JP6733432B2 - Inductively coupled plasma mass spectrometry method - Google Patents

Description

The present invention relates to an inductively coupled plasma mass spectrometry method capable of continuously and highly accurately analyzing a sample by using an inductively coupled plasma mass spectrometer.

A mass spectrometric method using inductively coupled plasma (hereinafter, sometimes referred to as ICP-MS) uses inductively coupled plasma as an ionization source to be introduced into a mass spectrometer, and analyzes currently known elements. Among the methods, it is one of the most sensitive analytical methods that enables quantitative and qualitative analysis.

The ICP-MS sprays a sample solution into a carrier gas such as argon to generate a mist containing the sample, and ionizes the constituent components by thermal excitation with a plasma device. Then, the constituent components including the ionized component to be analyzed are introduced into the mass spectrometric section in a vacuum state by a sampler having a conical metal tip with pores. The mass spectrometric unit includes a focusing lens, a mass separation device such as a double-convergence type mass separation unit and a quadrupole filter, and a detector, and measures ions according to the mass number as an electric quantity. The target component in the sample is quantified from the relationship between the amount of electricity and the concentration of the sample (for example, refer to Patent Document 1).

In the analysis using such ICP-MS, when a sample containing a high concentration of the coexisting main element (matrix) is introduced, there is a problem that the detection sensitivity gradually decreases each time the analysis is repeated. Further, by repeating the analysis of the sample, there is a problem that the element to be analyzed is accumulated on the path of the sample and the analysis accuracy is lowered. In particular, it is known that when a sample solution containing high concentration (for example, 0.1 mass% or more) of copper is used as a matrix, the accuracy of analysis of other elements to be analyzed is greatly reduced. Further, there is a phenomenon that the tendency of sensitivity decrease varies depending on the type of element. Therefore, it is difficult to correct the analysis sensitivity using the internal standard correction.

Conventionally, in order to prevent sensitivity deterioration due to repeated analysis of a sample using ICP-MS, a sample mist generation amount is reduced by a dilution operation of the sample itself or a rare gas in an analyzer, and a matrix load amount is reduced. The amount of accumulated elements was reduced by performing (hereinafter gas dilution). Hereinafter, these operations are referred to as dilution.

Further, in order to prevent a decrease in detection sensitivity due to the accumulation of elements, the sample path is washed for a long time each time one analysis is performed. In particular, samplers such as sampling cones and skimmer cones were removed from the analyzer for physical or chemical cleaning.

Japanese Patent No. 4903515

However, in the analysis by ICP-MS, if the sample liquid is used after being diluted with, for example, a liquid or gas in order to reduce the sample introduction route and the adhesion and accumulation of the sample on the sampler, the concentration of the element to be analyzed is reduced. However, there was a problem in that the analysis accuracy was reduced because it became extremely diluted.

In addition, when suppressing the decrease in detection sensitivity by removing the sampler from the analyzer and washing each time each analysis is performed, it is necessary to suspend the analysis for a long time for each analysis. However, there is a problem that it is difficult to efficiently analyze a plurality of samples in a short time.

The present invention has been made in view of the above-mentioned circumstances, without diluting a sample, even when performing continuous analysis, it is possible to suppress a decrease in detection sensitivity and analysis accuracy, and a plurality of It is an object of the present invention to provide an inductively coupled plasma mass spectrometry method capable of efficiently analyzing a sample in a short time.

In order to solve the above-mentioned problems, the inductively coupled plasma mass spectrometry method of the present invention comprises: a sample introducing section for introducing a sample solution; an ICP generating section having a plasma torch for generating inductively coupled plasma of the sample; A mass separation unit that separates ions according to a mass-to-charge ratio; and a conical sampler that is arranged between the ICP generation unit and the mass separation unit and that guides the inductively coupled plasma of the sample to the mass separation unit. An inductively coupled plasma mass spectrometric method using an inductively coupled plasma mass spectroscope comprising at least: an analysis step of supplying the sample solution to the sample introduction part to analyze the sample solution; and an aqueous solution of hydrogen chloride. And a nitric acid cleaning step of cleaning the flow channel with a second cleaning liquid composed of a nitric acid aqueous solution, and a step of cleaning the flow path of the sample liquid from the sample introduction part to the sampler using a first cleaning liquid composed of And a process.

According to the inductively coupled plasma mass spectrometry method of the present invention, even if a sample solution containing a high-concentration matrix is used, the sample solution flow path (path It is possible to reliably prevent the constituent elements of the sample liquid from accumulating (depositing) in (), and to analyze the constituent elements by the mass separation device with high sensitivity and high accuracy. Thereby, for example, it becomes possible to measure the lower limit of quantification to be low, and it is possible to precisely measure an extremely small amount of element or the like contained in a high-concentration matrix.

In addition, by performing the two-step cleaning process of the hydrochloric acid cleaning process and the nitric acid cleaning process after the analysis process, a time-consuming cleaning procedure such as removing the sampler from the analyzer and cleaning is not required, so that multiple samples can be collected. Can be efficiently analyzed in a short time.

The present invention is characterized in that the sample introducing unit sucks the sample liquid by self-suction.

In the present invention, the concentration of hydrogen chloride in the first cleaning liquid is in the range of 2% by mass or more and 4% by mass or less.

In the present invention, the second cleaning liquid has a nitric acid concentration of 2% by mass or more and 4% by mass or less.

The present invention is characterized in that the sample solution is continuously analyzed by repeating the analysis step, the hydrochloric acid cleaning step, and the nitric acid cleaning step a plurality of times.

In the present invention, the sample liquid is characterized by containing 0.1 mass% or more of copper as a main coexisting element.

According to the inductively coupled plasma mass spectrometry method of the present invention, it is possible to suppress deterioration of detection sensitivity and analysis accuracy even when performing continuous analysis without diluting the sample, and for a plurality of samples in a short time. It is possible to provide an inductively coupled plasma mass spectrometric analysis method capable of performing efficient analysis with.

It is a block diagram which shows an example of the inductively coupled plasma mass spectrometer used for the inductively coupled plasma mass spectrometry method of this invention. It is sectional drawing which shows the plasma torch and sampler of an inductively coupled plasma mass spectrometer. 3 is a flow chart showing a stepwise method of inductively coupled plasma mass spectrometry according to the present invention. It is a graph which shows the verification result of this invention example 1. 9 is a graph showing the verification results of Comparative Example 1. 9 is a graph showing the verification results of Comparative Example 2. 6 is a graph showing the verification results of the present invention example 2 and comparative example 3. 9 is a graph showing the verification results of Comparative Example 3.

(Inductively coupled plasma mass spectrometer)
First, an inductively coupled plasma mass spectrometer used in the inductively coupled plasma mass spectrometry method of the present invention will be described.
The wording "dilution" in the present invention is to reduce the amount of sample ions passing through the ICP generation unit 12 to be described later, and the dilution using a liquid or the so-called "dry" dilution that does not use a liquid is also applicable. It is meant.
FIG. 1 is a block diagram showing an example of an inductively coupled plasma mass spectrometer.
The inductively coupled plasma mass spectrometer 10 includes a sample introduction unit 11, an ICP generation unit 12, a mass separation unit 13, and a sampler 14 arranged between the ICP generation unit 12 and the mass separation unit 13. ..

The sample liquid introduction unit 11 is composed of a sample liquid table 21, a sprayer (nebulizer) 23, a spray chamber 24, a carrier gas supply unit 25, and a plurality of pipes 27 connecting these.

The sample liquid table 21 holds a plurality of sample liquids R contained in a container, and introduces the suction tube 28 into any sample liquid R. The sample liquid table 21 can also hold a container containing the first cleaning liquid C1 and the second cleaning liquid C2.
The sample liquid R in the present embodiment contains 0.1 mass% or more of copper (Cu) as a coexisting main element (matrix), and various metal elements and non-metal elements are dissolved as single or compound elements as analysis target elements. Is used as it is without dilution. Further, the first cleaning liquid C1 uses a hydrogen chloride aqueous solution having a hydrogen chloride (HCl) concentration of 2 to 4 mass% (hereinafter, may be referred to as diluted hydrochloric acid). Further, the second cleaning liquid C2 uses an aqueous nitric acid solution having a nitric acid (HNO ₃ ) concentration of 2 to 4% by mass (hereinafter sometimes referred to as diluted nitric acid).

