JP3148264B2 - Quadrupole mass spectrometer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a quadrupole mass spectrometer having a quadrupole rod used in a high frequency inductively coupled plasma analyzer and constituting a quadrupole mass filter. The present invention relates to a quadrupole mass spectrometer in which high resolution can be obtained in a low mass region by eliminating.

[0002]

2. Description of the Related Art A high-frequency inductively coupled plasma analyzer using a quadrupole mass spectrometer generally has an argon gas supplied from an argon gas supply source via a gas controller to an outer chamber and an outermost chamber of a plasma torch. The sample is supplied, and a sample (analysis target) is carried into the inner chamber from the sample introduction device. Also,
A high-frequency current flows through a high-frequency induction coil wound around the plasma torch, and a high-frequency magnetic field is formed around the coil. In this state, when electrons or ions are implanted in the argon gas in the vicinity of the high-frequency magnetic field, a high-frequency inductively coupled plasma is instantaneously generated by the action of the high-frequency magnetic field.

Further, the inside of the fore-chamber body sandwiched between the nozzle and the skimmer is sucked by a vacuum pump. An extraction electrode, an aperture lens, a quadrupole lens, an aperture, and an entrance lens are provided in the center chamber, and the inside of the center chamber is a first oil diffusion pump. It is sucked argument by the,
Rear chamber housing the quadrupole mass filter - in is Aspirate by the second oil diffusion pump.

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 are converged after passing through a nozzle or a skimmer, between extraction electrodes and an ion lens system, and are introduced into a quadrupole mass filter.

[0005] Among the ions entering the quadrupole mass filter in this way, only the ions having the desired mass-to-charge ratio pass through the quadrupole mass filter and are guided to the secondary electron multiplier to be detected. This detection signal is sent to the signal processing unit for calculation and
By performing the processing, an analysis value of the element to be measured in the sample is obtained. Further, in the quadrupole rod constituting the quadrupole mass filter, a mass spectrum can be obtained by utilizing a stable region called a first region.

[0006]

However, in the above conventional example, however, the resolution is M / (ΔM) = 2M, that is, 0.
Only about 5 was obtained, and it was difficult to further increase the resolution. Although it is known that the resolution can be greatly improved if a mass spectrum is obtained by using a region called a second region in another stable region of the quadrupole, uranium ions having a mass number of 238 ( That is,
²³⁸ U), ions having a mass number of 28.7 or less (eg, helium, lithium, beryllium, boron, carbon, nitrogen, oxygen, fluorine, niobium, magnesium,
Aluminum and silicon ions).

The present invention has been made in view of such circumstances, and an object thereof is to make it possible to accurately measure low mass ions without being disturbed by high mass ions coexisting in a sample. It is to provide a quadrupole mass spectrometer.

[0008]

SUMMARY OF THE INVENTION The present invention relates to an ion source .
Pass the ions introduced through the quadrupole mass filter
In a quadrupole mass spectrometer for analyzing the components of the ions,
The quadrupole mass filter is provided in two stages in series, and
1) Connect the quadrupole mass filter to the first region filter.
Luta uses second (second) quadrupole mass filter in second stage
This problem has been solved by forming the filter as a version filter .

[0009]

The present invention operates as follows. That is, the ions guided from the ion source 1 are converged by the first ion lens 2, passed through the first quadrupole mass filter 3, and then converged by the second ion lens 4, and then second quadrupole. Pass through the polar mass filter 5. First quadrupole mass filter 3
, U of mass number 238 is removed from the spectrum, so that sodium ions of mass number 23 can be measured accurately without being disturbed by such uranium ions.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings. FIG. 1 is an explanatory view of a main part configuration of an embodiment of the present invention. In the drawing, reference numeral 1 denotes an ion source composed of a high-frequency inductively coupled plasma or an electronic ion source;
4, a second ion lens, 5 a second quadrupole mass filter, 6 a a quadrupole mass filter power source for fast storage, 6 b a quadrupole mass filter for second The filter power supply 7 is a detector composed of a secondary electron multiplier.

FIG. 2 is a view showing an ion passage area of the quadrupole mass filter. In FIG. 2, (1) shows the ion passage area of the first quadrupole mass filter, and (2) shows the ion passage area of the second quadrupole mass filter. 3 shows an ion passage area of a quadrupole mass filter. Also,
In FIG. 2, the horizontal axis represents the mass number (amu),
A is a part of the band-pass filter shown in the low mass region,
B indicates a portion having a mass number of 238, C indicates a narrow bandpass region near a mass number of 23, and D indicates a portion of the high-pass filter shown in a high mass region.

In the embodiment of the present invention having such a main part configuration, a driving voltage is applied to the first quadrupole mass filter 3 from the power supply 6a for the quadrupole mass filter for fast positioning. the quadrupole mass filter 5 second Li - driving voltage from John for quadrupole mass filter power supply 6b is applied. In this state, the ions guided from the ion source 1 are converged by the first ion lens 2 and then pass through the first quadrupole mass filter 3 to obtain a spectrum in a mass range as shown in FIG. give. That is, the spectrum is given such that the part A of the bandpass filter appearing in the low mass region appears.

On the other hand, when the first quadrupole mass filter 3 is removed, the ions guided from the ion source 1 are converged by the first and second ion lenses 2 and 4 and then converged by the second quadrupole mass filter 3. 5 passes through, giving the spectrum shown in FIG. 2 (2). That is, the spectrum of the fast mass on the high mass side serving as a high-pass filter and the spectrum of the second mass on the low mass side serving as a band-pass filter overlap each other. Therefore, the mass number 238
When measuring a sodium ion having a mass number of 23 by using a sample containing uranium ions having a mass number of 23 and a sodium ion having a mass number of 23 as an analysis target, as described above,
Of uranium ion becomes a measurement interference component.

However, after being converged by the first ion lens 2, it passes through the first quadrupole mass filter 3, and then converged by the second ion lens 4, and then passes through the second quadrupole mass filter 5. Then, the uranium ions having the mass number of 238 are removed by passing through the first quadrupole mass filter 3, so that the sodium ions having the mass number of 23 can be accurately measured without being hindered by the uranium ions. . The present invention is not limited to the above-described embodiment, and various modifications are possible. For example, a magnetic field type filter, a Wien filter, or the like may be used as the first quadrupole mass filter 3.

[0015]

According to the present invention as described in detail above, in a quadrupole mass spectrometer, an ion source, a first ion lens for converging ions guided from the ion source, a first ion lens, A quadrupole mass filter, a second ion lens that converges ions passing through the first quadrupole mass filter, and a second quadrupole mass filter, wherein the ions converged by the first ion lens are provided. After passing through the first quadrupole mass filter, the light was converged by the second ion lens and then passed through the second quadrupole mass filter. Therefore, a quadrupole mass spectrometer capable of accurately measuring low mass ions without being disturbed by high mass ions coexisting in the sample is realized.

[Brief description of the drawings]

FIG. 1 is a main part block circuit diagram of an embodiment of the present invention.

FIG. 2 is a characteristic curve diagram for explaining the operation of the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ion source 2, 4 Ion lens 3, 5 Quadrupole mass filter 6a, 6b Quadrupole mass filter power supply 7 Computer for detection

Claims (1)

(57) [Claims] 1. The method according to claim 1, wherein the ions derived from the ion source are converted to a quadrupole mass.
Quadruple passing through a filter and analyzing the components of the ions
In a polar mass spectrometer, the quadrupole mass filters are connected in series.
Two stages, the first quadrupole mass filter
John filter, subsequent quadrupole mass filter
A quadrupole mass spectrometer characterized as being configured as a drainage filter