Patent Grant
9818592
This application is related to ion guides devices and methods of using them. More particularly, certain embodiments described herein are directed to rod assemblies that can be used in ion filters and/or ion guides.
Mass spectrometry separates species based on differences in the mass-to-charge (m/z) ratios of the ions. In many cases, the ionization occurs at a different pressure or location than the mass filter. To accommodate these configurations, ion guides and/or crude ion filters can be used.
Certain features, aspects and embodiments described herein are directed to devices, systems and methods that comprise one or more rod assemblies which comprise a plurality of poles that can be used, for example, to select, transmit or guide ions. In some configurations, the assemblies described herein can be used in devices and system where ions are travelling through different pressure regions while they are focused by electrical fields. In certain configurations, each of the rods of the rod assemblies can be operative as a pole which together may provide a field that can filter and/or guide ions through the device. In other configurations, the multipole assembly can be configured to provide fluidic coupling between an “inside region” (where ions travel) and an “outside region” (where the structure is mounted). In some instances, one or more rods or poles may be configured with an integral fluid path that provides the fluidic coupling between the inside and outside regions of the assembly. The exact configuration of the integral fluid path may vary and illustrative fluid paths, e.g., where one or more rods are serrated, comprise holes, slits or grooves oriented relative to the ion travel axis, are described in more detail herein. The assembly may comprise a single fluid path or a plurality of fluid paths separate from each other but each fluidically coupled to the outside region and/or a pump. As noted herein below, to contain ions within a multipole structure, RF and DC fields can be applied to opposing pole pairs, and these fields may continue along the ion travel axis (though the field may be varied along the ion travel axis if desired). The ion axis may be linear or curved or take other geometries. The rod segments or pole shapes may be any shape, for example round, hyperbolic, square, hexagonal or rectangular.
In certain aspects, the multipole assembly may comprise two or more pressure regions, e.g., an “inside region” or ion volume where the ions travel, and an “outside region” or outer volume, which is the area where the structure is mounted within. While not wishing to be bound by any particular scientific theory, the conductance between the two regions can be determined, at least in part, by the pole geometry. To increase the conductance between the ion volume and the outer volume, one or more rods may comprise an integral fluid path which fluidically couples the ion volume to the outer volume. The fluid path dimensions and spacing can be selected to maintain the electrical fields while increasing the pressure conductance. If desired, the fluid paths may be angled relative to the ion travel axis. To further enhance gas conductance between the ion volume and the outer volume, the dimensions of the fluid path may vary along the poles. For example, where a large gas conductance is desired, the integral fluid path may be larger than where a smaller gas conductance is desired.
In some aspects, the multipole assembly may comprise solid sections where low or no gas conductance is provided and sections comprising integral fluid paths to provide higher gas conductance at those sections. For example, at pressure transition regions of the assembly, it may be desirable to reduce the pressure rapidly using the integral fluid paths in the rods. At sections where no pressure reduction is needed, the rod section may be solid or otherwise not include any integral fluid path. The various different sections may be sized and arranged differently, may be electrically isolated from each other, may include a different number of poles and may be used with many different types of interfaces including atmospheric pressure interfaces and non-atmospheric pressure interfaces. The exact number of sections may vary and illustrative configurations include, but are not limited to, one, two, three, four or more sections. In some instances, the assemblies may be suitable for use in systems where the pressure may drop from atmospheric pressure (about 760 Torr) down to 10−7 Torr or less.
In one aspect, a device comprising a multipole assembly comprising a plurality of poles, in which at least one of the poles of the multipole assembly comprises an integral fluid path that fluidically couples an ion volume formed by the poles of the multipole assembly to an outer volume of the multipole assembly is provided.