The sample liquid R, the first cleaning liquid C1, and the second cleaning liquid C2 are supplied to the sprayer 23 via the suction pipe 28. In this embodiment, the sample liquid R, the first cleaning liquid C1, and the second cleaning liquid C2 are sucked by self-suction. That is, the negative pressure generated in the vicinity of the tip nozzle of the sprayer (nebulizer) 23, which will be described later, causes the sample liquid R, the first cleaning liquid C1, and the second cleaning liquid C2 to be naturally sucked. Therefore, the inductively coupled plasma mass spectrometer 10 of this embodiment is a pumpless type that does not use a liquid supply pump.

The sprayer 23 (nebulizer) is supplied with the sample liquid R, the first cleaning liquid C1, the second cleaning liquid C2, and a carrier gas for generating the aerosol from the carrier gas supply unit 25. An inert gas or the atmosphere is preferably used as the carrier gas, and in the present embodiment, argon gas is used. The atomizer 23 aerosolizes the sample liquid R, the first cleaning liquid C1, and the second cleaning liquid C2. The aerosolized sample liquid R (hereinafter sometimes referred to as sample mist) is carried by the carrier gas flow and introduced into the ICP generation unit 12.

The sprayer (nebulizer) 23 is arranged so that its tip nozzle is exposed in the spray chamber 24. The spray chamber 24 includes a cylindrical wall through which droplets of the sample mist can circulate. The sample mist is supplied to the ICP generation unit 12 by the carrier gas flow. On the other hand, a droplet having a relatively large diameter is discharged from a drain drain 29 connected to the bottom of the spray chamber 24. The tip nozzle of the atomizer (nebulizer) 23 has a coaxial type or a cross flow type so that the sample liquid R, the first cleaning liquid C1, and the second cleaning liquid C2 can be self-sucked (natural suction) without using a liquid supply pump. The thing of is adopted.

The ICP generation unit 12 includes a plasma torch 31 and a plasma gas supply unit 32.
FIG. 2 is a sectional view showing an outline of the plasma torch and the sampler. The plasma torch 31 includes a plasma generating cylinder 32 having an open surface 32 a at one end, a sample mist introducing section 33 connected to the plasma generating cylinder 32, a plasma gas introducing section 34, and a load coil 35. In addition, it is preferable that a cooling gas flow path (not shown) in which a cooling gas for cooling the plasma generation cylinder 32 flows is further formed on the outer periphery of the plasma generation cylinder 32.

The plasma generating cylinder 32 is a cylindrical member, and the inside thereof serves as a plasma generating chamber 36 for generating plasma of argon and elements of the sample liquid.
The sample mist introduction unit 33 introduces the sample mist supplied from the spray chamber 24 into the plasma generation chamber 36.

One end of the plasma gas introduction unit 34 is connected to the plasma gas supply unit 32 (see FIG. 1), and the plasma gas is introduced from the plasma gas introduction unit 34 into the plasma generation chamber 36. As the plasma gas, for example, an inert gas such as argon gas or helium gas is used. In this embodiment, argon gas is used as the plasma gas.

The load coil 35 is a conductor wound along the outer peripheral surface of the plasma generation cylinder 32, and a high frequency current that is energy for generating the plasma Z is applied to the plasma generation chamber 36. By applying a high-frequency current to the load coil 35 with the plasma gas introduced into the plasma generation chamber 36, the plasma Z can be brought into an ignition state. After that, the sample mist is introduced from the sample mist introducing unit 33 for the analysis of the sample solution R.

With such a configuration, each element constituting the sample liquid is ionized in the plasma Z. The plasma Z is emitted from the open surface 32a of the plasma generating cylinder 32 toward the sampler 14.

