Method for sampling headspace and transfer container

Abstract

The present invention relates to a device (1) for sampling headspace, comprising: a mobile station (2) provided with a plurality of housing seats (21) to house a plurality of containers (100) for sampling headspace; an oven (3); a blocking device (4) comprising at least one first mobile element (41) which moves between a first position suitable to prevent the passage of the containers (100) from the mobile station to the oven and a second position suitable to allow the passage of the containers (100) from the mobile station to the oven; at least one first sensor (5a) placed upstream of the first mobile element (41) to detect the presence of the containers in the housing seats (21); a movement element (6) which moves between said mobile station (2) and the oven (3), configured to move the containers (100) from the mobile station (2) to the oven (3).

Description

TECHNICAL FIELD

[0001] The present invention relates to material analysis. In particular, the present invention relates to an apparatus and a method for headspace sampling, a technique commonly used for analyzing liquid or solid samples via coupling with a gas chromatograph or similar analysis instrument. BACKGROUND

[0002] Gas chromatography is known to be an advantageous method for determining the components of a mixture. In order to perform a gas chromatographic analysis, the sample of the mixture to be analyzed must be volatilized and introduced into a gas chromatographic column, in which its different components are separated at different times and reach the outlet at different times. The various individual components can be detected by one or more of their chemical or physical properties.

[0003] Headspace sampling is a technique which involves analyzing the vapors generated by a solid or liquid sample in a closed container. In other words, a closed container or vial is partially filled with a liquid or solid sample; above the sample, i.e. in the so-called "headspace", vapors are generated which are then collected for analysis. Due to the temperature and, in the case of liquid samples, also the agitation, the substances to be analyzed "move" into the gas phase, which is then collected through special means such as a needle inserted through a septum into the vial.

[0004] Preferably, in order to increase the sensitivity of the gas chromatographic analysis, the substances to be analyzed should be highly concentrated in the headspace, i.e. the transition from the liquid phase to the headspace must be maximized; it is also particularly advantageous to minimize the time required to perform this operation.

[0005] In the known technique applied to liquid samples, the vial is heated and agitated in order to promote and accelerate the accumulation of the substances to be analyzed in the headspace until a thermodynamic equilibrium is reached, i.e. at the point at which the distribution of the substances between the two phases (liquid and gas) is maintained constant over time.

[0006] The apparatus for headspace sampling is therefore generally equipped with a moving station for housing the vials and with an incubation oven for heating and, if necessary, agitating the vials.

[0007] The movement of the vials from the moving station to the incubation oven is generally performed in an unattended manner. In particular, special means move the desired vials from the moving station to the incubation oven. At the end of the sampling process, the vials are then unloaded from the incubation oven and repositioned on the moving station, generally in their original position.

[0008] Potential system errors can cause unwanted vials to be moved in the incubation oven and / or to be present in the moving station. These situations can potentially cause errors in the subsequent steps of the gas chromatography analysis. In addition, the system can attempt to place a vial in a position that has already been occupied by a previous vial. In this case, the previous vial can be released from the moving station by mistake and can break due to the fall, thereby potentially releasing toxic substances.

[0009] It is therefore an object of the present application to solve the above-mentioned problems of the prior art. SUMMARY

[0010] It is a particular object of the present application to provide an apparatus and a method for headspace sampling that allow easy and safe management of vials or containers.

[0011] The present application solves these and other objects by means of an apparatus and a method according to one or more of the appended claims.

[0012] An aspect of the present application relates to an apparatus for headspace sampling, comprising: a moving station provided with a plurality of housing seats in order to house a plurality of containers for headspace sampling; a heater; a blocking device comprising at least one first moving element that moves between at least two positions, a first position configured to prevent the passage of a container from the moving station to the heater, and a second position configured to allow the passage of a container from the moving station to the heater; at least one first sensor placed upstream of the first moving element to detect the presence of a container in one of the housing seats; a movement element movable between the moving station and the heater, the movement element being configured to move a container from the moving station to the heater.

[0013] Thanks to the present solution, the headspace sampling apparatus is able to determine which moving station seats are provided with a container and which are empty, thus preventing positioning errors of the containers themselves.

[0014] According to one aspect of the present application, the apparatus comprises a second sensor placed downstream of the first moving element of the blocking device in order to detect the presence of a container in the heater.

