Patent Description:
A mass spectrometer can count ions constituting a substance by each mass-to-charge ratio to obtain ionic strength which is quantitative information on the substance. The mass spectrometer can perform more accurate analysis by obtaining ionic strength having a favorable signal-to-noise ratio. Therefore, an analysis target, which is an ionized or charged material, needs to be sufficiently introduced.

Examples of a method of ionizing a liquid sample include an electrospray ionization method. With the electrospray ionization method, high voltage of several kilovolts is applied to a sample solution in a narrow tube, a liquid cone (so-called Taylor cone) is formed at the tip of an outlet port, electrically charged droplets are ejected from the tip, solvents evaporate to reduce the volume of the electrically charged droplets, and the droplets finally split apart to generate gas-phase ions. This method can form electrically charged droplets at a rate of ejecting <NUM> to <NUM>µL/min of solution, in which the eject rate is not sufficient for use in conjunction with a liquid chromatography method.

A gas spray assisted electrospray ionization method (see, for example, <CIT>) may be an example of a method for supporting generation of electrically charged droplets and vaporization of solvents by ejecting a gas from an outer tube surrounding a narrow tube of a sample solution, in order to promote vaporization of electrically charged droplets.

<CIT> and <CIT> are other examples of spray ionization devices.

Patent Document <NUM>: <CIT>, Specification.

However, the gas spray assisted electrospray ionization method as disclosed in <CIT> generates electrically charged droplets having a large particle size; therefore, there is a need to use techniques such as promoting vaporization of solvents by using a heated gas, atomizing electrically charged droplets by collision with a plate-shaped target, or making the ejection direction orthogonal to the direction of introducing the atomized and electrically charged droplets in order to remove excessively large electrically charged droplets; as a result, electrically charged droplets cannot be efficiently obtained, which has been a problem.

One object of the present invention is to solve the aforementioned problems and provide a spray ionization device capable of efficiently obtaining atomized and electrically charged droplets to be ejected.

The present invention provides a spray ionization device, including: a first tube including a first channel through which a liquid can flow, the first tube including a first outlet for ejecting the liquid at one end; a second tube surrounding the first tube with a gap and including a second channel through which a gas can flow, the second tube including a second outlet arranged further toward a tip than the first outlet at the one end, the second channel being defined by an outer circumferential surface of the first tube and an inner circumferential surface of the second tube; an electrode that extends within the first channel of the first tube, and is arranged so that a leading end is at the same position as the first outlet or further toward the opposite end than the first outlet, the electrode being capable of applying voltage to the liquid by way of a power source connected to the electrode and being a wire formed from an electrode material including a platinum group metal, gold or an alloy thereof, or titanium or tungsten; and an opening provided to the second tube between the first outlet and the second outlet, the opening being a portion at which a diameter of the inner circumferential surface of the second tube is smallest and being narrower than an opening of the first outlet, wherein electrically charged droplets of the liquid can be ejected from the second outlet.

According to the aforementioned aspect, the liquid ejected from the first outlet of the first tube and the gas having flowed through the second channel collide with each other at high speed in the region between the first outlet and the opening, whereby droplets are atomized. The charged and atomized droplets are formed by voltage being applied to the liquid by the electrode extending within the first channel from the opposite end to the one end and the leading end and arranged so that the leading end becomes the same position as the first outlet or further to the opposite side than the first outlet, until flowing from the opposite end through the first channel and is sprayed from the first outlet. Therefore, a spray ionization device, which is capable of efficiently obtaining atomized and electrically charged droplets to be ejected, can be provided.

Note that elements that are common between a plurality of drawings are denoted by the same reference characters, and detailed description of such elements will not be repeated.

<FIG> is a diagram schematically illustrating a configuration of a spray ionization device according to a first embodiment not encompassed by the wording of the claims. <FIG> are cross-sectional views of a nozzle of a sprayer, in which <FIG> is an enlarged cross-sectional view of the nozzle of <FIG>, and <FIG> is a view along arrows Y-Y in <FIG>.

Referring to <FIG>, <FIG>, a spray ionization device <NUM> according to a first embodiment includes: a sprayer <NUM>; a container <NUM> containing a sample liquid Lf to be supplied to the sprayer <NUM>; a cylinder <NUM> for containing a spraying gas Gf to be supplied to the sprayer <NUM>; and a high-voltage power source <NUM> for applying high voltage to the sample liquid Lf via an electrode <NUM>. In the spray ionization device <NUM>, a nozzle <NUM> for ejecting electrically charged droplets is formed at one end (hereinafter also referred to as an ejection end) of the sprayer <NUM>. The sample liquid Lf and the spraying gas Gf are supplied from further toward the opposite end than the nozzle <NUM> (hereinafter also referred to as a supply end). The sample liquid Lf may be continuously or intermittently supplied from the container <NUM> by way of a pump <NUM> or the like. The sample liquid Lf may contain an analysis target in solvents, or may contain dissolved components, particulate matter, or the like, for example. The spraying gas Gf is supplied from the cylinder <NUM> through the valve <NUM> to the supply port <NUM>. Inert gas such as nitrogen gas or argon gas, or air can be used for the spraying gas Gf, for example. A heating unit <NUM> such as a heater or dryer for heating the spraying gas Gf may be provided between the cylinder <NUM> or the valve <NUM> and the supply port <NUM>. The spraying gas Gf is heated, whereby vaporization of solvents in the ejected sample liquid Lf can be promoted, and electrically charged droplets can be obtained more efficiently.

The sprayer <NUM> includes a liquid supply tube <NUM> and a gas supply tube <NUM> that surrounds the liquid supply tube <NUM> with a gap. The liquid supply tube <NUM> and the gas supply tube <NUM> have a double tube structure, in which the tubes are preferably coaxial (central axis X-X) with one another.