The sampler 14 includes a sampling cone 41 and a skimmer cone 42. The sampling cone 41 is a conical member, and an opening 41a is formed at the position of the tip of the cone. The skimmer cone 42 is a conical member having a smaller diameter than the sampling cone 41, and a part of the skimmer cone 42 is arranged so as to overlap the sampling cone 41. In the skimmer cone 42, an opening 42a is formed at the tip of the cone so as to coaxially overlap with the opening 41a of the sampling cone 41.

Referring again to FIG. 1, the mass separation unit 13 includes a focusing lens 51, a mass separation device 52, and a detection device 53.
The focusing lens 51 focuses the ions that have passed through the sampler 14 toward the mass separation device 52. An ion lens is used as the focusing lens 51.

The mass separation device 52 separates the ions introduced via the focusing lens 51 according to the mass-to-charge ratio. As the mass separator 52, a quadrupole separator, a magnetic field deflection separator, an ion trap separator, or the like can be used. Among them, the quadrupole separation device passes ions through four electrodes and applies a high frequency voltage to each electrode to perturb the ions so that only specific ions are transmitted. When ions pass through the four electrodes, by changing the voltage value of each electrode, the mass-to-charge ratio of the passable ions changes, and a mass spectrum can be obtained. In this embodiment, a quadrupole separator is used as the mass separator 52.

The detection device 53 detects the ions separated by the mass separation ratio in the mass separation device 52. As the detection device 53, for example, an electron multiplier, a microchannel plate, or the like can be used. Such a detection device sensitizes and detects the ions that have passed through the mass separation device 52.

The sampler 14 to the mass separation unit 13 are in a reduced pressure environment by a vacuum pump (not shown). For example, the pressure is gradually reduced from the ICP generation unit 12 in the atmospheric pressure environment toward the detection device 53 having a vacuum degree of about 1×10 ⁻⁶ torr.

(Inductively coupled plasma mass spectrometry method)
The inductively coupled plasma mass spectrometric method of the present invention using the inductively coupled plasma mass spectroscope having the above configuration will be described with reference to FIGS.
FIG. 3 is a flow chart showing each step of the inductively coupled plasma mass spectrometry method of the present invention step by step.
When performing a qualitative and quantitative analysis of a specific element contained in a sample solution containing a high-concentration matrix such as 0.1 mass% or more of copper using the inductively coupled plasma mass spectrometer 10 shown in FIG. First, the container containing the sample solution R to be analyzed is first placed on the sample solution table 21 (sample solution preparation step S1). In the present embodiment, as the sample liquid R, copper waste water containing copper as a main component and various metals is used. In order to improve the analysis accuracy, the sample solution R is used for the analysis as it is without being diluted. Further, on the sample liquid table 21, a container containing the first cleaning liquid C1 and the second cleaning liquid C2 in advance is also placed. As the first cleaning liquid C1, for example, dilute hydrochloric acid having a hydrogen chloride (HCl) concentration of 2 to 4 mass% is used. Further, as the second cleaning liquid C2, for example, dilute nitric acid having a nitric acid (HNO ₃ ) concentration of 2 to 4 mass% is used.

Next, the carrier gas is supplied from the carrier gas supply unit 25 toward the sprayer 23 (nebulizer). As a carrier gas, for example, argon gas is used. By the supply of the carrier gas, the vicinity of the tip nozzle of the sprayer 23 becomes a negative pressure, and the sample solution R placed on the sample solution table 21 is sucked up from the suction tube 28 by self-suction (natural suction), and the sample solution introduction part 11 The inside of the pipe 27 is replaced with the sample liquid R (preliminary suction step S2).

Further, in this preliminary suction step S2, a sample mist is formed in the spray chamber 24, and a plasma gas is supplied from the plasma gas introduction unit 34 to the plasma torch 31, and a high frequency current is supplied to the load coil 35 of the plasma torch 31. Is applied. As a result, plasma is generated in the plasma generation chamber 36 of the plasma torch 31.

When the inside of the pipe 27 is sufficiently replaced with the sample liquid R, next, the sample liquid R is analyzed (measured) (analyzing step S3). In the analysis step S4, the sample mist of the undiluted undiluted sample solution R, which is carried by the carrier gas, is exposed to the plasma formed by the plasma torch 31, and the high concentration copper as a component of the sample solution R, that is, the matrix. And the constituent components of the copper wastewater containing various metals are ionized for each element.

