Mass spectrometry device

Abstract

In order to provide a mass spectrometry device capable of stable analysis without deviation of a mass axis on a mass spectrum even in continuous measurement over a long period of time, the following configuration is adopted.　Provided is a mass spectrometry device comprising: a multipole electrode; an AC voltage source that generates an AC voltage that is applied to the multipole electrode when measuring a component to be measured; a voltage division circuit that is connected between the AC voltage source and the multipole electrode and divides the AC voltage output from the AC voltage source into a quadrupole electrode-applied AC voltage that is applied to the multipole electrode and an AC voltage for a detection circuit, wherein the amplitude of the AC voltage for the detection circuit changes in proportion to the amplitude value of the quadrupole electrode-applied AC voltage; a temperature sensor for measuring the temperature of the voltage division circuit; and a control unit that outputs an AC voltage DAC value for controlling the AC voltage source on the basis of the temperature measured by the temperature sensor and the mass-to-charge ratio of the component to be measured. The AC voltage source controls the voltage value of the AC voltage on the basis of the AC voltage DAC value and the AC voltage for the detection circuit output from the voltage division circuit.

Description

Mass spectrometer 【0001】 The present invention relates to a mass spectrometer. 【0002】 A mass spectrometer introduces generated ions into the apparatus and controls them in an electric field to selectively extract and measure only ions having specific mass and charge. Among mass spectrometers, a triple quadrupole mass spectrometer (Triple Quadrupole Mass Spectrometer, Triple QMS) is a typical mass spectrometer for quantitative analysis. Triple QMS can continuously pass specific ions of a sample to be measured and has high quantitative analysis performance. 【0003】 A mass spectrometer flows a sample solution through a capillary to which a high voltage is applied, ejects the sample from the tip of the capillary, and blows a heated gas from the periphery to generate charged droplets. These charged droplets split and ions are generated. The generated ions are controlled by an electric field or the like and drawn into a vacuum evacuated by a vacuum pump. These ions are guided to a quadrupole mass filter (Quadrupole Mass Filter, QMF). The quadrupole mass filter is composed of four cylindrical rod electrodes (hereinafter referred to as Q rods) and a holder for fixing them. 【0004】 The four Q rods are fixed to the holder such that the centers of the circles that are their cross-sections are located at the vertices of a square, respectively. When U is a DC voltage and Vcosωt is an AC voltage, the opposing Q rods are connected to each other, and U + Vcosωt is applied to the first combination of Q rods, and -U - Vcosωt is applied to the second combination of Q rods. 【0005】When a voltage is applied to the Q-rods, charged ions oscillate within the space enclosed by the Q-rods of the mass filter. Depending on the voltage and frequency applied to the Q-rods, ions with a specific mass and charge oscillate stably and pass through the mass filter. On the other hand, other ions oscillate more rapidly as they pass through the mass filter, colliding with the Q-rods, and thus being unable to pass through. In this way, the mass filter can separate only specific ions. By keeping the ratio of DC voltage to AC voltage constant and linearly changing the AC voltage, a mass spectrum can be obtained. 【0006】 As mentioned above, since mass spectrometers control ions with an electric field, the accuracy and stability of the DC and AC voltages applied to the electrodes directly affect the instrument's performance, such as mass axis stability. Therefore, the specifications required for DC and AC voltages are becoming stricter, and the voltage applied to the QMF requires accuracy and stability on the order of ppm. 【0007】 Furthermore, the operating environments are expanding from corporate and university research laboratories to hospital clinical laboratories, requiring the equipment to operate within a temperature range of, for example, 5 to 35°C. However, changes in the ambient temperature of the mass spectrometer also change the temperature of the control board that generates DC and AC voltages, which in turn can lead to changes in the DC and AC voltages, potentially resulting in fluctuations in the mass axis. 【0008】 In the mass spectrometer disclosed in Patent Document 1, it is described that voltage fluctuations and phase fluctuations associated with temperature changes when the frequency is changed are predicted in advance, and control information to guarantee against the effects of these fluctuations is stored in a memory unit based on the measurement results. When changing the mass of ions discharged from the ion trap during analysis, the control unit reads the control information corresponding to the frequency change from the control unit, predicts voltage fluctuations and phase fluctuations, generates a control signal to guarantee against these effects, and adjusts the voltage of the variable voltage via the voltage adjustment unit. 