The liquid supply tube <NUM> extends from the supply end to the ejection end. The liquid supply tube <NUM> includes a first channel <NUM> being tubular and defined by an inner circumferential surface 21b of the liquid supply tube <NUM>, and includes an outlet 21a of the nozzle <NUM> at the ejection end. A diameter (inner diameter) of the inner circumferential surface 21b of the liquid supply tube <NUM> is preferably <NUM> to <NUM>, and a diameter (outer diameter) of an outer circumferential surface 21c of the liquid supply tube <NUM> is preferably <NUM> to <NUM>. In terms of atomizing droplets, an opening diameter of the outlet 21a is preferably <NUM> to <NUM>. In terms of atomizing droplets, the thickness (wall thickness) of the liquid supply tube <NUM> is preferably <NUM> to <NUM>.

The liquid supply tube <NUM> is preferably formed from dielectric material made of glass and plastic. In the first channel <NUM> within the liquid supply tube <NUM>, the electrode <NUM> is provided as described later.

The gas supply tube <NUM> includes a second channel <NUM> defined by an inner circumferential surface 22b of the gas supply tube <NUM> and the outer circumferential surface 21c of the liquid supply tube <NUM>, and includes an outlet 22a of the nozzle <NUM>. Although not limited in particular, a diameter (inner diameter) of the inner circumferential surface 22b of the gas supply tube <NUM> is, for example, <NUM> further toward the supply end than the nozzle <NUM>.

The gas supply tube <NUM> is made of a dielectric material such as glass or plastics, and is preferably made of silica glass, in particular, fused silica glass.

The spraying gas Gf is pressurized and supplied from the supply port <NUM> of the gas supply tube <NUM>, flows through the second channel <NUM>, and is ejected from the outlet 22a. A flow rate of the spraying gas Gf is appropriately set in accordance with the flow rate of the sample liquid Lf, and is set to <NUM>/min to <NUM>/min, for example.

The high-voltage power source <NUM> is a power source for generating high-voltage direct current voltage, and is connected to the electrode <NUM> arranged so as to be able to contact the sample liquid Lf flowing through the sprayer <NUM>. The high-voltage power source <NUM> applies voltage of e.g., <NUM> kV to the electrode <NUM>, and preferably applies voltage in a range of <NUM> kV to <NUM> kV in terms of ionization.

The electrode <NUM> extends in the first channel <NUM> of the liquid supply tube <NUM> from the supply side to ejection side, and a leading end 18a is arranged at the same position as the outlet 21a or further towards the supply side than the outlet 21a. Since the electrode <NUM> can thereby generate a strong electric field by high voltage applied in the vicinity of the outlet 21a, electrostatic spray of the sample liquid Lf becomes possible. In the electrode <NUM>, the leading end 18a is preferably closer to the outlet <NUM>; however, it is preferably arranged so as not to project downstream from the outlet 21a. In terms of atomizing droplets, the electrode <NUM> preferably has the leading end 18a arranged in the range of <NUM> to <NUM> to the supply side from the outlet 21a. In terms of superior corrosion resistance, the electrode <NUM> is formed from a platinum group metal, gold or an alloy of these, or titanium or tungsten. In terms of being able to easily arrange within the first channel <NUM>, the electrode <NUM> is a wire of the above-mentioned material.

In the nozzle <NUM>, the outlet 22a of the gas supply tube <NUM> is arranged further toward the distal end than the outlet 21a of the liquid supply tube <NUM>. The gas supply tube <NUM> is formed such that a portion 22b<NUM> of the inner circumferential surface of the gas supply tube <NUM> has a diameter that progressively decreases from upstream toward downstream, whereby the channel area of the second channel <NUM> progressively decreases. Here, the channel area refers to an area occupied by the second channel <NUM> on a plane perpendicular to the central axis X, in which the area is surrounded by the inner circumferential surface 22b of the gas supply tube <NUM> and the outer circumferential surface 21c of the liquid supply tube <NUM> as illustrated in <FIG>. The gas supply tube <NUM> is formed such that the diameter of the inner circumferential surface of the outlet 22a of the gas supply tube <NUM> is equal to or larger than the opening diameter of the outlet 21a of the surface liquid supply tube <NUM>. With such a configuration, droplets of the sample liquid Lf are ejected from the outlet 21a of the liquid supply tube <NUM>, enveloped in the spraying gas Gf flowing through the second channel <NUM>, and flow in the X-axis direction while focusing along the X-axis in the central direction. As a result, droplets of the sample liquid Lf are suppressed from contacting the inner circumferential surface 22b<NUM> of the gas supply tube <NUM> in the vicinity of the outlet 21a of the liquid supply tube <NUM>, whereby the nozzle <NUM> can be prevented from clogging. The flow of the ejected sample liquid Lf focuses by the spraying gas Gf, whereby droplets are atomized. Since the electrode <NUM> applies high voltage supplied from the high-voltage power source <NUM> to the sample liquid Lf, the ejected and atomized droplets have been charged. In this manner, the spray ionization device <NUM> can eject atomized and electrically charged droplets.

The nozzle <NUM> of the sprayer <NUM> preferably includes a constriction portion <NUM> in the second channel <NUM>, in which the channel area of the second channel <NUM> is the smallest. The constriction portion <NUM> is provided to a portion 22d, in which the inner circumferential surface 22b<NUM> of the gas supply tube <NUM> has a diameter that progressively decreases from upstream toward downstream, and the distance between the inner circumferential surface 22b<NUM> and the outer circumferential surface 21c of the liquid supply tube <NUM> is the smallest. In the constriction portion <NUM>, a distance between the portion 22d of the inner circumferential surface 22b<NUM> of the gas supply tube <NUM> and the outer circumferential surface 21c of the liquid supply tube <NUM> is preferably set to <NUM> to <NUM>.

This arrangement increases the pressure of the spraying gas Gf flowing through the second channel <NUM> at the constriction portion <NUM>, increases the flow rate (linear velocity) of the spraying gas Gf having passed through the constriction portion <NUM>, and promoting the atomization of the sample liquid Lf ejected from the outlet 21a of the liquid supply tube <NUM>. Droplets ejected from the outlet 21a of the liquid supply tube <NUM> can be further suppressed from flowing backward through the second channel <NUM> and entering the constriction portion <NUM>. As a result, clogging of the constriction portion <NUM> due to precipitation of components such as salts contained in droplets can be suppressed, whereby stable ejection can be achieved. This constriction portion <NUM> achieves a flow-focusing effect, in which droplets ejected from the outlet 21a can be ejected at a narrower angle (i.e., in a smaller lateral spreading range with respect to the ejection direction) than the case without the constriction portion <NUM>. As a result, efficiency of generating gas phase ions in the ejected and electrically charged droplets can be enhanced.

The diameter of the inner circumferential surface 22b<NUM> of the gas supply tube <NUM> in the vicinity of the outlet 22a may progressively increase from the portion 22d of the constriction portion <NUM> toward the outlet 22a. As a result, the channel area of the second channel <NUM> is progressively widened toward the outlet 22a. As a result, the flow of the spraying gas Gf can be suppressed from being disturbed, and the flow of the ejected, atomized and electrically charged droplets can be suppressed from spreading laterally with respect to the ejection direction.

The outer circumferential face 21c of the liquid supply tube <NUM>, has an outer diameter formed to be constant towards the outlet 21a, whereby the flow of spraying gas Gf converges the ejected sample liquid Lf at the outlet 21a of the liquid supply tube <NUM>, and it is possible to suppress splashing of the sample liquid Lf and effectively form droplets. It should be noted that the end face of the outlet 21a may be formed so as to progressively decrease in diameter from the upstream side towards the outlet 21a.

The outlet 21a of the liquid supply tube <NUM> preferably has an opening diameter smaller than the diameter of the inner circumferential surface 22b of the gas supply tube <NUM> at the constriction portion <NUM>. As a result, the spraying gas Gf having passed through the constriction portion <NUM> can form a flow so as to envelop the flow of droplets of the sample liquid Lf, in the outlet 21a of the liquid supply tube <NUM>.

<FIG> are cross-sectional views illustrating alternative examples of the gas supply tube of the nozzle of the sprayer. Referring to <FIG>, the gas supply tube <NUM> is preferably formed in the nozzle <NUM> such that at least a portion 42b<NUM> of the inner circumferential surface 42b thereof has a diameter that progressively decreases toward the outlet 42a, and the opening diameter (D2) of the outlet 42a of the gas supply tube <NUM> is equal to or smaller than the diameter D1 of the outer circumferential surface 21c of the liquid supply tube, at the tip of the outlet 21a of the liquid supply tube <NUM> than the outlet 21a. Specifically, the formation satisfies a relationship of D1≥D2. As a result, the flow-focus effect is further enhanced, in which the ejected, atomized and electrically charged droplets can flow at a narrower angle than the case of the nozzle <NUM> illustrated in <FIG>.

Referring to <FIG>, as another alternative example, the gas supply tube <NUM> is formed in the nozzle <NUM> such that: a portion 52b<NUM> of the inner circumferential surface thereof has a diameter that progressively decreases downstream; the diameter of the inner circumferential surface of the gas supply tube <NUM> is the smallest at a portion 52e, further toward the tip than the outlet 21a of the liquid supply tube <NUM>; and the inner circumferential surface 52b<NUM> has a diameter that progressively increases toward the outlet 52a, further toward the tip than the outlet 21a of the liquid supply tube. An opening diameter D3 of a portion 52e, at which the diameter of the inner circumferential surface of the gas supply tube <NUM> is the smallest, is formed to be equal to or smaller than the diameter D1 of the outer circumferential surface 21c of the liquid supply tube <NUM>. Specifically, the formation satisfies a relationship of D1≥D3. As a result, the same flow-focus effect as that of the nozzle <NUM> of <FIG> can be achieved, and the content of the sample liquid Lf becomes more unlikely to adhere to the inner circumferential surface 52b<NUM> having a diameter that progressively increases, and clogging becomes more unlikely to occur even in a case of continuous operation for long hours.

Hereinafter, a variation of the sprayer according to the first embodiment will be described. In the variation, configurations different from those of the nozzle <NUM> illustrated in <FIG> will be described, and the same reference numerals as those in <FIG> will be assigned to the same configurations, and descriptions thereof will be omitted. The same configurations omitting description achieve the same effects in the variation, in which description of the effects is omitted for the sake of simplicity.

<FIG> are cross-sectional views of the nozzle of the first variation of the sprayer according to the first embodiment, in which <FIG> is an enlarged cross-sectional view, and <FIG> is a view along arrows Y-Y in <FIG>.

Referring to <FIG> together with <FIG>, the sprayer of the first variation of the first embodiment includes: the liquid supply tube <NUM>; a gas supply tube <NUM>; a protective tube <NUM> surrounding the liquid supply tube <NUM> and provided between the liquid supply tube <NUM> and the gas supply tube <NUM>; and an electrode <NUM> for applying high voltage to the sample liquid Lf flowing through the liquid supply tube <NUM>. The electrode <NUM> has the same configuration as illustrated in <FIG>. The sprayer has a triple tube structure, in which the tubes are preferably coaxial (central axis X-X) with one another.

The liquid supply tube <NUM> has the same configuration as the liquid supply tube <NUM> illustrated in <FIG>, <FIG>. A second channel <NUM> of the gas supply tube <NUM> is a space defined by the outer circumferential surface 127c of the protective tube <NUM> and the inner circumferential surface 122b of the gas supply tube <NUM>, in which the spraying gas Gf flows through the second channel <NUM>. Note that the spraying gas Gf is not supplied to a space defined by the outer circumferential surface 21c of the liquid supply tube <NUM> and the inner circumferential surface of the protective tube <NUM>.

In the nozzle <NUM>, a part 122b<NUM> of the inner circumferential face of the gas supply tube <NUM> is formed so as to progressively decrease in diameter from upstream towards downstream, whereby the channel area of the second channel <NUM> is formed to gradually narrow.

