JP2024080785A - Spray chamber - Google Patents

Abstract

[Problem] To provide a spray chamber that can be effectively cleaned in a short time. [Solution] The spray chamber AA has an end cap 40 that holds a nebulizer 10, a flow passage tube 30 with the end cap 40 attached to the upper end, an impactor 51 disposed inside the flow passage tube 30, a rod 52 with the impactor 51 attached to its tip, a sample discharge tube 31 attached to the flow passage tube 30, and a drain discharge tube 32 attached to the bottom of the flow passage tube 30. The rod 52 is supported by the drain discharge tube 32. When a cleaning solution is sprayed from the nebulizer 10, the cleaning solution that collides with the impactor 51 and aggregates is discharged from the drain discharge tube 32 along the rod 52. The cleaning solution is unlikely to remain on the inner wall of the flow passage tube 30 and is quickly discharged, allowing for effective cleaning in a short time. [Selected Figure] Figure 2

Description

The present invention relates to a spray chamber. More specifically, the present invention relates to a spray chamber that selects sample droplets by particle size.

Analytical devices that analyze liquid samples using analytical methods such as plasma emission spectrometry, plasma mass spectrometry, atomic absorption spectrometry, atomic fluorescence spectrometry, and liquid chromatography are known. In this type of analytical device, the liquid sample is atomized to obtain sample droplets, which are then introduced into an excitation/ionization source, etc. At this time, if large sample droplets are introduced, the excitation/ionization source, etc. becomes unstable. Therefore, the large sample droplets are removed, and only the fine sample droplets are introduced into the excitation/ionization source, etc. Specifically, the liquid sample is atomized using a nebulizer to obtain sample droplets, and then the large sample droplets are removed by colliding with and adhering to the inner wall of the spray chamber using gravity and inertia, and only the fine sample droplets are introduced into the excitation/ionization source, etc.

There are various types of spray chambers, but they can be broadly divided into three types: single-tube spray chambers, double-tube spray chambers (also known as Scott-type spray chambers), and cyclone-type spray chambers. Of these three types, the single-tube spray chamber is less effective at removing large sample droplets than the other two types of spray chambers. For this reason, an impactor is sometimes installed inside the single-tube spray chamber. Large sample droplets collide with the impactor as well as the inner wall of the spray chamber, making them more effective at removing them.

Specifically, for example, a single-tube spray chamber with the configuration shown in FIG. 12 is known (for example, Non-Patent Document 1). This spray chamber has a flow path tube 130. An end cap 140 is attached to one end of the flow path tube 130. The end cap 140 holds a nebulizer 110. The end cap 140 also has a drain discharge tube 132. A sample discharge port 131 is provided at the other end of the flow path tube 130. A support member 152 is fixed to the side wall of the flow path tube 130, and an impactor 151 is fixed to the tip of the support member 152.

For example, a single-tube spray chamber with the configuration shown in FIG. 13 is known (for example, Non-Patent Document 2). This spray chamber has a flow path tube 230. A sample discharge tube 231 and a drain discharge tube 232 are provided at one end of the flow path tube 230. An end cap 240 is attached to the other end of the flow path tube 230. A Babington-type nebulizer 210 is held by the end cap 240. In addition, a support member 252 having a curved portion is held by the end cap 240, and an impactor 251 is fixed to the tip of the support member 252.

When a liquid sample is introduced into the spray chamber, the sample adheres to the inner walls of the spray chamber and the impactor. For this reason, after each sample measurement, a cleaning liquid is supplied to the nebulizer, and the inside of the spray chamber is cleaned with the atomized cleaning liquid. If the spray chamber is not cleaned sufficiently, components contained in the sample remaining in the spray chamber will be mixed into the next sample when it is measured, and accurate measurement results will not be obtained. This phenomenon is called the memory effect.

In particular, if the sample contains easily vaporized components (such as boron, iodine, mercury, and osmium), these components will vaporize over a long period of time from the sample remaining in the spray chamber, necessitating a long cleaning time. Since the next sample cannot be measured until cleaning is complete, the overall measurement time will be long if a large number of samples are to be measured. This results not only in a decrease in measurement accuracy, but also in an increase in working hours and an increase in the electricity required to operate the analytical equipment and air conditioning equipment in the analysis room. For this reason, there is a demand for a method to clean the spray chamber effectively in a short period of time.