【0009】Furthermore, in the mass spectrometer disclosed in Patent Document 2, during the standby period from the end of one analysis to the next analysis, the standby frequency determination unit refers to data stored in the temperature control data storage unit in advance to determine the stable temperature corresponding to the analysis conditions of the next analysis to be performed, and calculates the frequency f1 of the drive pulse that maintains that stable temperature. Under the control of the control unit, the timing signal generation unit generates a drive pulse of frequency f1 and drives the switching elements to turn on alternately, so that the temperature of the main power supply unit is maintained at a state close to the stable temperature for the next analysis. As a result, even when the next analysis starts, there is almost no change in temperature, and the time drift of ion emission caused by temperature changes is reduced. 【0010】 Japanese Patent Publication No. 2009-277376 Japanese Patent Publication No. 2011-23167 【0011】 In mass spectrometers, temperature changes in the voltage divider circuit cause a discrepancy between the target AC voltage applied to the quadrupole and the AC voltage actually applied. As a result, the mass-to-charge ratio set for measurement shifts, making stable measurement impossible. Mass spectrometers can selectively isolate and detect only substances with a specific mass and charge corresponding to the AC voltage applied to the quadrupole. Since the mass-to-charge ratio (hereinafter also referred to as "m / z") of the substance being measured is very small, ranging from tens to thousands, it is necessary to apply the AC voltage to the quadrupole with high precision so that the AC voltage corresponds to a specific value for the substance. 【0012】 However, due to changes in capacitance caused by heat generation in the capacitors within the circuit, a discrepancy occurs between the amplitude of the target AC voltage applied to the quadrupole and the amplitude of the AC voltage actually applied. This discrepancy in AC voltage amplitude causes the mass axis on the mass spectrum to shift in the mass spectrometer, leading to misidentification of a substance other than the target substance and a decrease in quantitative accuracy, thus degrading the analytical performance of the mass spectrometer. To prevent such a decrease in analytical performance, it is necessary to eliminate the shift in the mass axis on the mass spectrum by correcting the AC voltage amplitude based on the temperature change of the circuit in real time. 【0013】Patent Document 1 discloses an approach that predicts voltage and phase fluctuations associated with temperature changes and adjusts the voltage based on the measurement results. However, the approach in Patent Document 1 focuses on voltage fluctuations, and its effect on the shift of the mass axis in the mass spectrum, which is the original objective, remains unclear. Furthermore, since it predicts voltage and phase fluctuations associated with temperature changes when the frequency is changed, real-time control based on the state during measurement is not possible, and there is a risk of discrepancy with the actual state of the device. 【0014】 Patent Document 2 discloses an approach that uses two main power supply units to determine a stable temperature corresponding to the analysis conditions of the next analysis to be performed by referring to data stored in a temperature control data storage unit in advance, adjusts the temperature of the main power supply unit to be used next, and maintains the temperature of the main power supply unit close to the stable temperature during analysis. However, the approach in Patent Document 2 is a method of predicting the temperature of the main power supply unit and keeping the temperature constant, and there is a risk that it may not be able to withstand the heat generated by continuous measurement over a long period of time. In addition, since the stable temperature depends on the environment around the device, if real-time control during analysis is not possible, there is a risk that a discrepancy will occur between the prediction and the actual state. 【0015】 The objective of the present invention is to provide a mass spectrometer that enables stable analysis without distortion of the mass axis in the mass spectrum, even during continuous measurements over long periods of time. 【0016】 The present invention, which solves the above problems, has the following configuration: A mass spectrometer comprising: a multipole electrode; an AC voltage source that generates an AC voltage to be applied to the multipole electrode when measuring a component to be measured; a voltage divider circuit connected between the AC voltage source and the multipole electrode, which divides the AC voltage output from the AC voltage source into a quadrupole electrode applied AC voltage and a detection circuit AC voltage whose amplitude changes in proportion to the amplitude value of the quadrupole electrode applied AC voltage applied to the multipole electrode; a temperature sensor that measures the temperature of the voltage divider circuit; and a control unit that outputs an AC voltage DAC value for controlling the AC voltage source based on the temperature measured by the temperature sensor and the mass-to-charge ratio of the component to be measured, wherein the AC voltage source controls the voltage value of the AC voltage based on the AC voltage DAC value and the detection circuit AC voltage output from the voltage divider circuit. 