JPS59125057A - Quadruple pole type mass spectrographic device - Google Patents

Abstract

PURPOSE:To enable precision determination of the mass number of a sample to be measured by providing means for setting two kinds of DC voltages to be impressed on a quadruple pole voltage part and means for measuring the value of the ratio between two kinds of said DC voltages. CONSTITUTION:The output voltages from the 1st and 2nd potentiometers 24a, 24b are respectively preliminarily set at approximately the voltage values corresponding to the ion peak positions of both samples Mu and Mr. The sample Mu is introduced from a gas chromatograph 1 through a molecule separator 2 into an ionizing chamber 5 and the standard sample Mr is introduced from a standard sample introducing part 4 into the chamber 5, respectively, by which the samples are ionized. The two ionized samples Mr, Mu are introduced into a quadruple pole electrode part 6. The output voltages set substantially with the 1st and 2nd potentiometers are superposed thereon with the sweep voltage and are impressed on the part 6. The ion of the sample Mr and the sample Mu past the part 6 are detected with a detector 7 and are converted to ion signals which are amplified with an amplifier 8. The ratio of the output voltages of the potentiometers 24a, 24b is measured in an arithmetic part 15 for the voltage ratio.

Description

[Detailed description of the invention] The present invention relates to a quadrupole mass spectrometer.

In general, a gas chromatograph, a mass spectrometer N, which combines a gas chromatograph GC and a mass spectrometer MS, /
MS is widely employed because it can separate a multicomponent mixture into components and identify each component.

By the way, there are two types of mass spectrometers that can be applied to such /MS, one is a magnetic field type and the other is a quadrupole type.In particular, the quadrupole type does not use a heavy magnet and has a simple structure. It has advantages over the magnetic field type in that it is simple, small and lightweight, and has excellent high-speed scanning properties.

However, in conventional quadrupole mass spectrometers, the precision of machining and assembly of the quadrupole electrodes is a limiting factor for resolution. In other words, in order to achieve high resolution and high sensitivity, the shape of the quadrupole electrode must be formed into a hyperbolic cross section, and the straightness of each electrode and the relationship between the placement positions must be adjusted with high precision. need to be kept.

This is extremely difficult at the current state of technology, and the processing is also complicated. Therefore, at present, the mass resolution of the magnetic field type is on the order of tens of thousands, while the mass resolution of the quadrupole type is on the order of several thousand. For this reason, quadruple separation mass spectrometers are mainly used for separation measurements of integer mass numbers.

The present invention has been made in view of the above problems, and includes:
A quadrupole system is provided with means for setting two types of DC voltages to be applied to the quadrupole electrodes and a means for measuring the ratio of the two types of DC voltages applied, thereby making it possible to measure the treetop density mass number. The purpose of the present invention is to provide a heavy separation mass spectrometer.

The basic idea of the present invention is based on the following principles. In other words, the quality of 41 by the exfoliating mass spectrometer +14
The relational expression for separation is given by the following equation.

lvl:=K, ・Vrf/f2−ri
il) Here, M: mass number of a singly charged ion, Vrf: radio frequency voltage 1ro° radius of the electric field formed by the quadrupole electrode.

f: High frequency frequency, ni: Proportionality constant DC voltage Udc for the quadrupole electrode 9 High frequency voltage VrfO
Since a superimposed voltage with a constant ratio is applied, the above (1)
The formula can be written as follows.

M: K2・Udc/f2-r:
+21'+1. In the +2i formula, the high frequency frequency f and the radius r of the electric field. is a constant determined by the device, so fll,
The +21 formula can be further expressed as follows.

M = K7 ・Vrf = K; -Udc
i3) Here, Kγ is an example constant. That is, in a quadruple horizontal mass spectrometer, the number of selectively detected ion masses M is determined by the voltage applied to the quadrupole electrodes (V
rf or Ud,c), which results in mass scanning.

Now, if we use a standard sample with a known accurate mass number Mr and selectively detect the ion, then from equation (3), Mr = K
', ・Udc (r)' f4) If a sample ion with unknown mass number Mu is selectively detected, then Mu = K4 ・Udc (D)
(5)+41. Accordingly, from the +51 formula, Mu-san”Ko 1Mr [6) Udc
(r) In other words, if we accurately measure the ratio between the voltage Uac (TJ) when detecting an ion with an unknown mass number and the voltage Udc (r) when detecting an ion with a known mass number from equation (6), By multiplying this by the known accurate mass number Mr, the required accurate mass number of the measurement sample can be determined.

The mass resolution required for this measurement may be R&lI1, Mu R--> or (M; 4.It is not a limiting factor when determining the required mass number, and the required mass number can be determined with high accuracy.
The Rukoto.

Next, a specific configuration of the present invention will be described with reference to FIGS. 1 and 2 in terms of embodiments.