D. W. Hausler and L. T. Taylor, Nonaqueous on-line simultaneous determination of metals by size exclusion chromatography with inductively coupled plasma atomic emission spectrometric detection, Analytical Chemistry (1981) 53, p.1223-1227 R. Nehm and J. A. Broekaert, Noise power spectra and recovery rates obtained with different nebulizer systems in ICP atomic emission spectrometric analyses in the case of different types of salts and salt contents, Fresenius J Anal Chem (2000) 368, p.156-161

When cleaning liquid is sprayed from the nebulizer 110 in the spray chamber configured as shown in FIG. 12, the cleaning liquid collides with the impactor 151 and condenses, travels along the support member 152 and the inner wall of the flow path pipe 130, and is then discharged from the drain discharge pipe 132. Because the inner wall of the flow path pipe 130 between the support member 152 and the drain discharge pipe 132 is nearly horizontal, cleaning liquid is likely to remain and it is difficult to quickly discharge it.

In addition, when cleaning liquid is sprayed from the nebulizer 210 in the spray chamber configured as shown in FIG. 13, the cleaning liquid that collides with the impactor 251 and condenses drips from the curved portion of the support member 252, then travels along the inner wall of the flow path pipe 230 and is discharged from the drain discharge pipe 232. In this case, too, it is difficult to quickly discharge the cleaning liquid because the inner wall of the flow path pipe 230 is nearly horizontal.

It is also possible to spray the cleaning solution in a spray chamber with the configuration shown in Figures 12 and 13, arranged vertically so that the spray direction of the nebulizers 110, 210 faces vertically downward. In this case, however, the cleaning solution adhering to the impactors 151, 251 will drip and collide with the cleaning solution accumulated on the inner walls of the flow tubes 130, 230, causing the components contained in the sample to be re-scattered.

As such, conventional spray chambers have the problem that effective cleaning is difficult, especially due to the presence of the impactor, and cleaning takes a long time.

In view of the above circumstances, the present invention aims to provide a spray chamber that can be effectively cleaned in a short time.

The spray chamber of the first aspect comprises an end cap that holds a nebulizer, a flow path tube having the end cap at its upper end and through which droplets are supplied from the nebulizer, an impactor that is disposed inside the flow path tube and causes coarse droplets to collide with each other to generate a drain, a rod having the impactor at its tip, a sample discharge tube that is disposed in the flow path tube and discharges fine droplets, and a drain discharge tube that is disposed at the bottom of the flow path tube and discharges the drain, and the rod is supported by the drain discharge tube or the bottom of the flow path tube.
The spray chamber of the second aspect is characterized in that in the first aspect, the rod is inserted into the drain discharge pipe.
The spray chamber of the third aspect is characterized in that in the first aspect, the rod is disposed adjacent to the drain discharge pipe.
The spray chamber of the fourth aspect is characterized in that, in the first aspect, the base end of the rod is connected to the upper end of the drain discharge pipe, and a hole is formed at the connection between the rod and the drain discharge pipe through which the drain flows into the inside of the drain discharge pipe.
The spray chamber of a fifth aspect is any one of the first to third aspects, characterized in that the rod penetrates the bottom of the flow path pipe and the insertion depth into the flow path pipe is adjustable.
The spray chamber of a sixth aspect is characterized in that, in any of the first to fifth aspects, the flow path pipe has an upstream section, a midstream section, and a downstream section along the spray direction of the nebulizer, the inner diameter of the midstream section is smaller than the inner diameters of the upstream section and the downstream section, the sample discharge pipe and the drain discharge pipe are provided in the downstream section, and the impactor is disposed inside the downstream section.
The spray chamber of a seventh aspect is characterized in that, in any of the first to fifth aspects, the flow path pipe has an upstream portion and a downstream portion along the spray direction of the nebulizer, the inner diameter of the downstream portion is smaller than the inner diameter of the upstream portion, the sample discharge pipe and the drain discharge pipe are provided in the downstream portion, and the impactor is disposed inside the downstream portion.

According to the first aspect, when the cleaning liquid is sprayed from the nebulizer, the cleaning liquid collides with the impactor and aggregates, which then travels down the rod and is discharged from the drain pipe. The cleaning liquid is unlikely to remain on the inner wall of the flow passage pipe and is quickly discharged, allowing for effective cleaning in a short period of time.
According to the second aspect, since the rod is inserted into the drain pipe, the cleaning liquid that has flowed down the rod is discharged directly from the drain pipe.
According to the third aspect, since the rod is adjacent to the drain pipe, the cleaning liquid easily flows along the rod into the drain pipe.
According to the fourth aspect of the present invention, the drain flows down along the outer surface of the rod and then flows into the drain discharge pipe to be discharged.
According to the fifth aspect, the distance between the nozzle of the nebulizer and the impactor can be adjusted by adjusting the insertion depth of the rod, thereby adjusting the particle size of the droplets to be removed.
According to the sixth aspect, the sample droplets collide with the impactor after passing through the midstream section with a small inner diameter and the carrier gas becomes a laminar flow, so that selectivity based on the particle size of the sample droplets can be improved.
According to the seventh aspect, the sample droplets collide with the impactor after the carrier gas has become a laminar flow in the downstream section with a small inner diameter, so that selectivity based on the particle size of the sample droplets can be improved.

