Analysis device

Abstract

To change the irradiation position of laser light when analyzing a liquid sample.SOLUTION: An analyzer (1) includes: a cell (11) having a housing section (11a) capable of housing a liquid sample (S); a laser light source (22) which outputs laser light (22a) for ablation of the surface of the liquid housed in the cell (11); mirrors (24, 25) which reflect the laser light (22a) output from the laser light source (22); a drive source (24b, 25b) which rotates the mirrors (24, 25); an optical system (23) which rotates the mirrors (24, 25) according to the irradiation position of the laser light (22a); and an analyzing instrument (2) which introduces an aerosol containing the sample (S) subjected to the laser ablation and delivered from the cell (11), and analyzes the introduced sample (S) by inductively-coupled plasma system.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an analytical apparatus that irradiates a sample with a laser to release (ablate) fine particles of the sample and analyzes the ablated fine particles, and more particularly to an analytical apparatus suitable for the case where the sample is a liquid.

Background Art

[0002] As a technique for subjecting a sample in the form of ions or fine particles to plasma by applying a high voltage and observing and analyzing light from excited atoms to perform qualitative and quantitative analysis of elements (mass spectrometry, MS: Mass Spectrometry), an inductively coupled plasma (ICP: Inductively Coupled Plasma) method of analytical technique is known. In an ICP mass spectrometer (ICP-MS), a sample is made into ions or fine particles and supplied to a plasma. A liquid sample in which the measurement target is dissolved in a solvent is generally measured by spraying it into fine droplets with a nebulizer (sprayer). In addition, for samples that are difficult to dissolve in a solvent or solid samples that are desired to be measured without being dissolved, ablation is performed by irradiating with a laser to form an aerosol (LA-ICP-MS). As a technique for atomizing a sample with respect to ICP-MS, the technique described in Non-Patent Document 1 below is known.

[0003] Non-Patent Document 1 (Gunther et al.) describes a technique in which a solution in which a trace element to be measured and NaCl are dissolved is placed in a 150 μL beaker, the surface is covered with a film for preventing evaporation, a 20 μm through-hole is formed in the film, and laser light of an excimer laser having a wavelength of 193 nm and a repetition frequency of 1 Hz - 20 Hz is irradiated through the through-hole toward the solution.

Prior Art Documents

Non-Patent Documents

[0004]

Non-Patent Document 1

[0005] (Problems of the Prior Art) In the technique described in Non-Patent Document 1, when performing liquid ablation, it is difficult to move the position where the laser beam is irradiated. If the laser beam is continuously irradiated at the same position, the temperature at the irradiation position will rise too much, the characteristics will change, or the ablation conditions will fluctuate, which will have an adverse effect on the measurement. Generally, the position where the laser beam is irradiated is achieved by moving the stage that supports the cell. However, if the cell containing the liquid is moved, there is a risk that the liquid will spill. If the liquid spills, the spilled liquid will evaporate and mix with the ablated material, which may have an adverse effect on the measurement results. In addition, when the cell is moved, if waves are generated on the surface of the liquid, the position of the liquid surface will not be stable, and there is a risk of deviation from the irradiation position (focus position) of the laser beam. Therefore, uneven ablation may occur, which may have an adverse effect on the measurement results. Furthermore, once waves are generated, it takes a long time for the waves to subside, and experiments cannot be conducted until the waves subside, resulting in a problem that the experiments take a long time.

[0006] The technical problem of the present invention is to make it possible to change the irradiation position of the laser beam when analyzing a liquid sample. Means for Solving the Problems

[0007] In order to solve the above technical problem, the analysis apparatus according to the invention described in claim 1 is Capable of accommodating a liquid sample DepressedA cell having a housing portion, A laser light source that outputs laser light for ablating the surface of the liquid contained in the cell, An optical system capable of moving the irradiation position of the laser light output from the laser light source, An analyzer into which an aerosol containing a sample that has been ablated and sent out from the cell is introduced, and the introduced sample is analyzed by an inductively coupled plasma method, characterized by comprising the above.