The tip 127a at the ejection end of the protective tube <NUM> is located further to the supply end than the outlet 21a of the liquid supply tube <NUM>. In the nozzle <NUM>, a constriction portion <NUM> of the second channel <NUM> is formed by the outer circumferential surface 127c of the tip 127a of the protective tube <NUM> and the portion 122b<NUM> of the inner circumferential surface of the gas supply tube <NUM>. As a result, the second channel <NUM> is formed such that the channel area of the second channel <NUM> progressively decreases from the supply end to the constriction portion <NUM>. The spraying gas Gf passes through the constriction portion <NUM> to gain the flow velocity, and the flow of electrically charged droplets of the sample liquid Lf ejected from the outlet 21a of the liquid supply tube <NUM> further focuses, promoting atomization of droplets. Furthermore, the droplet ejected from the outlet 21a of the liquid supply tube <NUM> can be suppressed from flowing back in the second channel <NUM>, and entering the constriction portion <NUM>. As a result, clogging of the constriction portion <NUM> due to precipitation of components such as salts contained in droplets can be suppressed, whereby stable ejection can be achieved.

The gas supply tube <NUM> is formed such that the inner circumferential surface 122b<NUM> has a constant diameter (inner diameter) from the constriction portion <NUM> toward the outlet 122a. As a result, the flow of the spraying gas Gf ejected from the constriction portion <NUM> is not blocked by any members, whereby turbulence can be suppressed from being generated. The gas supply tube <NUM> may be formed such that the inner circumferential surface 122b<NUM> of the gas supply tube <NUM> has a diameter that progressively increases from the constriction portion <NUM> toward the outlet 122a. As a result, the same effects as in the case of the constant diameter can be achieved.

<FIG> are cross-sectional views of an alternative example of the gas supply tube of the nozzle of the first variation. Referring to <FIG>, the gas supply tube <NUM> is formed in the nozzle <NUM> such that: at least a portion 132b<NUM> of the inner circumferential surface has a diameter that progressively decreases from the portion 132d of the constriction portion <NUM> toward an outlet 132a; and an opening diameter (D5) of the outlet 132a of the gas supply tube <NUM> is formed to be equal to or smaller than the diameter D4 of the outer circumferential surface 127c of the protective tube <NUM>, further toward the tip than the outlet 21a of the liquid supply tube <NUM>. Specifically, the formation satisfies a relationship of D4≥D5. As a result, the flow-focus effect can be further enhanced, and the ejected, atomized and electrically charged droplets can form a flow at a narrower angle.

As another alternative example, referring to <FIG>, the gas supply tube <NUM> is formed in the nozzle <NUM> such that: the portion 142b<NUM> of the inner circumferential surface thereof has a diameter that progressively decreases downstream from the portion 142d of the constriction portion <NUM>; the diameter of the inner circumferential surface of the gas supply tube <NUM> is the smallest at a portion 142e, further toward the tip than the outlet 21a of the liquid supply tube; and the inner circumferential surface 142b<NUM> has a diameter that progressively increases toward the outlet 142a. The opening diameter D6 of the portion 142e, at which the diameter of the inner circumferential surface of the gas supply tube <NUM> is the smallest, is formed to be equal to or smaller than the diameter D4 of the outer circumferential surface 127c of the protective tube <NUM>. Specifically, the formation satisfies a relationship D4≥D6. As a result, the same flow-focus effect as that of the nozzle <NUM> of <FIG> can be achieved, and the content of the sample liquid Lf becomes more unlikely to adhere to the inner circumferential surface 142b<NUM>, and clogging becomes more unlikely to occur even if an operation is continued for a long time.

In terms of ejecting droplets of the sample liquid Lf in a smaller lateral spreading range with respect to the ejection direction using the flow-focus effect of the flow of the spraying gas Gf, the opening diameter (diameter) of the outlet 21a of the liquid supply tube <NUM> is preferably smaller than the diameter of the outer circumferential surface 127c of the tip 127a of the protective tube <NUM> in the constriction portion <NUM>.

<FIG> is an enlarged cross-sectional view of the nozzle of a second variation of the sprayer of the first embodiment. Referring to <FIG>, the nozzle <NUM> of the second variation includes a blocking member <NUM> along a circumferential direction in a gap between the outer circumferential surface 21c of the liquid supply tube <NUM> and the inner circumferential surface 127b of the protective tube <NUM>, at the tip 127a toward the ejection end of the protective tube <NUM>. The gap is blocked by the blocking member <NUM>. Except that the closing member <NUM> is provided, the nozzle <NUM> has the same configuration as the nozzle <NUM> of the sprayer of the first variation illustrated in <FIG>. With this configuration, the blocking member <NUM> prevents the spraying gas Gf having passed through the constriction portion <NUM> from entering the gap between the outer circumferential surface 21c of the liquid supply tube <NUM> and the inner circumferential surface 127b of the protective tube <NUM>. As a result, turbulence of the spraying gas Gf is suppressed from occurring, the flow of electrically charged droplets of the sample liquid Lf focuses, and atomization of droplets is promoted. The blocking member <NUM> may be provided entirely along the axial direction of the gap between the outer circumferential surface 21c of the liquid supply tube <NUM> and the inner circumferential surface 127b of the protective tube <NUM>.

A spray ionization device according to a second embodiment encompassed by the wording of the claims has substantially the same configuration as the spray ionization device according to the first embodiment illustrated in <FIG>, and description of the same elements are omitted.

<FIG> are cross-sectional views of a nozzle of the spray ionization device according to the second embodiment, in which <FIG> is an enlarged cross-sectional view of the nozzle, and <FIG> is a view along arrows Y-Y shown in <FIG>.