In certain embodiments, the poles of the multipole assembly are configured together to transmit ions comprising a selected mass-to-charge ratio. In other embodiments, the pole comprising the integral fluid path comprises a first section comprising a width at a first end of the first section that is less than a width at a second end of the first section. In some instances, the pole comprising the integral fluid path comprises a second section configured to electrically couple to the first section. In some configurations, each of the first section and the second section comprises at least one integral fluid path configured to provide the fluid path between the ion volume formed by the multipole assembly and the outer volume of the multipole assembly to remove fluid from the ion volume to the outer volume. In other embodiments, at least two opposite poles of the multipole assembly are configured with an integral fluid path effective to remove fluid from the ion volume to the outer volume. In some instances, each pole of the multipole assembly is configured with an integral fluid path effective to remove fluid from the ion volume to the outer volume. In other configurations, opposite poles of the multipole assembly comprise an integral fluid path that each comprise a first section comprising a width at a first end of the first section that is less than a width at a second end of the first section. In additional configurations, the opposite poles comprising the integral fluid path each comprise a second section configured to electrically couple to the first section. In some embodiments, each of the first section and the second section of each of the opposite poles comprises an integral fluid path effective to remove fluid from the ion volume to the outer volume. In other instances, the integral fluid path is arranged at a non-orthogonal angle to the ion travel axis of the multipole assembly.
In further embodiments, multipole assembly is configured as a quadrupole assembly. In some configurations, each of first, second, third and fourth poles of the quadrupole assembly comprises an integral fluid path that fluidically couples the ion volume formed by the poles of the quadrupole assembly to an outer volume of the quadrupole assembly. In some instances, each integral fluid path is arranged at a non-orthogonal angle to the ion travel axis of the quadrupole assembly.
In some examples, the multipole assembly is configured as a hexapole assembly. In certain configurations, each of first, second, third, fourth, fifth and sixth poles of the hexapole assembly comprises an integral fluid path that fluidically couples the ion volume formed by the poles of the hexapole assembly to an outer volume of the hexapole assembly. In some instances, each integral fluid path is arranged at a non-orthogonal angle to the ion travel axis of the hexapole assembly.
In certain examples, the multipole assembly is configured as an octupole assembly. In additional embodiments, each of first, second, third, fourth, fifth, sixth, seventh and eighth poles of the octupole assembly comprises an integral fluid path that fluidically couples the ion volume formed by the poles of the octupole assembly to an outer volume of the octupole assembly. In further examples, each integral fluid path is arranged at a non-orthogonal angle to the ion travel axis of the octupole assembly.
In an additional aspect, a mass spectrometer comprising a sample introduction device, an ionization device fluidically coupled to the sample introduction device, a mass analyzer fluidically coupled to the ionization device, the mass analyzer comprising a multipole assembly comprising a plurality of poles, in which at least one of the poles of the multipole assembly comprises an integral fluid path that fluidically couples the ion volume formed by the poles of the multipole assembly to an outer volume of the multipole assembly, and a detector fluidically coupled to the mass analyzer is provided.
In certain examples, the mass spectrometer may comprise at least one pump fluidically coupled to the integral fluid path. In some embodiments, the pole comprising the integral fluid path comprises a first section comprising a width at a first end of the first section that is less than the width at a second end of the first section. In other configurations, the mass spectrometer may comprise an interface between the ionization device and the multipole assembly, in which the first end of the first section of the pole comprising the integral fluid path is configured to insert into the interface. In some embodiments, the interface is configured as a skimmer cone. In other embodiments, at least two opposite poles of the multipole assembly each comprise an integral fluid path that fluidically couples the ion volume formed by the poles of the multipole assembly to an outer volume of the multipole assembly. In further examples, the mass spectrometer may comprise at least one pump fluidically coupled to each of the integral fluid paths. In some embodiments, opposites poles comprising the integral fluid path comprise a first section comprising a width at first end of the first section that is less than a width at a second end of the first section. In some instances, the first end of each of the opposite poles is configured to insert into an interface, e.g., a skimmer cone. In some embodiments, the integral fluid path is arranged at a non-orthogonal angle to an ion travel axis of the multipole assembly.
In some configurations, the multipole assembly of the mass spectrometer is configured as a quadrupole assembly. In certain instances, each of first, second, third and fourth poles of the quadrupole assembly comprises an integral fluid path that fluidically couples the ion volume formed by the poles of the quadrupole assembly to an outer volume of the quadrupole assembly. In other instances, each integral fluid path is arranged at a non-orthogonal angle to the ion travel axis of the quadrupole assembly.