[0008] The invention according to claim 2 is the analyzer according to claim 1, It has a mirror that reflects the laser light output from the laser light source and a drive source that rotates the mirror, and the optical system in which the mirror is rotated according to the irradiation position of the laser light, characterized by comprising the above.

[0009] The invention according to claim 3 is the analyzer according to claim 2, The mirror having a first mirror rotatable about a first axis and a second mirror rotatable about a second axis different from the first axis, and the drive source having a first drive source that rotates the first mirror about the first axis and a second drive source that rotates the second mirror about the second axis, and the laser light from the laser light source is reflected by the first mirror, the laser light reflected by the first mirror is reflected by the second mirror toward the sample, and the optical system in which the repetition frequency, which is the frequency at which each mirror is rotated, is 10 kHz or more, characterized by comprising the above.

[0010] The invention according to claim 4 is the analyzer according to any one of claims 1 to 3, The laser light source that outputs femtosecond pulse laser light with a pulse width of the order of femtoseconds of the laser light, characterized by comprising the above.

Advantages of the Invention

[0011] According to the invention described in claim 1, when analyzing a liquid sample, the irradiation position of the laser beam can be changed. According to the invention described in claim 2, the irradiation position of the laser beam can be changed by controlling the mirror that reflects the laser beam. According to the invention described in claim 3, compared with the case where there is one mirror, the range where the laser beam can be irradiated can be widened, and compared with the case where the repetition frequency is low, the analysis can be executed in a shorter time. According to the invention described in claim 4, ablation can be surely performed compared with the case of using nanosecond laser light.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Modes for Carrying Out the Invention

[0013] Next, examples which are specific examples of the embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the following examples. In the following description using the drawings, illustrations other than the members necessary for the description are appropriately omitted for ease of understanding.

Examples

[0014] FIG. 1 is an overall explanatory view of the analyzer according to Embodiment 1 of the present invention. In FIG. 1, the analyzer 1 of Example 1 includes a mass spectrometer 2 as an example of an analyzer. The mass spectrometer 2 of Example 1 is configured as an inductively coupled plasma mass spectrometer (ICP-MS: Inductively Coupled Plasma - Mass Spectrometer). Note that the analyzer is not limited to ICP-MS, and for example, an inductively coupled plasma optical emission spectrometer (ICP-OES: Inductively Coupled Plasma - Optical Emission Spectroscopy) can also be used. Note that for ICP-MS and ICP-OES, conventionally known ones can be used, for example, as described in Japanese Patent Application Laid-Open No. 2013-130492 and the like, and since they are publicly known, detailed descriptions are omitted.

[0015] The downstream end of a connection tube 3 as an example of a connection part is connected to the mass spectrometer 2. A merging joint 4 is connected to the upstream end of the connection tube 3. The downstream end of an additional gas tube 6 as an example of an additional gas supply part is connected to the merging joint 4. In Example 1, argon (Ar) gas as an example of an additional gas (makeup gas) is supplied to the additional gas tube 6. Note that in Example 1, the argon gas is supplied at a flow rate of about 0.5 to 1.2 L / min as an example. The downstream end of a cell connection tube 7 as an example of a cell connection part is connected to the merging joint 4. A cell 11 is connected to the upstream end of the cell connection tube 7.

[0016] FIG. 2 is an explanatory diagram of the cell of Example 1. In FIG. 2, a well 11a as an example of a storage part capable of storing a liquid is formed in the cell 11. A liquid sample S is stored in the well 11a. Note that in this specification and the claims of the present application, the "liquid sample" is used in the sense that it includes not only the case where the sample itself is in a liquid state, but also the case where the sample is dissolved as ions in a solvent or the case where fine particles of the sample are dispersed in a solvent, that is, the case where the sample exists in a liquid. A carrier gas tube 12, which is an example of a carrier gas supply unit, is connected to the cell 11. In Example 1, helium (He) gas, which is an example of a carrier gas, is supplied to the carrier gas tube 12. In Example 1, the carrier gas is supplied at a flow rate of about 0.2 to 1 L / min as an example.