[0015] It should be noted that here and in the following the definitions of "upstream" and "downstream" will be used. These definitions refer to the direction of movement of the containers when moving from the moving station to the heater.

[0016] This also makes it possible to detect whether there is free space in the heater for a container, thus preventing the arrangement of a container in the heater when the latter is already occupied.

[0017] According to one aspect of the application, the first moving element is rotatable, preferably in the form of a disc, and is provided with an opening suitable for defining said first and second positions.

[0018] According to one aspect of the application, the first moving element is movable to a third position suitable for preventing the passage of the container from the moving station to the heater and suitable for allowing contact between the container and the moving element.

[0019] According to one aspect of the application, the blocking device comprises a second moving element placed downstream of the first moving element, movable between a first position suitable for preventing the passage of the container from the moving station to the heater and a second position suitable for allowing the passage of the container from the moving station to the heater.

[0020] Preferably, also the second moving element is rotatable, and generally disc-shaped.

[0021] According to one aspect of the application, the sensor placed downstream of the first moving element is placed upstream of the second moving element.

[0022] One aspect of the application also relates to a method for transferring a container from a moving station of a device according to one of the preceding aspects to a heater, the method comprising the following steps: i) moving the moving station so that the housing seat is arranged in the desired position; ii) operating the first sensor to verify the presence of a container in the housing seat; iii) operating the moving element to reach the container; iv) moving the first moving element to the second position; v) operating the moving element so that the container moves from the station to the heater; wherein steps iv) and v) are carried out only if the presence of a container in the housing seat has been confirmed in step ii).

[0023] Not all the operations listed above must be carried out in the order described above; in particular, step iii) and step iv) can occur at least partially simultaneously, or in the opposite order with respect to what is described.

[0024] According to one aspect of the application, preferably when a second sensor is also present in the device, in step v) the height and / or the volume of the container are estimated on the basis of the signal of the first sensor and / or of the second sensor, if present.

[0025] The determination of the height and / or the volume of the container is useful for the subsequent operation of the device. In particular, if the volume or at least the height of the container is correctly estimated, it is possible to determine the correct depth at which an element suitable for collecting a sample, generally in the form of a needle, must be inserted into the container, and it is also possible to determine the correct amount of gas to be inserted into the container itself.

[0026] One aspect of the present application also relates to a method for transferring a container from a heater to a mobile station, the method comprising the following steps: i') moving the mobile station so that the containing seat is arranged in the desired position; ii') operating the first sensor to verify the absence of a container in the containing seat; iii') moving the first mobile element to the first position; iv') operating the movement device so that the container moves from the heater to the mobile station; v') moving the first mobile element to the second position; BRIEF DESCRIPTION OF DRAWINGS

[0027] With reference now to the attached drawings, exemplary and non-limiting embodiments of the present application will be described.

[0028] - Figure 1 is a perspective view of the device according to an embodiment of the present application;

[0029] - Figure 2 is a front view of the upper part of the device of Figure 1 ;

[0030] - Figure 3 is a rear view of the content of Figure 2 ;

[0031] - Figure 4 is a top perspective view of the device of Figure 2 ;

[0032] - Figure 5 is a bottom perspective view of the content of Figure 2 ;

[0033] - Figure 6a and Figure 6b is a plan view of the mobile element of the blocking device of the device of Figure 1 ;

[0034] - Figures 7 to 9 is a plan view of the content of Figure 2 , in which the first mobile element of the blocking device is shown in different positions;

[0035] - Figure 10 is a bottom view of the content of Figure 2 ;

[0036] - Figure 11 and Figure 12 is a front view of the device of Figure 1 , in which the movement device 6 is shown in different positions. DETAILED DESCRIPTION

[0037] The headspace sampling apparatus 1 comprises a mobile station 2, a heater 3, a barrier device 4, usually placed between the mobile station 2 and the heater 3, at least one first sensor 5a and a motion element 6, configured to move the containers 100 between the mobile station 2 and the heater 3 (hereinafter also referred to as "oven 3" for simplicity).

[0038] As shown, the mobile station 2 is preferably in the form of a carousel conveyor, but other embodiments are possible, for example the mobile station can comprise a belt or a track or any element whose motion is at least partially substantially straight.

