JPH04137449A - High-frequency inductive coupling plasma mass spectrometer - Google Patents

Abstract

PURPOSE:To reduce the length of ion passage as the amount of the thickness of a gate valve so as to improve the ion transmissivity, and to improve the analysis sensitivity, by contracting a trunk to position an aperture lens to the aperture of the gate valve, while opening the gate valve, when the analysis is carried out. CONSTITUTION:When the analysis is carried out, a gate valve 21 is opened, and a center chamber 13 and a fore chamber 11 are engaged through the gate valve 21. When the device is pushed from the left side of a signal processer 20 manually, pneumatically, or by an automatical operation such as an electromotive operation under such a condition, a trunk 22 is contracted. And following the contraction of the trunk 22, ion lenses 14b to 14e, a quadrupole mass filter 16, and a photomultiplier tube 19 are moved to the right integrally, and the aperture lens 14b comes to position at the aperture of the gate valve 21. As a result, the distance between a pullout electrode 14a and the aperture lens 14b is shortened remarkably. Consequently, the ion transmissivity is improved, and the analysis sensitivity is also improved.

Description

Detailed Description of the Invention <Industrial Application Field> The present invention supplies high-frequency energy to a high-frequency induction coil to form a high-frequency magnetic field to generate high-frequency inductively coupled plasma, and utilizes the plasma to generate a high-frequency inductively coupled plasma in a sample. A radio frequency inductively coupled plasma mass spectrometer (rIcP-
For more information on ion lenses (referred to as MSJ),
ICPMS that improves analysis sensitivity by allowing the quadruple mass filter, photomultiplier tube, etc. to be moved as one unit.
Regarding.

<Prior Art> FIG. 3 is an explanatory diagram of the configuration of a conventional example of ICP-MS. In this figure, the outer chamber 1b and the outermost chamber 1 of the plasma torch 1
Argon gas is supplied from an argon gas supply source 3 to the chamber 1a via a gas regulator 2, and a sample introduction device 4 is supplied to the inner chamber 1a.
After the solid sample inside is vaporized by laser light emitted from a laser light source 5, it is carried in using argon gas as a carrier gas. If the sample is a liquid, the sample introduction device ff4 and the laser light source 5 shown in FIG. Also, the sample is more likely to be a liquid than a solid.

Further, a high frequency current is passed through a high frequency induction coil 6 wound around the plasma torch 1 by a high frequency power supply 10, and a high frequency magnetic field (not shown) is formed around the coil 6. When electrons or ions are planted in the argon gas in the vicinity of the high frequency magnetic field in this state, high frequency inductively coupled plasma 7 is instantaneously generated by the action of the high frequency magnetic field.

Further, the inside of the forechamber main body 11 sandwiched between the nozzle 8 and the skimmer 9 is heated by a vacuum pump 12, for example, by an I.T.
It is attracted to o r r. Further, an aperture lens 14b, a quadruple diameter lens 14c, and an aperture 14d are provided in the center chamber 13, and the inside of the center chamber 13 is sucked to, for example, 10-' Torr by a first oil diffusion pump 15. , entrance lens 14e and octupole mass filter 1
The interior of the rear chamber 17 housing the oil pump 6 is suctioned to, for example, 10-'Torr by the second oil diffusion pump 18. Furthermore, behind the skimmer 9 there is an extraction electrode 14a.

In this state, the sample vaporized as described above is introduced into the high-frequency inductively coupled plasma, and ionization and light emission are performed. The ions in the plasma 7 are removed by a nozzle 8 or a skimmer 9.
After passing through the extraction electrodes 14a and between the ion lens systems 4b to 14e, the light is focused and introduced into the octupole mass filter 16. Of the ions entering the octupole mass filter 16, only ions with the desired mass-to-charge ratio pass through and are guided to the primary electron multiplier tube 19 where they are detected.The detection signal is sent to the signal processing unit 20 for calculation. - Through processing, the analysis value of the element to be measured in the sample can be determined.

On the other hand, 21 is a gate valve whose housing is made of metal and whose potential is kept at ground potential like the chambers 11, 13, and 17.

Further, the gate valve 21 is provided because of the following necessity. That is, the mass spectrometer part of ICP-MS and the ion lens systems 14b to 14e are placed in a high vacuum (10'' to 1
It is necessary to operate the analyzer under a vacuum of 0'torr (0'torr or less), and the vacuum pump must be operated even when not performing analysis to avoid the time loss associated with releasing and starting up the vacuum. It is necessary to maintain a high vacuum in the vacuum chamber. Therefore, it is necessary to shut off the forechamber 11 and the center chamber 13 during non-analysis (for example, during standby), and to communicate the forechamber 11 and the center chamber 13 during analysis. <Problem to be solved by the invention> However, in the above conventional example, the gate valve 21
As a result, the ion trajectory length becomes longer by the thickness of the gate valve 21, and the distance between the extraction electrode 14a and the ion lens systems 14b to 14e becomes longer. For this reason, the ion beam cannot be kept narrow and has a strong tendency to diverge, resulting in a decrease in ion transmittance and ultimately a decrease in sensitivity as an ICP-MS.

Furthermore, once the ion beam diverges, even if an ion lens tries to refocus it, the number of ions entering the ion lens will greatly decrease.
There was also a drawback that the overall ion transmission efficiency was greatly reduced.

