JP7471575B2 - Sample introduction device, inductively coupled plasma analysis device and analysis method - Google Patents

Description

The present invention relates to a sample introduction device, an inductively coupled plasma analysis device, and an analysis method.

In order to atomize the sample liquid and introduce it into the analysis section as droplets, various analytical devices are equipped with a sample introduction device that includes a nebulizer (sprayer) and a spray chamber (see, for example, Patent Document 1).

JP 2008-157895 A

In order to obtain highly reliable analytical results using an analytical device, it is desirable that the measurement results do not fluctuate significantly even when the analytical device is used continuously. However, the inventor's investigation has revealed that the device described in Patent Document 1 is not necessarily sufficient in this respect.

One aspect of the present invention aims to provide a sample introduction device that enables highly reliable analytical results to be obtained in an analytical device.

One aspect of the present invention is
A nebulizer for atomizing the sample liquid;
a spray chamber into one end of which the spray nozzle of the nebulizer is inserted and into which at least a portion of the droplets of the sample liquid sprayed from the spray nozzle are discharged to the outside from the other end;
A heating electromagnetic wave irradiation unit arranged outside the spray chamber;
having
the heating electromagnetic wave irradiation unit irradiates heating electromagnetic waves from the outside of the spray chamber toward at least a part of the spray chamber excluding a part into which the spray nozzle of the nebulizer is inserted;
Regarding.

The above-mentioned Japanese Patent Application Laid-Open No. 2008-157895 (Patent Document 1) discloses a sample introduction device equipped with a heating light irradiation means. When the sample droplets atomized by the nebulizer and introduced into the chamber are heated by the heating light, at least a part of the solvent contained in the sample droplets can be vaporized. The present inventor believes that by heating the sample droplets in this way to vaporize at least a part of the solvent, the load of the solvent on the analysis unit of the analysis device can be reduced, which leads to an increase in the measurement signal intensity obtained in the analysis unit. However, in the device described in Japanese Patent Application Laid-Open No. 2008-157895, the irradiation of the heating light by the irradiation means is performed so as to cover the spray nozzle of the nebulizer (see claim 1, FIG. 1, etc. of the same publication). In contrast, in the sample introduction device according to one aspect of the present invention, the heating electromagnetic wave irradiation unit irradiates the heating electromagnetic wave toward at least a part of the spray chamber excluding the part into which the spray nozzle of the nebulizer is inserted. In other words, the spray nozzle of the nebulizer is not directly irradiated with the heating electromagnetic wave. The present inventors believe that this contributes to the fact that measurement results do not fluctuate significantly even when an analytical device including such a sample introduction device is used continuously.
It is believed that when heating light is applied so as to cover the nozzle of a nebulizer as in the device described in JP 2008-157895 A, as irradiation continues, the components contained in the sample liquid at the nozzle of the nebulizer dry out and precipitate inside or at the tip of the nozzle. If deposits such as such deposits or laminated carbides adhere to the inside or tip of the nozzle during analysis in an analyzer, the amount of sample droplets sprayed from the nebulizer will vary, which is believed to result in large fluctuations in the measurement results.
In contrast, in the sample introduction device according to one aspect of the present invention, the nozzle of the nebulizer is not directly irradiated with the heating electromagnetic waves, which makes it possible to suppress variation in the amount of sample droplets sprayed from the nebulizer during analysis in the analyzer, and as a result, it is believed that it is possible to perform a highly reliable analysis without significant fluctuations in the measurement results.

In one embodiment, the heating electromagnetic waves can include near-infrared radiation.

In one embodiment, the spray chamber can be made of glass, quartz, or fluororesin.

In one embodiment, the heating electromagnetic wave irradiation unit can irradiate the heating electromagnetic waves toward at least a portion of the spray chamber near the end from which at least a portion of the droplets are discharged.

In one embodiment, the heating electromagnetic wave irradiation unit can have a circular ring shape, and the spray chamber can be inserted into the hollow portion of this circular ring shape.

In one embodiment, the amount of sample liquid introduced into the nebulizer can be 1 μL/min or more and 500 μL/min or less.

One aspect of the present invention relates to an inductively coupled plasma analyzer including the above-mentioned sample introduction device and an analysis section.

In one embodiment, the inductively coupled plasma analyzer can include a plasma torch and an injector that introduces a sample to be analyzed into the plasma torch, and the inner diameter of the injector can be 0.50 mm or more and 1.50 mm or less.

In one embodiment, the inductively coupled plasma analyzer may further include a gas supply source that supplies argon gas to the plasma torch and a gas supply source that supplies one or more gases other than argon gas.

In one embodiment, the one or more other gases can be selected from the group consisting of nitrogen gas, oxygen gas, and hydrogen gas, and this gas can be supplied to the plasma torch in an amount per unit time that is less than that of argon gas.

In one embodiment, the inductively coupled plasma analyzer can be an inductively coupled plasma mass analyzer or an inductively coupled plasma optical emission spectrometer.

One aspect of the present invention relates to an analytical method that includes performing qualitative analysis, quantitative analysis, or qualitative analysis and quantitative analysis of a sample to be analyzed using the inductively coupled plasma analyzer described above.

In one embodiment, the above analytical method can perform qualitative analysis, quantitative analysis, or qualitative and quantitative analysis of metal components in a sample to be analyzed.

According to one aspect of the present invention, it is possible to provide a sample introduction device that enables an analytical device to obtain highly reliable analytical results. Furthermore, according to another aspect of the present invention, it is possible to provide an inductively coupled plasma analytical device that includes such a sample introduction device, and an analytical method that uses this inductively coupled plasma analytical device.

