JPH0455752A - Quadrupole mass filter - Google Patents

Abstract

PURPOSE:To prevent the change of the passing characteristic of ions in a mass filter by providing a temperature detecting end in the vicinity of rods, and regulating a voltage which is applied on the rods based on the detected temperature signal from the detecting end. CONSTITUTION:The preset mass-number signal from a CPU 22 is sent into a controller driving circuit 23. The circuit 23 receives the command signal and applies a necessary voltages to rods 16a - 16d of a quadrupole mass filter 16. The temperature of the rods 16a - 16d of the mass filter 16 and the vicinity of the rods is detected with a temperature detecting end 21. The detected temperature signal is sent into a temperature compensating part 24. The temperature correcting value which is obtained by the operation is sent into the circuit 23. As a result, the circuit 23 applies the correcting voltage to the rods 16a - 16d. The regulating operation such as this is repeated. The deviation of the mass number caused by the temperature rising in the rods 16a - 16d of the mass filter 16 is automatically corrected with an electric circuit, i.e. the hardware.

Description

Detailed Description of the Invention Industrial Field of Application 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 the sample. High-frequency Xi-coupled plasma analysis equipment (rlc
This invention relates to a quadrupole mass filter that is attached to a P-MSJ (P-MSJ) and allows ions excited by the plasma to pass therethrough.

<Prior art> Quadrupole mass filters are incorporated into many devices and used as a mechanism for passing ions having a specific mass ratio, but here, they are incorporated and used as a part of ICP-MS. Let's explain the case where it is.

Figure 2 shows I CP-MS17) - boat fishing 4111Is.
, is an explanatory diagram. In this figure, argon gas is supplied from an argon gas supply source 3 to an outer chamber 1b and an outermost chamber 1C of a plasma torch 1 via a gas regulator 2, and an inner chamber 1a
The solid sample in the sample introduction device wI4 is vaporized by the laser beam irradiated from the laser beam 195, and then introduced by argon gas, which is a carrier gas. If the sample is a liquid, the sample introducing device 14 and laser light source 5 shown in FIG. 2 are removed, and a nebulizer is installed to atomize the introduced liquid sample and supply it to W1a of the plasma torch 1. 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 frequency power source 10, and a high frequency magnetic field (not shown) is formed around the coil 6. In this state, when electrons or ions are implanted in the argon gas in the vicinity of the ^-frequency magnetic field, a high-frequency inductively coupled plasma 7 is instantaneously generated by the action of the a*-frequency wt magnetic field.

In addition, the inside of the forechamber body 11 sandwiched between the nozzle 8 and the skimmer 9 is heated by a vacuum pump 12, for example, by ITo.
It is attracted to rr. Furthermore, center chamber 1
Ion lenses 14a and 14b are provided in the center chamber 13, and the inside of the center chamber 13 is sucked to, for example, 10''' Torr by the seventh oil diffusion pump 15, and a mass filter (for example, a quadrupole mass filter) 16
The interior of the rear chamber 17 containing the oil is suctioned to, for example, 10-'Torr by the second oil diffusion pump 18. In this state, the sample vaporized as described above is introduced into the high-frequency LT coupled plasma, and ionization and light emission are performed. The ions in the plasma 7 pass through the nozzle 8 and the skimmer 9, and then enter the ion lenses 14a, 14b (
(double quadrupole lens) and is focused into the quadrupole mass filter 16. Of the ions entering the quadrupole mass filter 16, only ions of the desired quality INN pass through the quadrupole mass filter and enter the secondary electron multiplier 1.
9 to be detected. This detection signal is transmitted to the signal processing section 2.
The analysis value of the element to be measured in the sample can be obtained by sending the data to 0 and calculating and processing it.

<Problems to be Solved by the Invention> However, when measuring high quality ions using a quadrupole mass filter, a large amount of power is required to generate a large voltage in the rod of the quadrupole mass filter 16. It is necessary to supply Therefore, when high-mass ions are measured for a long time, the temperature of the rods of the quadrupole mass filter 16 increases and the four rods become engraved. As a result, the characteristics of the quadrupole mass filter change, and the ions that actually pass through the quadrupole mass filter and the set ions become different. Therefore, particularly when measuring ions of Yoshiyuki Hatake, there is a drawback that the peak position of the ions fluctuates, making accurate measurement of the ions difficult.

Also,[! ! The rods of the 1ffi polar mass filter 16 operate at high altitudes in the air, and the volume of the parts in contact to hold these rods is small. Therefore, the heat dissipation is poor and the temperature is likely to rise. Therefore, when the rod aim of the quadrupole mass filter 16 rises, the inscribed radius between the rods increases, and the capacity of ions passing through the quadrupole mass filter 16 changes. As a result of this change in ion transmission characteristics, there is also the drawback that accurate measurement of ions becomes difficult.