In other configurations, the multipole assembly of the mass spectrometer is configured as a hexapole assembly. In some embodiments, each of first, second, third, fourth, fifth and sixth poles of the hexapole assembly comprises an integral fluid path that fluidically couples the ion volume formed by the poles of the hexapole assembly to an outer volume of the hexapole assembly. In other embodiments, each integral fluid path is arranged at a non-orthogonal angle to the ion travel axis of the hexapole assembly.
In additional configurations, the multipole assembly of the mass spectrometer is configured as an octupole assembly. In some embodiments, each of first, second, third, fourth, fifth, sixth, seventh and eighth poles of the octupole assembly comprises an integral fluid path that fluidically couples the ion volume formed by the poles of the octupole assembly to an outer volume of the octupole assembly. In other embodiments, each integral fluid path is arranged at a non-orthogonal angle to the ion travel axis of the octupole assembly.
In another aspect, a device configured to transmit ions based on mass-to-charge ratio, the device comprising a rod assembly comprising a plurality of poles, in which at least one pole of the plurality of poles comprises a rod comprising an integral fluid path configured to fluidically couple an ion volume formed by the rod assembly to an outer volume of the rod assembly to remove fluid within the ion volume to the outer volume is provided.
In certain configurations, the integral fluid path is configured as at least one hole/slot pair that provides fluidic coupling between the ion volume and the outer volume. In other configurations, the slot is arranged at a non-orthogonal angle to the ion travel axis of the assembly. In some embodiments, the integral fluid path is configured as at least one non-orthogonal serration that provides fluidic coupling between the ion volume and the outer volume. In some examples, the integral fluid path comprises a plurality of non-orthogonal serrations each providing fluidic coupling between the ion volume and the outer volume. In additional examples, at least one rod of the rod assembly comprises a first section and a second section. In some embodiments, each of the first section and the second section comprises an integral fluid path configured to fluidically couple an ion volume formed by the rod assembly to an outer volume of the rod assembly to remove fluid within the ion volume to the outer volume. In some instances, the rod assembly comprises four rods constructed and arranged to provide a quadrupole assembly. In other instances, the rod assembly comprises six rods constructed and arranged to provide a hexapole assembly. In additional configurations, the rod assembly comprises eight rods constructed and arranged to provide an octupole assembly.
In another aspect, a method of reducing the pressure in a mass spectrometer stage, the method comprising providing at least one rod configured to form a rod assembly with a plurality of additional rods to provide a plurality of poles, the at least one rod comprising at least one integral fluid path configured to fluidically couple an ion volume formed by the rod assembly to an outer volume of the rod assembly to remove fluid within the ion volume to the outer volume is disclosed.
In certain embodiments, the method may comprise fluidically coupling a pump to the integral fluid path to reduce the pressure in the mass spectrometer stage. In other instances, the method may comprise configuring the rod with a plurality of integral fluid paths. In certain embodiments, at least two of integral fluid paths are sized and arranged to be different. In other embodiments, the rod assembly is configured as a quadrupole rod assembly, a hexapole rod assembly or an octupole rod assembly. In some configurations, the method may comprise configuring each rod of the rod assembly to comprise an integral fluid path configured to fluidically couple an ion volume formed by the rod assembly to an outer volume of the rod assembly to remove fluid within the ion volume to the outer volume.
In an additional aspect, a kit comprising a rod for use in a rod assembly, the rod comprising at least one integral fluid path configured to fluidically couple an ion volume formed by the rod in the rod assembly to an outer volume of the rod assembly to remove fluid within the ion volume to the outer volume, and instructions for using the rod to assemble the rod assembly is provided.
In certain configurations, the instructions of the kit are configured to assemble a quadrupole rod assembly using the rod, a hexapole rod assembly using the rod or an octupole rod assembly using the rod. In some embodiments, the kit may comprise a second rod comprising at least one integral fluid path configured to fluidically couple an ion volume formed by the rod assembly to an outer volume of the rod assembly to remove fluid within the ion volume to the outer volume. In certain instances, the kit may comprise a plurality of rods each comprising at least one integral fluid path configured to fluidically couple an ion volume formed by the rod assembly to an outer volume of the rod assembly to remove fluid within the ion volume to the outer volume. In some embodiments, the rod(s) of the kit may be configured as a first section and a second section separate from the first section and configured to electrically couple to the first section. In some instances, the first section comprises the integral fluid path, whereas in other configurations each of the first section and the second section comprise an integral fluid path. In some embodiments, the kit may comprise a plurality of rods, in which each rod comprises a first section and a second section separate from the first section and configured to electrically couple to the first section, in which the first section of each of the rods comprises at least one integral fluid path configured to fluidically couple an ion volume formed by the rod assembly to an outer volume of the rod assembly to remove fluid within the ion volume to the outer volume. In some configurations, the second section of each of the plurality of rods comprises at least one integral fluid path configured to fluidically couple an ion volume formed by the rod assembly to an outer volume of the rod assembly to remove fluid within the ion volume to the outer volume.
Additional features, aspect, examples and embodiments are described in more detail below.
Certain embodiments of the devices and systems are described with reference to the accompanying figures in which:
It will be recognized by the person of ordinary skill in the art, given the benefit of this disclosure, that certain dimensions or features of the components of the systems may have been enlarged, distorted or shown in an otherwise unconventional or non-proportional manner to provide a more user friendly version of the figures. In addition, the exact length, width, geometry, aperture size, etc. of the rods and other components described herein may vary.
Certain embodiments are described below with reference to singular and plural terms in order to provide a user friendly description of the technology disclosed herein. These terms are used for convenience purposes only and are not intended to limit the devices, methods and systems described herein.
In certain configurations, RF ion guides can be used to focus ions within a selected mass range. Where atmospheric pressure ionization (API) is used, atmospheric gas including charged molecules, e.g. ions, are sampled. While the exact system for such sampling may vary, and illustrative systems are described below, the system may include one, two, three or more vacuum stages. There may exist interfaces between gas stages to facilitate transfer of species from one stage to another. For example, a first gas restrictor may be present to permit gas to exit from a first stage. A sampling cone or sampling device may be present to separate the species based on momentum and to pump away the lighter species while maintaining the larger particles and ions. Behind the sampling cone, high pressure ion guides can be used to focus the ions into the center of the ion guide while pumping away any unwanted gas. Pressure may be reduced further using one or more additional vacuum stages to reach a desired mass analyzer pressure. Certain embodiments described herein are directed to devices, systems and methods that can result in a substantial pressure drop between the first and second vacuum stages (or between any two vacuum stages) and can select or transmit ions. The open nature of the rods and rod assemblies described herein permits a rapid pressure drop while at the same time maintaining suitable fields for ion guiding and/or transmission. In some configurations, the rods can be configured to have an integral fluid path to maximize gas conductance while still maintaining the RF fields to permit proper ion guidance and/or transmission.
While certain configurations are described below that show a plurality of serrations or slots configured as a fluid path that provides fluidic coupling between an ion volume and an outer volume, only a single fluid path, e.g., one serration, one slot, one hole/slot pair, etc. may be present if desired. For example, a pole section of the multipole assembly may comprise a generally solid body that can function as one pole of the multipole assembly with a single fluid path that provides fluidic coupling between the inside region of the assembly, e.g., the ion volume, and the outside region of the assembly, e.g., the outer volume. One or more pumps or other devices may be fluidically coupled to the outer volume such that fluid, e.g., gas, may flow from the ion volume, through the fluid path and the outer volume and be removed through the pump. Certain sections of the multipole assembly may be sealed or otherwise not include any integral fluid paths to minimize or eliminate gas flow from the ion volume to the outer volume at those sections. For example, sections which are closer to an interface such as a skimmer cone may comprise one or more fluid paths to drop the pressure in the multipole assembly, whereas downstream sections further away from the skimmer cone may have a sufficiently low pressure such that no or little gas conductance from the ion volume to the outer volume is needed at those sections. As gas is removed at sections comprising the integral fluid path(s), the poles are desirably configured to contain the ions within the ion volume and guide and/or filter the ions using the fields sustained with the poles. In some configurations, one or more sections may be configured to provide a rapid decrease in pressure in a minimal longitudinal length along the section.