FIG. 1 is a schematic diagram (side view) showing an example of a sample introduction device according to an embodiment of the present invention. FIG. 2 is a schematic diagram (side view) showing an example of a spray chamber. FIG. 2 is a schematic diagram (top view) showing an example of a spray chamber. FIG. 2 is a schematic diagram (side view) showing an example of a spray chamber. FIG. 4 is an explanatory diagram of the arrangement of an additional gas introduction pipe portion in the spray chamber shown in FIGS. 3A and 3B. FIG. 4 is an explanatory diagram of the arrangement of an additional gas introduction pipe portion in the spray chamber shown in FIGS. 3A and 3B. FIG. 4 is an explanatory diagram of the arrangement of an additional gas introduction pipe portion in the spray chamber shown in FIGS. 3A and 3B. FIG. 2 is a schematic diagram (top view) showing another example of a spray chamber. FIG. 2 is a schematic diagram (side view) showing another example of a spray chamber. 1 shows the monitoring results of In signal intensity obtained for Example 1 and Comparative Example 1. 1 shows the relative standard deviation (RSD) of the In signal intensities calculated for Examples 2 and 3. 1 shows the relative intensity ratios (signal intensity with heating electromagnetic wave irradiation/signal intensity without heating electromagnetic wave irradiation) of the signal intensities of various analytes obtained in Example 4. 1 shows the relative standard deviation (RSD) of the signal intensities of various analytes obtained in Example 4. 1 shows the relative intensity ratios (signal intensity with _N2 introduction/signal intensity without _N2 introduction) of the signal intensities of various analytes obtained in Example 5. 1 shows the relative standard deviation (RSD) of the signal intensities of various analytes obtained in Example 5.

[Sample introduction device]
The above-mentioned sample introduction device will be described in more detail below. Although the following description may refer to the drawings, the embodiments shown in the drawings are merely examples, and the present invention is not limited to these embodiments.

Figure 1 is a schematic diagram (side view) showing an example of a sample introduction device according to one embodiment of the present invention. The sample introduction device 1 shown in Figure 1 includes a spray chamber 10, a nebulizer 16, and a heating electromagnetic wave irradiation unit 17.

<Electromagnetic wave heating irradiation unit>
In the sample introduction device 1 shown in FIG. 1, the heating electromagnetic wave irradiation unit 17 is arranged at a position where the heating electromagnetic wave is not irradiated to the spray nozzle at the tip of the nebulizer 16. It is considered that such an arrangement of the heating electromagnetic wave irradiation unit can contribute to the fact that the measurement results do not fluctuate significantly even when the analysis device including this sample introduction device is used continuously. Furthermore, the fact that at least a part of the solvent contained in the sample droplets introduced from the nebulizer can be vaporized by the irradiation of the heating electromagnetic wave from the heating electromagnetic wave irradiation unit contributes to reducing the load of the solvent on the analysis unit of the analysis device, which is considered to lead to increasing the measurement signal intensity obtained in the analysis unit. In addition, by arranging the means for irradiating the heating electromagnetic wave outside the spray chamber, it is possible to prevent the occurrence of contamination inside the spray chamber by such means.

The heating electromagnetic waves irradiated from the heating electromagnetic wave irradiating unit can be various electromagnetic waves capable of heating droplets of the sample liquid flowing inside the spray chamber. Examples of such electromagnetic waves include infrared rays and microwaves. Here, "infrared rays" refers to electromagnetic waves with a wavelength in the range of 780 nm to 1000 μm, including near infrared rays (wavelength 780 nm to 2 μm), mid infrared rays (wavelengths greater than 2 μm to 4 μm), and far infrared rays (wavelengths greater than 4 μm to 1000 μm). "Microwaves" refers to electromagnetic waves with a wavelength in the range of 1 cm to 10 cm. In one embodiment, the heating electromagnetic waves irradiated from the heating electromagnetic wave irradiating unit are preferably electromagnetic waves capable of heating droplets of the sample liquid flowing inside the spray chamber without raising the temperature of the spray chamber (or with a small degree of temperature rise). This is because it is possible to prevent the spray chamber from being heated and contaminants from seeping out of the spray chamber, thereby contaminating the inside of the spray chamber. From this perspective, it is preferable that the heating electromagnetic waves include near-infrared rays, and more preferably are near-infrared rays.

In one embodiment, the heating electromagnetic wave irradiation unit can have a circular ring shape. A spray chamber can be inserted into the hollow portion of such a circular ring shape. The heating electromagnetic wave irradiation unit having a circular ring shape can irradiate the heating electromagnetic wave toward the inside of the ring. An example of such a heating electromagnetic wave irradiation unit is the heating irradiation unit 17 shown in FIG. 1. Such a heating electromagnetic wave irradiation unit can have, for example, a configuration in which a plurality of electromagnetic wave irradiation means (e.g., infrared lamps, microwave generation sources, etc.) are arranged in the circumferential direction inside the circular ring-shaped cover part, a configuration in which a circular ring-shaped electromagnetic wave irradiation means is arranged inside the circular ring-shaped cover part, etc. In addition, the inner wall of the circular ring-shaped cover part may be made of a material that is reflective to the heating electromagnetic wave. However, the heating electromagnetic wave irradiation unit of the sample introduction device is not limited to a circular ring shape as long as it can irradiate the heating electromagnetic wave from the outside of the spray chamber toward at least a part of the spray chamber except for the part where the spray nozzle of the nebulizer is inserted, and can have various shapes and configurations.
The location of the heating electromagnetic wave irradiator in the sample introduction device will be described later in more detail.

<Nebulizer>
The nebulizer of the sample introduction device may be a nebulizer (also called a sprayer) of a known configuration capable of atomizing droplets. The nebulizer can atomize the sample liquid introduced into the nebulizer, spray a gas flow containing droplets of the atomized sample liquid, and introduce it into the spray chamber. The amount of sample liquid introduced into the nebulizer may be determined according to the type of analytical device into which the sample is introduced by the sample introduction device, and may be, for example, 1 μL/min to 500 μL/min. In the nebulizer, for example, the sample liquid is mixed with a carrier gas and sprayed to generate a gas flow containing sample droplets (atomize the sample). As the carrier gas, one or more inert gases are generally used. A specific example of the carrier gas is argon gas.

The gas stream containing the sample droplets atomized by the nebulizer is introduced into the spray chamber and circulated within the spray chamber.

<Spray chamber>
The spray chamber of the sample introduction device may have a configuration capable of introducing droplets from one end by a gas flow and discharging at least a part of the introduced droplets to the outside from the other end. With such a configuration, droplets of the sample liquid can be introduced from one end of the spray chamber together with a gas flow and at least a part of the introduced droplets of the sample liquid can be discharged to the outside from the other end. The spray chamber usually plays a role of selecting the particle size of droplets by gravity difference using the difference in weight due to the difference in particle size of the droplets and selectively introducing fine droplets into the analysis device.