FIG. 2 is an explanatory diagram of a sample atomization and introduction device. FIG. 2 is a vertical cross-sectional view of the spray chamber of the first embodiment. FIG. 11 is a vertical cross-sectional view of a spray chamber according to a modified example of the first embodiment. FIG. 11 is a longitudinal sectional view of a spray chamber according to a second embodiment. FIG. 11 is a longitudinal sectional view of a spray chamber according to a modified example of the second embodiment. FIG. 13 is a vertical cross-sectional view of a spray chamber according to still another modified example of the second embodiment. FIG. 11 is a longitudinal sectional view of a spray chamber according to a third embodiment. FIG. 10 is a longitudinal sectional view of a spray chamber according to a fourth embodiment. FIG. 13 is a vertical cross-sectional view of a spray chamber according to a fifth embodiment. FIG. 13 is a longitudinal sectional view of a spray chamber according to a sixth embodiment. Fig. 13A is a vertical cross-sectional view of a spray chamber according to a modified example of the sixth embodiment, and Fig. 13B is an enlarged cross-sectional view taken along line bb in Fig. 13A. FIG. 1 is a vertical cross-sectional view of a conventional spray chamber. FIG. 11 is a vertical cross-sectional view of another conventional spray chamber.

Next, an embodiment of the present invention will be described with reference to the drawings.
First Embodiment
(Sample atomization introduction device)
As shown in FIG. 1, the spray chamber AA according to the first embodiment of the present invention is incorporated into a sample atomization introduction device AT. The sample atomization introduction device AT is a component of an analysis device that analyzes liquid samples by analysis methods such as plasma emission spectrometry, plasma mass spectrometry, atomic absorption spectrometry, atomic fluorescence spectrometry, and liquid chromatography. The sample atomization introduction device AT atomizes a liquid sample to generate sample droplets, and introduces the sample droplets after particle size selection into an excitation/ionization source EI in the analysis device. The excitation/ionization source EI is, for example, plasma in an ICP analysis device, and is generated by a plasma torch. In addition, in liquid chromatography, the sample droplets are introduced into a light scattering detector. Such a detector is also included in the excitation/ionization source EI.

The sample atomization and introduction device AT has a nebulizer 10 that atomizes the liquid sample, and a spray chamber AA that selects the sample droplets by particle size. The nebulizer 10 is attached to the spray chamber AA and supplies the sample droplets into the interior of the spray chamber AA.

A sample supply source 20 that supplies a liquid sample is connected to the nebulizer 10. The sample supply source 20 is composed of, for example, a container 21 that stores the liquid sample, a flexible tube 22 that connects the nebulizer 10 and the container 21, and a peristaltic pump 23 provided in the middle of the tube 22. The liquid sample is supplied to the nebulizer 10 by the operation of the sample supply source 20.

(Spray chamber)
As shown in Fig. 2, the spray chamber AA of this embodiment is a single-tube type spray chamber. The spray chamber AA has a flow passage pipe 30. The flow passage pipe 30 is a pipe with a bottom. The flow passage pipe 30 is usually a circular pipe with a circular cross section, but may be of other shapes such as a square pipe. In addition, the flow passage pipe 30 is preferably arranged vertically.

An end cap 40 is attached to the upper end of the flow tube 30. The upper end opening of the flow tube 30 is closed by the end cap 40. The end cap 40 holds the nebulizer 10. The nozzle of the nebulizer 10 is disposed inside the flow tube 30. It is preferable that the central axis of the nozzle of the nebulizer 10 is aligned with the central axis of the flow tube 30.

The nebulizer 10 may be of any type, such as a coaxial type, a cross-flow type, or a Babington type. The nebulizer 10 shown in the figure is of a coaxial type. A liquid sample is introduced into the inner tube of the nebulizer 10. A nebulizer gas is introduced into the outer tube of the nebulizer 10. The liquid sample supplied to the nebulizer 10 is atomized by the nebulizer gas and sprayed as sample droplets. The sample droplets sprayed from the nebulizer 10 are supplied to the inside of the flow path tube 30.

The nebulizer 10 is inserted into a through hole formed in the end cap 40. A gap is formed between the inner peripheral surface of the through hole and the outer peripheral surface of the nebulizer 10. The end cap 40 has a sheath gas supply port 41 that communicates with the gap. When sheath gas is supplied to the sheath gas supply port 41, the sheath gas is sprayed from the outer periphery of the nebulizer 10. The sheath gas can prevent sample droplets from adhering to the outer peripheral surface of the nebulizer 10. In this specification, the nebulizer gas and sheath gas are collectively referred to as carrier gas.

The flow path tube 30 is provided with a sample discharge tube 31 and a drain discharge tube 32. Both the sample discharge tube 31 and the drain discharge tube 32 are tubes that connect the inside and outside of the flow path tube 30. The sample discharge tube 31 is connected to the side wall close to the bottom of the flow path tube 30. The drain discharge tube 32 consists of a vertical tube 32a and a branch tube 32b that branches off from the middle of the vertical tube 32a. The vertical tube 32a is connected to the center of the bottom of the flow path tube 30.

At least a portion of the sample droplets supplied from the nebulizer 10 flows through the internal space of the flow path tube 30 from the upper end to the lower end and is discharged from the sample discharge tube 31. In this way, the flow path tube 30 forms a flow path for the sample droplets.

Among the sample droplets supplied from the nebulizer 10, droplets with a relatively large diameter collide with and adhere to the inner wall of the flow path tube 30, becoming drain and being discharged from the drain discharge tube 32. Among the sample droplets, only droplets with a relatively small diameter are discharged from the sample discharge tube 31.

In this specification, of the droplets supplied from the nebulizer 10, those discharged from the sample discharge tube 31 are referred to as "fine droplets," and those that become drain and are discharged from the drain discharge tube 32 are referred to as "coarse droplets." The average particle size of the fine droplets is smaller than the average particle size of the coarse droplets. However, the particle size of some of the fine droplets may be larger than the particle size of some of the coarse droplets.

An impactor 51 is disposed inside the flow tube 30 on the central axis of the jet from the nebulizer 10. Large droplets among the droplets supplied from the nebulizer 10 collide with the inner wall of the flow tube 30 as well as with the impactor 51, and become drains. The shape of the impactor 51 is usually a sphere, but it may be another shape, such as a disk.

The impactor 51 is large enough to ensure a space between the impactor 51 and the inner wall of the flow path pipe 30 through which the fine droplets can flow. Specifically, the diameter of the impactor 51 is preferably about 1/5 to 4/5 of the inner diameter of the flow path pipe 30. Furthermore, the larger the impactor 51, the easier it is for droplets to collide with the impactor 51, so the average particle size of the fine droplets that avoid collision with the impactor 51 can be made smaller. Conversely, the smaller the impactor 51, the larger the average particle size of the fine droplets can be.

The impactor 51 and the sample discharge tube 31 are arranged in this order along the spray direction of the nebulizer 10. Therefore, the fine droplets that avoid collision with the impactor 51 pass through the space next to the impactor 51, flow toward the bottom of the flow path tube 30, and are then discharged from the sample discharge tube 31.

The impactor 51 is provided at the tip of the rod 52. The rod 52 is a straight bar and is arranged along the central axis of the flow passage pipe 30. The rod 52 is inserted into the vertical pipe 32a of the drain discharge pipe 32. The outer diameter of the rod 52 is smaller than the inner diameter of the vertical pipe 32a. The rod 52 and the vertical pipe 32a are arranged concentrically. Therefore, a gap is provided between the outer surface of the rod 52 and the inner surface of the vertical pipe 32a through which the drain can flow.

A holder 60 is attached to the lower part of the vertical tube 32a. The bottom of the flow path tube 30 is closed by the holder 60 to prevent drain and carrier gas from leaking out. The rod 52 passes through the holder 60 and is held by the holder 60. In this way, the rod 52 is supported by the drain discharge pipe 32 via the holder 60.

A tubular gap filler 61 is inserted into the gap between the lower part of the vertical pipe 32a (the part below the connection with the branch pipe 32b) and the rod 52. The gap filler 61 prevents drainage from accumulating in the lower part of the vertical pipe 32a. The drainage passes through the upper part of the vertical pipe 32a and the branch pipe 32b and is discharged to the outside.

The rod 52 penetrates the bottom of the flow path pipe 30. That is, the tip of the rod 52, where the impactor 51 is provided, is disposed inside the flow path pipe 30, and the base end is disposed outside the flow path pipe 30. The holder 60 supports the rod 52 so that it can move up and down. For example, the holder 60 has a through hole into which the rod 52 is inserted. The rod 52 can be moved up and down by sliding the rod 52 along the through hole. The holder 60 may also have a screw mechanism or the like that moves the rod 52 up and down.