The present invention has been made in view of this situation, and its object is to provide a quadrupole mass filter in which the ion passage characteristics of the quadrupole mass filter do not change.

<Means for Solving the Problems> The present invention provides a quadrupole mass filter used in a frequency inductively coupled plasma analyzer, etc., in which a temperature detection end is provided near the rod, and temperature detection from the detection end is performed. The purpose is to adjust the voltage applied to the rod based on the signal.

<Effect> The invention works as follows.

That is, the CPU's set mass number signal is sent to the controller/drive circuit of the mass filter, and the controller/drive circuit applies the necessary voltage to the rod of the quadrupole mass filter. Also, once the temperature of the quadrupole mass filter rod and surrounding area is detected by the detection end, a! The correction value is sent to the degree compensator, a correction value is calculated once, and then sent to the controller/drive circuit. As a result, the controller drive circuit corrects the voltage applied to the rod and applies it to the rod of the quadrupole mass filter. This adjustment operation is repeated to adjust the rod a of the picture electrode mass filter.
The deviation in the maximum number of responsibilities due to the i degree increase will be automatically corrected by hardware.

<Example> Hereinafter, the present invention will be described in detail with reference to the drawings. 1st
The figure is an explanatory diagram of the main part configuration of the embodiment of the present invention, and in the figure, 16
a to 16d are rods of quadrupole mass filters, 21 is a temperature detection end such as a thermistor, 22 is a CPU consisting of, for example, a central processing unit of a microcomputer, and 23 is a C
A mass filter controller/drive circuit 24 receives a set mass number signal from the PU 22 and applies a necessary voltage to the rods 16a to 16d of the quadrupole mass filter 16; This is a temperature compensation section that calculates a temperature correction value by calculation and sends it to the controller/drive circuit 23. Note that the CPU 22 may be a switch or a voltage power supply depending on the system configuration.

In an embodiment of the present invention having such a main configuration,
A set mass number signal is sent from the CPU 22 to the controller/drive circuit 23 of the mass filter, and the controller/drive circuit 23 of the mass filter
The drive circuit 23 receives this command signal and applies a necessary voltage to the rods 16a to 16d of the quadrupole mass filter 16. In addition, the rods 16a of the quadrupole mass filter 16
16d and the temperature around the rod is detected by the temperature detection end 21, and the temperature detection signal is sent to the temperature compensator 24, where a temperature correction value is determined by calculation, and then sent to the controller/drive circuit 23. As a result, the controller
The drive circuit 23 corrects the voltages applied to the rods 16a to 16d and applies the corrected voltages to the rods 16a to 16d of the quadrupole mass filter 16. Such adjustment operations are repeated to adjust the rods 16a to 16a of the quadrupole mass filter 16.
The difference in mass number due to the temperature rise of 16d causes the electric circuit (
In other words, it is automatically corrected by hardware).

The operations of other parts of the embodiment of the present invention are the same as those of the prior art example described in detail with reference to FIG. 2, and therefore redundant explanation will be omitted here. Furthermore, the present invention is not limited to the above-described embodiments, and can be modified in various ways. For example, the temperature compensator 24 may be processed by computer software.

<Effects of the Invention> As explained in detail above, the present invention constantly monitors the temperature of the rod portion of the quadrupole mass filter and corrects the amount of change in alignment (dimensions) due to yArII. The voltage applied to the rod of the quadrupole mass filter is W! It was configured to perform lIm.

For this reason, even when the temperature of the rod portion of the quadrupole mass filter increases, such as when measuring ions with a mass number of ^^ for a long time, the mass number of ions passing through the quadrupole mass filter does not change. Therefore, according to the present invention, a quadrupole mass filter is realized in which the mass number of ions passing through the quadrupole mass filter does not change even if the temperature of the quadrupole mass filter changes.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the main part configuration of an embodiment of the present invention, and FIG. 2 is a high-frequency induced plasma 111 analysis i! FIG. 1...Plasma torch, 2...Flow a
u+ m part, 3...Argon gas supply source, 4.
...Sample cell, 6...High frequency cod conduction coil, 7...High frequency inductively coupled plasma, 8...
・Nozzle, 9... Skimmer, 16...
Mass filter, 168-16d... Quadrupole mass filter rod, 17... Rear chamber, 20.
... Signal processing section, 21 ... Temperature detection end, 22.
...CPU, 23...Quadrupole mass filter controller/drive circuit, 24...Temperature compensation section

Claims (1)

[Claims] In a quadrupole mass filter used in a high-frequency inductively coupled plasma analyzer, etc., a temperature detection end is provided near a rod, and a temperature detection signal is applied to the rod based on a temperature detection signal from the detection end. A quadrupole mass filter characterized by adjusting the voltage applied to the quadrupole.