As an example of the set value of each part in the analysis step S3, the flow rate of the carrier gas: 1.15 L/min, the sampling depth: 8 mm to 10 mm, and the holding time (execution time): 15 sec can be set. Further, in order to ionize the sample mist without diluting it and improve the analysis accuracy, it is preferable not to flow the additive gas. However, it is also possible to flow the additive gas in optimizing the analysis conditions.

The element ionized by the plasma torch 31 is focused by the focusing lens 51 and then introduced into the mass separation device 52. The mass separation device 52 separates the ions according to the mass-to-charge ratio. For example, in a quadrupole separator, a high frequency voltage is applied to each electrode to perturb the ions so that only specific ions are transmitted. At this time, by changing the voltage values of the respective electrodes, the mass-to-charge ratio of the ions that can pass through changes.

The ions separated by the mass separation device 52 for each mass-to-charge ratio are introduced into the detection device 53. The detector 53 sensitizes and detects the ions. As a result, a mass spectrum for each ion is obtained.

Through the above analysis step S3, the qualitative analysis and the quantitative analysis of the components constituting the sample liquid R can be performed. In the analysis step S4, the flow rate of the carrier gas may be changed depending on the element to be measured. Depending on the device configuration of the inductively coupled plasma mass spectrometer 10, analysis may be performed by changing the type of additive gas, and various combinations of condition settings are possible depending on the inductively coupled plasma mass spectrometer used and the components to be analyzed. is there.

When the analysis step S3 of one time (one turn) is completed, next, the cleaning step S4 is performed.
The cleaning step S4 includes a hydrochloric acid cleaning step S4a and a nitric acid cleaning step S4b.

When the sample liquid R is analyzed without being diluted in order to secure the detection sensitivity and/or improve the analysis accuracy, the constituent components of the sample liquid R adhere to the inside of the suction pipe 28 or the pipe 27, accumulate. Further, the constituent components of the sample liquid R ionized by the plasma torch 31 are easily deposited on the surfaces of the sampling cone 41 and the skimmer cone 42. Such accumulations and precipitates greatly reduce the detection sensitivity and the analysis accuracy. Therefore, in the cleaning step S4, two types of cleaning liquids, that is, the first cleaning liquid C1 and the second cleaning liquid C2 are sequentially used, and the flow of the sample liquid R such as the suction pipe 28, the pipe 27, the sampling cone 41, and the skimmer cone 42 is flown. Clean the path.

In the hydrochloric acid cleaning step S4a that is first performed in the cleaning step S4, the first cleaning liquid C1 made of dilute hydrochloric acid having a hydrogen chloride (HCl) concentration of 2 to 4 mass% is sucked from the suction pipe 28, and the inside of the pipe 27 is filled with the first cleaning liquid C1. At the same time, the sampling cone 41 and the skimmer cone 42 are sprayed with a carrier gas for cleaning. According to the hydrochloric acid cleaning step S4a, for example, even when the sample solution R containing a high-concentration copper matrix is used, the copper and the copper compound deposited on the pipe 27 due to hydrochloric acid acidity are reliably cleaned and removed. .. Further, the copper oxide deposited on the sampling cone 41 and the skimmer cone 42 is decomposed and removed by the reducing property of hydrochloric acid.

Next, in the nitric acid cleaning step S4b performed as a post-step of the hydrochloric acid cleaning step S4a, the second cleaning liquid C2 made of dilute nitric acid having a nitric acid (HNO ₃ ) concentration of 2 to 4 mass% is sucked from the suction pipe 28, and the inside of the pipe 27 is drawn. Is cleaned with this second cleaning liquid C2, and the sampling cone 41 and the skimmer cone 42 are sprayed with a carrier gas for cleaning. According to the nitric acid cleaning step S4b, for example, by removing the dilute hydrochloric acid used in the hydrochloric acid cleaning step S4a from the pipe 27, it is possible to prevent a decrease in analysis sensitivity due to a change in thermal conductivity or conductivity.

By the cleaning step S4 including the two-step cleaning steps of the hydrochloric acid cleaning step S4a and the nitric acid cleaning step S4b as described above, the sample liquid R is not diluted, for example, copper effluent containing a high-concentration copper matrix. Even when used, it is possible to reliably prevent the constituent elements of the sample solution R from accumulating (accumulating) in the flow path (path) of the sample solution R, such as the suction tube 28, the pipe 27, the sampling cone 41, and the skimmer cone 42. This makes it possible to analyze the component elements by the mass separation device 52 with high sensitivity and high accuracy. As a result, for example, it becomes possible to measure the lower limit of quantification at a low level, and it becomes possible to accurately measure an extremely small amount of metal impurities contained in a high-purity copper matrix.

Further, the sample liquid R, the first cleaning liquid C1, and the second cleaning liquid C2 are sucked by self-suction (natural suction) due to the negative pressure generated near the tip nozzle of the sprayer (nebulizer) 23, and the components of the sample liquid R tend to accumulate. By not using the liquid supply pump, it is possible to analyze the component elements by the mass separation device 52 with high sensitivity and high accuracy.

After the cleaning step S4 is completed, another sample liquid R can be continuously analyzed. At this time, the constituent element of the sample solution R remaining in the flow path (route) of the sample solution R is surely removed by the cleaning step S4 including the two steps of the hydrochloric acid cleaning step S4a and the nitric acid cleaning step S4b. Therefore, the deterioration of the analysis accuracy due to the residual element in the previous analysis step S3 is prevented.

Further, when there are a plurality of sample liquids R, even if the analysis step S3 is continuously performed, the cleaning step S4 including the two-step cleaning step of the hydrochloric acid cleaning step S4a and the nitric acid cleaning step S4b is performed each time. Qualitative analysis and quantification of the sample liquid R while maintaining a constant detection sensitivity and high analysis accuracy even if a sample solution (copper drainage liquid) containing a high-concentration copper matrix is used as the sample liquid R without being diluted. It becomes possible to perform an analysis.

Further, in the cleaning step S4, there is no time-consuming and time-consuming procedure of removing the sampler 14 such as the sampling cone 41 and the skimmer cone 42 from the inductively coupled plasma mass spectrometer 10, so that the cleaning step S4 is performed once for each analysis step S3. Even if the cleaning step S4 is performed, the plurality of sample liquids R can be efficiently analyzed in a short time.

Further, the hydrochloric acid cleaning step S4a and the nitric acid cleaning step S4b can be performed simultaneously. In this case, for example, the first cleaning liquid C1 made of dilute hydrochloric acid having a hydrogen chloride (HCl) concentration of 2 to 4 mass% and the second cleaning liquid C2 made of dilute nitric acid having a nitric acid (HNO ₃ ) concentration of 2 to 4 mass% are mixed. The flow path of the sample solution from the sample introducing section 11 to the sampler 14 may be cleaned using the mixed acid cleaning solution described above.

Although some embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and modifications thereof are included in the invention described in the claims and equivalents thereof as well as included in the scope and the gist of the invention.

For example, in the above embodiment, argon gas is used as the carrier gas and the plasma gas, but the present invention is not limited to this, and various inert gases can be used. Further, although the sampler 14 is shown as an example including the sampling cone 41 and the skimmer cone 42, the sampler is not limited to this, and the sampler may be configured only by the sampling cone.

Hereinafter, the verification result of verifying the effect of the present invention will be described.
(Verification example 1)
An inductively coupled plasma mass spectrometer having the above-described structure is prepared by using a sample solution containing 0.1% by mass of Cu as a matrix and trace amounts of Li, Be, Co, Y, In, Te, Cs, Tl, and Bi as elements to be analyzed. Was used to measure these elements to be analyzed by the analysis method of the present invention and the analysis method of the comparative example, and changes in the detection intensity (Relative Sensitivity) were investigated.
(1) As Example 1 of the present invention, approximately every 100 minutes of the analysis step, a hydrochloric acid washing step with dilute hydrochloric acid having a hydrogen chloride concentration of 3 mass% and a nitric acid washing step with dilute nitric acid having a nitric acid concentration of 3 percent by mass were performed.
(2) In Comparative Example 1, no washing process was performed during the analysis process.
(3) As Comparative Example 2, only the washing step with diluted nitric acid having a nitric acid concentration of 5 mass% was performed approximately every 100 minutes in the analysis step.
With respect to these inventive examples and comparative examples 1 and 2, when the detection intensity immediately after the start of the analysis is set to 100%, each of the elements Li, Be, Co, Y, In, Te, Cs, Tl, and Bi that are the analysis target elements is It was investigated how the relative detection intensities changed.
FIG. 4 shows the results of the present invention, FIG. 5 shows the results of Comparative Example 1, and FIG. 6 shows the results of Comparative Example 2. It should be noted that the place where the value of the detection accuracy in the graphs of FIGS. 4 and 6 is 0 is the timing when each cleaning process is performed.

According to the example of the present invention shown in FIG. 4, the detection intensity after performing the cleaning step S4 including the hydrochloric acid cleaning step S4a and the nitric acid cleaning step S4b every time one analysis step is completed is It can be seen that the recovery is 100% to 80%. Therefore, by cleaning the flow path (path) of the sample solution R from the sample introducing section 11 to the sampler 14, accumulation of the component elements of the sample solution R can be reliably suppressed, and a decrease in detection intensity can be prevented. Was confirmed.

On the other hand, according to the conventional example 1 shown in FIG. 5, when the analysis is continuously performed without passing through the cleaning step S4, the detection intensities of all the elements continue to decrease. It is considered that this is because the constituent elements of the sample liquid R continue to be accumulated in the flow path (route) of the sample liquid R.

Further, like the conventional example 2 shown in FIG. 6, when only the nitric acid cleaning step is performed every time one analysis step is completed, the detection intensity recovers only about 85% to 65% for most elements. There wasn't. This suggests that the washing with dilute nitric acid alone cannot prevent the sample liquid R from accumulating in the flow path (route) depending on the element, and suggests that the washing with dilute hydrochloric acid is effective in preventing the element accumulation.

(Verification example 2)
A sample liquid containing 0.1% by mass of Cu as a matrix and trace amounts of various kinds of metal elements as elements to be analyzed is prepared, and the inductively coupled plasma mass spectrometer (without liquid supply pump) and the liquid supply pump (nebulizer) having the above-described configuration are prepared. For each of the inductively coupled plasma mass spectrometers with the addition of a pump), the accumulation ratio of the sample liquid in the flow channel (path) was examined for each element.
(4) As Example 2 of the present invention, the sample liquid was introduced into a sprayer (nebulizer) by self-suction (natural suction).
(5) As Comparative Example 3, the sample liquid was introduced into a sprayer (nebulizer) by a liquid supply pump (nebulizer pump).
FIG. 7 shows the accumulation ratio of these sample liquids in the flow path (route) for each element.

According to the results of Verification Example 2 shown in FIG. 7, when the sample liquid R was supplied by self-suction without using the liquid supply pump (nebulizer pump), no accumulation was observed in all the elements.
On the other hand, when the sample liquid R is supplied using the liquid supply pump (nebulizer pump), accumulation is observed in B, Zn, As, Se, Zr, Mo, In, Sn, Te, Ta, W, Au, Bi. Was given. Especially, the accumulated amounts of Mo, Sn, Te, W, and B were remarkable.
From the above results, by supplying the sample liquid R by self-suction without using the liquid supply pump, it is possible to prevent element accumulation in the flow path (route) of the sample liquid, and to perform highly accurate analysis. It was confirmed that there is.

(Verification example 3)
Prepare a sample solution containing 0.1% by mass of Cu as a matrix and trace amounts of Li, Be, Co, Y, In, Te, Cs, Tl, and Bi as elements to be analyzed, and use diluted hydrochloric acid having a hydrogen chloride concentration of 3% by mass. A change in detection intensity (Relative Sensitivity) was examined by continuous long-time analysis after the hydrochloric acid washing step and the nitric acid washing step with dilute nitric acid having a nitric acid concentration of 3 mass %.
How did the relative detection intensities of Li, Be, Co, Y, In, Te, Cs, Tl, and Bi, which are the analysis target elements, change when the detection intensity immediately after the start of analysis was set to 100%? I checked.
FIG. 8 shows the result of verification example 3.