The insertion depth of the tip of the rod 52 into the flow path tube 30 can be adjusted by moving the rod 52 up and down. By adjusting the insertion depth of the tip of the rod 52, the distance between the nozzle of the nebulizer 10 and the impactor 51 can be adjusted, and the particle size of the droplets to be removed can be adjusted.

The particle size of the droplets removed by the spray chamber AA is determined by the flow rate of the carrier gas, the shape and dimensions of the flow tube 30, the position of the impactor 51, etc. The flow rate of the carrier gas needs to be greatly varied in order to optimize analytical performance such as analytical sensitivity, accuracy, and the degree of interference. In addition, there are individual differences in the shape and dimensions of the flow tube 30. Therefore, it is preferable to adjust the particle size of the droplets to be removed by the position of the impactor 51. In this embodiment, the position of the impactor 51 can be adjusted by moving the rod 52 up and down, thereby adjusting the particle size of the droplets to be removed.

Specifically, by shortening the distance between the nozzle of the nebulizer 10 and the impactor 51, the droplets are more likely to collide with the impactor 51, and the average particle size of the fine droplets that avoid collision with the impactor 51 can be reduced. Conversely, by increasing the distance between the nozzle of the nebulizer 10 and the impactor 51, the average particle size of the fine droplets can be increased.

The distance between the nozzle of the nebulizer 10 and the impactor 51 is adjusted depending on the type of analytical device and the operating conditions. For example, in plasma optical emission spectrometry and plasma mass spectrometry, droplets smaller than about 10 to 12 μm in diameter completely evaporate in the plasma and undergo sufficient atomization and ionization, so coarse droplets larger than about 10 to 12 μm in diameter are removed. To remove coarse droplets of this size, the distance between the nozzle of the nebulizer 10 and the impactor 51 is usually set to within 20 mm.

The drain discharge pipe 32 and the holder 60 may be configured as shown in FIG. 3. That is, the drain discharge pipe 32 consists of only a vertical pipe. A drain flow path 62 is formed inside the holder 60. One end of the drain flow path 62 is connected to the drain discharge pipe 32, and the other end is connected to the tube 33. The drain passes through the drain discharge pipe 32, the drain flow path 62, and the tube 33 and is discharged to the outside.

(Analysis Method)
Next, a method of using the spray chamber AA will be described.
As shown in Fig. 1, when a sample is analyzed by an analytical device, a liquid sample is supplied from a sample supply source 20 to a nebulizer 10. The liquid sample is atomized by the nebulizer 10 to form sample droplets.

As shown in FIG. 2, the sample droplets sprayed from the nebulizer 10 flow from the upper end to the lower end in the internal space of the flow tube 30. Coarse droplets with a relatively large particle size among the sample droplets collide with and adhere to the inner wall of the flow tube 30, becoming drain. The drain flows down along the inner wall of the flow tube 30 and is discharged from the drain discharge tube 32. In addition, since the coarse droplets have a large inertial force, they are likely to collide with the impactor 51. Many of the coarse droplets collide with the impactor 51 and aggregate to become drain. The drain generated by the impactor 51 flows down along the rod 52 due to gravity and the wind pressure of the carrier gas, and is discharged from the drain discharge tube 32. The drain discharged from the drain discharge tube 32 is collected in a container or the like.

On the other hand, fine droplets with a relatively small particle size among the sample droplets have a small inertial force and therefore avoid collision with the impactor 51, are carried by the flow of the carrier gas to the bottom of the flow path tube 30, and are discharged from the sample discharge tube 31. The fine droplets discharged from the sample discharge tube 31 are introduced via piping into an excitation/ionization source such as EI (see Figure 1) and are used for analysis.

(Cleaning method)
After the analysis of the sample is completed, the inside of the spray chamber AA is washed. The spray chamber AA is washed by supplying a washing liquid to the nebulizer 10. The washing liquid can be stored in the container 21 of the sample supply source 20 and can be supplied to the nebulizer 10 by using the sample supply source 20. Alternatively, the washing liquid may be supplied to the nebulizer 10 by using a syringe.

When the cleaning liquid is sprayed from the nebulizer 10, droplets of the cleaning liquid collide with the impactor 51, and the sample adhering to the impactor 51 is taken up into the cleaning liquid. In addition, the cleaning liquid (drain) that condenses upon colliding with the impactor 51 flows down the rod 52. At this time, the sample adhering to the rod 52 is taken up into the cleaning liquid.

