Patent Application
20240297033
This application claims priority from and the benefit of United Kingdom patent application No. 2108988.3 filed on 23 Jun. 2021. The entire contents of this application are incorporated herein by reference.
The present invention relates generally to mass and/or ion mobility spectrometry and in particular to a mass and/or mobility spectrometer which has an integrated vacuum pumping line for removing gas from one or more sub-atmospheric pressure regions of the spectrometer.
Conventional mass spectrometers typically require vacuum pumping and gas evacuation from various low-pressure regions of the mass spectrometer, such as an ion source region or a vacuum chamber. The apparatus used for vacuum pumping and gas evacuation can be bulky and the manner in which the vacuum pump is connected to the mass spectrometer can cause gas flow instability within the region to be pumped.
It is desired to provide an improved mass and/or mobility spectrometer.
The present invention provides a mass and/or mobility spectrometer comprising: a vacuum housing having a first vacuum chamber therein; and a first vacuum pump connected to said first vacuum chamber by a conduit; wherein at least a part of the conduit extends along the vacuum housing within a wall of the vacuum housing.
It is sometimes difficult to configure a spectrometer such that the vacuum pump can be provided in the vicinity of the vacuum chamber that it evacuates. Conventionally, this problem is overcome by using a bellows tube to connect the vacuum pump to the vacuum chamber. However, as such conventional tubing is easily movable, it can cause gas-flow instabilities in the vacuum chamber. Also, such tubing places restrictions on the geometry of the spectrometer and how it can be packaged. In contrast, embodiments of the present invention provide a conduit that is an integral part of the vacuum housing (i.e. formed from the body of the vacuum housing) and that extends from the vacuum chamber along and within the vacuum housing. This arrangement overcomes problems with conventional arrangements.
At least part of the conduit may have an axis therethrough that extends substantially parallel to said wall of the vacuum housing.
The first vacuum chamber may define a longitudinal axis, wherein at least a part of the conduit may have an axis therethrough that extends substantially parallel to the longitudinal axis of the first vacuum chamber.
The conduit within the wall of the housing may extend from an upstream end, that is coincident with a first aperture in a wall of the first vacuum chamber, to a downstream end. Moreover, the conduit may have a bend therein between its upstream and downstream ends.
For example, a first length of the conduit may extend downstream from the first aperture to the bend and a second length of the conduit may then extend downstream from the bend. The first and second lengths of the conduit may be substantially orthogonal to each other, or at an acute or obtuse angle to each other.
The axis through the first aperture (into the upstream end of the conduit) may be substantially orthogonal to said wall of the vacuum housing. Alternatively, the axis through the first aperture may be provided at an angle other than 90 degrees to said wall of the vacuum housing, and the first length of the conduit may extend from the first aperture to the bend along said angled axis.
The spectrometer may be configured to guide ions along a first axis through a second aperture in the first vacuum chamber, which is different to the first aperture into the upstream end of the conduit. The first axis may be substantially orthogonal to the axis through the first aperture (into the upstream end of the conduit).
The first vacuum chamber may comprise an ion-optical element housed therein, such as an ion guide.
The vacuum housing may have a front end at which an ion source is mounted and an opposite, rear end; wherein the conduit extends from a first aperture in a wall of the first vacuum chamber, within the wall of the vacuum housing in a direction extending from said front end to said rear end, and to a downstream end of the conduit that is connected to the vacuum pump.
In these embodiments, the first vacuum chamber may be a source vacuum chamber.
The downstream end of the conduit may be in the rear end of the vacuum housing.
The spectrometer may comprise an ion source; wherein the first vacuum chamber is adjacent the ion source or the ion source is within the first vacuum chamber.
In embodiments wherein the first vacuum chamber is adjacent the ion source, the ion source may be configured to generate ions to be analysed and to introduce said ions to be analysed into the first vacuum chamber.
It is difficult to provide the vacuum pump in the vicinity of such a vacuum chamber and hence a bellows tube has conventionally been used to connect the vacuum pump to such a vacuum chamber. However, as described elsewhere herein, there are problems with such conventional tubing. The conduits according to the embodiments of the present invention overcome such problems.
