arm and more specifically by the relative movement between them in the phase of depositing and of taking out of the instrument-holder assembly from the respective storage station.

According to a further aspect of the invention the storage station comprises means for unhooking the instrument-holder assembly from the head of the autosampler arm, which interact with the means for hooking said instrument-holder assembly to said head once the instrument-holder assembly is positioned in the storage station. Brief description of the drawings

Further features, and advantages, of the device for the automatic replacement of an instrument on a robotic autosampler arm according to the present invention will be apparent from the following description of one of its embodiments given by way of a non-limiting example with reference to the accompanying drawings in which:

Fig. 1 is an overall perspective view of the device according to the present invention;

Fig. 2 is an overall perspective view of the device of Figure 1 , seen however from the opposite direction;

Figs. 3 and 4 show in a perspective view from two opposite directions the instrument-holder assembly of the device according to the present invention;

Figs. 5 and 6 are exploded perspective views taken from two opposite directions of the instrument-holder assembly of the device according to the present invention;

Fig. 7 is a perspective view of the instrument-holder assembly mounted on the autosampler arm while moving away/approaching from/to its storage station;

Fig. 8 shows a vertical section of the instrument-holder assembly taken at one of the median hooks during the phase of engaging on the attachment plate; Fig. 9 is the same section of Fig. 8 after the instrument-holder assembly is engaged on the attachment plate;

Figs. 10 and 11 are two perspective views of the instrument-holder assembly, with parts removed for simplicity of illustration, showing two phases of the movement of the hooking means; Fig. 12 is a perspective view of a possible overall configuration of storage stations of instrument-holder assemblies each suitable for housing a different instrument.

Detailed description of the Invention

Referring to Figs. 1 and 2, 1 denotes the head of an autosampler arm which can translate along three orthogonal axes xyz under the control of a microprocessor unit or equivalent device, not shown. 2 then denotes another part of the autosampler arm integral with the head 1 and 3 a storage station acting as a transfer support for an instrument holding a sample to be analysed. The instrument may be an SPME probe, a syringe, a microsyringe, tips, pipettes and micropipettes, capillary tubes, dosers of solids, needles, instruments with special functions, such as sensors, pincers, micro stirrers, heating components, etc. An attachment plate 4 is secured to the front part of the head 1 of the autosampler arm, while a substantially L-shaped plate 5 is attached to the part 2. A pair of parallel pegs 6 extend from plate 5, said pegs being oriented in a substantially orthogonal direction to the plate 4. In the plate 4 two slots 7 are formed parallel and distanced one from the other, aligned in the direction of vertical translation z of the head 1 , and above them two projections 4a extend for attachment to the head 1 with a separator 4b between them.

The storage station 3 comprises a column 8 with a base 10 for its attachment to an underlying structure in a position compatible with the range of action of the autosampler arm. From the column 8, near the base 10, two fins 9 extend, vertical and parallel and distanced one from the other, for the control of the opening of a needle-guide device of an SPME probe, as described in the Italian patent application no. FI2006A000336 in the name of the same Applicants. At an intermediate height from the column 8 a pair of intermediate arms 1 1 extend horizontally, while a further arm, said upper arm 12, extends horizontally from the upper end of the column 8. The upper arm 12, the pair of intermediate arms 11 and the pair of fins 9 extend from the same side of the column 8.

The two intermediate arms 1 1 act as a support for an instrument-holder assembly generically denoted by 13. In Figs. 1-4 and 7, a holder 14 for SPME fibres of the type described in FI2005A000194 is mounted on the instrument-holder assembly 13, by way of an example, yet, as an alternative, on the instrument-holder assembly 13 a holder of another type or an adaptor for a syringe, a microsyringe or another instrument used in the analysis sector may be mounted. The instrument- holder assembly 13 is removably attached to the arms 11 via respective pins 15 (which can be seen in Fig. 7) rising up from the intermediate arms 1 1 and respective magnets 16 arranged at the side of the pins 15.