[0039] In general, the mobile station 2 (hereinafter also referred to as "station 2" for simplicity) is provided with a plurality of housing seats 21, shaped to house the containers 100 (usually in the form of vials or similar elements) for the analysis of the headspace. For example, in the embodiment shown in the figures, the station 2 is provided with twelve housing seats 21 (hereinafter also referred to as "seats 21").

[0040] The seats 21 can have various shapes. Preferably, as in the embodiment shown, the seats 21 are made as cylindrical openings. Usually, each container 100 is not supported from below by the seats 21 and therefore protrudes downwards from the seats 21. An associated surface 7, usually placed below the station 2, acts as lower support for the containers 100, at least along a portion of the path of the containers 100 moved by the mobile station 2.

[0041] The station 2 is configured to move the seats 21 so as to arrange the respective containers 100 in the desired positions. Usually, the motion element 6 cooperates with the containers 100 only when the containers 100 are placed in a particular position of the apparatus 1 (from now on referred to as "operating position"), while the other positions of the seats 21 will be referred to as "idle positions" for simplicity. This denomination is merely descriptive and does not exclude that, when each seat 21 is arranged in an "idle position", other operations can be performed on the containers 100 (in addition to those suitable to move the containers 100 between the station 2 and the oven 3).

[0042] Preferably, the station 2 is placed above the oven 3. Therefore, the oven 3 usually has a duct 31 configured to allow the displacement of the containers 100 between the station 2 and the oven 3. Therefore, the seats 21 arranged coaxially with the duct 31 are in the "operating position", while the other seats 21 are in the "idle position". In alternative embodiments not shown, the operating position can be more than one. For example, with reference to the embodiment shown, the oven can be provided with two ducts, for example a first duct suitable to allow the movement of the containers 100 from the station 2 to the oven 3 and a second duct suitable to allow the movement of the containers 100 from the oven 3 to the station 2.

[0043] The apparatus 1 generally has a motor M configured to move the stations 2. In the embodiment shown, a portion 22 of the outer surface of the stations 2 is toothed and engages with the motor M.

[0044] The blocking device 4 is interposed between the stations 2 and the oven 3, so as to selectively allow and prevent the passage of the containers 100 between the stations 2 and the oven 3. The blocking device comprises at least one first mobile element 41, which can be moved into at least two positions, a first position (shown) suitable for preventing the passage of the containers 100 between the stations 2 and the oven 3, a second position (shown) suitable for allowing the passage of the containers 100 between the stations 2 and the oven 3. Figure 4 and Figure 7 The first position (shown) is suitable for preventing the passage of the containers 100 between the stations 2 and the oven 3, the second position (shown) is suitable for allowing the passage of the containers 100 between the stations 2 and the oven 3. Figure 9 The first position (shown) is suitable for preventing the passage of the containers 100 between the stations 2 and the oven 3, the second position (shown) is suitable for allowing the passage of the containers 100 between the stations 2 and the oven 3.

[0045] In the embodiment shown, the first mobile element 41 is preferably rotatably mobile and is arranged between the stations 2 and the oven 3. According to one aspect, the first mobile element 41 has an opening 410, generally in the form of a slot. The opening 410 has at least one portion 410a which is substantially equal to or greater than the cross section of the seat 21 in size. Thus, in the embodiment shown, when the portion 410a is placed below the seat 21 in the operating position, the container 100 can detach itself from the seat 21 and enter the duct 31, or alternatively, climb back into the duct 31 so as to enter the seat 21.

[0046] When the first mobile element 41 is moved so that the opening 410 is not placed at the seat 21 arranged in the operating position, the container 100 housed in the seat is supported by the solid portion 411 of the first mobile element 41. In this case, the container 100 cannot pass through the first mobile element 41, i.e. the communication between the stations 2 and the oven 3 is prevented.

[0047] The first mobile element 41 is preferably placed flush with the surface 7 of the apparatus 1, i.e. at the same height, so that the containers can be alternately supported by the surface 7 or by the portion 411 of the first mobile element 41, depending on the position of the stations 2. The rotation axis of the first mobile element 41 is thus preferably different from the rotation axis of the stations 2, so that when the stations 2 rotate, the path of the containers 100 only partially overlaps (i.e. only a portion thereof overlaps) the first mobile element 41.