Referring to <FIG> together with <FIG>, the sprayer of the spray ionization device according to the second embodiment includes: a liquid supply tube <NUM>; a gas supply tube <NUM>; and an electrode <NUM> for applying high voltage to a sample liquid Lf flowing through the liquid supply tube <NUM>. The sprayer has a double tube structure, in which the tubes are preferably coaxial (central axis X-X) with one another. The liquid supply tube <NUM> has substantially the same configuration as the liquid supply tube <NUM> of the first embodiment illustrated in <FIG>, <FIG>. The liquid supply tube <NUM> includes a first channel <NUM> defined by the inner circumferential surface of the liquid supply tube <NUM> and extending in the axial direction. The sample liquid Lf flows through the liquid supply tube <NUM> and is ejected from an outlet 21a. The gas supply tube <NUM> has substantially the same configuration as the gas supply tube <NUM> illustrated in <FIG>, <FIG>. The gas supply tube <NUM> includes a second channel <NUM> defined by the inner circumferential surface 322b of the gas supply tube <NUM> and the outer circumferential surface 21c of the liquid supply tube <NUM> and extending in the axial direction. The spraying gas Gfs flows through the second channel <NUM>. The electrode <NUM> extends from the supply side to the first channel <NUM> within the liquid supply tube <NUM> so that the leading end 18a is the same position as the outlet 21a of the liquid supply tube <NUM> or further towards the supply side than the outlet 21a, and is similar to the configuration shown in <FIG>, <FIG>.

In the nozzle <NUM>, the outlet 21a of the liquid supply tube <NUM> of the sprayer is located further toward the supply end than the outlet 322a of the gas supply tube <NUM>. The gas supply tube <NUM> includes an ejection port 322d between the outlet 322a of the gas supply tube <NUM> and the outlet 21a of the liquid supply tube <NUM>. The ejection port 322d is a portion in which the diameter of the inner circumferential surface of the gas supply tube <NUM> is the smallest, and the ejection port 322d is formed narrower than the opening of the outlet 21a of the liquid supply tube <NUM>. The opening diameter of the ejection port 322d is smaller than the opening diameter of the outlet 21a of the liquid supply tube <NUM>. With this configuration, the charged sample liquid Lf ejected from the outlet 21a of the liquid supply tube <NUM> collides with the spraying gas Gf having flowed through the second channel <NUM>, at high speed in the region between the outlet 21a and the ejection port 322d, whereby the electrically charged droplets of the sample liquid Lf are atomized and ejected from the outlet 322a through the ejection port 322d.

In the nozzle <NUM>, the second channel <NUM> preferably includes a constriction portion <NUM> in which the channel area of the second channel <NUM> is the smallest. The constriction portion <NUM> is formed by a gap between a portion 322b<NUM>, in which the inner circumferential surface 322b of the gas supply tube <NUM> has a diameter that progressively decreases from upstream to downstream, and the outer circumferential surface 21c of the outlet 21a of the liquid supply tube <NUM>. The spraying gas Gf gains linear velocity in the constriction portion <NUM> and collides with the sample liquid Lf at high speed in the region between the outlet 21a of the liquid supply tube <NUM> and the ejection port 322d, whereby atomization of electrically charged droplets of the sample liquid Lf is promoted. The spraying gas Gf is ejected from the constriction portion <NUM> at high speed; therefore, the content of the sample liquid Lf is unlikely to adhere to the vicinity of the ejection port 322d, and clogging is unlikely to occur. The liquid supply tube <NUM> is supported in a cantilever manner at the supply end, whereby when the spraying gas Gf is ejected from the constriction portion <NUM> at high speed, the outlet 21a of the liquid supply tube <NUM> easily vibrates in a direction perpendicular to the ejection direction. Then, the gap at the constriction portion <NUM> temporally changes, so that the flow rate of the spraying gas Gf having passed through the constriction portion <NUM> changes, and the spraying gas flows locally at higher speed. As a result, the content of the sample liquid Lf is further unlikely to adhere to the vicinity of the ejection port 322d, and clogging is further unlikely to occur.

Hereinafter, a variation of the sprayer according to the second embodiment will be described. In the variation, configurations different from the nozzle <NUM> illustrated in <FIG> will be described, the same reference numerals as in <FIG> or <FIG> will be assigned to the same configurations, and description thereof will be omitted. The same configurations omitting description achieve the same effects in the variation, in which description of the effects is omitted for the sake of simplicity.

<FIG> are views illustrating a nozzle of a first variation not encompassed by the wording of the claims of the sprayer according to the second embodiment, in which <FIG> is an enlarged cross-sectional view, and <FIG> is a view of the nozzle from the ejection end.

Referring to <FIG> together with <FIG>, the sprayer of the first variation of the second embodiment includes a liquid supply tube <NUM>, a gas supply tube <NUM>, and an electrode <NUM> for applying high voltage to the sample liquid Lf flowing through the liquid supply tube <NUM>. The electrode <NUM> has the same configuration as illustrated in <FIG>, <FIG>. The sprayer has a double tube structure, in which the tubes are preferably coaxial (central axis X-X) with one another.

The liquid supply tube <NUM> has the same configuration as the liquid supply tube <NUM> of the second embodiment illustrated in <FIG>, and the sample liquid Lf is ejected from the outlet 21a in the nozzle <NUM>.

The gas supply tube <NUM> includes a second channel <NUM> defined by the inner circumferential surface 422b of the gas supply tube <NUM> and the outer circumferential surface 21c of the liquid supply tube <NUM> and extending in the axial direction. The spraying gas Gf flows through the second channel <NUM> and is ejected from the outlet 422a in the nozzle <NUM>.

In the nozzle <NUM>, a reticulated member <NUM> is provided to the outlet 422a of the gas supply tube <NUM>. The reticulated member <NUM> is retained by a retaining member <NUM> and arranged so as to cover the opening of the outlet 422a of the gas supply tube <NUM>. For example, a sheet-like mesh sheet can be used for the reticulated member <NUM>. A dielectric material can be used for the mesh sheet, and for example, nylon fiber can be used.

