JP2003016990A - Inductively coupled plasma mass spectrometer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce cost while ensuring sensitivity in an inductively coupled plasma mass spectrometer for identifying and determining trace impurity elements in a sample solution. SOLUTION: A first vacuum chamber 6 is evacuated by two pumps which are a first roughing vacuum pump 5b and a second roughing vacuum pump 14c for the rough evacuation of high vacuum pumps 10, 11.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inductively coupled plasma mass spectrometer for identifying and quantifying trace impurity elements in a sample solution. 2. Description of the Related Art A first prior art will be described with reference to FIG. In FIG. 2, reference numeral 1 denotes an inductively coupled plasma. A sample (not shown) to be analyzed is atomized by a nebulizer (not shown), introduced into the inductively coupled plasma 1, and ionized. 2 is a sampling cone and 3 is a skimmer cone. The sampling cone 2 and the skimmer cone 3 have pores. Ions generated by the inductively coupled plasma 1 are guided into a vacuum vessel 4 through a sampling cone 2 and a skimmer cone 3. 7 is an ion lens, 8
Is a mass analyzer and 9 is a detector. The ion lens 7 has a function of guiding ions passing through the skimmer cone 3 to a mass analyzer. The ions that have passed through the ion lens 7 are mass-separated by the mass analyzer 8 and detected by the detector 9. This inductively coupled plasma mass spectrometer identifies the impurity element in the sample from the setting of the mass analyzer 8 (that is, the ion mass number) when the ion is detected by the detector 9, and identifies the impurity element from the intensity of the ion detection. Perform quantification. Next, evacuation will be described. 5 is a first roughing pump, 6 is a first vacuum chamber, and 16 is a gate valve. A room between the sampling cone 2 and the skimmer cone 3 of the vacuum vessel 4 is called a first vacuum chamber 6, and is evacuated by the first roughing pump 4. As the first roughing pump 5, for example, a rotary pump is used. The pumping speed of the first roughing pump 5 is 500 to 700 L / min.
It is. The gate valve 16 is provided between the skimmer cone 3 and the ion lens 7 and can be opened and closed.
The gate valve 16 is in an open state when the analysis operation is performed to pass ions through the ion lens 7 and thereafter, and is closed when the analysis operation is stopped. 10 is the first high vacuum pump,
11 is a second high vacuum pump. The part of the vacuum vessel 4 where the ion lens 7 is installed is called a second vacuum chamber 12 and the part where the detector 9 is installed is called a third vacuum chamber 13. A first high vacuum pump 10 and a second high vacuum pump 11 are respectively provided. Is evacuated. As the first high vacuum pump 10 and the second high vacuum pump 11, for example, a turbo molecular pump is used. 1
Reference numeral 4 denotes a second roughing pump, which roughly exhausts the first high vacuum pump 10 and the second high vacuum pump 11 on the exhaust side. The pumping speed of the second roughing pump 14 is 200 to 300 L / m.