[0048] According to a possible aspect, the first mobile element 41 is also movable into a third position (shown) in which the passage of the containers 100 housed in the station seats 21 between the stations 2 and the oven 3 is prevented, but the contact between the mobile element 6 and the containers 100 housed in the seats 21 is allowed. Figure 8

[0049] ​Preferably, as in the illustrated embodiment, the opening 410 of the first mobile element 41 has at least one portion 410b having a section smaller than that of the seat 21, so that when the portion 410b is placed at the seat 21 provided with the container 100, the container 100 cannot pass through the first mobile element 41.

[0050] According to a possible aspect, as illustrated, the blocking device 4 comprises a second mobile element 42. The second mobile element 42 is located downstream of the first mobile element 41. As mentioned above, the definition of "upstream" and "downstream" refers to the direction of movement of the containers 100 from the station 2 to the oven 3 (in the case of the Figure 1 、 Figure 11 and Figure 12 , this direction corresponds to the movement from top to bottom).

[0051] The second mobile element 42 can also be mobile between a first position, suitable to prevent the passage of the containers 100 between the station 2 and the oven 3, and a second position, suitable to allow the passage of the containers 100 between the station 2 and the oven 3.

[0052] According to an aspect, the second mobile element 42 is rotatable and has an opening 420 having at least one portion 420a having a section equal to or greater than that of the seat 21, so as to allow the passage of the containers 100 through the portion 420a.

[0053] With reference to the embodiment illustrated in the figures, the second mobile element is in the second position when it is rotated so that the opening 420 is arranged on the path of the containers 100. On the other hand, when the solid portion 421 of the second mobile element 42 is arranged at the path of the containers 100, the containers 100 cannot pass through the second mobile element 42 and therefore the second mobile element 42 is in the first position described above, i.e. it prevents the passage of the containers from the oven 3 to the station 2.

[0054] Preferably, the angular extent β of the opening 420 of the second mobile element 42 is equal to or greater than the angular extent a of the opening 410 of the first mobile element 41. In this way, the first mobile element 41 and the second mobile element 42 can be rotated in phase (in coordination) so that the openings 410, 420 are always aligned with each other.

[0055] According to a preferred aspect, the second mobile element 42 is rotationally integral with the first mobile element 41, so as to ensure that the two elements are always in phase with each other. Furthermore, a single electric element can be used for both the first mobile element 41 and the second mobile element 42.

[0056] The oven 3 can be any element capable of receiving and heating the containers 100. Preferably, the oven 3 has a carousel conveyor 32, or in any case a movement system suitable to rock one or more containers 100.

[0057] Furthermore, the apparatus 1 also has movement means 6, which are adapted to move the container 100 between the seat 21 of the station 2 and the oven 3. Various means can be used for this purpose. In the preferred embodiment, as shown in the figures, the movement means 6 comprise an elevator 61, which is adapted to support the container 100 from below. In this way, the elevator 61 is able to lower the container 100 from the station 2 to the oven 3 and, later, to raise the container 100 from the oven 3 to the station 2.

[0058] The elevator 61 can be moved in several ways known in the art. For example, in the embodiment shown in the figures, the elevator 61 is equipped with a rack 61a, which is operatively coupled to a pinion 62, which is usually moved by a corresponding motor.

[0059] Preferably, the elevator 61 is provided with a coupling portion 61b, which allows the coupling with the container 100, which has a cross section smaller than the portion 410b of the opening 410 of the first mobile element 41, i.e. it is sized so that it can be contained inside the portion 410b, thus making it possible to pass through the portion 410b of the opening 410.

[0060] Therefore, when the first mobile element 41 of the blocking device 4 is in the third position described above, the container 100 is supported by the first mobile element 41, since it cannot pass through the portion 410b of the opening 410, but the elevator 61 can pass through the portion 410b of the opening 410, thus coming into contact with the lower surface of the container 100.

[0061] The apparatus 1 also comprises a first sensor 5a and, preferably, a second sensor 5b.

[0062] The first sensor 5a is a sensor adapted to detect the presence of the container 100 in the seat 21, usually in the seat 21 in the operating position. Therefore, the first sensor 5a is preferably arranged upstream of the first mobile element 41 of the blocking device 4 and, when the container 100 is arranged in the seat 21, it is directed towards the position occupied by the container 100.