According to the example of the present invention shown in FIG. 8, the detection intensity after the cleaning step S4 including the hydrochloric acid cleaning step S4a and the nitric acid cleaning step S4b is 140 after the start of the analysis each time one analysis step is completed. Even after the lapse of minutes, the high detection intensity of 85% or more was maintained for all the elements to be analyzed. Therefore, by cleaning the flow path (path) of the sample solution R from the sample introducing section 11 to the sampler 14, accumulation of the component elements of the sample solution R is reliably suppressed, and the detection intensity is prevented from lowering over a long period of time. It was confirmed that it could be prevented.

Summarizing the above Verification Examples 1 to 3, it was confirmed that the accumulation of elements can be surely suppressed by combining the cleaning with diluted hydrochloric acid and the cleaning with diluted nitric acid as in the present invention. This means that the accumulation of the element adsorbed in the path of the sample solution is alleviated by the effect of hydrochloric acid. Therefore, when it was necessary to reduce the blank test value and measure the lower limit of quantification low, it was found that it is effective to make the sample liquid acid nitric acid+hydrochloric acid and to measure by self-suction.

Further, even when a high concentration copper matrix component is contained, it is possible to effectively suppress the decrease in detection sensitivity due to the copper matrix by making the liquid properties of the sample liquid and the cleaning liquid acidic with hydrochloric acid+nitric acid. That is, the copper oxide deposited on the sampler (orifice) can be decomposed by using hydrochloric acid, which is a reducing acid, and the sensitivity decrease due to blockage and the sensitivity fluctuation due to changes in thermal conductivity and electrical conductivity can be suppressed. Is.

10 Inductively Coupled Plasma Mass Spectrometer 11 Sample Introducing Section 12 ICP Generating Section 13 Mass Separation Section 14 Sampler 31 Plasma Torch 41 Sampling Cone 42 Skimmer Cone R Sample Solution C1 First Cleaning Solution C2 Second Cleaning Solution

Claims (6)

A sample introducing section for introducing a sample solution, an ICP generating section having a plasma torch for generating inductively coupled plasma of the sample, a mass separating section for separating ions of the sample according to a mass-to-charge ratio, and the ICP generating section. And a mass separation part, and a conical sampler for guiding the inductively coupled plasma of the sample to the mass separation part, and an inductively coupled plasma mass spectrometry method using an inductively coupled plasma mass spectrometer. And
An analysis step of supplying the sample solution to the sample introducing unit to analyze the sample solution,
A hydrochloric acid cleaning step of cleaning the flow path of the sample liquid from the sample introducing part to the sampler using a first cleaning liquid composed of an aqueous solution of hydrogen chloride;
And a nitric acid cleaning step of cleaning the flow path using a second cleaning liquid composed of an aqueous nitric acid solution ,
The inductively coupled plasma mass spectrometry method , wherein the hydrochloric acid cleaning step is a step before the nitric acid cleaning step . The inductively coupled plasma mass spectrometric method according to claim 1, wherein the sample introduction unit sucks the sample liquid by self-suction. The inductively coupled plasma mass spectrometric method according to claim 1, wherein the first cleaning liquid has a hydrogen chloride concentration of 2% by mass or more and 4% by mass or less. The inductively coupled plasma mass spectrometric method according to claim 1, wherein the second cleaning liquid has a nitric acid concentration of 2% by mass or more and 4% by mass or less. The inductively coupled plasma mass spectrometer according to any one of claims 1 to 4 , wherein the sample solution is continuously analyzed by repeating the analysis step, the hydrochloric acid cleaning step, and the nitric acid cleaning step a plurality of times. Method. The sample solution is inductively coupled plasma mass spectrometry method of claims 1 to 5 any one claim, characterized in that it comprises copper or 0.1 wt% as a coexisting main element.

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