As shown in greater detail in Figs. 3, 4, 5 and 6, the instrument-holder assembly 13 comprises two side panels 16a, b held together by a substantially U- shaped plate 17 arranged between them and by a substantially C-shaped band 18 engaging in a groove 19a, b formed in the side panels 16a, b and extending along three adjacent sides of the assembly 13. More particularly, the U-shaped plate 17 has two arms 17a, b extending from opposite sides thereof, for attachment, for example, by means of screws not shown, to the two side panels 16a and 16b, while the band 18 is fixed with its end arms 18a and 18b to the external faces of the side panels 16a, b, for example by means of screws, not shown.

The U-shaped plate 17 defines a seat 20 intended to house the instrument, for example as shown in Figs. 3 and 4, the holder 14 for an SPME probe not shown. Using U-shaped plates 17 with the same external dimensions yet with a different section of the chamber 20, it is possible to adapt the instrument-holder assembly 13 to the dimensions of other instruments, such as syringes or microsyringes, simply by replacing the plate 17.

The instrument-holder assembly 13 also comprises a crosspiece 22 and a pair of vertical guides 21 extending from the crosspiece 22, parallel to the axis of the instrument and slidingly connected to one of the two side panels, in the example illustrated the side panel 16b of the instrument-holder assembly. When the instrument-holder assembly is positioned on the storage station 3, the crosspiece 22 rests on the upper arm 12 of the column 8 and is removably attached thereto by means of attachment pegs 23 (which can be seen in Fig. 7) extending from said arm. On the crosspiece 22 two front seats 24 are also formed, intended to engage with the pegs 6 of the plate 5, to make it integral with the latter when the instrument-holder assembly is taken from the head of the autosampler arm. The crosspiece 22 also comprises a lower seat 25 for engaging with the mobile element of the instrument, for example the head of the piston 14a of the holder 14. In this way it is possible to actuate the instrument at the time of use, acting with traction or compression on the plate 5, by means of an appropriate actuator of a known type and not shown, placed in the head of the autosampler arm 1. The guides 21 have the function of conferring the maximum stability to the movement of the instrument once it has been brought into an operative position, for example at the time of injection into a gas chromatograph.

On the two side panels 16a, b respective slot apertures 26a, b are formed, immediately to the side of the U-shaped plate 17, and respective L-shaped teeth or lower hooks 27a, b project from the slot 26a, b. A third L-shaped tooth or upper hook 28 projects centrally in front of the U-shaped wall 17 and parallel thereto above the lower hooks 27a, b. The upper hook 28 is attached to the two side panels 16a, b by means of two arms 28a, b, extending laterally therefrom, and relative screws 29.

Referring also to Figs. 8 and 9, the upper hook 28 and the two lower hooks 27a, b are secured one to the other by means of two stems 30a, b slidingly housed in respective seats 31a, b, formed in the side panels 16a, b. More particularly, the stems 30a, b, are attached to the arms 28a, b of the upper hook 28 by means of screws 29 which engage axially inside thereof, the lower hooks 27a, b being screwed to the stems 30a, b via one of their threaded ends. Also positioned in the seats 31a, b, coaxially to the stems 30a, b are respective helical springs 32a, b, which abut above on a shoulder 33 of the respective seat 31 a, b and below on a spacer ring 34 resting on the respective lower hook 27a, b and screwed to the stem 30a, b. The seats 31a, b are aligned axially with a respective through hole 35 formed in a base 17c of the U-shaped plate 17, said base being intended to rest on the median arms 11 of the column 8 when the assembly 13 is positioned on the station 3. Each through hole 35 is in axial alignment with the respective pin 15 of the arm 1 1 , so that, when the assembly 13 is positioned on the arms 1 1 , the relative pins 15 will engage in the holes 35 aligned with them. This situation is illustrated in Fig. 8, wherefrom it can be seen that when the pins 15 engage in the holes 35 they abut in the lower hooks 27a, b, pushing them upwards and overcoming the elastic reaction of the springs 32a, b which are compressed between the shoulder 33 and the ring 34. The same situation is also illustrated in a perspective view in Fig. 11 , while in Fig. 10 the springs 32a, b are in an uncompressed position, because the pins 15 are disengaged from the holes 35, corresponding to the condition of the instrument-holder assembly being integral with the head 1.

In this way, at the time of positioning of the instrument-holder assembly 13 on the arms 1 1 of the station 3, the hooks 27a, b and 28 are pushed upwards by the pins 15, overcoming the elastic reaction of the respective springs 32a, b.