[0063] Various sensors adapted to act as first sensors 5a, such as, for example, proximity sensors of the optical type, are known in the art and will not be discussed in detail here.

[0064] The possible variations of the preferred embodiment having an optical reflection sensor can use a sensor adapted to detect the presence of a ferromagnetic material, i.e. the threaded cap of the container 100, such as a magnetoresistive sensor.

[0065] Preferably, the apparatus 1 has a second sensor 5b adapted to detect the presence of the container 100 inside the oven 3. As mentioned above, different sensors, typically proximity sensors (for example optical sensors) can be used as second sensor 5b. According to a possible aspect, the second sensor 5b is placed downstream of the first mobile element 41 and, if present, is preferably interposed between the first mobile element and the second mobile element of the blocking device 4.

[0066] Generally, the second sensor 5b should preferably be placed outside the oven 3, or in any case outside the heating area of the oven 3, so as to prevent the sensor itself from being damaged. Therefore, the second sensor 5b does not directly detect the presence of the container in the oven 3. In fact, preferably, in order to verify the presence of the container 100 in the oven 3, the operating movement device 6 is operated to move the container 100 from the oven 3 to a position close to the second sensor 5b, which can therefore verify the actual presence of the container 100 constrained to the movement device 6.

[0067] With reference to the embodiment shown, in order to use the sensor 5b, the elevator 61 raises the container 100 so that it passes through the second mobile element 42 and not the first mobile element 41, which is preferably arranged in the third position. As mentioned above, according to the preferred embodiment, the first mobile element 41 and the second mobile element 42 are rotationally integral with each other, so as to ensure the alignment of the openings 410, 420 of the first mobile element 41 and of the second mobile element 42.

[0068] In use, one or more containers 100 are arranged in the corresponding seats 21 of the station 2.

[0069] When it is necessary to transport the container 100 from the station 2 to the oven 3, the station 2 is moved so as to arrange the container 100 in the desired position, i.e. in a position that allows the container 100 to be picked up and released by the movement device 6 from the respective seat 21. In other words, with reference to the previous description, the station 2 is moved so as to arrange the seat 21 containing the desired container 100 in the operating position.

[0070] Then, the first sensor 5a is operated so as to check that the container 100 is actually present inside the seat 21. For example, an optical proximity sensor can check whether an element is in its vicinity. If the sensor does not detect any element, the seat 21 does not contain the container 100 and the subsequent operations of the apparatus 1 are not performed.

[0071] When the first sensor 5a confirms the presence of the container 100, the first movement element 6 is moved so as to reach the container 100.

[0072] In the embodiment shown, the elevator 61 is raised near the lower part of the container 100. The second moving element is placed in the second position to allow the elevator 61 to pass, while the first moving element 41 is preferably moved to the third position, so as to support the container 100 but at the same time allow the elevator 61 to pass through the portion 410b of the opening 410. Then, the elevator 61 comes into contact with the bottom of the container 100.

[0073] The first moving element 41 is then rotated to the second position, thereby allowing the container 100 to pass through the portion 410a of the opening 410. Now, the moving element 6 can transport the container 100 from the station 2 to the oven 3. In the embodiment shown, the first moving element 41 is moved to the second position. The container 100 is no longer supported by the first moving element, but only by the elevator 61. The elevator 61 is then lowered so as to transfer the container 100 from the station 2 to the oven 3.

[0074] At this point, the oven 3 can operate to heat, and, if necessary, to shake the container 100. The second moving element 42 is preferably rotated so as to block the duct 31, thereby preventing the loss of heat from the oven 3 and preventing the sensors 5a, 5b from being heated.

[0075] According to a possible aspect, the signal of the first sensor 5a or of both the first sensor and the second sensor 5b, if the latter is present, can be used to determine or at least estimate the height of the container 100, and preferably, but not necessarily, also the volume.

[0076] In particular, the diameter of the container 100 is a datum known to the apparatus 1, since it is slightly smaller than the seat 21, or in any case it is communicated to the apparatus 1 by the user. The apparatus 1 also knows the speed of the moving element 6. Therefore, it can evaluate for how long its sensor or sensors detect the presence of the container 100, so as to evaluate the height of the container 100. Therefore, knowing the height and the diameter of the container, the apparatus 1 is able to evaluate the volume of the container 100.