The spray chamber can be a single tubular member, or a member made up of two or more members. From the viewpoint of the transparency of the heating electromagnetic waves, the spray chamber is preferably made of glass, quartz, or fluororesin.

Below, an example of the spray chamber of the sample introduction device is described with reference to the drawings. However, the spray chamber of the sample introduction device is not limited to this example.

Figure 2 is a schematic diagram (side view) showing an example of a spray chamber. The spray chamber 10 shown in Figure 2 is composed of a flow path pipe section 13 including a first pipe section 11 and a second pipe section 12. In the spray chamber 10 of the embodiment shown in Figure 2, the first pipe section 11 is connected to an analysis section, the details of which will be described later. More specifically, the first pipe section 11 is connected to an inlet section 14, which is the part of the analysis section located closest to the spray chamber, via a joint member 15. In addition, in the spray chamber 10 shown in Figure 2, the second pipe section 12 is connected to a nebulizer 16. Furthermore, Figures 3A and 3B are drawings showing a schematic diagram of only the spray chamber. Figure 3A is a top view, and Figure 3B is a side view. Note that in the figures, the dotted lines indicate thickness and do not indicate a double pipe.

The spray chamber 10 shown in Figures 3A and 3B is composed of a flow path pipe section 13 having an outlet section 110 at one end and a sample introduction section 121 at the other end. The flow path pipe section 13 is composed of a first pipe section 11 and a second pipe section 12. The first pipe section 11 is composed of an outlet section 110, a conical section 111, and a cylindrical section 112. On the other hand, the second pipe section 12 is composed of a cylindrical section 120 and a sample introduction pipe section 121. The cylindrical section 112 of the first pipe section 11 and the cylindrical section 120 of the second pipe section 12 are at least partially overlapped and connected to form a double pipe section 100. Therefore, the inner wall surface of the double pipe space of the double pipe section 100 is the outer side surface of the cylindrical section 120 of the second pipe section 12, and the outer wall surface of the double pipe space of the double pipe section 100 is the inner wall surface of the cylindrical section 112 of the first pipe section 11.

Next, the first and second tube sections will be explained in more detail.

3A and 3B, the first pipe portion 11 has an outlet portion 110 at one end, and the outlet portion 110 is connected to a conical portion 111. The conical portion 111 has a conical shape with an inner diameter that decreases toward the outlet portion side. The conical portion 111 is connected to a cylindrical portion 112 including the other end of the first pipe portion.
On the other hand, the second tubular part 12 has a cylindrical part 120 including one end thereof communicating with a sample introduction port part 121 including the other end thereof.
The first pipe section 11 and the second pipe section 12 having the above structure constitute the flow passage pipe section 13. Furthermore, at the connection section between the first pipe section 11 and the second pipe section 12, the cylindrical sections of both pipe sections overlap to constitute the double pipe section 100. The double pipe section is the section between the end opening of the cylindrical section of the first pipe section and the end opening of the cylindrical section of the second pipe section. Therefore, both ends of the double pipe section are open, but the imaginary plane surrounded by the openings will be referred to as the bottom surface hereinafter. In the embodiment shown in Figures 3A and 3B, the first pipe section 11 and the second pipe section 12 are separate members, and the first pipe section 11 and the second pipe section 12 are connected to each other by inserting the cylindrical section 120 of the second pipe section 12 into the end opening of the cylindrical section 112 of the first pipe section 11 to constitute the flow passage pipe section 13. For example, the cylindrical portion 112 of the first pipe portion 11 is tapered at the end, and the inner diameter of the end opening is approximately the same as the outer diameter of the end opening of the cylindrical portion 120 of the second pipe portion 12, so that the additional gas introduced into the double pipe portion 100 formed by connecting both pipe portions can be prevented from leaking to the outside from the connection portion of both pipe portions. Alternatively, the sealing property of the connection portion may be ensured by a seal member or the like. Note that, with regard to the sealing property of the connection portion, it is not essential to completely prevent the leakage of the additional gas, and leakage to the extent that it does not hinder the additional gas introduced into the double pipe portion from flowing as a gas flow is permitted. Alternatively, the first pipe portion and the second pipe portion may be integrally molded to form a flow path pipe portion.

The double pipe section 100 has an opening on the outer side, that is, on the outer side of the cylindrical section 112 of the first pipe section 11. This opening is an opening (additional gas introduction opening) for introducing additional gas into the double pipe section (i.e., the space surrounded by the inner wall surface and the outer wall surface of the double pipe section). The additional gas introduction pipe section 101 serves as an introduction path for introducing additional gas into the double pipe section through the above-mentioned opening. By introducing additional gas from the additional gas introduction pipe section into the double pipe section through the opening, the introduced additional gas can swirl inside the double pipe section and produce a spiral gas flow (additional gas flow) toward the conical section 111 of the first pipe section 11. The presence of a conical section whose inner diameter becomes smaller toward the outlet section side of the spray chamber can also contribute to the additional gas flow becoming a spiral gas flow. The additional gas flow generated in this way can become a gas flow that spirals along the wall surface of the conical section toward the outlet section. This additional gas flow can prevent the sample droplets from adhering to the wall surface of the cone, and can also pick up the sample droplets and guide them to the outlet.

In the embodiment shown in Figures 3A and 3B, the cylindrical portion 112 of the first pipe portion 11 has a waste liquid opening and a waste liquid pipe portion 113 for draining liquid through the waste liquid opening in addition to the additional gas introduction opening. This waste liquid pipe portion 113 can serve as a drainage path for draining liquid from the inside of the double pipe portion 100 to the outside. In addition, in the embodiment shown in Figures 3A and 3B, the second pipe portion 12 also has a waste liquid pipe portion 122. This waste liquid pipe portion 122 can serve as a drainage path for draining liquid from the inside of the second pipe portion 12 to the outside.

Next, each part of the spray chamber will be explained in more detail.

Figures 4A to 4C are explanatory diagrams of the arrangement of the additional gas introduction pipe section in the spray chamber shown in Figures 3A and 3B. Figure 4A is a drawing showing explanatory arrows in the top view shown in Figure 3A, and Figure 4B is a cross-sectional view of a portion including the additional gas introduction pipe section of the double pipe section. Figure 4C is a drawing showing explanatory arrows in the side view shown in Figure 3B. The arrows in the drawings indicate the following directions. The X direction is the central axis direction of the additional gas introduction pipe section. The Y direction is the central axis direction of the cylindrical section of the first pipe section, and coincides with the central axis direction of the conical section of the first pipe section and the central axis direction of the cylindrical section of the second pipe section. The Y direction also coincides with the central axis direction of the flow passage pipe section. The Z direction is the central axis direction of the introduction pipe section.