The cleaning liquid that flows down the rod 52 is discharged from the drain discharge pipe 32. Here, the cleaning liquid flows down quickly due to gravity and the wind pressure of the carrier gas. In addition, since the rod 52 is inserted into the drain discharge pipe 32, the cleaning liquid that flows down the rod 52 is discharged directly from the drain discharge pipe 32. In other words, the cleaning liquid is led to the drain discharge pipe 32 without passing through the inner wall of the flow path pipe 30. Therefore, the cleaning liquid is unlikely to remain on the inner wall of the flow path pipe 30 and is quickly discharged. As a result, effective cleaning can be achieved in a short time.

The droplets of the cleaning solution sprayed from the nebulizer 10 also collide with the inner wall of the flow tube 30, and the sample adhering to the flow tube 30 is taken up by the cleaning solution. The cleaning solution (drain) that condenses upon collision with the inner wall of the flow tube 30 flows down along the inner wall of the flow tube 30 and is discharged from the drain discharge pipe 32. Here, the cleaning solution flows down quickly due to gravity and the wind pressure of the carrier gas.

The inner wall of the flow tube 30 and the surfaces of the impactor 51 and rod 52 may be subjected to hydrophilic treatment such as ground glass processing, chemical etching, or coating with a hydrophilic coating agent. In this way, a liquid film flow of the cleaning liquid can be formed on the entire surfaces of the inner wall of the flow tube 30, the impactor 51, and the rod 52, and these can be effectively cleaned.

The cleaning liquid is guided to the drain discharge pipe 32 by the wind pressure of the carrier gas as well as the effect of gravity. To effectively utilize the effect of gravity, it is preferable to arrange the flow path pipe 30 vertically with the nebulizer 10 on top and the drain discharge pipe 32 on the bottom. Specifically, it is preferable to set the angle of the central axis of the flow path pipe 30 to the horizontal plane at 75 to 90 degrees.

By arranging the flow path pipe 30 vertically, the cleaning liquid flows down by gravity, and can be quickly guided to the drain discharge pipe 32. The sample remaining inside the spray chamber AA can be quickly discharged, effectively reducing the memory effect.

The cleaning liquid used for cleaning is not particularly limited. When the liquid sample to be analyzed is an aqueous solution, pure water and an acid solution such as nitric acid can be used as the cleaning liquid. The cleaning liquid may contain a surfactant. The surfactant reduces the surface tension of water, so that the cleaning liquid spreads easily on the wall surface. If a cleaning liquid containing a surfactant is used, a liquid film flow can be formed that covers the entire surfaces of the flow tube 30, the impactor 51, and the rod 52, and these can be effectively cleaned. Examples of the surfactant that can be used include RBS-25 manufactured by Sigma-Aldrich and TritonX manufactured by Dow Chemical. A cleaning liquid containing a surfactant is also effective for cleaning after the analysis of organic solvent samples such as gasoline and toluene.

A solution containing a masking agent, a complexing agent, etc. may be used as the cleaning solution. For example, when cleaning a sample containing mercury after analysis, the memory effect of mercury can be reduced by using a cleaning solution containing 0.001% L-cysteine or 10 ng/mL gold (Au).

Second Embodiment
Next, a spray chamber BB according to a second embodiment of the present invention will be described.
As shown in Fig. 4, in this embodiment, the flow path pipe 30 is narrowed in the center. Specifically, the flow path pipe 30 is composed of three sections, an upstream section 36, a midstream section 37, and a downstream section 38, along the injection direction of the nebulizer 10. The inner diameter of the midstream section 37 is smaller than the inner diameters of the upstream section 36 and the downstream section 38. The inner diameters of the upstream section 36 and the downstream section 38 may be the same or different. The connecting section between the upstream section 36 and the midstream section 37 and the connecting section between the midstream section 37 and the downstream section 38 are preferably shaped so that the inner diameter changes continuously and gently to prevent vortex flow of the carrier gas.

The sample discharge pipe 31 and the drain discharge pipe 32 are both provided in the downstream section 38. The impactor 51 is also disposed inside the downstream section 38. Therefore, the tip portion of the rod 52 is also disposed inside the downstream section 38.

In the upstream section 36 of the flow tube 30, particularly near the nebulizer 10, the carrier gas is forcefully ejected, creating a turbulent flow state, such as a swirling circulation flow. When the carrier gas passes through the midstream section 37 with a small inner diameter, it becomes a laminar flow state. By disposing the impactor 51 in the downstream section 38 where the flow of the carrier gas becomes a laminar flow state, only the droplets with a large diameter among the sample droplets carried by the carrier gas can be selectively collided with the impactor 51. In other words, the sample droplets collide with the impactor 51 after the carrier gas passes through the midstream section 37 with a small inner diameter and becomes a laminar flow state, improving the selectivity based on the particle diameter of the sample droplets.