FIG. 1 is a block diagram of a gas chromatograph/mass spectrometer equipped with a quadruple horizontal mass spectrometer according to the present invention. In the figure, 1 is a gas chromatograph, 2 is a molecular separator, and 3 is a gas chromatograph.
This is a quadruple horizontal mass spectrometer of the present invention. 4 A standard sample introduction section into which a standard sample with a known mass number is introduced, 5 an ionization chamber, 6 a quadrupole electrode section having a quadrupole electrode, 7 an ion detector, and 8 a detector 7. This is an amplifier that amplifies the signal. Reference numerals 9a and 9b denote first and second signal measurement units, and the signal measurement unit 9a measures signals of unknown mass numbers among the ion signals from the detector 7. Dota,
The second signal measuring section 9b measures ion signals from a standard sample with a known mass number. Reference numeral 10 denotes a display section such as an ononroscope for displaying the signals measured by the first and second signal measuring sections 9a and 9b. 12 is a quadrupole electrode section 6
This is a power supply section that applies a DC/high frequency voltage to the quadruple electrode section 6 , and the output of this power supply section 12 to the quadruple electrode section 6 is controlled by the travel control section 14 . Normally, based on the scan signal from the scan control unit 14, the power supply unit 12 changes the high frequency voltage while keeping the ratio between the DC voltage and the high frequency voltage constant, performs mass scanning, and measures the mass spectrum. It is done. 1
Reference numeral 6 denotes a switch control unit, which switches the first and second switches Sl+S at high speed in synchronization. 18
is a sweep signal generator, which operates the on-roscope 1 in synchronization with the switch switching signal output from the switch control section 16.
0 and a sweep voltage to the power supply unit 12. 22
2 is a stabilized reference voltage power source, and 24a and 24b are highly accurate first and second potentiometers that are means for setting two types of DC voltages to the quadrupole electrode section 6. Also 26
2 is a voltage ratio calculating section which is a means for measuring the values of I and H of the two types of DC voltages output from the potentiometers 24a and 241).

Next, a procedure for accurately measuring the mass number of an unknown sample in the above configuration will be explained.

In the step before starting the measurement of the number of dense particles (I6), it is necessary to
A purchase scan has been performed on a sample to be measured Mu whose number is unknown, and the ion peak positions of both samples Mr and Mu have been measured. Therefore, before starting the measurement of the accurate mass number, the output voltages of the first and second potentiometers 24a, 241) are adjusted in advance for both samples Mu.

Each voltage value is set approximately corresponding to the ion peak position of Mr. Next, the sample to be measured Mu is introduced from the gas chromatograph 1 through the molecular separator 2 to the ionization chamber 5, and the standard sample Mr is introduced from the standard sample introduction section 4 to the ionization chamber 5, where they are ionized. and both ionized samples p, M r .

Mui is connected to the quadrupole electrode section 6.Meanwhile, in parallel with this, the switch control section 16 outputs a switching signal to the first and second switches S,...
S2 is switched at high speed. By switching this 2.2 switch S2, the two glaze DC voltages set by the button meter 24a, 24b are alternately output to the quadrupole electrode section 5 via the power supply section 12 17. At the same time, the sweep signal generator 18 controls the switch control i! The sweep voltage j pressure is outputted to the quadrupole electrode section 6 via the display section 10 and the power supply section 12 in synchronization with the switch switching signal from the 141 section 16. Therefore, the sweep voltage is applied to the quadrupole electrode section 6 in a manner that is substantially superimposed on the output voltage set by the first and second potentiometers. Standard sample M passed through the quadrupole electrode section 6
The ions of r and the sample to be measured Mu are detected by a detector 7, converted into an ion signal, and amplified by an amplifier 8. By switching the first switch S1, the ion signal of the sample to be measured Mu is measured by the first signal measuring section 9a, and the ion signal of the standard sample MrK is measured by the second signal measuring section 9b, both of which are displayed on the display section 1o. is output to.

Since the sweep signal from the sweep signal generator 18 has already been output to the display unit 10, the ion peak of the sample to be measured Mu and the ion peak of the standard sample Mr are displayed together on the screen of the display unit 100. . Therefore, the ion beaks of the sample to be measured Mu and the standard sample Mr displayed on the display unit 10 are adjusted using the buttons/ometers 24a and 24btJA6 so that their peak positions coincide as shown in FIG. The ratio of the output voltages of the potentiometers 24a and 24b is measured by the voltage ratio calculating section 15. What is the value of this voltage ratio in equation (6)? After measuring the pressure ratio, the mass number of the sample to be measured Mu can be determined with high precision by multiplying this value by the accurate mass number of the standard sample Mr.

According to the present invention, as in ``Me-2'', means for setting two types of DC voltages to be applied to the quadrupole electrode section, and a setting for measuring the ratio value of these two types of DC voltages are provided. Therefore, b
Excellent practical effects can be obtained.

[Brief explanation of drawings]

The drawings show embodiments of the present invention, and FIG. 1 is a block diagram of a gas chromatograph mass spectrometer equipped with a quadrupole mass spectrometer, and FIG. 2 is an explanation of an ion beak. 3. Quadrupole mass spectrometer, 6. Quadrupole electrode section, 2
4a, 24b...first and second buttons/ohmeters, 26...voltage ratio calculation section. Patent applicant Shimadzu Corporation representative 1 person Patent attorney Kazuhide Okada

Claims (1)

[Claims] (1) A quadrupole characterized by comprising means for setting two types of DC voltages applied to the quadrupole electrode section, and means for measuring a value of the ratio of the two types of voltages set. Heavy separation mass spectrometer.