【0017】According to the present invention, it is possible to provide a mass spectrometer that enables stable analysis without shifting the mass axis on the mass spectrum, even during continuous measurements over long periods of time. 【0018】 Other issues, configurations, and effects not mentioned above will become clear from the following description of the embodiments. 【0019】 Configuration of the mass spectrometer used in the example First configuration diagram of the AC voltage generation section of the quadrupole mass spectrometer Calculation method of the correction coefficient of the correction formula Screen for setting the reference temperature, maximum m / z and correction coefficient of the correction formula Effects of AC voltage correction Second configuration diagram of the AC voltage generation section of the quadrupole mass spectrometer Third configuration diagram of the AC voltage generation section of the quadrupole mass spectrometer Fourth configuration diagram of the AC voltage generation section of the quadrupole mass spectrometer Fifth configuration diagram of the AC voltage generation section of the quadrupole mass spectrometer Sixth configuration diagram of the AC voltage generation section of the quadrupole mass spectrometer Seventh configuration diagram of the AC voltage generation section of the quadrupole mass spectrometer 【0020】 The embodiments of the present invention will be described below with reference to the drawings. 【0021】 Figure 1 shows the configuration of the mass spectrometer 100 according to this embodiment. The sample to be measured, delivered by a pump (not shown) such as a liquid chromatograph, is ionized by the ion source 200. Since the ion source 200 operates under atmospheric pressure and the mass spectrometer 100 operates in a vacuum, ions are introduced into the mass spectrometer 100 through the air-vacuum interface 220 (the ion movement trajectory is shown by the dashed line 210). Although the ions generated from the ion source 200 have various masses, an AC voltage and a DC voltage are applied from the quadrupole power supply 280 to the first quadrupole electrode section 240 (equipped with a quadrupole electrode 230 inside) to selectively allow only the target ions originating from the measurement target to pass through. 【0022】In the second quadrupole electrode section 241, a collision gas 270 (such as nitrogen gas or argon gas) for dissociating target ions is introduced from a supply source via a gas line 271. Normally, only an AC voltage is applied to the quadrupole electrode 231 of the second quadrupole electrode section 241 from the quadrupole power supply 280 to eliminate mass selectivity, and fragment ions are generated by colliding the target ions that have passed through the first quadrupole electrode section 240 with the gas. The generated fragment ions pass through the second quadrupole electrode section 241 and enter the third quadrupole electrode section 242. 【0023】 When an AC voltage and a DC voltage that allow the target fragment ions to pass through are applied from the quadrupole power supply 280 to the third quadrupole electrode 232 provided on the third quadrupole electrode section 242, only the target fragment ions pass through the third quadrupole electrode section 242. The target fragment ions that have passed through are detected by the detector 250. The detection signal is sent to the data processing unit 260, and mass spectrometry is performed. The analysis results from the data processing unit 260 are output to the output unit 261 (display, printer, etc.). The data processing unit 260 is composed of a PC (personal computer) equipped with a CPU, and measurement conditions and other inputs can be made via a data input unit (not shown). Alternatively, the data processing unit 260 may consist of a dedicated board specialized for data processing. 【0024】 Here, a triple-quadrupole mass spectrometer, known as a Triple QMS, is shown as an example. However, the technology of the present invention is also applicable to Single QMS and quadrupole mass spectrometers, which have a single QMF installed internally. Furthermore, although a quadrupole type mass filter is used as an example in the embodiments, the technology of this disclosure is not limited to quadrupoles but is also applicable to multipole mass filters such as sextupole and octupole filters. 【0025】 Figure 2 shows an example of the configuration of the quadrupole power supply 280 of a quadrupole mass spectrometer. The quadrupole power supply 280 consists of a control unit 300, a DAC (digital-to-analog converter) 320, an AC voltage source 330, a voltage divider circuit 340, an AD converter (ADDC) 350, and a detection circuit 360. A temperature sensor 341 is also installed near the voltage divider circuit 340. 