Many of the coarse droplets contained in the sample droplets are removed by collision with the inner wall of the upstream section 36. In the downstream section 38, it is desirable to remove as much of the small amount of coarse droplets remaining in the carrier gas as possible, while removing as few fine droplets as possible so as not to reduce analytical sensitivity. In other words, it is desirable to improve the selectivity based on the particle size of the sample droplets in the downstream section 38. By placing an impactor 51 in the area where the flow of the carrier gas becomes laminar, it is possible to improve the selectivity based on the particle size of the sample droplets.

When the impactor 51 is a sphere or a disk, making its diameter larger than the inner diameter of the midstream section 37 can improve the removal rate of coarse droplets that collide with the impactor 51 and reduce the average particle size of fine droplets that avoid collision with the impactor 51. In this way, it is preferable that the impactor 51 is of a size that allows substantially all droplets of the particle size to be removed to collide with it.

In this embodiment, too, the position of the impactor 51 can be adjusted by moving the rod 52 up and down, thereby adjusting the particle size of the droplets to be removed. Moreover, the rod 52 extends toward the bottom of the flow path pipe 30 and does not pass through the midstream section 37. Therefore, the laminar flow of the carrier gas in the midstream section 37 is not disturbed by the rod 52.

By supplying a cleaning liquid to the nebulizer 10, the inside of the spray chamber BB can be cleaned. Samples adhering to the flow path tube 30, the impactor 51, and the rod 52 can be discharged in a short time, reducing the memory effect.

Compared to the first embodiment, in which the impactor 51 is placed near the nozzle of the nebulizer 10 (within about 20 mm), in this embodiment the droplets collide with the impactor 51 at a slower speed. This makes it possible to prevent the sample droplets from fragmenting and re-scattering. As a result, the amount of sample droplets adhering to the inner wall of the flow tube 30 and the tip of the nebulizer 10 is reduced, making it possible to reduce the memory effect. In addition, there is less risk of re-nebulization, a phenomenon in which sample droplets adhering to the outer circumferential surface of the nebulizer 10 move to the nozzle of the nebulizer 10 and are sprayed again.

As shown in FIG. 5, the downstream section 38 may be divided into upper and lower sections. Specifically, the downstream section 38 is made up of a first section 38a connected to the midstream section 37, and a second section 38b connected to the first section 38a. The first section 38a and the second section 38b are joined by flanges formed at each end. By separating the first section 38a and the second section 38b from each other, the impactor 51 can be attached and detached.

As shown in FIG. 6, the inner diameter of the vertical pipe 32a of the drain discharge pipe 32 may be made slightly larger than the diameter of the impactor 51. In this way, the impactor 51 passes through the vertical pipe 32a, so that the impactor 51 can be attached and detached without the downstream section 38 having a separate structure.

Third Embodiment
Next, a spray chamber CC according to a third embodiment of the present invention will be described.
7, the flow path pipe 30 of this embodiment is composed of two sections, an upstream section 36 and a downstream section 38, along the spray direction of the nebulizer 10. The flow path pipe 30 does not have a midstream section 37. The inner diameter of the downstream section 38 is smaller than the inner diameter of the upstream section 36. The connecting portion between the upstream section 36 and the downstream section 38 is preferably shaped so that the inner diameter changes continuously and gently to prevent the generation of a vortex in the carrier gas.

The sample discharge pipe 31 and the drain discharge pipe 32 are both provided in the downstream section 38. The impactor 51 is also disposed inside the downstream section 38. Therefore, the tip portion of the rod 52 is also disposed inside the downstream section 38.

The bottom of the downstream section 38 is not narrowed and is open. A holder 60 is attached to the bottom of the downstream section 38. The opening of the downstream section 38 is closed by the holder 60. The rod 52 is passed through the opening of the downstream section 38 and held by the holder 60. In this way, the rod 52 is supported at the bottom of the flow path pipe 30 via the holder 60. In addition, a gap filler 61 is inserted into the gap between the bottom of the downstream section 38 and the rod 52.

The drain discharge pipe 32 is connected directly above the upper surface of the gap filling material 61. Therefore, the drain is discharged from the drain discharge pipe 32 via the upper surface of the gap filling material 61. In addition, a portion of the rod 52 is disposed adjacent to the drain discharge pipe 32. The sample discharge pipe 31 is connected to the side wall of the downstream portion 38 above the drain discharge pipe 32.

The sample droplets collide with the impactor 51 after the carrier gas has become a laminar flow in the downstream section 38 with a small inner diameter, improving the selectivity based on the particle size of the sample droplets. Moreover, the flow path tube 30 of this embodiment has a simpler structure and is easier to manufacture than the second embodiment. In addition, the impactor 51 can be attached and detached without the need for a divided structure for the flow path tube 30.