Figure 5A shows a top view of another type of spray chamber, and Figure 5B shows a side view. The embodiments shown in Figures 5A and 5B are similar to the spray chambers shown in Figures 2 to 4C, except that the arrangement of the additional gas inlet tube 101 and the sample inlet 121 is different. A description of the similarities will be omitted.

The angle θ1 between the X direction and the Y direction is 90° in the embodiment shown in FIG. 4A to FIG. 4C, and 110° in the embodiment shown in FIG. 5A and FIG. 5B. The angle θ1 is defined in the range of 0° to 180°. The angle θ1 is preferably in the range of 90° to 130° from the viewpoint of smoothly rotating the gas flow of the additional gas introduced from the additional gas introduction pipe section in the double pipe section. In addition, the additional gas introduction opening can be provided at any position on the outer side surface of the double pipe section. For example, it may be provided at a position closer to the second pipe section, or closer to the first pipe section, based on the center of the outer side surface of the double pipe section, or it may be provided at a position where the center of the additional gas introduction opening coincides with the center of the outer side surface of the double pipe section. From the viewpoint of smoothly swirling the gas flow of the additional gas introduced from the additional gas introduction pipe section within the double pipe section, it is preferable to provide the additional gas introduction opening at a position closer to the second pipe section on the outer side surface of the double pipe section, and the closer it is to the second pipe section, the more preferable it is.

From the viewpoint of smoothly swirling the gas flow of the additional gas introduced from the additional gas introduction pipe section within the double pipe section, it is preferable that the length of the double pipe section, i.e., the shortest distance between the bottom surface of the first pipe section and the bottom surface of the second pipe section, is in the range of 10.0 mm to 30.0 mm. In addition, it is preferable that the diameter of the additional gas introduction opening is in the range of 0.1 to 3.0 mm. The same applies to the diameter of the waste liquid opening.

In the first tube section, the conical section is located between the cylindrical section and the outlet section, and the inner diameter becomes smaller toward the outlet section. In the first tube section, the position where the inner diameter change from the cylindrical section side toward the outlet section side starts is one end of the conical section, and the position where the inner diameter change ends is the other end of the conical section. The shortest distance from one end of the conical section to the other end is called the length of the conical section. The ratio of the length of the conical section to the maximum inner diameter of the conical section (length/maximum inner diameter) is preferably 0.3 or more from the viewpoint of reducing the wall adhesion loss of the sample droplet in the conical section. By having the above ratio be 0.3 or more (more preferably 0.5 or more, even more preferably 0.8 or more), the gas flow of the additional gas can be more smoothly spirally swirled in the conical section. In addition, the larger the above ratio, the longer the length of the conical section becomes relative to the maximum inner diameter of the conical section. The above ratio can be, for example, 4.0 or less or 3.5 or less. However, the longer the conical section is made and the larger the above ratio is, the longer the overall length of the spray chamber becomes, and the larger the spray chamber becomes. On the other hand, according to the inventors' studies, no further change in analytical sensitivity was observed even if the conical section was made longer so that the above ratio exceeded 3.0. Therefore, from the standpoints of both improving analytical sensitivity and miniaturizing the spray chamber, it is preferable that the above ratio is 3.0 or less.

The maximum inner diameter of the conical portion of the first tubular portion is preferably in the range of, for example, 25.0 to 65.0 mm. The maximum inner diameter of the conical portion is the inner diameter of the cylindrical portion that communicates with the conical portion. As described above, the cylindrical portion may have a tapered shape at the end. In this case, the inner diameter of the cylindrical portion refers to the maximum inner diameter of the cylindrical portion. The minimum inner diameter of the conical portion of the first tubular portion is preferably in the range of, for example, 5.0 to 10.0 mm. It is not essential that the cross-sectional shape of the conical portion passing through the central axis is part of a perfect triangle, and it is acceptable for at least a portion of the cross-sectional shape to include a curve.

In the spray chamber, the outer diameter of the cylindrical portion of the second pipe is smaller than the inner diameter of the cylindrical portion of the first pipe. This allows the cylindrical portion of the first pipe and the cylindrical portion of the second pipe to overlap at least partially to form a double pipe. The difference between the inner diameter of the cylindrical portion of the first pipe and the outer diameter of the cylindrical portion of the second pipe is preferably in the range of 1.0 mm to 6.0 mm. If the difference is in the range of 1.0 mm to 6.0 mm, the width of the space surrounded by the wall surface of the cylindrical portion of the first pipe and the outer side surface of the cylindrical portion of the second pipe in the double pipe, that is, the space into which the additional gas is introduced, can be in the range of 0.5 mm to 3.0 mm. It is preferable that the width of the space is 0.5 mm or more from the viewpoint of facilitating the discharge of the waste liquid from the double pipe. In addition, it is preferable that the width of the space is 3.0 mm or less from the viewpoint of smoothly swirling the gas flow of the additional gas introduced from the additional gas introduction pipe within the double pipe. As an example, it is preferable that the inner diameter of the cylindrical portion of the second pipe is in the range of 20.0 mm to 60.0 mm, for example. For example, if the inner diameter of the cylindrical portion of the second tube is 20 mm or more, collisions between sample droplets in the gas flow introduced from the sample inlet can be effectively suppressed, and droplet loss due to collisions between droplets can be reduced. Also, for example, if the inner diameter of the cylindrical portion of the second tube is 60 mm or less, this is preferable from the viewpoint of miniaturizing the second tube and further miniaturizing the spray chamber.