【0026】The control unit 300 is composed of a (control) computer including a CPU and has a setting unit 311 and a correction unit 312. Measurement information such as the m / z (mass-to-charge ratio), a predetermined AC voltage DAC value (as a design value), and the measurement method is input to the setting unit 311 from an external CPU such as a PC having a data processing unit 260 in Figure 1. Based on the measurement information input to the setting unit 311 from the external CPU, the setting unit 311 passes the m / z information to be measured, AC voltage DAC value information which is a signal for controlling the amplitude of the AC voltage generated from the AC voltage source 330, etc. to the correction unit 312. If the correction unit 312 is not located inside the control unit 300, the setting unit 311 can also output the AC voltage DAC value directly. 【0027】 The correction unit 312 receives m / z information, predetermined AC voltage DAC value information, and temperature information of the voltage divider circuit from the temperature sensor 341 as inputs from the setting unit 311. The correction unit 312 also has a correction coefficient, a reference temperature, and maximum m / z information, which are constants included in the correction formula described later. The values ​​of the correction coefficient, reference temperature, and maximum m / z information can be changed by the voltage divider circuit AC voltage amplitude correction function described later. The reference temperature is the reference temperature of the voltage divider circuit when the mass spectrometer is started, and the maximum m / z is the maximum value of m / z that the mass spectrometer can measure. The method for determining the correction coefficient will be described later. From the three input values ​​(m / z information, AC voltage DAC value information, and temperature information of the voltage divider circuit from the temperature sensor 341) and the three constants (correction coefficient, reference temperature, and maximum m / z information), the correction unit 312 generates a correction signal to control the AC voltage source 330 based on the correction formula described later, and corrects the AC voltage generated from the AC voltage source 330. 【0028】 The correction formula when the correction unit is in the software or digital circuit is as shown in Equation 1. 【0029】 【0030】 Alternatively, if we define the maximum AC voltage DAC value (before correction) as the value at which the maximum m / z is measured at the reference temperature, then since the m / z measured in the correction formula and the AC voltage DAC value (before correction) are in a proportional relationship, we can also calculate by substituting it with Equation 2. 【0031】 【0032】 When there is a correction unit in the analog circuit, the following correction formula is set in the analog circuit in advance. Since the AC voltage DAC value is proportional to the magnitude of the output AC voltage and m / z, assuming the correction value of the AC voltage DAC value is D, the increment of the correction value D is ΔD, the associated AC voltage is V, and A and B are coefficients, then Equation 3 and Equation 3' hold. 【0033】 【0034】 Also, since ΔD can be considered as the difference between the AC voltage DAC value (after correction) and the AC voltage DAC value (before correction) from Equation 1, Equation 4 holds. 【0035】 【0036】 Assuming C is a coefficient, ω is the angular velocity of the AC voltage, r is the radius of the inscribed circle of the quadrupole, and q is a coefficient (0 <= q < 0.908), Equation 5 is known from the Mathieu equation (C = q × ω^2 · r^2 / 4e). Therefore, Equation 6 holds from Equations 3, 4, and 5. 【0037】 【0038】 【0039】 Also, when Equation 2 is transformed, Equation 7 holds. 【0040】 【0041】 Substituting Equation 7 into Equation 6 gives Equation 8. 【0042】 【0043】 A, B, and C are constants, and based on the voltage output from the DA converter, it is possible to obtain the relationship between the AC voltage generated from the AC voltage source 330 and the DAC value and the relationship of the measured m / z. Since V is the input to the voltage divider circuit, correction can be performed according to Equation 8 with the difference between the temperature of the voltage divider circuit and the reference temperature and the AC voltage input to the voltage divider circuit. Therefore, when there is a correction unit 312 in the analog circuit, the correction formula can be corrected by Equation 9. 【0044】 【0045】 The AC voltage calculated using these correction formulas is output to the DA converter 320. The DA converter 320 takes the AC voltage DAC value output from the control unit 300 as input, converts it to an analog value, and outputs it to the AC voltage source. 【0046】 The AC voltage source 330 takes the analog value (voltage value) output from the DA converter 320 and the amplitude analog value of the AC voltage output from the detection circuit 360 as feedback as input, and outputs an AC voltage to the voltage divider circuit 340. Inside the AC voltage source, the analog value corresponding to the amplitude of a predetermined AC voltage (AC voltage before correction) output from the DA converter is compared with the amplitude analog value of the AC voltage applied to the quadrupole, which is fed back from the detection circuit. The AC voltage source 330 is controlled to amplify or attenuate the amplitude to adjust the amplitude of the AC voltage so that it becomes the predetermined AC voltage amplitude. 