In some instances, the various sections of the multipole assemblies described herein may be electrically isolated from each other so that different fields may exist in different sections. Similarly, the size and/or shape of the ion volume may be different at different sections of the multipole assembly. Different sections may also comprise a different number of poles, if desired, e.g., a quadrupole in one section and a hexapole in another section.
In certain configurations, one or more pumps may be fluidically coupled the outer volume of the multipole assembly. In some instances, a single pump can be used, but different sections of the multipole assembly may be pumped at different speeds to provide a desired gas conductance at each section. In other configurations, two or more pumps may be present with each pump fluidically coupled to a respective section. Depending on the number of integral fluid paths present in a particular section and the desired pressure drop, the exact speed at which the pump is operated may vary. In some embodiments, a single turbopump may be fluidically coupled to the multipole assembly. For example, the turbopump or turbomolecular pump may comprise a plurality of stages any one or more of which can be fluidically coupled to the outer volume to pump gas out of the multipole assembly. In some instances, the pump may be present as a component of a larger system, e.g., a mass spectrometer, and may be used to provide reduced pressure, e.g., a vacuum, at other areas of the system. In some instances, a pump stage with a higher pumping speed (or volume) may be fluidically coupled to an outer volume of a first multipole section adjacent to an interface, e.g., a skimmer come, and a pump stage with a lower pumping speed (or volume) may be fluidically coupled to an outer volume of a multipole section that is downstream of the first multipole section. As noted below, discs or other suitable components may separate the various multipole sections to isolate each section from other sections.
In some configurations, the overall size of the ion volume and/or spacing of the poles may vary depending on the desired gas conductance. As described in more detail below, the size of the ion volume can be altered or selected using inserts such as insulator shims, e.g., ceramic shims or inert material shims, to reduce the overall conductance. Without wishing to be bound by any particular scientific theory, where a large gas conductance is desired the ion volume and/or spacing between poles may be larger than where a smaller gas conductance is desired. Similarly, different cross-sectional shapes of the ion volume may provide for different gas conductances. In some embodiments, the ion volume may have a diameter, length or width of about 3-8 mm, for example, about 4-6 mm or about 4.5-5.5 mm. The spacing between poles may vary between about 0.5 mm to about 4 mm, more particularly about 1 mm to about 2 mm. The exact shape and/or dimension of the poles may vary and in some instances, the structures that provide the poles are square, circular, hexagonal, or may take other shapes.
In certain embodiments and referring to
In certain examples, the integral fluid path present in the rod may be sized and arranged in many different manners. For example and referring to
In certain embodiments, the rods may include one or more slots, serrations or grooves that are arranged at an angle to the longitudinal axis of the rod body. Referring to
In certain configurations, the holes of the rods may be omitted and the slots may be sized and arranged to extend into the body of the rod to provide an integral fluid path in the rod. For example and referring to
In certain examples, the rods described herein may be segmented or broken into a plurality of individual rods or sections which can be electrically coupled to each other through a suitable interface. For example, one of the rods can be split into a first or front section and a second or back section. The two sections can be electrically coupled to each other to provide a desired field when the sections are part of a rod assembly. If desired, the sections may function differently depending on the overall configuration. Referring to
In certain examples, the second section 550 may electrically couple to the front section 500 to provide an electrical connection between the two different sections. For example, the end 562 of the back section 550 may be placed adjacent to the end 514 of the front section 500 to provide an electrical connection between the two sections 500, 550. If desired one or more interfaces may be present between the sections 500, 550. In some embodiments, the first section 500 and the second section 550 may be separated by one or more mounting blocks or discs configured to hold the various sections at a desired position to provide a selected rod assembly. The discs may also serve to isolate the various sections from each other, e.g., electrically isolate them or isolate the gas conductance of one section from another section or both. In certain instances, the different sections of a rod may be configured to provide different functions if desired. For example, the front section 500 may be designed as a space charge section and the back section 550 may be configured as an ion transport section. The space charge effect results as charged species interact with each other, e.g., ion-ion repulsion of particles with like charge. As new ions arrive at an interface, they newly arrived ions repel ions already present at the interface and push the ions forward. Ions can be initially selected in the front section 500 and then provided to the ion transport section 550 to provide the selected ions through the rod assembly and to another stage or to a detector. If desired, the ion transport section 550 may provide additional mass filtering/selection to select or transmit ions having a desired mass-to-charge ratio.