The autosampler arm takes out the instrument-holder assembly 13 as follows. Referring to Figs. 1 and 2, the head of the autosampler arm 1 holding the hooking plate 4 approaches the station 3 frontally so that the hooks 27a, b are aligned with the highest part of the slots 7 formed in the plate 4. When the plate 4 has come into contact with the U-shaped plate 17 (see Fig. 8), the two lower hooks 27a, b are engaged in the two slots 7, while the upper hook 28 is between the two upper projections 4a of the plate 4 above the separator 4b. At this point the head of the autosampler arm 1 performs a vertical translation upwards, engaging a separator 7a (see Fig. 8), inside of each of the slots 7 of the hooking plate 4, in the respective lower hooks 27a, b, while the separator 4b of the same plate 4 engages in the upper hook 28. In this way the instrument-holder assembly 13 is firmly hooked to the head of the autosampler arm 1.

In order to allow the instrument-holder assembly 13 to disengage from the storage station 3 the head of the autosampler arm 1 continues its upward movement to overcome the force exerted by the magnetic connection between the magnet 16 and the base 17c of the U-shaped plate 17 (see Fig. 9). As a result of this movement the pins 15 disengage from the respective seats 31a, b and from the through holes 35, causing the elongation of the spring 32a, whose elastic force is discharged on the intermediate hooks 27a, b, ensuring the stability of the connection between the instrument-holder assembly 13 and the hooking plate 4.

Once the instrument-holder assembly 13 has been made integral with the head of the autosampler arm 1 , the latter may perform all the operations relating to the specific instrument mounted on the instrument-holder assembly 13. For example in the case wherein the instrument is an SPME probe as illustrated in some figures, the instrument-holder assembly 13 is equipped with the specific holder 14 by means of which the SPME probe is moved exactly as described in the two aforementioned Italian patent applications in the name of the same Applicants. In the case wherein however the instrument is for example a syringe or a microsyringe, once the instrument-holder assembly 13 has been detached from its storage station 3, the syringe will be moved to perform operations of dilution, injection and the like according to the type of analysis to be performed. As shown in Fig. 12, an advantageous implementation of the invention provides for the creation of a battery of storage stations, for example (but not limited to) three stations denoted by 3A, 3B and 3C, suitable for supporting respective instrument-holder assemblies 13A, 13B and 13C, which can be used for example for an SPME probe, a 10Oμl microsyringe and a 5ml syringe. The three stations are attached to a common base 40 which can be connected by means of two brackets 41 to the autosampler track in a conventional manner. Thanks to the device for automatic replacement of the instrument according to the invention it therefore becomes possible to use an autosampler arm for different types of analysis and analytical operations without the intervention of the operator. In fact the operator is only required to position beforehand the various analysis instruments (such as a holder for SPME probes, suitable adaptors for a syringe or a microsyringe or other) in the instrument-holder assemblies of the storage stations as provided and the autosampler arm will then equip itself on each occasion with the instrument-holder assembly which the predefined analysis programme commands it to use.

The disengagement operation of the instrument-holder assembly from the hooking plate attached to the instrument-holder head takes place by performing in reverse order the operations described above. The head of the autosampler arm 1 approaches frontally the preset storage station and rests the instrument-holder assembly on the intermediate arms 11 in such a way that the pins 15 penetrate the seats 31 a, b, forcing against the stems 30a, b which are pushed upwards. In this way the hooks 27a, b and 28 also disengage from the respective separators 7a and 4a, freeing the plate 4 from the instrument-holder assembly 13.

The interactions between the means of hooking of the instrument-holder assembly to the head of the autosampler arm, i.e. between the hooks 27a, b and 28, and the means of unhooking of the instrument-holder assembly from the storage station, i.e. the pins 15, are such that minimal mechanical stresses and vibrations are transmitted to the autosampler arm.

The possibility of replacing the instruments automatically allows, without causing intervention of an operator who might not even be present (this apparatus often operates also at night), the creation of a continuity in the processing of the sample, thus eliminating down times and operations to be performed manually with relative probability of making analytical errors.

In the present description reference has been made to an instrument-holder assembly formed by assembling four parts: the two side panels 16a, b, the U-shaped plate 17 and the C-shaped band 18. This solution was chosen for constructional reasons, but it is understood that any other constructional solution comes within the sphere of the invention, for example a functionally equivalent construction in a single part.