The second tube portion has a cylindrical portion and a sample introduction port portion, and is preferably composed of a cylindrical portion and a sample introduction port portion. In the embodiment shown in FIG. 4C, the angle θ2 between the central axis direction (Z direction) of the sample introduction port portion 121 and the central axis direction (Y direction) of the cylindrical portion of the first tube portion is 30°. On the other hand, in the embodiment shown in FIG. 5B, the Z direction is the same as the Y direction (i.e., the angle θ2 between the Z direction and the Y direction = 0°). θ2 is defined in the range of 0° to 90°. When θ2 is 0°, when a gas flow containing sample droplets is introduced into the spray chamber from a direction substantially the same as the central axis direction of the sample introduction port portion, the sample droplets are less likely to collide with the wall surface of the cylindrical portion of the second tube portion. It is considered that this can more effectively reduce the loss of droplets adhering to the wall surface in the spray chamber. Therefore, from the viewpoint of further improving the analytical sensitivity, it is preferable that the Z direction and the Y direction are the same direction.
On the other hand, when the Z direction is inclined with respect to the Y direction, when a gas flow containing sample droplets is introduced into the spray chamber from a direction substantially the same as the central axis direction of the sample introduction port, at least a part of the sample droplets is likely to collide with the wall surface of the cylindrical part of the second tube part. When the droplets collide with the wall surface of the cylindrical part of the second tube part, they are crushed by collision and can become finer droplets, so that the droplets discharged from the spray chamber tend to be finer. The finer sample droplets are preferable from the viewpoint of the stability of the sensitivity in the analysis part of the analysis device. Therefore, when stability is important, it is preferable that the Z direction is inclined with respect to the Y direction, and for example, θ2 is preferably in the range of 10° to 60°.

In the above spray chamber, the length of the cylindrical portion of the second tube is preferably, for example, 10.0 to 70.0 mm. At least a portion of the cylindrical portion constitutes a double tube portion, and the above length includes the length of the portion that constitutes the double tube portion. Note that the cylindrical portion of the second tube portion may not be a perfect cylinder, and the bottom surface portion on the sample introduction port side may be inclined with respect to the central axis direction of the cylindrical portion of the second tube portion, as shown in Figures 3B and 4C, for example. In this case, the length of the cylindrical portion refers to the shortest length (for example, l in Figure 4C).

In the above-mentioned spray chamber, the shape and length of the outlet part of the first tube part are not particularly limited as long as it has an opening that serves as the outlet. The tip of the outlet part is usually a connecting part with an analysis part in an analysis device, so the shape of the tip can be determined according to the shape of the analysis part.
On the other hand, the shape and length of the sample introduction port of the second tube part are not particularly limited as long as it has an opening for introducing a gas flow containing sample droplets from a nebulizer. The sample introduction port is usually an insertion port into which the tip of a nebulizer is inserted. The sample introduction port can have, for example, a cylindrical shape, but as described above, the shape is not particularly limited.

Regarding the overall length of the spray chamber, generally, the shorter the overall length, the more likely it is that the droplet loss in the spray chamber will be reduced, while the longer the overall length, the more likely it is that the particle size selection ability will be improved. In consideration of the above, it is preferable that the overall length of the spray chamber is, for example, in the range of 80.0 mm to 200.0 mm. The overall length of the spray chamber refers to the shortest distance from one extreme end to the other extreme end when viewed from the side. For example, it is the length L in Figure 4C and the length L in Figure 5B.

The spray chamber can introduce additional gas from the double tube section, which can reduce the wall adhesion loss of the sample droplets. However, due to the particle size selection of the sample droplets using the gravity difference in the spray chamber, some of the sample liquid introduced as droplets may remain in the spray chamber without being discharged from the spray chamber. In addition, some of the sample liquid introduced as droplets may remain in the spray chamber due to wall adhesion. It is preferable that the spray chamber has at least one waste liquid path for discharging the remaining sample liquid to the outside. For example, the waste liquid path for discharging the sample liquid remaining in the first tube section can be provided at any position in the first tube section, and in one embodiment, it can be provided in a part that constitutes the double tube section. That is, the spray chamber can have a waste liquid opening on the outer side surface of the double tube section and a waste liquid pipe section that serves as a waste liquid path for discharging liquid from the inside of the double tube section to the outside through the waste liquid opening (for example, waste liquid pipe section 113 in FIG. 3B). The outer side of the second tube section may also have a waste liquid opening for discharging sample liquid remaining in the second tube section, and a waste liquid pipe section that serves as a waste liquid path for discharging liquid from inside the second tube section to the outside via the waste liquid opening (for example, waste liquid pipe section 122 in FIG. 3B).

In this invention and this specification, the term "cylinder" used in relation to the cylindrical portion is not limited to a perfect cylindrical shape, but also includes an embodiment in which the end portion connected to the cylindrical portion has a different inner diameter, as described above. The term "cone" used in relation to the conical portion is not limited to a perfect conical shape, as described above. Furthermore, "almost the same" used in relation to the positional relationship in two directions, and "almost the same" used in relation to the size of the two diameters, are used to mean not only complete sameness, but also a generally acceptable range of error. The above-mentioned range of error means, for example, a range of 0.1° or less for the positional relationship in two directions, and, for example, a range of 1% or less for the size of the two diameters.

The first and second tube sections described above can be members made of any material. From the viewpoint of chemical durability such as acid resistance and alkali resistance, the above-mentioned materials are preferably various glasses, quartz, fluororesin, and various resins classified as engineering plastics or super engineering plastics. Examples of fluororesin include various fluororesins such as polytetrafluoroethylene. Examples of engineering plastics include various engineering plastics such as polycarbonate (PC), and examples of super engineering plastics include various super engineering plastics such as polyether ether ketone (PEEK). For the reasons described above, it is preferable that the first and second tube sections are made of glass, quartz, or fluororesin. In addition, the first and second tube sections can be members of a single tube structure. The first and second tube sections can be manufactured by a known molding method.

The heating electromagnetic wave irradiation unit described above irradiates heating electromagnetic waves toward at least a part of the spray chamber except the part where the spray nozzle of the nebulizer is inserted. The heating electromagnetic waves can be irradiated to any part of the spray chamber except the part where the spray nozzle of the nebulizer is inserted. In one embodiment, it is preferable to irradiate the heating electromagnetic waves toward at least a part of the spray chamber near the end where at least a part of the gas flow introduced from the nebulizer is discharged. The part near the end refers to at least a part of the part from the position of L/2 to the end where at least a part of the gas flow is discharged, assuming that the shortest distance from one end to the other end in a side view of the spray chamber is L and the position of L/2 is the center. This part is also referred to as the "rear part" below. On the other hand, the part near the end where the gas flow is introduced from the nebulizer refers to at least a part of the part from the end to the position of L/2. This part is also referred to as the "front part" below. Irradiating the rear portion with electromagnetic waves for heating is considered preferable from the viewpoint of suppressing condensation in the spray chamber due to a drop in temperature of droplets of sample liquid contained in the gas flow after heating. Suppressing condensation is preferable from the viewpoint of reducing variation in signal strength in the analysis device. In one embodiment, it is preferable to irradiate electromagnetic waves for heating only toward the rear portion, and in another embodiment, toward both the rear portion and the front portion.

The above sample introduction device can be suitably used to atomize sample liquid and introduce it into various analytical devices.

[Inductively Coupled Plasma Analyzer]
One aspect of the present invention relates to an inductively coupled plasma analyzer (hereinafter also simply referred to as "analyzer") including the above-mentioned sample introduction device and an analysis section.

Details of the sample introduction device included in the above analytical device are as described above.

The above-mentioned analytical device is an inductively coupled plasma analytical device, and may include at least a plasma torch in the analytical section. For example, the inlet section 14 of the analytical device shown in FIG. 2 is the part of the analytical section that is located closest to the sample introduction device, and may be the inlet section of the plasma torch. The plasma torch is, for example, a part that performs ionization by plasma in an inductively coupled plasma mass spectrometer (ICP-MS) or an inductively coupled plasma atomic emission spectrometer (ICP-AES), which are examples of inductively coupled plasma analytical devices.

The installation angle of the sample introduction device in the above-mentioned analysis device is preferably in the range of 0° to 90° (i.e., parallel to the horizontal direction of the installation surface to perpendicular to the horizontal direction of the installation surface) as the angle θ3 between the horizontal direction of the installation surface on which the sample introduction device is installed (e.g., H direction in FIG. 2) and the central axis direction of the spray chamber (e.g., Y direction in FIG. 2). This makes it possible to improve the particle size selection ability of selecting the particle size by allowing droplets with a large particle size to fall by gravity among the sample droplets introduced from the nebulizer to the spray chamber. The angle θ3 is specified in the range of 0° to ±90°. When θ3 is a negative value, the spray chamber is installed so that the rear part is located lower than the front part. When θ3 is a positive value, the spray chamber is installed so that the front part is located lower than the rear part. In addition, one or more waste liquid openings for discharging the sample liquid remaining in the discharge port part may be provided at any position on the outer side surface of the discharge port part of the spray chamber. In particular, when θ3 has a negative value, it is preferable to provide such an opening for waste liquid on the outer side surface of the outlet portion of the spray chamber.
Considering both the efficiency of sample introduction into the analytical section and the particle size selection ability, the angle θ3 is more preferably in the range of 20° to 90°, even more preferably in the range of 20° to 70°, still more preferably in the range of 20° to 50°, and even more preferably in the range of 20° to 30°.

The inlet of the plasma torch may include an injector. Sample droplets introduced from the sample introduction device may pass through the injector and be introduced into the plasma torch. From the viewpoint of more stable introduction of sample droplets into the center of the plasma torch, the inner diameter of the injector is preferably 1.50 mm or less, more preferably 1.20 mm or less, even more preferably 1.00 mm or less, even more preferably 0.90 mm or less, and even more preferably 0.80 mm or less. From the viewpoint of sample droplet introduction efficiency, the inner diameter is preferably 0.50 mm or more.

An inductively coupled plasma analyzer typically includes a gas supply source for supplying a plasma generating gas to the plasma torch. Argon gas is typically used as the plasma generating gas. Therefore, the analyzer may also include a gas supply source for supplying argon gas to the plasma torch. In one embodiment, the analyzer may include a gas supply source for supplying one or more other gases other than argon gas to the plasma torch in addition to the gas supply source for supplying argon gas. Introducing such other gases into the plasma torch is preferable from the viewpoints of increasing the electron density in the plasma, promoting ionization by introducing gases with different viscosities and specific heats, and improving signal strength. From the above viewpoints, it is preferable that such other gases are supplied to the plasma torch in a smaller amount per unit time than the argon gas introduced as the plasma generating gas. In one embodiment, such gases may also be introduced in the spray chamber. The gas may be one or more gases selected from the group consisting of nitrogen gas, oxygen gas, and hydrogen gas. For argon gas introduced into the plasma torch as a plasma generating gas, the supply amount to the plasma torch per unit time can be, for example, 16 L/min to 20 L/min. In contrast, for the other gases mentioned above, the supply amount to the plasma torch per unit time can be, for example, 1 mL/min to 30 mL/min. The argon gas for plasma generation and the other gases mentioned above can be introduced into the plasma torch from the same gas flow path or different gas flow paths.

The sample to be analyzed, contained in the sample droplets introduced into the plasma torch, is ionized by the plasma generated at the tip of the plasma torch. Specific examples of inductively coupled plasma analyzers include ICP-MS and ICP-AES. For example, in the case of ICP-MS, ions generated by the above ionization are introduced into a mass spectrometer, which selects them by mass and detects them with an ion detector. In this way, qualitative analysis can be performed based on the mass of the ions detected by the ion detector, and quantitative analysis can be performed based on the signal intensity of ions of each mass.

[Analysis Method]
One aspect of the present invention relates to an analytical method including performing qualitative analysis, quantitative analysis, or qualitative analysis and quantitative analysis of a sample to be analyzed by the inductively coupled plasma analyzer described above.

In the sample introduction device exemplified in FIG. 2, when a gas flow containing sample droplets is circulated through the flow path tube, an additional gas is introduced from the additional gas introduction tube. As described above, the introduced additional gas can rotate within the double tube and produce a spiral gas flow (additional gas flow) toward the conical part of the first tube. As the additional gas, for example, various gases exemplified as examples of carrier gas can be used. For example, the gas supply source and the additional gas introduction tube can be connected with a tube such as a resin tube, and the additional gas can be introduced from the additional gas supply source through the additional gas introduction tube and the additional gas introduction opening into the double tube. From the viewpoint of durability, a tube made of a fluororesin such as polytetrafluoroethylene is suitable as the resin tube. The additional gas flow rate can be, for example, 0.3 to 0.5 L/min, but is not limited to the above range, as it can be set appropriately taking into account the width of the space into which the additional gas is introduced in the double tube, the size of the conical part, etc.