In certain examples, the exact cross-sectional shape of the end of the first section that can be positioned adjacent to a sampling interface such as a skimmer cone may vary. Referring to
In certain embodiments, the shape of the ends of the rods may vary and different rods within a rod assembly may comprise ends with different shapes. For example and referring to
In certain examples, the rod sections described herein may be part of a larger rod assembly comprising a plurality of rods that are operative as poles. Referring to
In some configurations, the spacing between the two sections of a particular rod may be altered to change the voltage between the two sections. For example, the rods 705, 710 may be spaced apart a suitable distance to form an inner space or ion volume 725 between the rods 705, 710. While the spacing of the fluid paths in the various sections of the rod assembly 700 are shown as being substantially the same, unequal spacing may be implemented if desired. In addition, the different fluid paths may have different shapes and different angles as desired. An additional disc 730 may be present to seal the second sections 709, 714 from the surrounding components of the system such that gas is removed from the ion volume 725 through the hole/slot pairs of the second sections.
In certain embodiments, the rod assembly may comprise 4 rods. At least one rod may comprise a body comprising at least one integral fluid flow path configured to provide fluidic coupling between the ion volume and outer volume to remove fluid, e.g. gas, from within the ion volume. In some instances, two of the four rods may each comprise an integral fluid flow path. In additional configurations, three of the four rods may each comprise an in integral fluid flow path. In some embodiments, each of the four rods may each comprise an in integral fluid flow path. For illustration purposes, a quadrupole rod assembly comprising four rods each of which comprises a plurality of integral fluid flow paths, e.g., hole/slot pairs, is shown in
Referring to
In certain embodiments, the rod assemblies described herein may be present as part of a larger system. Referring to
In certain examples, a hexapolar assembly may be positioned similar to the quadrupole assembly shown in
In some instances, an octapolar assembly may be positioned similar to the quadrupole assembly shown in
In some examples, the rods and/or rod sections described herein can be used in rod assemblies that include fewer than four poles. For example, the rods and/or rod sections may be used in a tripole or a dipole to reduce the pressure through such systems. While the exact configuration may vary, in some instances the first rod section may include an integral fluid path, whereas in other examples, each of a first rod section and a second rod section may include an integral fluid path. It will be within the ability of the person of ordinary skill in the art, given the benefit of this disclosure, to select suitable rods and rod sections for use in rod assemblies other than quadrupoles, hexapoles and octupoles.
In some embodiments, two or more slots may be present for a single hole or aperture present in the integral fluid path. For example, the slots may take the form of serrations each of which provides a fluid path between the hole and the ion volume formed by the rod assembly. In some instances, two, three or more slots or serrations may be present and fluidically coupled to a hole or aperture present in a body of the rod.
In some instances, the rods and/or rod sections may comprise one or more conductive materials that can receive a current from a power source. For example, the rods may comprise stainless steel, gold, platinum, silver or other conductive materials. In some embodiments, a conductive coating or plating may be added to the rods, whereas in other instances the entire rod body may comprise the conductive material. In preparing the rods or rod sections, the holes/slots may be laser cut or material may otherwise be removed from a generally planar body to provide the rod sections and/or the hole/slot pairs. The thickness of the rods may be selected to provide suitable conductivity while at the same time permitting close spacing of the rod ends to provide an inner space of a suitable size.