[0077] For example, the apparatus 1 picks up a container 100 from a seat adapted to contain a container having a diameter of 2 cm. First, when the container is lowered, the sensor, for example the second sensor 5b, does not detect the presence of the container 100. Later, the sensor detects the presence of the container 100 for the first time; subsequently, the sensor continues to detect the presence of the container until a third instant, at which the sensor no longer detects the presence of the container 100. For example, if there is a time difference of 3 seconds between the second and the third instant, and the elevator 61 is lowered at a speed of 1 cm / s, the apparatus estimates the height of the container 100 to be 3 cm. Once the diameter and the height of the container 100 are known, the apparatus has all the data necessary to estimate the volume of the container 100. If the distance between the sensors themselves is known, these operations can be performed more quickly by using the signals of a plurality of sensors.

[0078] The operations to move the containers 100 from the oven 3 to the station 2 are performed in the reverse order to that described above. Briefly, the station 2 is arranged so that the movement means 6 can reach the seat 21 selected for housing the container 100. The first sensor 5a is then operated to verify whether this seat 21 is actually empty.

[0079] On the other hand, the second sensor is used to check the presence of a container 100 in the oven. As mentioned above, this step preferably involves movement of the movement means so as to arrange the container 100 close to the second sensor 5b. With reference to the embodiment shown in the figures, the height to which the elevator 61 is raised is such that the container 100, if present, does not enter the seat 21, but is arranged close to the second sensor 5b in any case. For example, previously (i.e. during the descent of the container), the apparatus 1 estimates the height of the container and is therefore able to evaluate the amount of movement required for the elevator 61.

[0080] Preferably, the first mobile element 41 is arranged in the first position or in the third position so as to prevent the container 100 from entering the respective seat 21 before the sensors 5a, 5b perform the respective checks in the event of an erroneous movement of the movement means 6.

[0081] If the first sensor 5a has confirmed that the seat 21 is not occupied and the second sensor 5b has confirmed that there is actually a container 100 in the oven 3, the operations of the apparatus 1 can continue.

[0082] In particular, the first mobile element 41 is arranged in the second position, thereby allowing passage of the container 100 to the seat 21 by operation of the movement means 6.

[0083] Subsequently, the movement means 6 are released from the container 100, which remains in the seat 21. In particular, with reference to the embodiment shown, when the container 100 passes the first mobile element 41, the first mobile element 41 moves to the third position. In this position, the movement means are still in contact with the container 100, although the container is also supported by the first mobile element 41 itself, i.e. by the edge of the portion 410b of the opening 410. The elevator 61 can then be lowered and the first mobile element can be arranged in the first position.

[0084] It should be noted that, among the possible variants, the second position and the third position of the first mobile element 41 can coincide. In particular, the first mobile element 41 can be movable only between a first position, suitable to prevent the passage of the containers between the station 2 and the oven 3, and a second position, suitable to prevent the passage of the containers between the station 2 and the oven 3, but suitable to allow the containers 100 and the mobile element 6 to come into contact with each other. With reference to the embodiment shown, the first mobile element 41 can therefore be movable so as to arrange only the portion 410a or the portion 410b of the opening 410 below the seat 21 placed in the operating position.

[0085] In another possible variant, the blocking device can comprise a single mobile element, suitable to selectively allow and prevent the passage of the containers 100 between the station 2 and the oven 3, and preferably also suitable to close the oven 3 during the operation thereof, limiting or preventing the loss of heat. In this embodiment, the sensor(s) are preferably arranged upstream of this mobile element.

Claims

1. A method for transferring a container (100) from a mobile station (2) of an apparatus (1) to a heater (3), comprising the following steps: - step i) moving the mobile station (2) so that a housing seat (21) of the mobile station (2) is arranged in a desired position; - step ii) operating a first sensor (5a) of the apparatus (1) to verify the presence of a container (100) in the housing seat (21) and operating a second sensor (5b) of the apparatus (1) to verify the presence of the container (100) in the heater (3), wherein the first sensor (5a) is placed upstream of a first mobile element (41) and the second sensor (5b) is placed downstream of the first mobile element (41) and outside the heater (3); - step iii) operating a movement element (6) of the apparatus (1) to reach the container (100); - step iv) moving the first mobile element (41) of a blocking device (4) of the apparatus (1) from a first position, suitable to prevent the passage of a container (100) from the mobile station (2) to the heater (3), to a second position, suitable to allow the passage of a container (100) from the mobile station (2) to the heater (3); - step v) operating the movement element (6) so that the container moves from the mobile station (2) to the heater (3); wherein steps iv) and v) are carried out only if in step ii) the presence of the container (100) in the housing seat (21) has been confirmed; wherein in step v) the height of the container (100) is determined from the signal of the first sensor (5a) and from the signal of the second sensor (5b), which are the duration of time in which at least one of the first sensor (5a) and the second sensor (5b) detects the container (100) when the container (100) moves from the mobile station (2) to the heater (3).