Changes and/or modifications may be made to the automatic instrument replacement device for robotic autosampler arms without thereby departing from the scope of the invention as defined in the following claims.

Claims

1. Device for the automatic replacement of an instrument on a robotic autosampler arm ending with an operating head (1 ) moving in three orthogonal directions and co-operating with at least one station (3) for the temporary storage of said instrument, characterised in that it comprises an attachment plate (4) which can be connected to the head (1 ) of the autosampler arm and an instrument-holder assembly (13) positioned removably on said at least one storage station (3) and provided with hooking means (27a,b;28) for engaging on said attachment plate (4) following a movement of approach of said head (1 ) of the autosampler arm towards said storage station (3), whereby said instrument-holder assembly (13) is disengaged from said storage station (3) and made temporarily integral with said head (1 ), said storage station (3) comprising means (15) for disconnecting the instrument-holder assembly from said head suitable for moving said hooking means (27a,b;28) in relation to said attachment plate (4) to cause their mutual disengagement when said instrument-holder assembly (13) is deposited on said storage station (3).

2. Device according to claim 1 , wherein several storage stations (3A, 3B, 3C) are provided, each one being equipped with an instrument-holder assembly (13A, 13B, 13C) dedicated to a specific instrument and mountable on said head (1 ) of the autosampler arm automatically.

3. Device according to claims 1 or 2, wherein said hooking means comprise hooks (27a,b;28) extending frontally from said instrument-holder assembly (13) and said attachment plate (4) comprises corresponding engagement seats (7) for said hooks.

4. Device according to claim 3, wherein said hooks comprise a pair of lower hooks (27a, b) and an upper hook (28) positioned at two different heights and suitable for engaging respectively on two separators (7a) formed in two corresponding vertical slots (7) of said attachment plate (4) and on a further separator (4b) formed in the upper part of said plate (4).

5. Device according to claims 3 or 4, wherein said lower hooks (27a, b) and said upper hook (28) are integrally sliding on the instrument-holder assembly (13).

6. Device according to claim 5, wherein said lower hooks (27a, b) are connected to said upper hook (28) by guide means (30a, b) engaged slidingly in said instrument- holder assembly, said guide means comprising elastic means (32a, b) for keeping said lower and upper hooks in an engagement on said separators of said attachment plate.

7. Device according to any one of the previous claims, wherein said instrument- holder assembly (13) comprises a replaceable seat (17, 20) for housing a container (14) for the instrument.

8. Device according to any one of the previous claims, wherein said instrument- holder assembly (13) comprises two side panels (16a, b) connected one to the other by a substantially U-shaped plate (17) arranged between them and defining said seat (20), on said plate (17) two parallel slot apertures (26a, b) being formed from which said lower hooks (27a, b) project, said guide means being formed by a pair of stems (30a, b) engaged slidingly in respective seats (31 a, b) formed in said side panels (16a,b), said elastic means being formed by springs (32a, b) coaxial to said stems (30a, b) placed between said lower hooks (27a, b) and respective shoulders (33) of said seats (31 a, b).

9. Device according to any one of the previous claims, wherein said instrument- holder assembly (13) comprises a portion (22) sliding along the axis of the instrument for actuation of the instrument, said sliding portion being temporarily attachable to said storage station (3) together with said instrument-holder assembly (13) and being temporarily connectable to an actuator member positioned in said head (1 ).

10. Device according to claim 10, wherein said sliding portion is a crosspiece (22) wherefrom vertical guides (21 ) extend, connected slidingly to the side panels (16a,b) of said instrument-holder assembly (13).

1 1. Device according to any one of the previous claims, wherein said means for disconnecting the instrument-holder assembly from said head comprise at least one pin (15) integral with said storage station (3) which, when the instrument-holder assembly (13) is deposited thereon, engages in a through hole (35) formed correspondingly in the base of the instrument-holder assembly and, while it makes the latter temporarily integral with the storage station, pushes said hooks in a disengagement direction from said head.

12. Device according to any one of the previous claims, wherein said instrument is an SPME probe, a syringe, a microsyringe, tips, pipettes and micropipettes, capillary tubes, dosers of solids, needles, instruments with special functions, such as sensors, pincers, micro stirrers, heating components, etc.