In certain embodiments, the rod assemblies described herein may be present in a mass spectrometer. While the number and type of components may vary from mass spectrometer (MS) to mass spectrometer, an illustration of certain components is shown in
In certain embodiments, the mass analyzer 1530 of the MS device 1500 may take numerous forms depending on the desired resolution and the nature of the introduced sample. In certain examples, the mass analyzer is a scanning mass analyzer, a magnetic sector analyzer (e.g., for use in single and double-focusing MS devices), a quadrupole mass analyzer, an ion trap analyzer (e.g., cyclotrons, quadrupole ions traps), time-of-flight analyzers (e.g., matrix-assisted laser desorbed ionization time of flight analyzers), and other suitable mass analyzers that may separate species with different mass-to-charge ratios and may comprise one or more of the collision cells described herein. In some embodiments, the mass analyzer 1530 may comprise one of the rod assemblies described herein, e.g., a quadrupole rod assembly, hexapole rod assembly or octupole rod assembly with one or more of the rods comprising an integral fluid path configured to provide fluidic coupling between an ion volume and an outer volume. In other instances, two or more rods present in the mass analyzer 1530 may each comprise an integral fluid path. In some configurations, each rod of the mass analyzer 1530 may comprise an integral fluid path.
In certain embodiments, the rod assemblies described herein may be present in a first stage that is coupled to a second device comprising a rod assembly. Referring to
In additional configurations, a system comprising more than two rod assemblies in which at least one of the rod assemblies comprises a rod assembly as described herein, e.g., a rod assembly where at least one rod comprises an integral fluid path is provided. Referring to
In some examples, the MS devices disclosed herein may be hyphenated with one or more other analytical techniques. For example, MS devices may be hyphenated with devices for performing liquid chromatography, gas chromatography, capillary electrophoresis, and other suitable separation techniques. When coupling an MS device with a gas chromatograph, it may be desirable to include a suitable interface, e.g., traps, jet separators, etc., to introduce sample into the MS device from the gas chromatograph. When coupling an MS device to a liquid chromatograph, it may also be desirable to include a suitable interface to account for the differences in volume used in liquid chromatography and mass spectroscopy. For example, split interfaces may be used so that only a small amount of sample exiting the liquid chromatograph may be introduced into the MS device. Sample exiting from the liquid chromatograph may also be deposited in suitable wires, cups or chambers for transport to the ionization devices of the MS device. In certain examples, the liquid chromatograph may include a thermospray configured to vaporize and aerosolize sample as it passes through a heated capillary tube. Other suitable devices for introducing liquid samples from a liquid chromatograph into a MS device will be readily selected by the person of ordinary skill in the art, given the benefit of this disclosure. In certain examples, MS devices can be hyphenated with each other for tandem mass spectroscopy analyses.
In certain embodiments, the rods and rod sections described herein may be packaged in the form of a kit to permit a user to assemble a rod assembly having a desired configuration. For example, a kit may include a rod comprising at least one hole/slot pair configured to provide a fluid path to an ion volume formed by the rod assembly to remove fluid from within the ion volume through the fluid path, and the kit may also include instructions for using the rod to assemble the rod assembly. In some embodiments, enough rods may be present in the kit so that a quadrupole rod assembly can be assembled using the rods and the instructions. In other embodiments, enough rods may be present so that a hexapole rod assembly can be assembled using the rods and the instructions. In additional embodiments, enough rods may be present so that an octupole rod assembly can be assembled using the rods and the instructions. In some instances, the kit may comprise one, two, three, four or more rods each of which may comprise an integral fluid path. In other instances, each rod of the kit may comprise an integral fluid path. If desired, the kit may include rod sections, e.g., a first section and a second section separate from the first section and configured to electrically couple to the first section. The rod sections can be assembled by a user to provide a rod with a desired configuration. For example, the kit can include a plurality of rods in which each rod comprises a first section and a second section separate from the first section and configured to electrically couple to the first section, in which the first section of each of the rods comprises at least one integral fluid path. If desired, the second section of each of the plurality of rods comprises at least one integral fluid path. In other configurations, one or more discs or insulative inserts can be packaged in the kits to permit a user to separate various rod sections and/or alter the overall size of the ion volume formed by rod sections.