in. Reference numeral 15 denotes a roughing valve having a structure that can be opened and closed. The roughing valve 15 is provided between the second vacuum chamber 12 and the third vacuum chamber 13 and the second roughing pump 14, and is opened when vacuum evacuation is performed and closed when vacuum evacuation is stopped. Next, the state of vacuum evacuation of the apparatus will be described. There are three states of evacuation: an operating state, a standby state, and a stopped state. The operating state is a state in which the inductively coupled plasma 1 is turned on to perform analysis, and the first roughing pump 5, the first high vacuum pump 10, the second high vacuum pump 11,
The second roughing pump 14 is operating and the roughing valve 1
5 and the gate valve 16 are open. At this time, the pressure in the first vacuum chamber 6 is about 100 to 300 Pa, the pressure in the second vacuum chamber 12 is about 10 −2 Pa, and the pressure in the third vacuum chamber 13 is about 10 −4 to 3 Pa. Exhausting. In the standby state, the plasma 1 is turned off, but the second vacuum chamber 12 and the third vacuum chamber 13 are evacuated to a state where the operation state can be easily shifted. At this time, the first high vacuum pump 10, the second high vacuum pump 11, and the second roughing pump 14 are in the operating state, the roughing valve 15 is open, the first roughing pump 5 is stopped, the gate valve Reference numeral 16 denotes a closed state. The vacuum pressure in the first vacuum chamber 6 is the atmospheric pressure, and the second vacuum chamber 12 and the third vacuum chamber 13
Is 10 −4 Pa or less. The stopped state is a state in which the apparatus is stopped, the first roughing pump 5, the first high vacuum pump 10, the second high vacuum pump 11, and the second roughing pump 14 are stopped, and the roughing valve 15 and the gate are stopped. The valve 16 is in a closed state. The pressure in the first vacuum chamber 6 is atmospheric pressure. The second vacuum chamber 12 and the third vacuum chamber 13 are isolated from the outside and are depressurized or purged with an inert gas such as argon so that the next evacuation does not take excessive time. As a second conventional example, there is an apparatus configuration shown in FIG. In FIG. 3, 14b is a second roughing pump, and 17 is an interface valve. In the second conventional example, the first roughing pump is omitted. The first vacuum chamber 6 is evacuated by the second roughing pump 14 b via the interface valve 17. Therefore, the exhaust speed of the second roughing pump 2b is about 500 to 700 L / min, which is higher than that of the second roughing pump 14 shown in the first conventional technique. In the operating state, the first high vacuum pump 1
0, the second high vacuum pump 11, and the second roughing pump 14b are operating, and the roughing valve 15, the gate valve 16,
The interface valve 17 is open. In the standby state, the first high vacuum pump 10, the second high vacuum pump 11, and the second roughing pump 14b are in the operating state, and the roughing valve 15
Is open, and the gate valve 16 and the interface valve 17 are closed. In the stopped state, the first high vacuum pump 1
0, the second high vacuum pump 11, and the second roughing pump 14b are stopped, and the roughing valve 15, the gate valve 16,
The interface valve 17 is in a closed state. This conventional example is disclosed in, for example, Japanese Patent Application Laid-Open No. 11-162399, in which a single roughing pump is used to reduce the price of the apparatus. The lower the pressure in the first vacuum chamber 6 is, the higher the sensitivity of the apparatus tends to be.
The prior art has the following problems. In the first conventional example, the pumping speed of the first roughing pump 5 is as large as 500 to 700 L / min, so that the apparatus price and running cost (power consumption) increase. On the other hand, in the second conventional example, the device price is lower than in the first conventional example. However, it is necessary to continue operating the second roughing pump 14b even in the standby state. Since this apparatus is normally in a standby state at night or on holidays, the standby state is longer than the operation state, and rarely in the stopped state. Therefore, the running cost (power consumption) becomes larger than in the first conventional example. Since the second roughing pump 14b accounts for more than half of the power consumption of the apparatus during standby, the problem of running cost (power consumption) is large. SUMMARY OF THE INVENTION The present invention has been made to solve the problems of the prior art, and has been made in order to analyze an impurity element in a sample. And a mass analyzer and a detector, a first roughing pump and a first pipe for evacuating a first vacuum chamber sandwiched between the sampling cone and the skimmer cone, and a second in which the ion lens is installed. An inductively coupled plasma mass spectrometer comprising a high vacuum pump for evacuating a vacuum chamber and a third vacuum chamber in which the detector is installed, and a second roughing pump and a second pipe for roughly evacuating the high vacuum pump. In the apparatus, the first pipe and the second pipe are connected by a third pipe, an interface valve is installed in the middle of the third pipe, and in an operating state of performing an analysis, An inductively coupled plasma mass spectrometer characterized in that an interface valve is opened and the first vacuum chamber is evacuated by two of the first roughing pump and the second roughing pump. According to the present invention, while maintaining the pressure in the first vacuum chamber 6 in a preferable state, the first vacuum chamber is connected to the first roughing pump 5.
Vacuum exhaust is performed by two units, b and the second roughing pump 14c. Therefore, the first roughing pump 5b can be smaller than the first conventional example, and the second roughing pump 14c can be smaller than the second conventional example. Embodiments of the present invention will be described based on examples. An embodiment of the present invention will be described with reference to FIG.