By supplying cleaning liquid to the nebulizer 10, the inside of the spray chamber CC can be cleaned. The cleaning liquid (drain) that collides with the impactor 51 and condenses flows down along the rod 52. Because the rod 52 is adjacent to the drain discharge pipe 32, the cleaning liquid can easily flow along the rod 52 to the drain discharge pipe 32. The cleaning liquid is unlikely to remain on the inner wall of the flow path pipe 30 and is quickly discharged, allowing for effective cleaning in a short time.

Fourth Embodiment
8, the impactor 51 and the rod 52 may be formed integrally with the flow passage pipe 30. In this case, the base end of the rod 52 may be fixed to the bottom of the flow passage pipe 30. The impactor 51 and the rod 52 may be hollow or solid.

Fifth Embodiment
9, the diameters of the impactor 51 and the rod 52 may be the same. That is, the impactor 51 and the rod 52 may be integrated into a cylindrical member. The impactor 51 and the rod 52 may be hollow or solid.

Alternatively, the base end of the rod 52 may be fixed to the center of the bottom of the flow passage pipe 30, and the drain discharge pipe 32 may be connected to a position adjacent to the rod 52 at the bottom of the flow passage pipe 30. Even in this case, the cleaning liquid that flows down the rod 52 can be led directly to the drain discharge pipe 32.

Sixth Embodiment
10 , the base end of the rod 52 may be connected to the upper end of the drain discharge pipe 32. That is, the rod 52 and the drain discharge pipe 32 may be formed into a single pipe. The part of this pipe that is disposed inside the flow path pipe 30 is the rod 52, and the part that is disposed outside the flow path pipe 30 is the drain discharge pipe 32. The rod 52 and the drain discharge pipe 32 are connected at the bottom of the flow path pipe 30.

One or more holes 34 are formed at the connection between the rod 52 and the drain discharge pipe 32 (inside the flow passage pipe 30, near the bottom). The drain generated by the impactor 51 flows down the outer surface of the rod 52, then passes through the holes 34 into the drain discharge pipe 32 and is discharged.

The rod 52 may be hollow as shown in FIG. 10, or may be solid as shown in FIG. 11(A). Even when the rod 52 is solid as shown in FIG. 11(A) and FIG. 11(B), a hole 34 is formed at the connection between the rod 52 and the drain discharge pipe 32. The drain generated by the impactor 51 flows down the outer surface of the rod 52, then flows through the hole 34 into the inside of the drain discharge pipe 32 and is discharged.

AA, BB, CC Spray chamber 10 Nebulizer 30 Flow path 31 Sample discharge tube 32 Drain discharge tube 40 End cap 51 Impactor 52 Rod 60 Holder

Claims (7)

an end cap for holding the nebulizer;
a flow passage pipe at an upper end of which the end cap is provided and through which droplets are supplied from the nebulizer;
an impactor disposed inside the flow passage pipe, which impacts large droplets to generate drainage;
A rod having the impactor at its tip;
a sample discharge pipe provided in the flow channel pipe and discharging minute droplets;
a drain discharge pipe provided at a bottom of the flow path pipe and discharging the drain,
A spray chamber characterized in that the rod is supported at the bottom of the drain discharge pipe or the flow path pipe. 2. The spray chamber of claim 1, wherein the rod is inserted into the drain discharge pipe. 2. The spray chamber of claim 1, wherein the rod is disposed adjacent to the drain outlet pipe. The base end of the rod is connected to the upper end of the drain discharge pipe,
2. The spray chamber according to claim 1, wherein a hole is formed at a connection between the rod and the drain discharge pipe, through which the drain flows into the inside of the drain discharge pipe. 2. The spray chamber according to claim 1, wherein the rod penetrates the bottom of the flow passage pipe and the depth of insertion into the flow passage pipe is adjustable. the flow passage pipe has an upstream portion, a midstream portion, and a downstream portion along the injection direction of the nebulizer,
an inner diameter of the midstream portion is smaller than inner diameters of the upstream portion and the downstream portion;
the sample discharge pipe and the drain discharge pipe are provided in the downstream portion,
2. The spray chamber of claim 1, wherein the impactor is disposed within the downstream portion. the flow passage pipe has an upstream portion and a downstream portion along the spray direction of the nebulizer,
The inner diameter of the downstream portion is smaller than the inner diameter of the upstream portion,
the sample discharge pipe and the drain discharge pipe are provided in the downstream portion,
2. The spray chamber of claim 1, wherein the impactor is disposed within the downstream portion.