In some instances, the pressure in a mass spectrometer stage can be reduced using one or more of the rod assemblies described herein. For example, at least one rod configured to form a rod assembly can be provided with a plurality of additional rods to provide a plurality of poles. The at least one rod comprises at least one integral fluid flow path. A pump, e.g., a vacuum pump, can be fluidically coupled to the ion volume by way of the integral fluid path and the outer volume to reduce the pressure in the mass spectrometer stage. The vacuum open nature provided by the integral fluid paths permits the use of cheaper and less efficient pumps while at the same time rapidly reducing the pressure. If desired, the rod may be configured with a plurality of integral fluid paths. In some configurations, at least two of the plurality of integral fluid paths are sized and arranged to be different. The rod assembly may be configured as a quadrupole rod assembly, a hexapole rod assembly, an octupole rod assembly or as assemblies with two or more rods present. In some instances, each rod of the rod assembly may be configured to comprise at least integral fluid path to provide the fluid path to inner space formed by the rod assembly to remove fluid from within the ion volume.
Certain specific examples are described to facilitate a better understanding of the technology described herein.
A quadrupole rod assembly was assembled comprising four stainless steel rods each of which was constructed to be substantially the same. Referring to
Pressure measurements were made at various sections of the rod assembly of Example 1. The ion volume was 4.5 mm by 4.5 mm square with about 1 mm spacing between hexagonal shaped rods. The length of the rod surfaces that were adjacent to each other was about 4 mm. The section 1810 was about 30 mm in length (along the direction of the ion travel axis), and the section 1820 was about 40 mm in length. Section 1830 was about 30 mm in length. An atmospheric pressure interface (API) was used in a liquid chromatography-mass spectrometer (LC-MS). The pressure at the API was about 759.8 Torr. The multipole assembly of
During operation of the instrument, upstream of section 1810, e.g., at the skimmer cone, the pressure in the system was measured to be about 1.4 Torr. At section 1810, the pressure was measured to be about 0.17 Torr. At the second disc section 1820, the pressure was not measured but was estimated to be about 2×10−3 Torr. At the orifice near the disc 1835, the pressure was measured to be about 6×10−6 Torr. The measurements were consistent with integral fluid paths in the multipole assembly providing a rapid drop in pressure over a relatively small longitudinal length.
Similar measurements were performed using the system of Example 2, but the size of the ion volume was 3 mm by 3 mm square. During operation of the instrument, upstream of section 1810, e.g., at the skimmer cone, the pressure in the system was measured to be about 1.4 Torr. At section 1810, the pressure was measured to be about 0.19 Torr. At the second disc section 1820, the pressure was not measured but was estimated to be about 1×10−3 Torr. At the orifice near the disc 1835, the pressure was measured to be about 5.7×10−6 Torr. The measurements were consistent with integral fluid paths in the multipole assembly providing a rapid drop in pressure over a relatively small longitudinal length even where the size of the ion volume is altered.
Based on the measurements taken in Examples 1 and 2, the size of the ion volume was altered to provide as large a pressure drop as possible based on the dimensions of the sections in
When introducing elements of the examples disclosed herein, the articles “a,” “an,” “the” and “said” are intended to mean that there are one or more of the elements. The terms “comprising,” “including” and “having” are intended to be open-ended and mean that there may be additional elements other than the listed elements. It will be recognized by the person of ordinary skill in the art, given the benefit of this disclosure, that various components of the examples can be interchanged or substituted with various components in other examples.
Although certain aspects, examples and embodiments have been described above, it will be recognized by the person of ordinary skill in the art, given the benefit of this disclosure, that additions, substitutions, modifications, and alterations of the disclosed illustrative aspects, examples and embodiments are possible.
This application is related to, and claims priority to, U.S. Provisional Application No. 61/830,231 filed on Jun. 3, 2013, the entire disclosure of which is hereby incorporated herein by reference for all purposes.
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| Number | Date | Country | |
|---|---|---|---|
| 20160372315 A1 | Dec 2016 | US |
| Number | Date | Country | |
|---|---|---|---|
| 61830231 | Jun 2013 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 14293073 | Jun 2014 | US |
| Child | 15153816 | US |