【0047】 The voltage divider circuit 340 has a capacitor or a resistor. An AC voltage is input to the voltage divider circuit 340 from the AC voltage source 330. The input AC voltage is divided into an output to the quadrupole 370 and an output to the detection circuit 360, according to the capacitance of the capacitor and the resistance of the resistor. Since the output from the AC voltage source 330 is a high voltage of several tens of kV to be applied to the quadrupole 370, it is technically difficult to directly input this output to the detection circuit 360 due to the voltage rating of the detection circuit 360. Therefore, the voltage divider circuit 340 divides the output voltage into a voltage below the voltage rating of the detection circuit 360 (referred to as the "AC voltage for the detection circuit") and a voltage to be applied to the quadrupole 370 (referred to as the "AC voltage applied to the quadrupole electrodes"). When the voltage applied to the quadrupole 370 fluctuates, the voltage applied to the detection circuit 360 also changes proportionally. By utilizing this, it is possible to monitor the voltage fluctuations applied to the quadrupole 370 based on the voltage changes applied to the detection circuit. 【0048】At this time, heat is generated by the capacitor and resistor, and this heat causes changes in capacitance and resistance, resulting in a change in the voltage output from the voltage divider circuit 340. A temperature sensor 341 is installed near the voltage divider circuit to monitor its temperature. The temperature information of the voltage divider circuit 340 obtained from the temperature sensor 341 is output to the AD converter 350, where it is converted into a digital signal (ADC value) indicating temperature and then output to the control unit 300. 【0049】 Furthermore, to prevent temperature changes in the pressure divider circuit due to changes in the surrounding environment, the temperature of the pressure divider circuit 340 can be adjusted using a heater or cooling device installed near the pressure divider circuit 340, thereby keeping the reference temperature of the pressure divider circuit 340 constant. 【0050】 In this case, the heater or cooling device can be controlled by feeding back the temperature information from the temperature sensor 341 near the voltage divider circuit 340. Alternatively, it is also possible to provide another temperature sensor near the heater or cooling device and perform feedback control. 【0051】 The detection circuit 360 takes the AC voltage output from the voltage divider circuit 340 as input and has the function of extracting only the amplitude from the AC voltage. The extracted amplitude of the AC voltage is output to the AC voltage source 330 as feedback control, and has the effect of checking whether the correct amplitude of the AC voltage is being output from the AC voltage source. 【0052】 When the temperature of the voltage divider circuit 340 changes, the measured m / z value shifts, which negatively affects the analytical accuracy of the mass spectrometer. The relationship between the AC voltage output from the voltage divider circuit 340 and the temperature can be explained, for example, as follows, since capacitors and resistors are used in the voltage divider circuit. The relationship between the voltage input and output of the voltage divider circuit is as follows, when the voltage output is Vout, the voltage input is Vin, and the impedances of the capacitor or resistor are Z1 and Z2. 【0053】 【0054】 Furthermore, the capacitance of a capacitor has the following relationship, where C(T) is the capacitance at temperature T, C0 is the capacitance at a reference temperature T0, and α is the temperature coefficient. 【0055】 【0056】 From the relationship between equations 3 and 4 mentioned above, the effect of temperature on the voltage output of a voltage divider circuit is as follows: 【0057】 【0058】 Therefore, the temperature of the voltage divider circuit 340 is related to the output AC voltage. Furthermore, the relationship between AC voltage and m / z is given by Matthew's equation, where V is the AC voltage, q is the coefficient, m / z is the mass-to-charge ratio, e is the elementary charge, ω is the angular frequency of the AC voltage, and r is the radius of the inscribed circle of the quadrupole. 【0059】 【0060】 Therefore, the AC voltage V is proportional to the frequency in m / z. 【0061】 From the above relationship, when the temperature of the voltage divider circuit 340 changes, the AC voltage output to the quadrupole changes due to the influence of the voltage divider circuit, causing the measured m / z to shift. In order to correct the shift in the measured m / z, it is necessary to perform a correction that takes into account the temperature of the circuit before it is applied to the quadrupole, for example, the voltage divider circuit 340, the measured m / z, and the AC voltage. 【0062】 The correction coefficients in Equations 1, 2, and 3 are determined by the calculations shown in Figure 3. First, the m / z of several types of materials is measured several times without using the AC voltage correction function, and the measurement results are recorded as follows: (1) AC voltage DAC value measurement 1st time and (2) AC voltage DAC value measurement 2nd time. Since the AC voltage DAC value is digitally processed, it is easy to record what values ​​were used. 【0063】Next, based on the measurement results, a regression line is calculated for the relationship between each temperature and the AC voltage DAC value, such as the slope of the regression line for (3) (temperature, (1) or (2)), and the slope of that regression line is derived and recorded. In the example shown in the figure, there are two measurements, but the number is not limited to two; multiple measurements are acceptable. After deriving the relationship between temperature and AC voltage DAC value in (3), the relationship between m / z in (4) and (5) and (3) is derived and recorded as the slope and intercept of the regression line. Finally, for the lines obtained in (4) and (5), the value obtained when taking the maximum m / z used in the device's measurement is used is used as the correction coefficient. That is, the correction coefficient is given by Equation 14. 【0064】 【0065】 The voltage divider circuit AC voltage amplitude function allows for changes to the correction formula constants, namely the reference temperature, maximum m / z, and correction coefficient, in cases where modifications such as changes to the components or circuit configuration of the mass spectrometer are made, or when the surrounding environment changes during installation. 【0066】 Figure 4 shows an example of a screen for changing constants. The operator enters new values ​​for the reference temperature, maximum m / z, and correction coefficient in the boxes located next to each item, and then presses the OK button at the bottom of the screen to set the new constants. The set values ​​are saved in the correction unit, which uses the saved constants to correct the AC voltage. This operation allows the AC voltage correction to be adjusted according to modifications and the surrounding environment. 【0067】 The effects obtained by this correction will be explained using Figure 5. Figure 5 illustrates the reduction of the mass axis misalignment obtained by AC voltage correction, showing that the center of the mass axis is measured as m' / z' before correction, but becomes m / z after correction. 【0068】 Figures 2 and 6 show the configuration diagrams of the quadrupole power supply of a quadrupole mass spectrometer when correcting the AC voltage using software or a digital circuit in this embodiment. 【0069】Figure 2 shows that the correction unit 312 is located within the control unit 300, and calculates the correction as a digital value. The control unit 300, which is composed of a CPU and the like, receives the digital value sent as the measurement condition and passes the digital value to the correction unit 312 via the setting unit 311. The correction unit 312 also receives the analog temperature information obtained from the temperature sensor 341, which is converted into a digital value by the AD converter 350. Furthermore, the correction unit 312 combines the reference temperature, the maximum m / z, and the correction coefficient information recorded in the correction unit 312 and processes the aforementioned correction formula, Equation 1, as a digital value to calculate the correction value. The calculated correction value is converted into an analog value by the DA converter 320, and thereafter, a voltage is applied to the quadrupole 370 according to the operation determined in the circuit. The voltage applied to the quadrupole 370 is corrected by the correction of the AC voltage output from this voltage divider circuit 340, eliminating the discrepancy between the m / z to be measured and the measured m / z. 【0070】 Figure 6 is a configuration diagram showing the case where the correction unit 612 is separated from the control unit 600 and correction is performed by a digital circuit. The correction unit 612 is separated from the CPU of the control unit 600 and exists as a digital circuit. The digital circuit is made to record the correction formula and perform the correction. As in the case of Figure 2, the correction unit 612 receives digital values ​​of m / z information measured from the setting unit 611, the AC voltage DAC value (before correction), and temperature information from the temperature sensor 641. The correction unit 612 outputs the corrected AC voltage DAC value from the inputs and inputs it to the AC voltage source 630. The AC voltage source 630, as a digital circuit, performs feedback control of the digital value, generates a sine wave, and amplifies the voltage value to output a digital AC voltage. The output digital AC voltage is converted to an analog value by the DA converter 620 and the AC voltage is applied to the quadrupole 670 via the voltage divider circuit 640. 【0071】 Depending on the configuration of the device and the cost of the device, either the correction method shown in Figure 2 or the correction method shown in Figure 6 can be selected. Figure 2 can be used when processing is done by the CPU as software, while Figure 6 can be used when processing is done as a digital circuit. 【0072】Figures 7, 8, and 9 show the configuration diagrams of the quadrupole power supply for a quadrupole mass spectrometer when the AC voltage is corrected using analog circuits rather than software or digital circuits. 【0073】 The correction unit 712 in Figure 7 is composed of an analog circuit. First, the digital value of the AC voltage DAC value (before correction) output from the setting unit 711 in the control unit 700 is input to the DA converter 730, and the analog value is output from the DA converter 730 to the correction unit 712. Temperature information output from the temperature sensor 741 is input to the correction unit 712 as an analog value. The correction unit 712 takes the AC voltage (before correction) and temperature information as input and outputs the AC voltage (after correction) according to Equation 9. Subsequent operations are the same as in Embodiment 2. 【0074】 The correction unit 812 in Figure 8 is composed of an analog circuit. First, the digital value of the AC voltage DAC value (before correction) output from the setting unit 811 in the control unit 800 is input to the DA converter 830, and the analog value is output from the DA converter 830 to the AC voltage source 820. The correction unit 812 receives the AC voltage feedback from the voltage divider circuit 840 via the detection circuit 860, and also receives temperature information from the temperature sensor 841. The AC voltage value from the input detection circuit 860 is used as the AC voltage (before correction), and the AC voltage is corrected according to Equation 3. The corrected AC voltage is input to the AC voltage source 820, and the AC voltage source 820 compares the AC voltage sent from the DA converter 830 with the AC voltage sent from the correction unit 812 (which is the feedback) and adjusts the amplitude of the AC voltage. The subsequent operation is the same as in Embodiment 2. 【0075】The correction unit 912 in Figure 9 is composed of a digital circuit, and the AC voltage source 920 is also composed of a digital circuit. First, the AC voltage DAC value (before correction) output from the setting unit 911 in the control unit 900 is input to the AC voltage source 920. The outputs from the temperature sensor 941 and the detection circuit 960 are converted to digital values ​​via the AD converter 931 and input to the correction unit 912. The correction unit 912 corrects the AC voltage according to Equation 1. The AC voltage source 920 receives the digital values ​​of the AC voltage from the setting unit 911 and the correction unit 912, and after feedback control, adds a sine wave to the corrected amplitude value to output the AC voltage to the DA converter 930. The DA converter 930 outputs an analog value of the AC voltage, which is input to the voltage divider circuit 940. The subsequent operation is the same as in Embodiment 2. 【0076】 Figures 10 and 11 show an embodiment where the correction unit is located within an AC voltage source. The correction unit in Figure 10 (not shown) is composed of an analog circuit. First, the AC voltage DAC value (before correction) output from the setting unit 1011 in the control unit 1010 is input to the DA converter 1030, and the DA converter 1030 outputs an analog value to the AC voltage source 1020. The AC voltage source 1020 feedback-controls the AC voltage via the DA converter 1030 and the detection circuit 1060 and inputs the AC voltage to the correction unit. The correction unit also receives temperature information from the temperature sensor 1041. Based on the input AC voltage and temperature information, the correction unit corrects the AC voltage according to equation 9. The corrected AC voltage has a sine wave applied to it and the AC voltage is input to the voltage divider circuit 1040. 【0077】The correction unit (not shown) and the AC voltage source 1120 in Figure 11 are composed of digital circuits. First, the digital value of the AC voltage DAC value (before correction) output from the setting unit 1111 in the control unit 1110 is input to the AC voltage source 1120. The temperature information from the temperature sensor 1141 is converted to a digital value via the AD converter 1132 and input to the AC voltage source 1120. The AC voltage source 1120 receives the AC voltage via the setting unit 1111 and the detection circuit 1160 as an analog value, and after feedback control, the correction unit corrects the AC voltage according to Equation 1. The corrected AC voltage is converted to an analog value by the DA converter 1131, then boosted (amplified) to a high voltage and input to the voltage divider circuit 1140. 【0078】 200... Ion source 210... Ions 220... Interface between air and vacuum 230... First quadrupole electrode 231... Second quadrupole electrode 232... Third quadrupole electrode 240... First quadrupole electrode section 241... Second quadrupole electrode section 242... Third quadrupole section 250... Detector 260... Data processing section 270... Collision gas 271... Gas line 280... Quadrupole power supply 320... DA converter 350... AD converter