In FIG. 1, reference numeral 1 denotes an inductively coupled plasma. A sample (not shown) to be analyzed is atomized by a nebulizer (not shown), introduced into the inductively coupled plasma 1, and ionized. 2 is a sampling cone and 3 is a skimmer cone. The sampling cone 2 and the skimmer cone 3 have pores. Ions generated by the inductively coupled plasma 1 are guided into a vacuum vessel 4 through a sampling cone 2 and a skimmer cone 3. 7 is an ion lens, 8 is a mass analyzer, and 9 is a detector. The ion lens 7 has a function of guiding ions passing through the skimmer cone 3 to a mass analyzer. The ions that have passed through the ion lens 7 are mass-separated by the mass analyzer 8 and detected by the detector 9. This inductively coupled plasma mass spectrometer identifies the impurity element in the sample from the setting of the mass analyzer 8 (that is, the ion mass number) when the ion is detected by the detector 9, and identifies the impurity element from the intensity of the ion detection. Perform quantification. Next, the evacuation will be described. 5b is a first roughing pump, 6 is a first vacuum chamber, 16 is a gate valve, and 18a is a first pipe. A room between the sampling cone 2 and the skimmer cone 3 of the vacuum vessel 4 is called a first vacuum chamber 6, and the first pipe 18 is moved by the first roughing pump 4.
It is evacuated via a. First roughing pump 5b
For example, a rotary pump is used. The pumping speed of the first roughing pump 5b is 300 to 400 L / min. The gate valve 16 is provided between the skimmer cone 3 and the ion lens 7 and can be opened and closed. The gate valve 16 is in an open state when the analysis operation is performed to pass ions through the ion lens 7 and thereafter, and is closed when the analysis operation is stopped. 10 is the first high vacuum pump, 1
1 is a second high vacuum pump. The part of the vacuum vessel 4 where the ion lens 7 is installed is called a second vacuum chamber 12 and the part where the detector 9 is installed is called a third vacuum chamber 13. A first high vacuum pump 10 and a second high vacuum pump 11 are respectively provided. Is evacuated. As the first high vacuum pump 10 and the second high vacuum pump 11, for example, a turbo molecular pump is used. 14
c is a second roughing pump, and 18b is a second pipe. The exhaust side of the first high vacuum pump 10 and the second high vacuum pump 11 is roughly exhausted by the second roughing pump 14c via the second pipe 18b. The pumping speed of the second roughing pump 14c is about 200 to 300 L / min. Reference numeral 15 denotes a roughing valve having a structure that can be opened and closed. Roughing valve 1
Reference numeral 5 is provided between the second vacuum chamber 12 and the third vacuum chamber 13 and the second roughing pump 14, and is in an open state when performing vacuum evacuation and in a closed state when stopping vacuum evacuation. 17b
Is an interface valve, and 18c is a third pipe.