[0017] Also, a laser ablation device 21 is disposed above the cell 11. The laser ablation device 21 irradiates the sample S in the cell 11 with laser light to ablate the sample S. The analyzer 1 of Example 1 includes a computer device 31, which is an example of an information processing device. The computer device 31 includes a computer main body 32, a display 33, which is an example of a display unit, and a keyboard 34 and a mouse 35, which are examples of input units. The computer main body 32 outputs a signal for controlling the driving of the laser ablation device 21 and receives a detection result from the mass spectrometer 2 and can display it on the display 33.

[0018] (Description of the laser ablation device) FIG. 3 is an explanatory diagram of the main part of the laser ablation device of Example 1. In FIG. 3, the laser ablation device 21 of Example 1 includes a femtosecond laser 22, which is an example of a laser light source. The femtosecond laser 22 outputs femtosecond laser light 22a having a pulse width on the order of femtoseconds as an example of laser light. The femtosecond laser 22 of Example 1 outputs femtosecond laser light 22a having a pulse width of 230 fs as an example, but the pulse width is not limited to the illustrated value and can be changed. In Example 1, the femtosecond laser 22 has a shutter (not shown) disposed therein and is configured to be able to control the frequency (the reciprocal of the interval at which the femtosecond laser light 22a is output) at which the femtosecond laser light 22a is output. In Example 1, as an example, the frequency can be controlled between 100 Hz and 60 kHz. That is, from the femtosecond laser 22, the femtosecond laser light 22a is output at 60 kHz, and in the case of 60 kHz, the shutter is kept open at all times. In the case of 10 kHz, the femtosecond laser light 22a of 5 out of 6 shots can be blocked by the shutter to obtain an output of 10 kHz. When other repetition frequencies are used, it is possible to cope by changing the number of blocks by the shutter according to the target frequency.

[0019] The femtosecond laser light 22a is introduced into a galvano optical system 23 as an example of an optical system capable of moving the irradiation position of the femtosecond laser light 22a in the cell 11. The galvano optical system 23 of Example 1 includes a first galvano mirror 24 as an example of a first mirror and a second galvano mirror 25 as an example of a second mirror. The first galvano mirror 24 reflects the femtosecond laser light 22a from the femtosecond laser 22 toward the second galvano mirror 25, and the second galvano mirror 25 reflects the femtosecond laser light 22a from the first galvano mirror 24 toward the sample S. The first galvano mirror 24 is rotatably supported about a first mirror axis 24a. Driving is transmitted to the first mirror axis 24a from a first galvano motor 24b as an example of a first drive source. Therefore, in response to the drive from the first galvano motor 24b, the first galvano mirror 24 rotates and tilts about the first mirror axis 24a to change the reflection direction of the femtosecond laser light 22a.

[0020] The second galvanometer mirror 25 also has a second mirror axis 25a and a second galvanometer motor 25b as an example of a second drive source, similar to the first galvanometer mirror 24, and changes the reflection direction of the femtosecond laser beam 22a. In Example 1, as an example, the first galvanometer mirror 24 mainly controls the irradiation position in the X direction along the gas flow direction on the surface of the sample S, and the second galvanometer mirror 25 mainly controls the irradiation position in the Y direction intersecting the gas flow direction. Therefore, by controlling the two galvanometer mirrors 24 and 25, it is possible to two-dimensionally scan the femtosecond laser beam 22a. In Example 1, as an example, it is configured to be able to irradiate the femtosecond laser beam 22a in a range of 20 cm × 20 cm. A lens 26 as an example of an optical member is disposed between the second galvanometer mirror 25 and the cell 11. The lens 26 condenses the passing femtosecond laser beam 22a so that the position of the focus of the femtosecond laser beam 22a becomes the surface of the sample S.