The reticulated member <NUM> has horizontal lines 430x and vertical lines 430y with an interval of <NUM>, for example, in which a vertical and horizontal size of each aperture is <NUM>, for example. The distance between the outlet 21a of the liquid supply tube <NUM> and the reticulated member <NUM> is set to <NUM>, for example, and is preferably set to <NUM> to <NUM>.

With this configuration, electrically charged droplets of the sample liquid Lf ejected from the outlet 21a of the liquid supply tube <NUM> together with the spraying gas Gf having flowed through the second channel <NUM> collides with the reticulated member <NUM> at high speed, whereby the electrically charged droplets of the sample liquid Lf are atomized in the region between the outlet 21a and the reticulated member <NUM>, and ejected through the opening of the reticulated member <NUM> by way of the spraying gas Gf.

<FIG> is an enlarged cross-sectional view of a nozzle of a second variation of the sprayer of the second embodiment. Referring to <FIG> together with <FIG>, the second variation of the sprayer of the second embodiment includes a liquid supply tube <NUM>, a gas supply tube <NUM>, and an electrode <NUM> for applying high voltage to the sample liquid Lf flowing through the liquid supply tube <NUM>. The electrode <NUM> has the same configuration as illustrated in <FIG>, <FIG>. The sprayer has a double tube structure, in which the tubes are preferably coaxial (central axis X-X) with one another.

The liquid supply tube <NUM> has the same configuration as the liquid supply tube <NUM> of the second embodiment illustrated in <FIG>, and the sample liquid Lf is ejected from the outlet 21a in the nozzle <NUM>. The gas supply tube <NUM> includes a second channel <NUM> defined by the inner circumferential surface 522b of the gas supply tube <NUM> and the outer circumferential surface 21c of the liquid supply tube <NUM> and extending in the axial direction. The spraying gas Gf flows through the second channel <NUM> and is ejected from the outlet 522a in the nozzle <NUM>.

In the nozzle <NUM>, the inner circumferential surface 522b of the gas supply tube <NUM> has a diameter that decreases at a portion <NUM> further toward the tip than the outlet 21a of the liquid supply tube <NUM>, and the inner circumferential surface 522b<NUM> is bent perpendicularly to the X-axis direction. A bent portion <NUM> bent toward the outlet 21a of the liquid supply tube <NUM> is formed in the second channel <NUM>. As a result, the spraying gas Gf flows toward the outlet 21a of the liquid supply tube <NUM> at the bent portion <NUM>, and collides with the sample liquid Lf at high speed in the region between the outlet 21a and an ejection port 522d, whereby the electrically charged droplets of the sample liquid Lf are atomized.

The inner circumferential surface 522b<NUM> of the gas supply tube <NUM> is bent perpendicularly to the X-axis direction, or may be bent at an angle that is larger or smaller than the vertical angle, depending on the flow velocity or the like of the spraying gas Gf. The spraying gas Gf enters the inside of the liquid supply tube <NUM> from the outlet 21a and collides with the electrically charged droplets of the sample liquid Lf, whereby atomization of the electrically charged droplets of the sample liquid Lf is promoted.

The ejection port 522d may be provided with the reticulated member <NUM> of the sprayer of the first variation illustrated in <FIG>. As a result, atomization of electrically charged droplets of the sample liquid Lf is further promoted.

As a further variation of the sprayer of the spray ionization device according to the second embodiment, a second gas supply tube may be provided so as to surround the gas supply tube with a gap.

<FIG> is a diagram schematically illustrating a configuration of another variation of the spray ionization device according to the second embodiment. Referring to <FIG>, a spray ionization device 61C includes a second gas supply tube <NUM> in which a sprayer <NUM> surrounds a gas supply tube <NUM>, and the nozzle <NUM> is the nozzle <NUM> illustrated in <FIG>. In the second gas supply tube <NUM>, a cylinder <NUM> supplies sheath gas Gf<NUM> via a valve <NUM> to a supply port <NUM> of.

The second gas supply tube <NUM> includes a third channel <NUM> defined by an outer circumferential surface 322c of the gas supply tube <NUM> and an inner circumferential surface 628b of the second gas supply tube <NUM> and extending in the axial direction. The inner circumferential surface 628b of the second gas supply tube <NUM> is formed so as to have a constant diameter toward an outlet 628a. The flow of sheath gas Gf<NUM> flowing through the third channel <NUM> is restricted from spreading by the inner circumferential surface 628b of the second gas supply tube <NUM> toward the outlet 628a, and the atomized and electrically charged droplets ejected from the nozzle <NUM> are enveloped in the sheath gas Gf<NUM>. As a result, the outlet 628a of the second gas supply tube <NUM> ejects the focused, atomized and electrically charged droplets along the axis in the ejection direction. With this configuration, even if the nozzle <NUM> cannot eject atomized droplets with sufficient focusing thereof, the sprayer <NUM> can eject focused and atomized droplets.

A heating unit <NUM> may be provided downstream of the valve <NUM> so as to supply the sheath gas Gf<NUM> as heated gas; or a heating unit such as a ring heater (not illustrated) may be provided downstream of the outlet 322a of the gas supply tube <NUM> so as to surround a second gas supply tube <NUM>. As a result, desolvation of droplets can be supported.

The sprayer <NUM> can employ the nozzle <NUM> illustrated in <FIG> or the nozzle <NUM> illustrated in <FIG>, whereby the same effects as the nozzle <NUM> can be achieved.

The sprayer <NUM> may employ the nozzle <NUM> illustrated in <FIG>, the nozzle <NUM> or <NUM> illustrated in <FIG>, the nozzle <NUM> illustrated in <FIG>, the nozzle <NUM> or <NUM> illustrated in <FIG>, or the nozzle <NUM> illustrated <FIG> of the first embodiment.

<FIG> is a diagram schematically illustrating a configuration of the alternative example of the second gas supply tube of another variation of the spray ionization device. Referring to <FIG>, a second gas supply tube <NUM> of a sprayer <NUM> of a spray ionization device <NUM> has the same configuration as the second gas supply tube <NUM>, except that the tip shape of the second gas supply tube <NUM> differs from the tip shape of the second gas supply tube <NUM> illustrated in <FIG>. An inner circumferential surface 728b of the second gas supply tube <NUM> is formed to have a diameter that progressively decreases toward an outlet 728a, and the channel area of a third channel <NUM> progressively decreases accordingly.