2. The method of claim 1, wherein, In step iii) the first mobile element (41) is moved to a third position, suitable to prevent the passage of a container (100) from the mobile station (2) to the heater (3) and to allow the contact between a container (100) and the movement element (6).

3. The method according to claim 1 or 2, characterized in that, In step v) the volume of the container (100) is also estimated from the signal of the first sensor and from the signal of the second sensor (5b).

4. A method for transferring a container (100) from the heater (3) of the apparatus (1) to the mobile station (2) after the method according to any one of claims 1 to 3, comprising the following steps: - step i') moving the mobile station (2) so that a housing seat (21) is arranged in a desired position; - step ii') operating the first sensor (5a) to verify the absence of a container (100) in the housing seat (21); - step iii') operating a movement element (6) of the apparatus (1) to reach the container (100); - step iv') moving the first mobile element (41) of a blocking device (4) of the apparatus (1) from a first position, suitable to prevent the passage of a container (100) from the heater (3) to the mobile station (2), to a second position, suitable to allow the passage of a container (100) from the heater (3) to the mobile station (2); - step v') operating the movement element (6) so that the container moves from the heater (3) to the mobile station (2); wherein steps iv') and v') are carried out only if in step ii') the absence of a container (100) in the housing seat (21) has been confirmed. - step iii') operating said second sensor (5b) to verify the presence of a container (100) in said heater (3); - step iv') moving said first mobile element (41) to said second position; - step v') operating said movement element (6) so that said container (100) moves from said heater (3) to said mobile station (2); - step vi') moving said first mobile element (41) to said first position; wherein steps iv'), v') and vi') are performed only if in said step ii') it has been verified that no container (100) is present in said housing seat (21) and in said step iii') it has been verified that a container (100) is present in said heater (3).

5. An apparatus (1) for headspace sampling suitable for carrying out the method according to any one of claims 1 to 4, comprising: - a mobile station (2) provided with a plurality of housing seats (21) to house a plurality of containers (100) for headspace sampling; - a heater (3); - blocking means (4) comprising at least one first mobile element (41) which moves between at least two positions, a first position suitable to prevent the passage of a container (100) from said mobile station (2) to said heater (3) and a second position suitable to allow the passage of a container (100) from said mobile station (2) to said heater (3); - at least one first sensor (5a) placed upstream of said first mobile element (41) to detect the presence of a container (100) in one of said housing seats (21); - a movement element (6) which moves between said mobile station (2) and said heater (3), said movement element being configured to move a container (100) from said mobile station (2) to said heater (3), wherein said apparatus comprises a second sensor (5b) placed downstream of said first mobile element (41) and outside said heater (3) to detect the presence of a container (100) in said heater (3).

6. The device (1) according to claim 5, characterized in that Said first mobile element (41) is rotatable and is provided with an opening (410) suitable to define said first position and said second position.

7. The device (1) according to claim 5 or 6, characterized in that Said first mobile element (41) is movable to a third position suitable to prevent the passage of a container (100) from said mobile station (2) to said heater (3) and to allow the contact between a container (100) and said movement element (6).

8. The device (1) according to claim 5 or 6, characterized in that Said blocking means (4) comprise a second mobile element (42) placed downstream of said first mobile element (41), said second mobile element (42) being movable between a first position suitable to prevent the passage of a container (100) from said mobile station (2) to said heater (3) and a second position suitable to allow the passage of a container (100) from said mobile station (2) to said heater (3).

9. The device (1) according to claim 8, characterized in that The sensor placed downstream of the first mobile element (41) is placed upstream of the second mobile element (42). The sensor placed downstream of the first mobile element (41) is placed upstream of the second mobile element (42).

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