JPH1092372A - Inductively coupled plasma device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent metal impurity contamination from a plasma torch and make analysis with high sensitivity and high precision by forming the plasma torch of quartz containing an OH group. SOLUTION: A sample solution is dropped on a carbon tube heater 21 in a high-temperature vaporizer 20 by means of a micro-pipette, heated at a specified temperature, dried, and laid in ashing. Solvent vapor evaporated in this process is exhausted via a four-way cock 22. Next, when the cock 22 is switched so as to communicate with a quartz plasma torch part 3, then temperature of a heater 21 is made to rise to a high temperature of 2300 to 2500 deg.C, it is evaporated by means of radiation heat from a carbon tube heater interior wall, introduced into a plasma P, inductively energized, and ionized, a mass spectrum is measured, and an impurity content in the sample is analyzed. In this case, by setting an OH group content in the quartz of the torch part 3 to 500 to 1500ppm, release of metal impurity from the quartz is suppressed, deformation of the quartz-based torch due to heat of plasma gas is minimized, and analysis with high sensitivity and high precision is possible.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an inductively coupled plasma (ICP) apparatus using an inductively coupled plasma (ICP) ion source.

[0002]

2. Description of the Related Art FIG. 2 shows a conventional ICP-MS. In the figure, reference numeral 1 denotes an ICP ion source, and a high-frequency induction coil 2
And a nebulizer 4 for spraying a sample liquid. 5 is a high-frequency power supply for applying a high-frequency voltage to the coil 2; 6 is a sample bottle containing a sample liquid 7 and connected to the nebulizer 4 via an introduction pipe 8; 9 is a nebulizer 4 connected to the plasma torch 3; This is a spray chamber for equalizing the particle size of the mist sprayed by the mist.

[0003] Reference numeral 10 denotes an interface including a sampling cone 11 and a skimmer 12, and 13 denotes a mass spectrometer, in which a mass spectrometer 14 is provided. Reference numeral 15 denotes an electrode group for accelerating and converging ions and introducing the ions into the mass spectrometer 14. 16 and 17 are turbo molecular pumps for keeping the inside of the mass spectrometer 13 at a high vacuum, 18 is a rotary pump for exhausting the space between the sampling cone 11 and the skimmer 12, and 19 is a spare for the turbo molecular pump. It is a rotary pump for exhausting.

In such a configuration, the plasma torch 3
Inside, an argon gas is supplied from a gas supply source (not shown), and a sample liquid 7 is introduced in a nebulized form from a nebulizer 4. In this state, when high-frequency power is applied from the high-frequency power supply 5 to the coil 2 to form a high-frequency magnetic field, a high-frequency inductively-coupled plasma (hereinafter referred to as plasma) P is generated. It enters the interface 10 through each skimmer 12. The ions that have entered the interface are accelerated and converged by the electrode group 15, introduced into the mass spectrometer 14, and subjected to mass analysis. As the mass spectrometer, either a Q pole type or a magnetic field type may be used.

[0005] As a material of the plasma torch,
Quartz has been widely used in terms of electrical insulation, heat resistance, and acid resistance (excluding hydrofluoric acid). However, when used continuously, the temperature of the quartz torch becomes high due to the heat of the plasma gas, and metal impurities such as iron, which are impurities contained in the quartz, are likely to be released. When metal impurities were released from the plasma torch, the blank value became high, and it became difficult to measure a trace amount.

[0006]

As described above, the prior art has a problem that a blank value is increased due to contamination of metal impurities from a plasma torch, and it is difficult to measure a trace amount.

The present invention has been made in order to solve such a problem, and an object of the present invention is to prevent contamination of metal impurities from a plasma torch and perform analysis with high sensitivity and high accuracy. It is an object of the present invention to provide an inductively-coupled plasma device which can be used.

[0008]

In order to achieve the above object, according to the present invention, a plasma ion source formed under atmospheric pressure, and a sample are ionized using the ion source.
An apparatus for introducing generated ions into a mass spectrometer through a sampling cone, wherein the plasma torch is made of quartz having an OH group content of 500 to 1500 ppm.

The plasma torch may be made of any material as long as the sample can be efficiently excited and ionized by the generated plasma gas. Quartz is widely used in terms of electrical insulation, heat resistance, and acid resistance (excluding hydrofluoric acid).

The OH group in quartz acts as a certain kind of defect in quartz and has a function of suppressing the diffusion of impurity metals.
However, since an increase in OH groups causes a decrease in viscosity, it is necessary to minimize the increase particularly when used at high temperatures. Usually, the content of OH groups in quartz is less than 500 ppm. Therefore, in order to suppress the diffusion and release of the impurity metal more than usual, the content is desirably higher than this. ,
On the other hand, if the content of OH groups in the quartz exceeds 1500 ppm, the viscosity decreases and it cannot be used at high temperatures. From the above, the content in quartz is 500 to 150
0 ppm is desirable.

[0011] The method for producing these quartz glass is based on SiC.
l oxyhydrogen melting method as a raw material of _4, natural quartz oxyhydrogen melting method is preferable. As described above, OH groups in quartz can suppress the diffusion of metal impurities in quartz, that is, can suppress the diffusion and release of metal impurities in quartz. On the other hand, when the OH group content in the quartz is high, the viscosity of the quartz decreases, that is, the quartz torch is easily deformed by the heat of the plasma gas, and the processing accuracy decreases. Therefore, according to the inductively coupled plasma apparatus of the present invention, O
By setting the H group content to 500 to 1500 ppm, release of metal impurities from quartz can be suppressed, and deformation of the quartz torch due to heat of the plasma gas can be minimized. As a result, analysis can be performed with high sensitivity and high accuracy.

[0012]

Embodiments of the present invention will be described below in detail with reference to the embodiments. FIG. 1 is a schematic diagram showing a sample introduction device of an inductively coupled plasma mass spectrometer used in an embodiment of the present invention.

In the figure, reference numeral 20 denotes a high-temperature vaporizer, and the carbon tube heater 21 has an outer diameter of 8 mmφ, an inner diameter of 6 mmφ,
One having a sample injection hole of 28 mm in length and 2 mmφ in the center is provided. The vaporizer 20 is connected through a four-way cock 22 to a torch portion 3 of plasma P which is induced and excited by high frequency and ionized. Argon whose flow rate is controlled by a flow meter 23 is introduced into the four-way cock 22.

Next, the operation of the sample introduction device shown in FIG. 1 will be described. The sample solution is dropped on the carbon tube heater 21 in the vaporizer 20 by a micropipette, and is heated and dried and ashed at a predetermined temperature. The solvent vapor evaporated in this step is exhausted through the four-way cock 22.
After the four-way cock 22 is switched to communicate with the plasma torch part 3, the heater 21 is heated to a high temperature of 2300 to 2500 ° C., and is vaporized by radiant heat from the inner wall of the carbon tube heater and introduced into the plasma P. Then, induction excitation and ionization are performed, and a mass spectrum is measured to analyze an impurity content in the sample.

[0015]

Example 1 OH group concentration of 560 pp as quartz torch 3
m, Fe 0.16 ppm, Cr 31 ppm, Ni 24 p
An experiment was performed using an inductively coupled plasma mass spectrometer using pm and Cu of 19 ppm.

[0016]

[Comparative example 1] OH group concentration 120pp as quartz torch 3
m, Fe0.17ppm, Cr29ppm, Ni27p
The same experiment as in Example 1 was performed using an inductively coupled plasma mass spectrometer using pm and 18 ppm of Cu.

Thus, using the inductively coupled plasma mass spectrometer of Example 1 and Comparative Example 1, a blank solution (0.
20% of 1% sulfuric acid solution)
The ionic strength of r, Ni, and Cu was measured 10 times.

Carrier gas in sample introduction device: 3.5 l
/ Min argon. Drying in sample introduction device; 150 ° C, 40s. Ashing in sample introduction device; 800 ° C, 20s.

Evaporation and evaporation in the sample introduction device; 2800 ° C.
3s. Frequency of high frequency power supply in plasma torch; 27.12M
Hz. High frequency output of high frequency power supply in plasma torch; 1.3k
W.

Cooling gas in plasma torch; 15 l / m
in. 0.8 l / min of plasma gas in the plasma torch. As a result, in Example 1, the detection limit (3σ) obtained by measuring the blank solution was 20 ppt or less for any of the elements as shown in Table 1.
For e, Cr, and Ni, the detection limit deteriorated due to the increase in the background. However, no effect was observed with respect to Cu because the morphology in quartz was different.

[0021]

[Table 1] The present invention can be applied to an inductively coupled plasma emission spectrometer and can analyze a trace component in a sample with high sensitivity.

[0022]

As described above in detail, according to the present invention, contamination of metal impurities from the quartz torch is small, that is, the blank value can be reduced, so that analysis can be performed with high sensitivity and high accuracy.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a sample introduction device of an inductively coupled plasma mass spectrometer showing one embodiment of the present invention.

FIG. 2 is a schematic diagram of an inductively coupled plasma mass spectrometer.

[Explanation of symbols]

1: ICP ionization source, 2: high frequency induction coil, 3: plasma torch, 4: nebulizer, 5: high frequency power supply, 6:
Sample bottle, 7: sample liquid, 8: introduction tube, 9: spray chamber, 10: interface, 11: sampling cone, 12: skimmer, 13: mass spectrometer, 1
4: mass spectrometer, 15: electrode group, 16: turbo molecular pump, 17: turbo molecular pump, 18: rotary pump, 19: rotary pump, 20: high temperature vaporizer, 2
1: carbon tube heater, 22: four-way cock, 23: flow meter, P: plasma

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Shoji Kozuka 1 Toshiba-cho, Komukai-Toshiba-cho, Saisaki-ku, Kawasaki-shi, Kanagawa Inside the Toshiba R & D Center

Claims (1)

[Claims] A plasma ion source formed under atmospheric pressure and an apparatus for ionizing a sample using the ion source and introducing the generated ions into a mass spectrometer through a sampling cone. An inductively coupled plasma apparatus, wherein the torch is made of quartz having an OH group content of 500 to 1500 ppm.