The sheath gas Gf<NUM> flowing through the third channel <NUM> flows toward the outlet 728a such that the flow focuses while being restricted by the inner circumferential surface 728b of the second gas supply tube <NUM>. The atomized and electrically charged droplets ejected from the nozzle <NUM> are enveloped in the sheath gas Gf<NUM> and focus onto the axial center along the ejection direction, and the focused, atomized and electrically charged droplets are ejected from the outlet 728a of the second gas supply tube <NUM>. With this configuration, even if the nozzle <NUM> cannot eject atomized droplets with sufficient focusing thereof, the sprayer <NUM> can eject focused and atomized droplets.

Hereinafter, measurement examples prepared using examples of a spray ionization device according to embodiments not encompassed by the wording of the claims will be shown. The Examples used a configuration in which the sprayer <NUM> has the nozzle <NUM> shown in <FIG> in the spray ionization device <NUM> of a first variant of the second embodiment, shown in <FIG>. Tungsten (W) wire of <NUM> diameter was used in the electrode <NUM>, and provided from a supply side to outlet in the liquid supply tube. It should be noted that the W wire was arranged so as not to project from the outlet. The inside diameter of the liquid supply tube was <NUM>, and the outlet diameter of the liquid supply tube was <NUM>. A reference example defined a case of not applying voltage to the electrode <NUM> in the Examples. In the Examples and Reference Example, heating of the sprayed droplets was performed by heating the sheath gas.

The spray ionization device of the Comparative Example was an ESI ion source applying the gas spray assist electrospray ionization (ESI) method, and used a sprayer (ESI probe (ion source)) belonging to a mass spectrometer model LCMS-<NUM> manufactured by Shimadzu Corp. The ESI probe of the Comparative Example has a triple-tube structure, and includes a liquid supply tube, a first gas supply tube surrounding the liquid supply tube and circulating the spraying gas, and a second gas supply tube surrounding the first gas supply tube, and circulating heated gas. The ejection port of the liquid supply tube is provided further downstream than the ejection port of the spraying gas of the first gas supply tube and the ejection port of the heated gas of the second gas supply tube. The liquid supply tube and first gas supply tube are formed with a metal material (SUS316). Using the first gas supply tube as an electrode, a high-voltage power source was connected to this.

The spray ionization devices of the Examples, Reference Example and Comparative Example were applied to the LC (liquid chromatography)/MS (mass spectrometry)/MS device, a model LC-<NUM> series manufactured by Shimadzu Corp. was used as the LC device, and the model LCMS-<NUM> manufactured by Shimadzu Corp. was used as the MS/MS device. At the interface between the LC device and MS/MS device, it sprays towards the ion capture port of the MS/MS device, and heating of sprayed droplets was performed by heating the sheath gas. The heating of sprayed droplets in the Comparative Example was performed by heating the interface space. It should be noted that, in the Comparative Example, the interface space became <NUM>, even in a case without this heating. The heating of these sprayed droplets is called simply heat treatment hereinafter.

In the Examples and Comparative Example, the high-voltage power supply (model HCZE-30PN0. <NUM> manufactured by Matsusada Precision Inc. ) was connected to the electrode, and direct current voltage was applied to the sample liquid at the ion capture port of the MS/MS device.

A reserpine solution having a concentration of <NUM> ppb was introduced in an amount of <NUM>µL from the injector of the LC device, a <NUM>% acetonitrile aqueous solution with mobile phase: acetonitrile = <NUM>:<NUM> was fed at <NUM> pL/min as eluent using the LC device, multiple-reaction monitoring (MRM) analysis was performed by the MS/MS device by ejecting by the spray ionization devices of the Examples, Reference Example and Comparative Example, and the total area of the peak of the ion signal in the positive ion mode with mass-to-charge ratio m/z = <NUM> > <NUM> was measured, for a specific product ion produced by destroying precursor ion.

Using nitrogen gas as the spraying gas, a flowrate of <NUM>/min was established for the Examples and Reference Example, and the flowrate of <NUM>/min was established for the Comparative Example.

<FIG> are graphs showing the measurement example of reserpine, with <FIG> being a case of not performing heat treatment, and <FIG> being a case of performing heat treatment at <NUM> in the Examples and Reference Example, and at <NUM> in the Comparative Example. The vertical axis is the peak area (count number), and by counting for <NUM> milliseconds per one measurement and measuring four times, the average value, standard deviation and relative standard device (RSD) (%) (=average value/standard deviation x <NUM>) were calculated, and the average value is shown by circles and the standard deviation is shown by error bars.

Referring to <FIG>, the Examples were <NUM>. 8x10<NUM> counts at applications of +<NUM> kV and +<NUM> kV; whereas, the Reference Example was a <NUM>. 9x10<NUM> count without voltage application, and the Comparative Example was <NUM>. 45x10<NUM> at application of +<NUM> kV. In the Examples, <NUM> times the signal intensity was obtained in the case of no heat treatment relative to Comparative Example, whereby it was found that the Examples much more efficiently ionized than the Comparative Example. In addition, in the Examples, <NUM> times the signal intensity was obtained relative to the case without voltage application of the Reference Example, whereby it was found to be more efficiently ionized by voltage application.

Referring to <FIG>, the Examples were <NUM>. 7x10<NUM> counts at the application of +<NUM> kV, and <NUM>. 8x10<NUM> counts at the application of +<NUM> kV; whereas, the Reference Example was <NUM>. 0x10<NUM> counts without voltage application, and the Comparative Example was <NUM>. 3x10<NUM> counts with the application of +<NUM> kV. In the Examples, <NUM> times the signal intensity was obtained in the case of there being heat treatment relative to the Comparative Example, whereby it was found that the Examples much more efficiently ionized reserpine than the Comparative Example. In addition, in the Examples, <NUM> times the signal intensity was obtained relative to the case of no voltage application of the Reference Example, whereby it was found to efficiently ionize reserpine by voltage application.