The conduit may extend at least 2 cm within the wall of the vacuum housing.
For example, the conduit may extend a length within the wall of the vacuum housing that is at least 5 cm, at least 10 cm, at least 15 cm, at least 20 cm, at least 25 cm, at least 30 cm, at least 35 cm, at least 40 cm, at least 45 cm, at least 50 cm, at least 60 cm, at least 70 cm, at least 80 cm, at least 90 cm, or at least 100 cm.
Such configurations ensure that the rigid conduit provided by the body of the vacuum housing extends a relatively long distance downstream from the first vacuum chamber. This helps to minimise gas-flow instabilities when evacuating the first vacuum chamber.
The vacuum housing may house one or more ion-optical elements and/or a mass analyser therein.
The vacuum housing may further comprise one or more vacuum chambers downstream of the first vacuum chamber.
A first downstream vacuum chamber of the one or more vacuum chambers may be immediately adjacent the first vacuum chamber and is configured to receive said analyte ions from the vacuum chamber through the second aperture of the vacuum chamber.
The first downstream vacuum chamber may comprise an aperture and an ion guide arrangement; wherein a second downstream vacuum chamber of the one or more downstream vacuum chambers may be downstream of the first downstream vacuum chamber; and wherein the ion guide arrangement may be configured to transmit said analyte ions from the first downstream vacuum chamber through the aperture to the second downstream vacuum chamber.
The conduit may comprise a cross-section which is one of: (i) circular; (ii) or rectangular or square; (iii) triangular; (iv) V-shaped; (v) elongated oval shaped, and (vi) crescent-shaped. Where the cross-sectional shape is elongated, it is desirably elongated in the horizontal direction such that conduit (and therefore instrument height) may be relatively small.
The conduit may comprise a cross-section which varies along the length of the conduit.
The conduit may comprise one or more turns and/or follows a curvilinear path through the body of the vacuum housing.
The vacuum housing may further comprises a second vacuum chamber configured to receive ions from said first vacuum chamber and a second vacuum pump having an inlet port for evacuating gas from said second vacuum chamber and an outlet port for discharging the evacuated gas, wherein the discharge port is connected in fluid communication with said conduit such that said first vacuum pump pumps gas from the discharge port.
In embodiments where the first vacuum chamber is the source vacuum chamber, the second vacuum chamber may be the first downstream vacuum chamber described herein (i.e. the first vacuum chamber downstream of the source vacuum chamber).
The spectrometer may comprise a port through said wall of the vacuum housing for allowing gas to pass from outside the vacuum housing into the conduit, wherein a tube connects the discharge port of the second vacuum chamber to said port.
The vacuum housing may comprise a plurality of vacuum chambers configured to receive ions from said first vacuum chamber, wherein said second vacuum pump has: a plurality of inlet ports, wherein each inlet port is for evacuating gas from a respective vacuum chamber of said plurality of vacuum chambers; and a single outlet port for discharging the evacuated gas.
The second pump may be a turbomolecular pump.
The first pump may be a roughing pump.
The present invention also provides a method of mass and/or mobility spectrometry, comprising: providing a spectrometer as described herein; and evacuating gas from the first vacuum chamber via said conduit using said first vacuum pump.
The present invention also provides a method of manufacturing a vacuum housing for a mass and/or mobility spectrometer, comprising: forming a vacuum housing having a first vacuum chamber therein; and forming a conduit within and along a wall of the vacuum housing that extends to a first end that opens into the first vacuum chamber.
The method may comprise forming the conduit: by drilling through the vacuum housing; or during casting or three-dimensional printing of the vacuum housing.
The present invention also provides a method of manufacturing a mass and/or ion mobility spectrometer comprising: performing any of the methods described above; and connecting a first vacuum pump to a second end of the conduit that is opposite to the first end.