The gas flow containing the sample droplets discharged from the spray chamber is introduced into the analysis section of the above-mentioned analysis device, where qualitative and/or quantitative analysis is performed. Details of the specific examples of the analysis section are as described above. Components to be analyzed include, for example, various metal components such as heavy metals, non-metal components, etc.

According to the analysis method according to one aspect of the present invention described above, for example, for various silicon samples such as various silicon wafers used as semiconductor substrates and single crystal ingots cut from silicon wafers, metal component analysis of the silicon samples can be performed to evaluate the presence and/or degree of metal impurity contamination. Metal impurity contamination can cause device defects in semiconductor devices, so it is desirable to grasp the presence and/or degree of metal impurity contamination, and to eliminate silicon wafers contaminated with metal impurities as defective products, or to reduce metal impurity contamination by changing manufacturing conditions or replacing or repairing manufacturing equipment. In recent years, with the improvement of device performance, semiconductor substrates are required to have even higher quality. In order to meet such demands, it is desirable to reduce metal impurity contamination of silicon samples. The above analysis method is suitable, for example, as a method for analyzing metal components of various silicon samples. By using the above analysis method, for example, qualitative analysis and/or quantitative analysis of metal components can be performed as an evaluation of metal impurity contamination of silicon samples. When evaluating metal impurity contamination of a silicon sample, a sample liquid obtained by dissolving a part or all of the silicon sample to be evaluated, or a sample liquid obtained by scanning a recovery liquid such as an acid solution over the surface of the silicon sample to incorporate metal components attached to the surface into the recovery liquid, can be pretreated, for example, by diluting with an acid solution, if necessary, before being introduced into a nebulizer for metal component analysis. The analysis results thus obtained can be used to evaluate the presence or absence and the degree of various metal impurity contaminations, such as surface layer metal impurity contamination, bulk metal impurity contamination, and surface metal impurity contamination of the silicon sample.
However, the present invention is not limited to the evaluation of metal impurity contamination of silicon samples, but can be applied to component analysis in various fields.

The present invention will be further described below with reference to examples, although the present invention is not limited to the embodiments shown in the examples.
In the following, a polytetrafluoroethylene tube was connected to the additional gas inlet pipe of the spray chamber to introduce gas, and a polyvinyl chloride tube was connected to the waste liquid pipe to discharge the waste liquid. In the following examples, the first and second pipes of the spray chamber were made of glass.

[Example 1]
The spray chamber of a commercially available double-convergence ICP-MS was changed to the spray chamber of the configuration shown in Figures 5A and 5B except that θ1 = 90 °, and the ICP-MS of Example 1 was prepared. In the ICP-MS of Example 1, θ1 = 90 °, θ2 = 0 °, θ3 = 30 °, the maximum inner diameter of the conical part of the first tube is 45.0 mm, the ratio of the length of the conical part to the maximum inner diameter of the conical part (length / maximum inner diameter) is 0.5, the length of the double tube is 20.0 mm, the diameter of the additional gas introduction opening and the waste liquid opening of the double tube and the second tube is 3.0 mm, the inner diameter (maximum inner diameter) of the cylindrical part of the first tube is 45.0 mm, the outer diameter of the cylindrical part of the second tube is 42.0 mm, and the total length of the spray chamber was 130.0 mm.
A ring-shaped electromagnetic wave heating irradiation unit was installed at the rear of the outside of the spray chamber as shown in Fig. 1. In this electromagnetic wave heating irradiation unit, a plurality of near-infrared lamps were arranged in the circumferential direction inside a ring-shaped cover unit.
As a sample liquid, hydrofluoric acid (HF aqueous solution) containing 1 ppb (volume basis) of In and 2000 ppm (volume basis) of Si and having an HF concentration of 1 mass % was prepared.
In the ICP-MS, the sample liquid was introduced into the nebulizer at an introduction rate of 100 μL/min, the sample liquid was atomized by the nebulizer using a carrier gas (argon gas; flow rate 0.75 L/min) to generate a gas flow containing sample droplets, and this gas flow containing sample droplets was introduced from the sample introduction tube of the spray chamber to the flow path tube of the spray chamber. While the gas flow was flowing through the flow path tube, near-infrared radiation was continuously irradiated from the heating electromagnetic wave irradiation unit, and argon gas was continuously introduced as an additional gas from the additional gas introduction tube unit through the additional gas introduction opening at a flow rate of about 0.4 L/min into the double tube unit, while monitoring the signal intensity of In output from the ICP-MS. From the monitoring results thus obtained, a graph was created by plotting the relative intensity ratio of In intensity against the near-infrared irradiation time as a relative intensity ratio with the signal intensity at the start of near-infrared irradiation (0 minutes) being set to 1.0.

[Comparative Example 1]
The position of the heating electromagnetic wave irradiator was moved to a position covering the sample inlet side of the cylindrical part of the second tube part of the spray chamber and the sample inlet, and the signal intensity of In was monitored in the same manner as in Example 1, except that the irradiation of near-infrared rays was directed toward the part into which the spray nozzle of the nebulizer was inserted. A graph was created from the obtained monitoring results in the same manner as in Example 1.

The graphs created for Example 1 and Comparative Example 1 are shown in Figure 6.

From the results shown in Figure 6, it can be seen that in Comparative Example 1, the longer the near-infrared irradiation time, the lower the relative intensity ratio became, in other words, a decrease in analytical sensitivity occurred, compared to Example 1. This is thought to be because in Comparative Example 1, near-infrared irradiation was performed toward the part where the nebulizer nozzle was inserted, causing the Si contained in the sample liquid to dry out at the tip of the nebulizer nozzle, causing clogging. In contrast, in Example 1, near-infrared irradiation was performed toward a part other than the part where the nebulizer nozzle was inserted, which is presumably the reason why it was possible to suppress the decrease in analytical sensitivity associated with near-infrared irradiation.

[Example 2]
Except for using hydrofluoric acid (HF aqueous solution) containing 1 ppb (volume basis) In and having an HF concentration of 1 mass %, the signal intensity of In was monitored in the same manner as in Example 1. Twenty measurement results (In signal intensity) were extracted from the obtained monitoring results, and their relative standard deviations (RSD) were calculated.