Claims

1. A mass spectrometer comprising: a multipole electrode; an AC voltage source that generates an AC voltage to be applied to the multipole electrode when measuring a component to be measured; a voltage divider circuit connected between the AC voltage source and the multipole electrode, which divides the AC voltage output from the AC voltage source into a quadrupole electrode applied AC voltage and an AC voltage for a detection circuit whose amplitude changes in proportion to the amplitude value of the quadrupole electrode applied AC voltage applied to the multipole electrode; a temperature sensor that measures the temperature of the voltage divider circuit; a detection circuit that detects the AC voltage for the detection circuit; and a control unit that outputs an AC voltage DAC value for controlling the AC voltage source based on the temperature measured by the temperature sensor and the mass-to-charge ratio of the component to be measured, wherein the AC voltage source outputs a voltage value of the AC voltage to be applied to the multipole electrode based on the AC voltage DAC value and the AC voltage for the detection circuit detected by the detection circuit.

2. A mass spectrometer according to claim 1, characterized in that the control unit calculates the AC voltage DAC value using software.

3. A mass spectrometer according to claim 1, wherein the control unit comprises a setting unit into which the mass-to-charge ratio of the component to be measured is input, and a correction unit into which the mass-to-charge ratio of the component to be measured output from the setting unit is input, and the AC voltage DAC value for controlling the AC voltage source based on the temperature measured by the temperature sensor and the mass-to-charge ratio of the component to be measured.

4. A mass spectrometer according to claim 3, characterized in that the correction unit comprises a digital circuit storing an algorithm for controlling the voltage value of the AC voltage generated from the AC voltage source.

5. A mass spectrometer according to claim 4, characterized in that the correction unit is provided as a separate substrate from the setting unit.

6. A mass spectrometer according to claim 1, wherein the control unit comprises: a setting unit into which the mass-to-charge ratio of the component to be measured is input; a DAC unit into which the digital signal output from the setting unit is converted into an analog signal; and a correction unit into which the analog signal is input and which outputs an analog signal for controlling the AC voltage source based on the temperature measured by the temperature sensor and the mass-to-charge ratio of the component to be measured.

7. A mass spectrometer according to claim 1, wherein the control unit comprises: a setting unit into which the mass-to-charge ratio of the component to be measured is input; a DAC unit into which the digital signal output from the setting unit is converted to an analog value; and a correction unit that outputs a signal for controlling the AC voltage source based on the detected AC voltage for the detection circuit output from the detection circuit and the output of the temperature sensor.

8. A mass spectrometer according to claim 1, wherein the control unit comprises: a setting unit into which the mass-to-charge ratio of the component to be measured is input; an ADC unit provided in each of the detection circuit and the temperature sensor, which converts the respective outputs into digital values; and a correction unit that outputs a signal for controlling the AC voltage source based on the digital signal from the ADC unit, the temperature measured by the temperature sensor, and the voltage value output from the AC voltage source.

9. A mass spectrometer according to claim 1, wherein the control unit has a setting unit into which the mass-to-charge ratio of the component to be measured is input, and the AC voltage source controls the AC voltage value output to the voltage divider circuit based on the output from the DAC unit which converts the mass-to-charge ratio of the component to be measured output from the setting unit into an analog value, and the outputs of the detection circuit and the temperature sensor.

10. A mass spectrometer according to claim 1, wherein the control unit has a setting unit into which the mass-to-charge ratio of the component to be measured is input, the AC voltage source outputs a digital signal by adding a sine wave to a signal generated based on the mass-to-charge ratio of the component to be measured output from the setting unit and the output from an ADC unit provided in each of the detection circuit and the temperature sensor, which converts the outputs of the detection circuit and the temperature sensor into digital values, and the digital signal output from the AC voltage source is input to the multipole electrode via a DAC unit that converts it into an analog signal.

11. A mass spectrometer according to claim 1, wherein the control unit receives the mass-to-charge ratio of the component to be measured, the AC voltage DAC value, and the temperature of the voltage divider circuit measured by the temperature sensor as input, and corrects the AC voltage DAC value input from the AC voltage source to the multipole electrode based on a correction coefficient stored in the control unit, a reference temperature that serves as a reference for the voltage divider circuit when the mass spectrometer is started, and the maximum mass-to-charge ratio which is the maximum value of the mass-to-charge ratio that the mass spectrometer can measure, based on the formula: AC voltage DAC value (after correction) = AC voltage DAC value (before correction) + correction coefficient × (temperature of the voltage divider circuit - reference temperature) × (mass-to-charge ratio to be measured / maximum mass-to-charge ratio).

12. A mass spectrometer according to claim 11, characterized in that it is equipped with a display unit that displays an input screen on which at least one of the reference temperature, the maximum mass-to-charge ratio, and the correction coefficient can be input.

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