Various embodiments of the invention, together with other arrangements given for illustrative purposes only, will now be described, by way of example only, and with reference to the accompanying drawings in which:
Ions to be analysed are generated in the ion source 104 and then introduced into the source vacuum chamber 112. The ions to be analysed may then be separated within the source vacuum chamber 112 from non-analyte waste material and gasses. For example, the analyte ions may be guided through the source vacuum chamber 112 and into the downstream vacuum chamber 124, whereas most of the gas and waste material may be pumped out of the source vacuum chamber 112 and not transmitted.
As shown in
As will be appreciated, the vacuum chambers house various ion-optical devices, such as ions guides and mass analysers (not shown). For example, ions to be analysed may be transferred from the ion source 104 to the source vacuum chamber 114, then in a downstream direction through the various vacuum chambers.
The vacuum chambers of vacuum housing 110 will preferentially have progressively higher levels of vacuum (i.e. progressively lower pressures) going from the upstream end to downstream end of the mass spectrometer 100. Turbomolecular pumps are provided to evacuate the vacuum chambers 114 that are downstream of the source vacuum chamber 112. As shown in
As can be seen in
The inventors have recognised that such a configuration of a conventional pumping arrangement 102 can be problematic. For instance, the roughing line 116 may comprise a NW/KF style corrugated hose or other flexible tubing. Accordingly, this tubing cannot be reliably held in the same position, particularly if the roughing line 116 is detached from the main body of the spectrometer and then reattached. The inventors have discovered that such a conventional pumping arrangement 102 can lead to gas flow instability in the source vacuum chamber 112. For example, without willing to be bound by theory, it is thought that changes in the position of the roughing line 116 relative to the fitting 120 that is attached to the source vacuum chamber 112 may cause instabilities in the source vacuum chamber such as variations in the gas flow being evacuated through pumping line 116. It has been found that this is particularly problematic when such movement of the roughing line 116 occurs at a location close to pumping port of the source vacuum chamber 112. Moreover, the conventional roughing line 116 can be awkward to package in the overall instrument and places limitations on the geometry of the rest of the instrument.
The embodiments of the present invention provide arrangements in which at least an upstream portion of the roughing line is provided by a void within the body of the vacuum housing so as to create a roughing line that is an integral part of the vacuum housing.
Referring to
A first aperture 248 is provided in a first side wall 250 of the source vacuum chamber 212 through which gas from the ion source may be evacuated from the source vacuum chamber 212. A second aperture 252 is provided in a second side wall 254 of the source vacuum chamber 212, through which ions to be analysed are transferred to the first vacuum chamber 224, which is immediately adjacent to and downstream of the source vacuum chamber 212. The source vacuum chamber 212 may include an ion guide 256 to efficiently confine and transfer ions downstream into the one or more further vacuum chambers 214 (through second aperture 252), whilst enabling neutral contamination and gas to be removed from the ion stream.
Still referring to
The roughing conduit 216 enables gas (and waste material) to be pumped out of the source vacuum chamber 212 so as to reduce the pressure therein to sub-atmospheric pressure. The roughing conduit 216 extends through the body of the vacuum housing 210 to an upstream end at which the first aperture 248 is provided. As will be appreciated, there is no requirement for a vacuum fitting between the roughing conduit 216 and the source vacuum chamber 212, and the roughing conduit 216 is unable to move relative to the source vacuum chamber 212. As such, the gas flow out of the source vacuum chamber 212 remains stable. Also, by forming the roughing conduit 212 within the body of the vacuum housing 210, this removes the complexities encountered when attempting to package conventional roughing tubes (in the form of flexible bellows) within the spectrometer.
The downstream end 222 of the roughing conduit 216 is connected to a roughing pump (not shown) to provide the required pumping pressure differential to evacuate the source vacuum chamber 212. The end 222 of the roughing conduit 216 may be fitted with an interface or fitting 223 to enable connection of the roughing conduit 216 with the conventional vacuum fittings of a conventional roughing pump. The downstream end 222 of the roughing conduit 216 may be configured such that the fitting 223 is a conventional vacuum fitting. The downstream end 222 of the roughing conduit 216 may be connected directly to the roughing pump (not shown) without any further intermediate tubing, or may alternatively be connected to the pump via further tubing. However, even when further tubing is required to connect to the roughing pump, it has been found that the provision of the integral roughing conduit 216 in the vicinity of the source vacuum chamber 212 is sufficient to reduce gas flow instability within the source vacuum chamber 212.