One of the third pipes 18c is connected to the second pipe 18b, and the other is connected to the first pipe 18a. Third pipe 18c
Interface valve 1 that can be opened and closed in the middle
7b is installed. The gas exhausted by the pump is argon gas or sample vapor, and sometimes oxygen, nitrogen,
Helium and ammonia may be added. Next, the state of vacuum evacuation of the apparatus will be described. There are three states of evacuation: an operating state, a standby state, and a stopped state. The operating state is a state in which the inductively coupled plasma 1 is turned on to perform analysis, and the first roughing pump 5b, the first high vacuum pump 10, and the second high vacuum pump 1
1. The second roughing pump 14c is operating, and the roughing valve 15, the gate valve 16, and the interface valve 17b are open. At this time, the first vacuum chamber 6 is evacuated by the first roughing pump 5b and the second roughing pump 14c. The pressure in the first vacuum chamber 6 is about 100 to 200 Pa, the pressure in the second vacuum chamber 12 is about 10 −2 Pa, and the pressure in the third vacuum chamber 13 is about 10 −4 to 3 Pa. . In the standby state, the plasma 1 is turned off, but the second vacuum chamber 12 and the third vacuum chamber 13 are evacuated to a state where the operation state can be easily shifted. At this time, the first high vacuum pump 10, the second high vacuum pump 11, and the second roughing pump 14c are operating, the roughing valve 15 is open, the first roughing pump 5 is stopped, the gate valve 16 and The interface valve 17b is in a closed state. The vacuum pressure in the first vacuum chamber 6 is the atmospheric pressure, and the pressure in the second vacuum chamber 12 and the third vacuum chamber 13 is 10 −4 Pa or less. The stopped state is a state in which the apparatus is stopped, the first roughing pump 5b, the first high vacuum pump 10, the second high vacuum pump 11, and the second roughing pump 14c are stopped, and the roughing valve 15 and the gate are stopped. The valve 16 is closed, and the interface valve 17b may be open or closed. The pressure in the first vacuum chamber 6 is atmospheric pressure. The second vacuum chamber 12 and the third vacuum chamber 13 are isolated from the outside and are depressurized or purged with an inert gas such as argon so that the next evacuation does not take excessive time. Also, since the roughing valve 15 is closed, oil from the second roughing pump 14c (usually a rotary pump using oil) is supplied to the vacuum container 4c.
Prevents backflow inside. As shown in FIG. 4, the first high vacuum pump 1
The 0 and second high vacuum pumps 11 may be evacuated by one high vacuum pump 19. This high vacuum pump is, for example, a type of turbo molecular pump having two ports depending on the compression ratio (referred to as a dual pump). The high compression ratio port exhausts the third vacuum chamber, and the middle compression ratio port exhausts the second vacuum chamber. Evacuate the vacuum chamber. Also in this case, the rough evacuation of the high vacuum pump 19 is performed by the second roughing pump 14c and the third pipe 18c
And the interface valve 17b, and the first vacuum chamber is connected to the first roughing pump 15b and the second roughing pump 1
It is possible to exhaust with two units 4c, and the present invention is effective. According to the present invention, the exhaust of the first vacuum chamber is
Since the first roughing pump and the second roughing pump for rough evacuation of the high vacuum pump are used, the first roughing pump 5b or the second roughing pump 14c is used while ensuring the sensitivity of the apparatus. Can be made smaller than the prior art. Therefore, it is possible to simultaneously reduce the device price and the running cost (power consumption).

[Brief description of the drawings] FIG. 1 shows a configuration of the present invention. FIG. 2 is a diagram showing a first conventional example. FIG. 3 is a diagram showing a second conventional example. FIG. 4 is a diagram for supplementary explanation of the present invention. [Explanation of symbols] 1. Inductively coupled plasma 2. Sampling cone 3. Skimmer cone 4: Vacuum container 5, 5b ... first roughing pump 6 ... first vacuum chamber 7 ... ion lens 8 Mass spectrometer 9 Detector 10 ... first high vacuum pump 11 ... second high vacuum pump 12 ... second vacuum chamber 13: Third vacuum chamber 14, 14b, 14c ... second roughing pump 15… Roughing valve 16 ... Gate valve 17, 17b ... Interface valve 18a, 18b, 18c ... piping 19 ... High vacuum pump

Claims (1)

Claims: 1. A sampling cone, a skimmer cone, an ion lens, a mass analyzer, a detector, and a sampling cone and a skimmer cone for analyzing an impurity element in a sample. A first roughing pump and a first pipe for evacuating the first vacuum chamber, and a high vacuum for evacuating a second vacuum chamber in which the ion lens is installed and a third vacuum chamber in which the detector is installed. In an inductively coupled plasma mass spectrometer equipped with a pump and a second roughing pump and a second pipe for performing rough evacuation of the high vacuum pump, a third pipe is provided between the first pipe and the second pipe. Connected, an interface valve is installed in the middle of the third pipe, and in an operating state for performing analysis, the interface valve is opened to exhaust the first vacuum chamber to the second Inductively coupled plasma mass spectrometer, characterized in that made in the two roughing pump and the second roughing pump.