The Examples had smaller relative standard deviation (RSD) than the Reference Example and Comparative Example, either without heat treatment or with heat treatment, and from this matter it is found that the spray ionization device of the Examples was able to ionize reserpine much more stably than the Reference Example and Comparative Example.

A concentration of <NUM> ppb chloramphenicol was introduced in an amount of <NUM>µL from the injector of the LC device, a <NUM>% acetonitrile aqueous solution prepared with mobile phase: acetonitrile = <NUM>:<NUM> was delivered at <NUM>µL/min using the LC device as eluate, was sprayed by the spray ionization devices of the Examples, Reference Example and Comparative Example, MRM analysis was performed by the MS/MS device similarly to Measurement Example <NUM>, and the total area of the peak of the ion signal was measured in the negative ion mode of mass-to-charge ratio m/z=<NUM> > <NUM>.

Using nitrogen gas as the spraying gas, the flowrate was set to <NUM>/min in the Examples and the Reference Example, and set to <NUM>/min in the Comparative Example.

<FIG> are graphs illustrating a Measurement Example of chloramphenicol, with <FIG> being a case of not performing heat treatment, and <FIG> being a case of performing heat treatment at <NUM> in the Examples and Reference Example, and at <NUM> in the Comparative Examples. In <FIG>, the vertical axis is the peak area (count number), and shows the average value, standard deviation and RSD, similarly to Measurement Example <NUM>.

Referring to <FIG>, the Examples were <NUM>. 3x10<NUM> counts to <NUM>. 6x10<NUM> counts with application of -<NUM> kV to -<NUM> kV; whereas, the Reference Example was <NUM>. 1x10<NUM> counts without voltage application, and the Comparative Example was <NUM>. 3x10<NUM> counts with application of -<NUM> kV. In the Examples, <NUM> times the signal intensity was obtained in the case of applying -<NUM> kV and no heat treatment relative to the Comparative Example, whereby it was found that the Examples could much more efficiently ionize than the Comparative Example. In addition, in the Example, <NUM> times the signal intensity was obtained at application of -<NUM> kV relative to a case of no voltage application in the Reference Example, whereby it was found it could be more efficiently ionized by voltage application.

Referring to <FIG>, the Examples were <NUM>. 0x10<NUM> counts to <NUM>. 4x10<NUM> counts with application of -<NUM> kV to -<NUM> kV; whereas, it was <NUM>. 6x10<NUM> counts without voltage application in the Reference Example, and the Comparative Example was <NUM>. 0x10<NUM> counts with application of -<NUM> kV. In the Examples, <NUM> times the signal intensity was observed in the case with application of -<NUM> kV and heat treatment relative to the Comparative Example, whereby it was found that the Example could ionize chloramphenicol much more efficiently than the Comparative Example. In the Examples, <NUM> times the signal intensity was obtained with the application of -<NUM> kV relative to the case without voltage application in the Relative Example, whereby it was found that chloramphenicol could be ionized more efficiently by voltage application.

In the foregoing, the preferred embodiments of the present invention have been described in detail; however, the present invention is not limited to the specific embodiments, and various modifications and changes can be made within the scope of the present invention described in the claims.

The shape of the cross-section and the channel of the liquid supply tube has been described as circular, but may be triangular, square, pentagonal, hexagonal or other polygonal shapes, or other shapes such as an elliptical shape. The shape of the outer circumferential surface and the inner circumferential surface of the gas supply tube and the second gas supply tube can be selected from these shapes, depending on the shape of the liquid supply tube.

The spray ionization device of each of the aforementioned embodiments can be used as an ion source of various devices; for example, in the field of trace sample analysis, the spray ionization device can be used for mass spectrometry such as mass spectrometry of molecules in a biological sample, elemental analysis, chemical morphology analysis, and charged particle analysis.

In the field of surface treatment, the spray ionization device of each of the aforementioned embodiments can be used in surface coating techniques of spraying electrically charged droplets, and in the field of granulation, can be used in particle forming techniques by spraying electrically charged droplets of suspension.

Claim 1:
A spray ionization device (<NUM>, <NUM>, <NUM>), comprising: a first tube (<NUM>) including a first channel (<NUM>) through which a liquid (Lf) can flow, the first tube (<NUM>) including a first outlet (21a) for ejecting the liquid (Lf) at one end;
a second tube (<NUM>, <NUM>) surrounding the first tube (<NUM>) with a gap and including a second channel (<NUM>, <NUM>) through which a gas (Gf) can flow, the second tube (<NUM>, <NUM>) including a second outlet (322a, 522a) arranged further toward a tip than the first outlet (21a) at the one end, the second channel (<NUM>, <NUM>) being defined by an outer circumferential surface of the first tube (<NUM>) and an inner circumferential surface of the second tube (<NUM>, <NUM>);
an electrode (<NUM>) that extends within the first channel (<NUM>) of the first tube (<NUM>) from an opposite end to the one end, and is arranged so that a leading end is at the same position as the first outlet (21a) or further toward the opposite end than the first outlet (21a), the electrode (<NUM>) being capable of applying voltage to the liquid (Lf) by way of a power source (<NUM>) connected to the electrode (<NUM>) and being a wire formed from an electrode material including a platinum group metal, gold or an alloy thereof, or titanium or tungsten; and
an opening (322d, 522d) provided to the second tube (<NUM>, <NUM>) between the first outlet (21a) and the second outlet (322a, 522a), the opening (322d, 522d) being a portion at which a diameter of the inner circumferential surface of the second tube (<NUM>, <NUM>) is smallest and being narrower than an opening of the first outlet (21a), wherein
electrically charged droplets of the liquid (Lf) can be ejected from the second outlet (322a, 522a).