[0021] (Description of the control unit in Example 1) A computer main body 32 as an example of a control unit has an input / output interface I / O for performing input / output of signals with the outside. The computer main body 32 also has a ROM (Read Only Memory) in which programs and information for performing necessary processing are stored. The computer main body 32 also has a RAM (Random Access Memory) for temporarily storing necessary data. The computer main body 32 also has a CPU (Central Processing Unit) for performing processing according to the programs stored in the ROM and the like. Therefore, the computer main body 32 can realize various functions by executing the programs stored in the ROM and the like.

[0022] (Functions of the computer main body 32) The computer main body 32 has a function of executing processing according to input signals from signal output elements such as a keyboard 34, a mouse 35, a mass spectrometer 2, and other sensors (not shown in the figure), and outputting control signals to each control element such as the galvanometer motors 24b and 25b and the shutter of the femtosecond laser 22. That is, the computer main body 32 rotates the galvanometer mirrors 24 and 25 respectively according to the target irradiation position in the liquid sample S in the cell 11, and irradiates the femtosecond laser beam 22a to the target irradiation position. Also, it has functions such as controlling the shutter according to the set repetition frequency and displaying the analysis result on the display 33.

[0023] (Operation of Example 1) In the analyzer 1 of Example 1 having the above configuration, when ablating the target analysis position in the liquid sample S, the position where the femtosecond laser beam 22a is irradiated by the galvanometric optical system 23 is controlled. Therefore, in the analyzer 1 of Example 1, when moving the irradiation position of the femtosecond laser beam 22a, it is not necessary to move the cell 11 side. Therefore, it is possible to prevent the liquid sample S from spilling from the well 11a of the cell 11 or the liquid sample S from being agitated. Therefore, when analyzing a liquid sample, while making it possible to change the irradiation position of the laser beam, it is possible to suppress an adverse effect on the measurement result. In particular, in the conventional configuration that moves the stage, the moving speed of commercially available ones is generally about 100 μm / sec to 200 μm / sec. In contrast, in the galvanometric optical system 23, it is possible to scan the laser beam even at 200 mm / sec or more. That is, it is possible to realize a moving speed of 1000 to 2000 times. Therefore, when the repetition frequency is the same, the moving distance (interval, pitch) between the irradiation of the next laser beam after one pulse-shaped laser beam is irradiated and the irradiation of the next laser beam becomes 1000 to 2000 times. For example, when the repetition frequency is 1 kHz, in the case of stage movement, the pitch is 100 nm to 200 nm, whereas in Example 1, it can be 200 μm. Therefore, in the case of stage movement, there is a concern that the irradiation position of the next laser beam overlaps with the irradiation position of the previous laser beam and the temperature rises too much, but this is suppressed in Example 1.

[0024] In Example 1, the galvanometric optical system 23 has two galvanometric mirrors 24 and 25. In a configuration with only one galvanometric mirror, the irradiation position of the femtosecond laser beam 22a can only be adjusted along one axis (linear), but in Example 1 with two galvanometric mirrors 24 and 25, the irradiation position can be adjusted in two axes, that is, in the plane. Therefore, compared with the case where there is only one galvanometric mirror, it is possible to significantly expand the irradiable range.