The roughing conduit 216 may extend axially through the vacuum housing 210 such that the downstream end 222 of the roughing conduit 216 discharges at a downstream end of the vacuum housing 210 which may be substantially opposite to the upstream end of the vacuum housing 210 comprising the source vacuum chamber 212. That is, the roughing conduit 216 may extend from the source vacuum chamber 212 through the body of the vacuum housing 210 to the rear of the mass spectrometer. The roughing conduit 216 is shown in
Still referring to
The chambers 212, 214 of vacuum housing 210 in
In particular, the mass spectrometer 300 has a roughing conduit 216 with an end region 358, wherein the roughing conduit 216 is open to the aperture 248 of the source region vacuum chamber 212 at the end region 358 of the roughing conduit 216. A passageway 360 extends between the aperture 248 and the end region 358, wherein the passageway 360 is angled with respect to the roughing conduit 216 at an angle other than ninety degrees. This arrangement enables the manufacture of the instrument to be simplified and easier.
The angled passageway 360 may also increase the pumping efficiency of the roughing pump.
The roughing conduit 216 of
Still referring to
The roughing conduit 216 may also have a side port 378 provided within an exterior wall of the vacuum housing 210. The side port 378 may be used to insert and seal a pressure sensor within the conduit 216 for monitoring the pressure in the conduit 216. As shown in
Referring again to
As described above, the backing line 484 connects the output of the turbomolecular pump 227 to the roughing conduit 216. Therefore, the roughing pump (not shown) is able to pump down the output of the turbomolecular pump 227, via the conduit 216 and backing line 484, to a pressure that is below atmospheric pressure. This reduces the amount of work that the turbomolecular pump 227 is required to do in order to evacuate the vacuum chambers 214 to their respective desired sub-atmospheric pressures.
Turning now to
As will be understood, evaporated solvent from the ion source may condense against the internal walls of the source vacuum chamber and drip towards a base of the source region vacuum chamber. Accordingly, an entrance to a waste drainage internal conduit 216 may be adjacent a lowermost internal surface of the source vacuum chamber. In this manner, the solvent waste may drain out of the ion source enclosure by means of gravity. The waste drainage internal conduit 216 may be provided at an angle and extend from the entrance through the vacuum housing to any convenient exhaust port in the housing, such that the solvent flows from the source region vacuum chamber to the exhaust port. The cross-sectional shape of the conduit 216 is an elongated oval extending generally in the horizontal direction. This enables the vacuum housing 210 to be provided with a reduced size in the vertical direction.
As will be understood, the above internal conduits 503, 505 may also extend to and communicate with the one or more further vacuum chambers in a similar manner as described above in relation to the source region vacuum chamber.
As will be understood, one or more of the above described embodiments allows the vacuum housing 210, and therefore the mass spectrometer, to be more compact and have a lower complexity of parts. For example, all of the required conduits such as the roughing conduit, the backing line for the turbomolecular pump, gas feed lines, waste drainage channels, and electronics conduits may be provided as respective extruded within the body of a single integral vacuum housing unit. In some embodiments, the single integral vacuum housing unit may be manufactured via: (i) mould casting, wherein the mould defines the vacuum housing as well as all of the volumes to form the conduits within the vacuum housing; (ii) mould casting, wherein the various conduits are drilled out of the casted block vacuum housing unit; and/or (iii) additive manufacturing or 3D printing.
Although the present invention has been described with reference to preferred embodiments, it will be understood by those skilled in the art that various changes in form and detail may be made without departing from the scope of the invention as set forth in the accompanying claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2108988.3 | Jun 2021 | GB | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/GB2022/051603 | 6/23/2022 | WO |