[Example 3]
The position of the heating electromagnetic wave irradiation unit was moved to a position covering the cylindrical part of the second tube part of the spray chamber (but not covering the part where the spray nozzle of the nebulizer was inserted), and near-infrared radiation was irradiated toward the front part of the spray chamber, and the signal intensity of In was monitored in the same manner as in Example 2. Twenty measurement results (In signal intensity) were extracted from the obtained monitoring results, and their relative standard deviations (RSD) were calculated.

The relative standard deviations (RSDs) calculated for Examples 2 and 3 are shown in Figure 7.

The results shown in Figure 7 confirm that in Example 2, in which the heating electromagnetic waves were irradiated to the rear part of the spray chamber, the variation in signal strength was suppressed compared to Example 3 (i.e., a signal with a more stable strength was obtained).

[Example 4]
In an ICP-MS having the same configuration as in Example 1, three types of injectors with different inner diameters (inner diameters 0.75 mm, 1.00 mm, and 1.50 mm) were used as the injectors of the plasma torch, and hydrofluoric acid (HF aqueous solution) containing 1 ppb (volume basis) of each of the analytes Co, Y, Ce, and Tl and having an HF concentration of 1 mass% was used as the sample solution. For comparison, the above sample solution was analyzed in the same manner without irradiating electromagnetic waves from the heating electromagnetic wave irradiating unit, and the signal intensity of the analytes was measured. The signal intensity of each analyte is shown in FIG. 8 as a relative intensity ratio (signal intensity with heating electromagnetic wave irradiation/signal intensity without heating electromagnetic wave irradiation) to the signal intensity without heating electromagnetic wave irradiation.
Furthermore, 20 signal intensities for each analyte obtained using each injector were extracted, and their relative standard deviations (RSDs) were calculated. The calculated results are shown in FIG.

The results shown in Figure 8 confirm that, regardless of which of the three types of injectors was used, the signal strength was increased by irradiating electromagnetic heating waves compared to the case without irradiation, i.e., the analytical sensitivity was improved. Furthermore, the results shown in Figure 8 also confirm that the analytical sensitivity was improved more when an injector with a smaller inner diameter was used. Furthermore, the results shown in Figure 9 confirm that the variation in signal strength could be suppressed more when an injector with a smaller inner diameter was used.

[Example 5]
In an ICP-MS having the same configuration as in Example 1, N ₂ (flow rate: 30 mL/min) was introduced into the plasma torch from a flow path separate from the argon gas for plasma generation (flow rate: 18 L/min), and hydrofluoric acid (HF aqueous solution) with an HF concentration of 1 mass% containing 1 ppb (volume basis) of analytes Co, Y, Ce, and Tl was used as the sample solution, and the signal intensity of the analytes was measured in the same manner as in Example 4 (using an injector with an inner diameter of 1.50 mm). Apart from this measurement, measurements were performed in the same manner except that N ₂ was not introduced. The signal intensity of each analyte is shown in FIG. 10 as the relative intensity ratio (signal intensity with N ₂ introduction/signal intensity without N ₂ introduction) to the signal intensity without N ₂ introduction.
Furthermore, 20 measurement results (signal intensity of each analyte) were extracted from the measurement results with _N2 introduction, and their relative standard deviations (RSD) were calculated. The calculated results are shown in Figure 11.

From the results shown in FIG. 10, it can be confirmed that the introduction of N ₂ into the plasma torch increased the signal intensity compared to the case where it was not introduced, that is, the analytical sensitivity was improved.
Furthermore, when the results shown in FIG. 11 are compared with the results in FIG. 9 in which an injector with an inner diameter of 1.50 mm was used (without _N2 introduction), it can be confirmed that the introduction of _N2 into the plasma torch can further suppress the variation in signal intensity.

From the above results, it can be confirmed that according to one aspect of the present invention, it is possible to obtain highly reliable analysis results in an inductive plasma analysis device.

Claims (12)

A nebulizer for atomizing the sample liquid;
a spray chamber into one end of which the spray nozzle of the nebulizer is inserted and into which at least a portion of the droplets of the sample liquid sprayed from the spray nozzle are discharged to the outside from the other end;
A heating electromagnetic wave irradiation unit arranged outside the spray chamber;
having
The heating electromagnetic wave irradiation unit irradiates heating electromagnetic waves from the outside of the spray chamber toward at least a part of the spray chamber excluding a part into which a spray nozzle of the nebulizer is inserted; and
A sample introduction device , wherein the heating electromagnetic wave is near infrared radiation . The sample introduction device according to claim 1 , wherein the spray chamber is made of glass, quartz, or fluororesin. 3. The sample introduction device according to claim 1, wherein the heating electromagnetic wave irradiating unit irradiates the heating electromagnetic wave toward at least a portion of the spray chamber near an end from which at least a portion of the droplets are discharged. 4. The sample introduction device according to claim 1, wherein the heating electromagnetic wave irradiation unit has a circular ring shape, and the spray chamber is inserted into a hollow portion of the circular ring shape. 5. The sample introduction device according to claim 1, wherein the amount of the sample liquid introduced into the nebulizer is 1 μL/min or more and 500 μL/min or less . An inductively coupled plasma analyzer comprising the sample introduction device according to any one of claims 1 to 5 and an analysis section. A plasma torch and an injector for introducing a sample to be analyzed into the plasma torch,
7. The inductively coupled plasma analyzer according to claim 6 , wherein the inner diameter of the injector is not less than 0.50 mm and not more than 1.50 mm. 8. The inductively coupled plasma analyzer of claim 7 , further comprising a gas supply source for supplying argon gas to the plasma torch and a gas supply source for supplying one or more gases other than argon gas. 9. The inductively coupled plasma analyzer of claim 8, wherein the one or more other gases are selected from the group consisting of nitrogen gas, oxygen gas, and hydrogen gas, and the gas is supplied to the plasma torch in an amount less than that of argon gas per unit time. The inductively coupled plasma analyzer according to any one of claims 6 to 9 , which is an inductively coupled plasma mass analyzer or an inductively coupled plasma optical emission spectrometer. An analytical method comprising performing qualitative analysis, quantitative analysis, or qualitative analysis and quantitative analysis of a sample to be analyzed by the inductively coupled plasma analyzer according to any one of claims 6 to 10 . The analytical method according to claim 11 , wherein a qualitative analysis, a quantitative analysis, or a qualitative analysis and a quantitative analysis of metal components in a sample to be analyzed is performed.