[0025] In Example 1, the galvanometric mirrors 24 and 25 are driven at a high repetition frequency of 10 kHz. Therefore, when the number of irradiation positions is the same, compared with the case where the repetition frequency is low, the time required to irradiate the femtosecond laser beam 22a is shortened. For example, when the repetition frequency is 10 Hz, it takes 600 seconds = 10 minutes to irradiate 6000 laser beams, but in Example 1 with a repetition frequency of 10 kHz, it only takes 0.6 seconds to irradiate 6000 laser beams. Therefore, compared with the case where the repetition frequency is low, in Example 1, the number of fine particles ablated in a short time increases, and the amount of aerosol generated can be increased. Therefore, the amount of aerosol introduced into the mass spectrometer 2 can be increased, and the signal intensity measured by the mass spectrometer 2 also becomes stronger. Furthermore, in Example 1, femtosecond laser beam 22a is used as the laser beam. Therefore, compared with a laser beam with a nanosecond pulse width, the intensity of the laser beam is high, and ablation can be surely performed.

[0026] (Modified Example) As described above, the embodiments of the present invention have been described in detail, but the present invention is not limited to the above embodiments, and various modifications can be made within the scope of the gist of the present invention described in the claims. Modified examples (H01) to (H05) of the present invention are exemplified below. (H01) In the above embodiment, the galvanometric optical system 23 is exemplified as a two-axis control configuration, but it is also possible to adopt a configuration with three or more axes. It is also possible to adopt a one-axis configuration. (H02) In the above embodiment, it is desirable to use the femtosecond laser 22 as the laser light source, but it is not limited thereto. Depending on the object to be measured, etc., it is also possible to use lasers other than the femtosecond laser, for example, nanosecond lasers such as excimer lasers and YAG lasers.

[0027] (H03) In the above embodiment, specific numerical values and shapes can be arbitrarily changed according to the design, specifications, etc. (H04) In the above embodiment, it is preferable to use He gas as the carrier gas, but it is not limited thereto. Depending on the type of sample to be analyzed and the required accuracy, etc., it can be changed to, for example, hydrogen gas, neon gas, argon gas, etc. (H05) In the above embodiment, the galvano optical system 23 is exemplified as an example of the optical system capable of moving the irradiation position of the femtosecond laser light 22a, but it is not limited thereto. For example, as an example of the optical system, it is also possible to use a rotating polygon mirror (polygon mirror) provided with a plurality of reflecting mirrors on the outer surface of a rotating polygonal prism. In addition, for example, it is also possible to use an LCOS (Liquid Crystal On Silicon), which is a reflective liquid crystal element using liquid crystal, as an optical element.

Description of Reference Numerals

[0028] 1…Analyzer, 2…Analyzer, 11…Cell, 11a…Accommodation part, 22…Laser light source, 22a…Laser light, 23…Optical system, 24…First mirror, 24,25…Mirrors, 24a…First axis, 24b…First drive source, 24b,25b…Drive sources, 25…Second mirror, 25a…Second axis, 25b…Second drive source, S…Sample.

Claims

1. a cell having a depression-shaped storage portion capable of storing a liquid sample; a laser light source that outputs a laser beam that ablates the surface of the liquid contained in the cell; an optical system capable of moving an irradiation position of the laser light output from the laser light source; an analyzer into which an aerosol containing the sample ablated and discharged from the cell is introduced, and which analyzes the introduced sample by an inductively coupled plasma method; An analytical device comprising:

2. an optical system including a mirror that reflects the laser light output from the laser light source and a drive source that rotates the mirror, the mirror being rotated according to an irradiation position of the laser light; The analysis device according to claim 1 , further comprising:

3. the optical system including a first mirror rotatable around a first axis and a second mirror rotatable around a second axis different from the first axis, and a drive source including a first drive source for rotating the first mirror around the first axis and a second drive source for rotating the second mirror around the second axis, wherein a laser beam from the laser light source is reflected by the first mirror and the laser beam reflected by the first mirror is reflected by the second mirror toward the sample, and a repetition frequency, which is a frequency at which each of the mirrors is rotated, is 10 kHz or more; The analysis device according to claim 2 , further comprising:

4. the laser light source outputs femtosecond pulsed laser light having a pulse width on the order of femtoseconds; 4. The analysis device according to claim 1, further comprising:

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