The present invention was made in view of the above circumstances, and its object is to improve the analytical sensitivity of ICP-MS by shortening the ion trajectory length by the thickness of the gate valve and improving the ion transmittance. It is about providing.

Means for Solving the Problems> The present invention provides a gate valve provided between a forechamber and a center chamber, and when the gate valve is closed, a pull-out pole and an aperture lens are placed on the opposite side across the gate valve. ICP-MS installed in
A body part made of an elastic member and connecting the rear chamber and the signal processing section is provided, and when not in analysis, the gate valve closes to cut off communication between the center chamber and the forechamber, and the body part extends. The aperture lens is located at a distance from the gate valve, and during analysis, the gate valve is opened and the body is contracted so that the aperture lens is located at the opening of the gate valve.

<Example> Hereinafter, the present invention will be described in detail using the drawings. 1st
2 and 2 are configuration explanatory diagrams of an embodiment of the present invention. In the drawings, the same symbols as in FIG. 3 are used with the same meanings, and repeated explanations here will be omitted. In addition, 22 is an elastic member such as a stainless steel bellows, and the rear chamber 1
7 and the signal processing section 20.

In an embodiment of the present invention having such a main configuration,
During so-called standby before starting analysis, the gate valve 21
is closed as shown by the broken line in FIG. 1, and the gate valve 21 blocks communication between the center chamber 13 and the forechamber 11. In this state, no voltage is applied to the ion lens systems 1.4a to 14e, and the inside of the forechamber 17 in the center chamber 13 is kept in a vacuum, or the rotary pump 12 is turned off and the inside of the forechamber 11 is not applied. The vacuum is released (ie, no vacuum is created). For this reason, the nozzle 8, skimmer 9. Alternatively, maintenance work such as cleaning can be easily performed by removing the lead-out power supply [i 14 a].

On the other hand, during analysis, the gate valve 21 is open as shown by the broken line in FIG. 1, and the center chamber 13 and the forechamber 11 communicate with each other via the gate valve 21. In this state, when the signal processing section 20 is pressed from the left side by manual operation or automatic operation using pneumatic pressure or electric power, the body section 22 contracts and becomes as shown in FIG. That is, as the body portion 22 shrinks, the ion lenses 14b to 14e, the quadrupole mass filter 16. The photomultiplier tube 19 is integrally moved rightward on the paper surface of FIG. 2, and the aperture lens 14b is positioned at the opening of the gate valve 21. Therefore, the distance between the extraction electrode 14a and the aperture lens 14b is significantly shorter (for example, about 1/3) than the distance between the extraction electrode 14a and the aperture lens 14b in the conventional example shown in FIG. Therefore, even if the ion beam that has passed through the extraction t-pole 14a diverges, it can be narrowed down again by the aperture lens 14b. For this reason, compared to the conventional example in which the number of ions entering the ion lens is greatly reduced even if the ion beam diverges due to a large distance between the extraction electrode 14a and the aperture lens 14b and then is refocused, the number of ions entering the ion lens is greatly reduced. As a result, the ion transmission efficiency of the entire ion lens system 14b to 14e is greatly improved.

The operation of other parts of the embodiment of the present invention is the same as that of the conventional example described in detail with reference to FIG. Various modifications are possible without being limited to this embodiment.

<Effects of the Invention> As explained in detail above, the present invention provides an ICPMS in which the gate valve is closed during non-analysis to cut off communication between the center chamber and the forechamber, and the aperture lens is moved to a position away from the gate valve. During analysis, a drive voltage is applied to the gate valve to open it and the aperture lens is positioned at the opening of the gate valve, so even if the ion beam that has passed through the extraction electrode diverges, the aperture You will be able to narrow down the aperture again with your lens.

Due to this slant, the distance between the extraction electrode and the aperture lens during analysis is large, and the number of ions entering the ion lens is greatly reduced even if the ion beam diverges and then refocuses. Ion loss is drastically reduced, and as a result, the ion transmission efficiency of the entire ion lens system is greatly improved, ultimately realizing ICP-MS with improved ion transmission and analysis sensitivity.

Therefore, according to the present invention, the ICP-MS has improved analysis sensitivity by shortening the ion trajectory length by the thickness of the gate valve and improving ion transmission.

[Brief explanation of the drawing]

FIGS. 1 and 2 are diagrams illustrating the configuration of an embodiment of the present invention, and FIG. 3 is a diagram illustrating the configuration of main parts of a conventional example. 1... Plasma torch, 6... High frequency induction coil 7... High frequency inductively coupled plasma, 8.
...Nozzle 9...Skimmer, 11...
... Fore chamber 13 ... Center chamber 14a ... Extraction electrode, 14b to 14e.
...Ion lens, 16...Quadrupole mass filter, 17...One rear chamber...Detector, 20...Signal processing unit-21 ...Gate valve, 22...Body part

Claims (1)

[Claims] In a high-frequency inductively coupled plasma mass spectrometer, a gate valve is provided between a forechamber and a center chamber, and when the gate valve is closed, an extraction electrode and an aperture lens are provided on opposite sides of the gate valve. The gate valve is closed to cut off communication between the center chamber and the forechamber and the body extends to connect the aperture when not in analysis. The lens is located at a distance from the gate valve, and during analysis, a driving voltage is applied to the gate valve to open it, and the body portion contracts so that the aperture lens is located at the opening of the gate valve. A high-frequency inductively coupled plasma mass spectrometer featuring: