JP2013148372A - Mercury atomic absorption spectrometer and mercury analysis system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mercury atomic absorption spectrometer, etc. capable of suppressing noise and variation in a baseline in spite of a long-term use and capable of automatically adjusting gain even when an output standard voltage is deviated from an allowable range.SOLUTION: In a mercury atomic absorption spectrometer 100, a measurement side amplifier circuit 13 includes a measurement side gain adjusting digital potentiometer 15 for adjusting measurement side gain so that a measurement side output standard voltage composing the baseline for measurement is adjusted to a predetermined set voltage; a reference side amplifier circuit 14 includes a reference side gain adjusting digital potentiometer 16 for adjusting reference side gain so that a reference side output standard voltage composing the baseline for measurement is adjusted to a predetermined set voltage; and control means 17 controls respective gain adjusting digital potentiometers 15, 16. The control means 17 monitors the measurement side and reference side output standard voltages and respective digital potentiometers 15, 16 respectively perform automatic gain adjustment.

Description

  The present invention relates to a mercury atomic absorption spectrometer and a mercury analysis system for analyzing mercury in a sample.

  Conventionally, mercury analyzers and mercury analysis systems based on atomic absorption spectrometry have been widely used in environmental analysis and quality control analysis for many years. In the analysis of river water, etc., an apparatus using the reduction vaporization method (Patent Document 1), in the analysis of exhaust gas discharged from the chimney of a garbage incinerator, in the apparatus for measuring mercury in the exhaust gas online, in the analysis of solid samples, There is a mercury analysis system in which a sample in a sample container is thermally decomposed in a sample heating furnace and mercury generated from the sample is collected and measured by a mercury collecting tube while flowing a predetermined flow rate of air with an air pump. .

  In the conventional mercury analyzer, since the light intensity of the mercury lamp fluctuates during measurement, a double beam type mercury analyzer is used to compensate for the fluctuation of the light intensity. However, even in a double beam mercury analyzer, if the measurement is performed for a long time or is used for a long time (for example, more than one year), noise and fluctuations occur in the baseline of the mercury analyzer, resulting in inaccurate measurement data. Therefore, there is a problem that accurate analysis cannot be performed.

  In order to solve this problem, there is a mercury analyzer 500 shown in FIG. The apparatus 500 divides the light beam 2 emitted from the mercury lamp 1 into the measurement light 5 and the reference light 6 by the half mirror 4, and the measurement side detector 8 for detecting the measurement light 5 and the reference side detection for detecting the reference light. A pre-amplifier 80, 90 for amplifying currents from the respective detectors, and a measurement-side amplification signal that is the measurement-side light intensity and a reference-side amplification signal that is the reference-side light intensity; Is input to the control means 70, and the mercury in the sample is quantified by the quantification means 21 based on the ratio of these signals.

  The preamplifiers 80 and 90 of the apparatus 500 have the same configuration on the measurement side and the reference side, and the measurement side preamplifier 80 is shown in FIG. The measurement-side preamplifier 80 includes a measurement-side current-voltage conversion circuit 85 and a measurement-side amplification circuit 86. The measurement-side amplification circuit 86 has a measurement-side output reference voltage that forms a baseline at the time of measurement. In order to adjust the measurement-side offset voltage so that the measurement-side output voltage becomes 0 V, having a gain adjustment trimmer (trimmer volume, semi-fixed resistor) 81 for adjusting the measurement-side gain so as to be the set voltage. The offset adjusting trimmer 82 is provided.

  In an ideal double beam mercury analyzer, even if the light intensity of the mercury lamp fluctuates, if the fluctuation ratio of the light intensity on the measurement side and the reference side is the same, the measurement light intensity and the reference light intensity Since the measurement is based on the ratio, it is not affected by fluctuations in the light intensity of the mercury lamp. However, in an actual device, the fluctuation ratio between the measurement side amplification signal and the reference side amplification signal is not the same, and if measurement is performed for a long time, noise and fluctuations occur in the baseline, resulting in inaccurate measurement data. , Accurate analysis may not be possible. In this case, the cause is that the output reference voltages of the measurement side amplifier and the reference side amplifier constituting the baseline are out of the allowable range, and the gain adjustment trimmer 81 is set so that these output reference voltages become a predetermined set voltage. Adjust each gain with. At this time, since the output voltage when the mercury lamp is turned off often deviates from 0V, each offset voltage is adjusted by the offset adjusting trimmer 82 so that the voltage becomes 0V. If the voltage deviates from 0V, the linearity of the calibration curve is deteriorated.

JP 2008-102068 A

  However, since the conventional apparatus manually operates the gain adjustment trimmer 81 and the offset adjustment trimmer 82 based on the operator's judgment, it takes time and effort. In addition, since gain adjustment and offset voltage adjustment are performed with a trimmer, the resistance value set by the jitter and temperature change of the internal contact sliding part to change the resistance value changes, and the baseline at the time of measurement is configured The output reference voltage fluctuates, deviates from the allowable range, and noise and fluctuations occur in the baseline, resulting in inaccurate measurement data and inaccurate analysis.

  The present invention has been made in view of the above-mentioned conventional problems, and even if it is used for a long time (for example, 5 years or more), there is little noise and fluctuation in the baseline, and the output reference voltage constituting the baseline is within an allowable range. It is an object of the present invention to provide a mercury atomic absorption spectrometer or the like that automatically adjusts the gain even if the deviation occurs, stabilizes the baseline, suppresses the generation of noise, and improves the lower limit of quantification and accuracy.

  In order to achieve the above object, a mercury atomic absorption spectrometer of the first configuration of the present invention includes a mercury lamp that emits a ray of mercury analysis line, a light beam emitted from the mercury lamp, and a second beam. A beam splitter that divides the beam, a flow cell through which the first beam and measurement gas pass, a measurement-side detector that detects the light intensity of the first beam that has passed through the flow cell, and a light intensity of the second beam. The mercury in the measurement gas flowed to the flow cell is quantified based on the ratio of the reference side detector and the light intensity detected by the measurement side detector and the light intensity detected by the reference side detector. Quantifying means, a measurement-side current-voltage conversion circuit that converts photocurrent from the measurement-side detector into voltage, a reference-side current-voltage conversion circuit that converts photocurrent from the reference-side detector into voltage, and Measurement It comprises a measurement side amplifier circuit that amplifies the converted converted voltage by the current-voltage conversion circuit, and a reference-side amplifier circuit that amplifies the converted converted voltage by the reference side current-voltage conversion circuit.

  Furthermore, in the mercury atomic absorption spectrometer of the first configuration according to the present invention, the measurement side amplification circuit adjusts the measurement side gain so that the measurement side output reference voltage constituting the baseline at the time of measurement becomes a predetermined set voltage. A reference-side gain adjustment digital potentiometer, and the reference-side amplifier circuit adjusts the reference-side gain so that a reference-side output reference voltage constituting a baseline at the time of measurement becomes a predetermined set voltage. And a control means for controlling the measurement-side gain adjustment digital potentiometer and the reference-side gain adjustment digital potentiometer, and the control is performed when the mercury lamp is turned on. Means for monitoring the measurement-side output reference voltage and the reference-side output reference voltage, So that automatically adjusts the respective gains the each of the digital potentiometer.

  According to the apparatus of the first configuration of the present invention, even if it is used for a long time (for example, 5 years or more), there is little noise and fluctuation in the baseline, and the output reference voltage constituting the baseline is out of the allowable range. Gain can be adjusted automatically, the baseline can be stabilized, noise can be suppressed, and the lower limit of quantification and accuracy can be improved.

  In the mercury atomic absorption spectrometer of the first configuration of the present invention, the measurement side amplification circuit has a measurement side offset adjustment digital potentiometer for adjusting the measurement side offset voltage so that the measurement side output voltage becomes 0V. The reference-side amplifier circuit has a reference-side offset adjustment digital potentiometer for adjusting the reference-side offset voltage so that the reference-side output voltage becomes 0 V, and when the mercury lamp is turned off, Preferably, the control means monitors the measurement-side output voltage and the reference-side output voltage, and automatically adjusts the respective offset voltages with the respective digital potentiometers so as to be 0V, respectively. With this configuration, the linearity of the calibration curve can be maintained, and the accuracy and precision of mercury analysis can be maintained.

  A mercury atomic absorption spectrometer of a second configuration of the present invention includes a mercury lamp that emits a ray of mercury analysis line, a beam splitter that splits the ray emitted from the mercury lamp into a first beam and a second beam, A flow cell through which the first beam and measurement gas pass, a measurement side detector for detecting the light intensity of the first beam that has passed through the flow cell, a reference side detector for detecting the light intensity of the second beam, and Based on the ratio of the light intensity detected by the measurement side detector and the light intensity detected by the reference side detector, a quantification means for quantifying mercury in the measurement gas flowed to the flow cell, and the measurement side A measurement-side current-voltage conversion circuit that converts photocurrent from the detector into voltage, a reference-side current-voltage conversion circuit that converts photocurrent from the reference-side detector into voltage, and the measurement-side current-voltage conversion circuit It comprises a measurement side amplifier circuit for amplifying the conversion transform voltage, and a reference-side amplifier circuit that amplifies the converted converted voltage by the reference side current-voltage conversion circuit.

  Furthermore, the mercury atomic absorption spectrometer of the second configuration of the present invention adjusts the measurement side gain so that the measurement side output reference voltage constituting the baseline at the time of measurement in the measurement side amplification circuit becomes a predetermined set voltage. A measurement-side gain adjustment digital potentiometer for measurement, a measurement-side offset adjustment digital potentiometer for adjusting the measurement-side offset voltage so that the measurement-side output voltage becomes 0 V, and the reference-side amplifier circuit during measurement The reference side gain adjustment digital potentiometer for adjusting the reference side gain so that the reference side output reference voltage constituting the base line becomes a predetermined set voltage, and the reference side so that the reference side output voltage becomes 0V Digital potentiometer for reference side offset adjustment for adjusting offset voltage, and each of the above Control means for controlling the digital potentiometer, and instruction means for the measurer to instruct to automatically adjust the respective gain and the respective offset voltage, when the mercury lamp is turned on Based on the instruction to the instruction means, the control means automatically adjusts the respective gains with the respective digital potentiometers so that the respective output reference voltages become the respective predetermined set voltages, and the automatic adjustment thereof. Thereafter, the mercury lamp is automatically turned off, and the respective offset voltages are automatically adjusted by the respective digital potentiometers so that the respective offset voltages become 0V.

  According to the second configuration apparatus of the present invention, since the instruction means is provided, the gain and the offset voltage can be automatically set using the instruction means when the second configuration apparatus is manufactured, and the measurer can The gain and the offset voltage can be automatically adjusted using the instruction means. In addition, since each digital potentiometer automatically adjusts each gain, there is no jitter, there is little change in resistance value due to temperature change, the output reference voltage that makes up the baseline is stable, it is difficult to deviate from the allowable range, and it can be The baseline can be stabilized, noise can be suppressed, and the lower limit of quantification and accuracy can be improved.

  In the mercury atomic absorption spectrometer of the first configuration or the second configuration of the present invention, the measurement-side current-voltage conversion circuit has a measurement-side current-voltage conversion resistor, and the reference-side current-voltage conversion circuit is a reference-side current-voltage conversion resistor. It is preferable that the temperature coefficient of each of the current-voltage conversion resistors and each of the digital potentiometers is 25 ppm / ° C. or less. With this configuration, each current-voltage conversion circuit and each amplification circuit are not easily affected by temperature changes, and the lower limit of quantification and accuracy can be further improved.

  In the mercury atomic absorption spectrometer of the first configuration or the second configuration of the present invention, it is preferable that the measurement side amplification circuit and the reference side amplification circuit have both functions of amplification and attenuation. With this configuration, the gain adjustment range of the measurement side amplifier circuit and the reference side amplifier circuit can be expanded, the baseline can be stabilized for a longer period, noise can be suppressed, and the lower limit of quantification and accuracy can be improved.

  In the mercury atomic absorption spectrometer of the first configuration or the second configuration of the present invention, the control means individually provides control pulses having variable pulse numbers to the measurement-side gain adjustment digital potentiometer and the reference-side gain adjustment digital potentiometer. According to the number of individual transmission pulses that are transmitted and individually transmitted, the resistance values of the measurement-side gain adjustment digital potentiometer and the reference-side gain adjustment digital potentiometer are varied, The number of individual transmission pulses is monitored, and when the number of transmission pulses on the measurement side or reference side falls below a predetermined number, an abnormal signal is generated indicating that the output current of the detector is greater than or equal to the maximum rated value. preferable. When the output current of the detector is used at the maximum rated value or more, there has been a problem that the detector is deteriorated. However, this configuration can prevent the detector from being deteriorated.

  The mercury analysis system of the third configuration of the present invention is a mercury atomic absorption spectrometer of the first or second configuration of the present invention, and vaporizes mercury in a sample and introduces it into the mercury atomic absorption analyzer as a measurement gas. And a mercury vaporizer.

  According to the mercury analysis system of the third configuration of the present invention, since the mercury atomic absorption analyzer of the first configuration or the second configuration of the present invention is provided, the mercury atomic absorption of the first configuration or the second configuration of the present invention is provided. The same operations and effects as the analyzer can be achieved.

It is the schematic of the mercury analyzer which is 1st Embodiment of this invention. It is a figure which shows the measurement result measured with the same apparatus. It is a figure which shows the baseline measured with the same apparatus. It is the measurement data measured with the same device. It is a figure which shows the baseline measured with the conventional mercury analyzer. It is the measurement data measured with the conventional mercury analyzer. It is the schematic of the mercury analyzer which is 2nd Embodiment of this invention. It is a figure which shows the optical system adjustment screen of the display means of the apparatus. It is a schematic block diagram of the mercury analysis system which is 3rd Embodiment of this invention. It is the schematic of the conventional mercury analyzer. It is the schematic of the preamplifier of the conventional mercury analyzer.

  Hereinafter, the mercury atomic absorption spectrometer according to the first embodiment of the present invention shown in FIG. 1 will be described. The mercury atomic absorption spectrometer 100 includes a mercury lamp 1 that emits a 253.7 nm light beam that is a mercury analysis line, a lamp power source 10 that lights the mercury lamp 1, and a light beam 2 emitted from the mercury lamp 1. After passing through the condenser lens 3, a beam splitter 4 that splits the first beam 5 and the second beam 6, a flow cell 7 through which the first beam 5 and the measurement gas S pass, and a first beam 5 that has passed through the flow cell 7. A measurement-side detector 8 that detects the light intensity, a reference-side detector 9 that detects the light intensity of the second beam 6, the light intensity detected by the measurement-side detector 8, and the reference-side detector 9 Based on the ratio to the light intensity, the quantification means 21 for quantifying mercury in the measurement gas S flowing into the flow cell 7, and the measurement-side current-voltage conversion circuit 11 that converts the photocurrent from the measurement-side detector 8 into a voltage. And the reference side detector 9 The reference-side current-voltage conversion circuit 12 that converts the photocurrent into a voltage, the measurement-side amplification circuit 13 that amplifies the converted voltage converted by the measurement-side current-voltage conversion circuit 11, and the conversion by the reference-side current-voltage conversion circuit 12 And a reference side amplifier circuit 14 for amplifying the converted voltage.

  Further, in the mercury atomic absorption spectrometer 100, the measurement-side gain circuit 13 adjusts the measurement-side gain so that the measurement-side output reference voltage constituting the baseline at the time of measurement becomes a predetermined set voltage. A reference-side gain adjustment for adjusting the reference-side gain so that the reference-side output reference voltage constituting the baseline at the time of measurement has a predetermined set voltage. Control potentiometer 16 and control means 17 for controlling the measurement-side gain adjustment digital potentiometer 15 and the reference-side gain adjustment digital potentiometer 16. When the mercury lamp 1 is lit by the lamp power supply 10, the control is performed. The means 17 monitors the measurement-side output reference voltage and the reference-side output reference voltage, and Each of the digital potentiometers 15 and 16 transmits a control pulse having a variable number of pulses to each of the digital potentiometers 15 and 16 so that the predetermined set voltage is obtained. Variable and automatically adjusts the gain. The mercury atomic absorption spectrometer 100 is a so-called double beam type mercury atomic absorption spectrometer.

  The output-side reference voltage on the measurement side is an output voltage that forms a baseline at the time of measurement, that is, an output voltage in a state where the measurement gas S is not present in the flow cell 7, and is set to a predetermined set voltage, for example, 4V. The output side reference voltage on the reference side is also an output voltage constituting the baseline at the time of measurement, but is set to a predetermined set voltage, for example, 4 V, regardless of the presence or absence of the measurement gas S in the flow cell 7. The measurement side current / voltage conversion circuit 11 includes an amplifier 101 and a measurement side current / voltage conversion resistor 102, and the reference side current / voltage conversion circuit 12 includes an amplifier 121 and a measurement side current / voltage conversion resistor 122. The current-voltage conversion resistors 102 and 122 on the measurement side and the reference side are both 10 MΩ, for example, and both have a temperature coefficient of 25 ppm / ° C. or less. With this configuration, each current-voltage conversion circuit is not easily affected by temperature changes, the baseline is stabilized, noise is suppressed, and the lower limit of quantification and accuracy can be further improved.

  The measurement-side amplifier circuit 13 includes the measurement-side gain adjustment digital potentiometer 15, the measurement-side offset adjustment digital potentiometer 18 for adjusting the measurement-side offset voltage so that the measurement-side output voltage becomes 0 V, the inverting amplifier 131, and It has an input resistor 132 to the inverting amplifier 131 and has an amplification function and an attenuation function. The reference side amplifying circuit 14 includes a reference side gain adjusting digital potentiometer 16, a reference side offset adjusting digital potentiometer 19 for adjusting the reference side offset voltage so that the reference side output voltage becomes 0 V, an inverting amplifier 141, and It has an input resistor 142 to the inverting amplifier 141, and has an amplification function and an attenuation function. The gain of the measurement-side inverting amplifier 131 is determined by the ratio between the measurement-side gain adjustment digital potentiometer 15 and the input resistor 132. The same applies to the gain on the reference side.

  The maximum resistance values of the measurement side and reference side gain adjusting digital potentiometers 15 and 16 are both 50 KΩ, for example, and the measurement side and reference side input resistors 132 and 142 are both 5 KΩ, for example. The temperature coefficients of the measurement side and reference side gain adjusting digital potentiometers 15 and 16 are both 25 ppm / ° C. or less. As a result, each amplifier circuit is not easily affected by temperature changes, the baseline is stabilized, noise is suppressed, and the lower limit of quantification and accuracy can be further improved.

  The control means 17 monitors the measurement-side output voltage and the reference-side output voltage when the mercury lamp 1 is turned off. From the digital data transmission unit 171, the measurement-side offset adjustment digital is set so that each becomes 0V. A control pulse having a variable number of pulses is individually transmitted to the digital data receiving unit 181 of the potentiometer 18 and the digital data receiving unit 191 of the digital potentiometer 19 for reference-side offset adjustment, and the respective digital potentiometers 18 and 19 automatically control the respective offset voltages. adjust.

  The mercury lamp 1 is a mercury lamp or a mercury hollow cathode lamp usually used for atomic absorption analysis. The flow cell 7 has a cylindrical flow cell main body having an inlet and an outlet for mercury vapor as a measurement gas S, and an analysis made of, for example, fused silica at both ends of the cylinder of the flow cell main body. An incident window for entering the line and an exit window for emitting the analysis line are provided. The detectors 8 and 9 are, for example, a photoelectric tube, a photomultiplier tube, a photodiode, or the like. The beam splitter 4 is, for example, a 1 mm-thick quartz plate having aluminum deposited in a stripe shape on the surface, and the light beam 2 emitted from the mercury lamp 1 is a first beam 5 that is transmitted light and reflected light. The second beam 6 is divided at a ratio of 1: 1.

  The quantification unit 21 is provided in, for example, a personal computer 20, and the personal computer 20 includes a display unit 22.

  Next, the operation of the mercury analyzer according to the first embodiment will be described. When the mercury atomic absorption spectrometer 100 of FIG. 1 is turned on, the light beam 2 emitted from the mercury lamp 1 is equally divided into the first beam 5 and the second beam 6 by the beam splitter 4 and transmitted through the flow cell 7. The light intensity of the first beam 5 is detected by the measurement side detector 8, and the light intensity of the second beam 6 is detected by the reference side detector 9.

  In the state where the measurement gas S does not exist in the flow cell 7, the output current Ip from the measurement side detector 8, for example, 0.1 μA is converted to −1V by the measurement side current / voltage conversion circuit 11, and the measurement side amplification circuit 13 enter. The gain of the measurement side amplifier circuit 13 is automatically adjusted by the control pulse transmitted from the control means 17 so that the output reference voltage becomes 4V. In order to amplify −1V to 4V, since the input resistance 132 is 5 KΩ, the measurement-side gain adjustment digital potentiometer 15 having a maximum resistance value of 50 KΩ may be set to 20 KΩ, and the control means 17 is, for example, 256 bits. Is used as a control pulse, a 102-bit control pulse is transmitted from the digital data transmission unit 171 of the control means 17 to the digital data reception unit 151 of the measurement-side gain adjustment digital potentiometer 15 to measure the measurement-side gain. The adjustment digital potentiometer 15 is automatically set to 20 KΩ.

  More specifically, when the mercury atomic absorption spectrometer 100 is turned on and the standby time after the mercury lamp 1 is turned on, for example, 10 minutes after the power is turned on, the output reference voltage is, for example, 4 ± 0.2V. When outside the allowable range, 102 bits of control pulses corresponding to the deviation from the predetermined set voltage 4V are transmitted from the control means 17 to the measurement-side gain adjustment digital potentiometer 15, and the measurement-side gain is automatically adjusted. The reference side gain is automatically adjusted in the same manner as the measurement side gain.

  In addition, when the high light intensity of the mercury lamp 1 and the detectors 8 and 9 having high photosensitivity are combined, the outputs of the current-voltage conversion circuits 11 and 12 may exceed −4V. The amplifier circuits 13 and 14 are caused to function as an attenuator. With this function, the adjustment range of the measurement-side gain and reference-side gain can be expanded, the baseline can be stabilized for a longer period of time, noise can be suppressed, and the lower limit of quantification and accuracy can be improved.

  For example, when the mercury atomic absorption spectrometer 100 is turned on and the output voltage of the measurement side amplifier circuit 13 deviates from 0 V before the mercury lamp 1 is turned on, the automatic adjustment of the measurement side offset voltage is performed by the control means 17. The number of control pulses corresponding to the deviation from 0 V from the digital data transmission unit 171 is transmitted to the digital data reception unit 181 of the measurement-side offset adjustment digital potentiometer 18 to automatically adjust the measurement-side offset voltage. The reference side offset voltage is also automatically adjusted in the same manner as the measurement side offset voltage.

  After the mercury atomic absorption spectrometer 100 is turned on, when the gain on the measurement side and the reference side and the offset voltage on the measurement side and the reference side are automatically adjusted, the measurement gas S is introduced into the flow cell 7, the measurement is started, and the measurement is started. The output voltage of the side amplifier circuit 13 and the output voltage of the reference side amplifier circuit 14 are transmitted to the quantification means 21 through the control means 17, and the output voltage of the measurement side amplifier circuit 13 and the output voltage of the reference side amplifier circuit 14 are transmitted. Mercury in the measurement gas S is quantified based on the ratio signal. The measurement result shown in FIG. 2 is displayed on the display means 22.

  A baseline of the mercury atomic absorption spectrometer 100 of the first embodiment is shown in FIG. FIG. 4 shows the respective measurement results of the measurement gas S obtained by reducing and vaporizing the sample solution having mercury concentrations of 0.5 ppt and 1.0 ppt in 5 ml. For reference, a baseline of a conventional mercury atomic absorption spectrometer 500 is shown in FIG. FIG. 6 shows the measurement results of the measurement gas S obtained by reducing and vaporizing the sample solution having mercury concentrations of 0.5 ppt and 1.0 ppt in 5 ml. The mercury atomic absorption analyzer 100 of the first embodiment has less noise and better reproducibility than both the conventional mercury atomic absorption analyzer 500 and the baseline and measurement results. The lower limit of quantification was 1.2 ppt in the conventional mercury atomic absorption analyzer 500, but 0.46 ppt in the mercury atomic absorption analyzer 100 of the first embodiment, and the lower limit of quantification was improved three times.

  As described above, since the mercury atomic absorption spectrometer 100 of the first embodiment can automatically adjust the gains of the amplifier circuits 13 and 14, it can be used even if it has been used for a long time (for example, 5 years or more). The output reference voltage that constitutes the line has little fluctuation, and even if the output reference voltage falls outside the allowable range, the gain is automatically adjusted, the baseline is stabilized, noise generation is suppressed, and the lower limit of quantification and accuracy can be improved. . Furthermore, since the offset voltage of the amplifier circuits 13 and 14 can be automatically adjusted, the linearity of the calibration curve can be maintained.

  Further, the control means 17 of the mercury atomic absorption spectrometer 100 of the first embodiment monitors the number of individual transmission pulses, and when the number of transmission pulses on the measurement side or reference side becomes equal to or less than the allowable number of pulses, the measurement side detector 8 or an alarm signal indicating that the output current Ip of the reference-side detector 9 is equal to or greater than the maximum rated value, and a warning recommending replacement with the low-sensitivity detector 8 or 9 or the low-intensity mercury lamp 1 The measurer is warned by displaying it on the display means 22 or generating a warning sound.

  For example, the output reference voltage is 4 V, the maximum number of control pulses transmitted from the control means 17 is 256 bits, the measurement-side current-voltage conversion resistor 102 is R1, the measurement-side input resistor 132 is R2, and the measurement-side gain adjusting digital potentiometer 15 The output current Ip of the measurement-side detector 8 can be expressed by the following equation 1, where RDPmax is the maximum resistance value and Ddg is the number of control pulses transmitted to the measurement-side gain adjusting digital potentiometer 15.

    Ip = (4 × 256 × R2) / (R1 × RDPmax × Ddg) (1)

  Here, R1, R2, and RDPmax are resistance values determined by the apparatus, and if the maximum rated value of the output current Ip of the measurement-side detector 8 is applied to Ip of the formula 1, it corresponds to the maximum rated value of the output current Ip. Since the control pulse number Ddg to be obtained is obtained, the control pulse number Ddg is monitored, and when the control pulse number Ddg is less than the allowable pulse number, an abnormal signal can be generated. Accordingly, as described above, by displaying a warning recommending replacement to the low-sensitivity detectors 8 and 9 or the low-intensity mercury lamp 1, or generating a warning sound to notify the measurer, Deterioration of the detectors 8 and 9 can be prevented.

  Hereinafter, a mercury atomic absorption spectrometer 200 according to the second embodiment of the present invention shown in FIG. 7 will be described. The mercury atomic absorption spectrometer 200 according to the second embodiment includes a control unit 27 having a configuration and operation different from those of the control unit 17 of the mercury atomic absorption spectrometer 100 of the first embodiment. The personal computer 20 is provided with instruction means 28 for instructing the control means 27 to automatically adjust the respective offset voltages. Since other configurations are the same, the control unit 27 and the instruction unit 28 will be described, and the description of the other configurations will be omitted.

  When the measurer calls the optical system adjustment screen by the instruction unit 28 provided in the personal computer 20 while the mercury lamp 1 is turned on, the optical system adjustment screen shown in FIG. 8 is displayed on the display unit 22. When the AUTO button 29 displayed on this screen is clicked, the control means 27 sets the respective gains with the respective digital potentiometers 15 and 16 so that the respective output reference voltages become the respective predetermined set voltages. Automatic adjustment is performed, and after the automatic adjustment, the mercury lamp 1 is automatically turned off, and the respective offset voltages are automatically adjusted by the respective digital potentiometers 18 and 19 so that the respective offset voltages become 0V.

  When the AUTO button 29 is clicked, first, the control means 27 causes the measurement side (Sig) gain adjustment (SPAN) to function, and increases the number of control pulses transmitted to the measurement side gain adjustment digital potentiometer 15 from zero. When the output reference voltage reaches 4V, the data transmission is terminated and the data is held. Subsequently, the reference side (Ref) gain adjustment (SPAN) is made to function, and the control pulse is transmitted to the reference side gain adjustment digital potentiometer 16 in the same manner as the measurement side to automatically adjust the output reference voltage to 4V. To do. The measurement-side SPAN data 31 on the screen of FIG. 8 is 45 bits (bit) and the resistance value is about 8.8 KΩ, and the reference-side SPAN data 32 is 111 bits (bit) and the resistance value is about 22 KΩ. It has become.

  After the automatic adjustment of the gain (SPAN), the mercury lamp 1 is automatically turned off, the zero adjustment (ZERO) on the measurement side (Sig) is functioning, and the output voltage of the measurement side amplifier circuit 13 is deviated from 0V. The control pulses of the number corresponding to the deviation from 0V from the 27 digital data transmission units 171 are transmitted to the digital data reception unit 181 of the measurement-side offset adjustment digital potentiometer 18 so that the output voltage becomes 0V. Is automatically adjusted. The reference side offset voltage is also automatically adjusted in the same manner as the measurement side offset voltage.

  It is also possible to individually adjust each gain and each offset voltage by clicking the SPAN button 33 and ZERO button 34 on the screen of FIG. 8, and input data directly to the data input unit 35. It is also possible to do. As described above, it is possible to automatically adjust the gain and the offset voltage of each of the measurement side and the reference side by a simple operation from the screen of the display means 22, and it is troublesome to manually operate the trimmer as in the prior art. There is no need for work.

  According to the mercury atomic absorption spectrometer 200 according to the second embodiment of the present invention, since the indicator means 28 is provided, the gain and offset voltage are automatically set using the indicator means 28 when the mercury atomic absorption analyzer 200 is manufactured. In addition to being able to set, the measurer can automatically adjust the gain and offset voltage using the instruction means 28. In addition, since each digital potentiometer 15 and 16 automatically adjusts each gain, there is no jitter, there is little change in resistance value due to temperature change, there is little fluctuation in the output reference voltage constituting the baseline, and the output reference voltage is allowed Even if out of range, the gain is automatically adjusted, the baseline is stabilized over a long period of time, noise is suppressed, and the lower limit of quantification and accuracy can be improved.

  Hereinafter, a mercury analysis system 300 according to the third embodiment of the present invention shown in FIG. 9 will be described. The mercury analysis system 300 is a mercury vaporization apparatus that vaporizes mercury in a mercury atomic absorption spectrometer 100, 200 according to the first or second embodiment and introduces it into the mercury atomic absorption spectrometer 100, 200 as a measurement gas S. 301. Since the mercury atomic absorption spectrometers 100 and 200 have been described above, description thereof will be omitted. The mercury vaporization apparatus 301 is an apparatus that generates the measurement gas S using a reduction vaporization method. A solid sample or a liquid sample is thermally decomposed in a sample heating furnace, and the mercury in the measurement gas S generated from the sample is collected by a mercury collecting tube. It is a device to collect.

  In addition, although 1st, 2nd embodiment demonstrated as a non-dispersion type | mold mercury atomic absorption analyzer, this invention may be a wavelength dispersion type | mold mercury atomic absorption analyzer.

DESCRIPTION OF SYMBOLS 1 Mercury lamp 2 Light beam 4 Beam splitter 5 1st beam 6 2nd beam 7 Flow cell 8 Measurement side detector 9 Reference side detector 11 Measurement side current voltage conversion circuit 12 Reference side current voltage conversion circuit 13 Measurement side amplification circuit 14 Reference side Amplification circuit 15 Digital potentiometer for measurement side gain adjustment 16 Digital potentiometer for reference side gain adjustment 17 Control means 18 Digital potentiometer for measurement side offset adjustment 19 Digital potentiometer for reference side offset adjustment 21 Quantitative means 100 Mercury atomic absorption spectrometer

Claims (7)

A mercury lamp that emits rays of mercury analysis lines;
A beam splitter that splits a light beam emitted from the mercury lamp into a first beam and a second beam;
A flow cell through which the first beam and measurement gas pass;
A measurement-side detector that detects the light intensity of the first beam that has passed through the flow cell;
A reference side detector for detecting the light intensity of the second beam;
Based on the ratio of the light intensity detected by the measurement side detector and the light intensity detected by the reference side detector, a quantification means for quantifying mercury in the measurement gas passed through the flow cell;
A measurement-side current-voltage conversion circuit that converts the photocurrent from the measurement-side detector into a voltage;
A reference-side current-voltage conversion circuit that converts a photocurrent from the reference-side detector into a voltage;
A measurement-side amplifier circuit that amplifies the converted voltage converted by the measurement-side current-voltage conversion circuit;
A reference-side amplifier circuit that amplifies the converted voltage converted by the reference-side current-voltage converter circuit;
A mercury atomic absorption spectrometer comprising:
The measurement side amplification circuit has a measurement side gain adjustment digital potentiometer for adjusting the measurement side gain so that the measurement side output reference voltage constituting the baseline at the time of measurement becomes a predetermined setting voltage,
The reference side amplification circuit has a digital potentiometer for reference side gain adjustment for adjusting a reference side gain so that a reference side output reference voltage constituting a baseline at the time of measurement becomes a predetermined set voltage,
Control means for controlling the measurement-side gain adjustment digital potentiometer and the reference-side gain adjustment digital potentiometer;
When the mercury lamp is lit, the control means monitors the measurement-side output reference voltage and the reference-side output reference voltage, and the respective digital potentiometers are set to the respective predetermined set voltages. Mercury atomic absorption spectrometer that automatically adjusts each gain. The mercury atomic absorption spectrometer according to claim 1,
The measurement side amplification circuit has a measurement side offset adjustment digital potentiometer for adjusting the measurement side offset voltage so that the measurement side output voltage becomes 0V,
The reference side amplifier circuit has a digital potentiometer for reference side offset adjustment for adjusting the reference side offset voltage so that the reference side output voltage becomes 0V,
When the mercury lamp is turned off, the control means monitors the measurement-side output voltage and the reference-side output voltage, and automatically sets each offset voltage by each of the digital potentiometers so that each becomes 0V. Adjusting mercury atomic absorption spectrometer. A mercury lamp that emits rays of mercury analysis lines;
A beam splitter that splits a light beam emitted from the mercury lamp into a first beam and a second beam;
A flow cell through which the first beam and measurement gas pass;
A measurement-side detector that detects the light intensity of the first beam that has passed through the flow cell;
A reference side detector for detecting the light intensity of the second beam;
Based on the ratio of the light intensity detected by the measurement side detector and the light intensity detected by the reference side detector, a quantification means for quantifying mercury in the measurement gas passed through the flow cell;
A measurement-side current-voltage conversion circuit that converts the photocurrent from the measurement-side detector into a voltage;
A reference-side current-voltage conversion circuit that converts a photocurrent from the reference-side detector into a voltage;
A measurement-side amplifier circuit that amplifies the converted voltage converted by the measurement-side current-voltage conversion circuit;
A reference-side amplifier circuit that amplifies the converted voltage converted by the reference-side current-voltage converter circuit;
A mercury atomic absorption spectrometer comprising:
In the measurement-side amplifier circuit, a measurement-side gain adjustment digital potentiometer for adjusting the measurement-side gain so that the measurement-side output reference voltage constituting the baseline at the time of measurement becomes a predetermined set voltage, and the measurement-side output A digital potentiometer for measuring side offset adjustment for adjusting the measuring side offset voltage so that the voltage becomes 0V;
In the reference side amplifier circuit, a reference side gain adjusting digital potentiometer for adjusting a reference side gain so that a reference side output reference voltage constituting a baseline at the time of measurement becomes a predetermined set voltage, and a reference side output A digital potentiometer for reference side offset adjustment for adjusting the reference side offset voltage so that the voltage becomes 0V;
Control means for controlling the respective digital potentiometers;
Instruction means for instructing the measurer to automatically adjust the respective gain and the respective offset voltage;
With
When the mercury lamp is turned on, based on an instruction to the instruction unit, the control unit is configured to use the respective digital potentiometers so that the respective output reference voltages become the respective predetermined set voltages. The mercury lamp is automatically turned off, and the mercury lamp is automatically turned off, and each offset voltage is automatically adjusted by each digital potentiometer so that each offset voltage becomes 0V. Analysis equipment. In the mercury atomic absorption spectrometer as described in any one of Claims 1-3,
The measurement-side current-voltage conversion circuit has a measurement-side current-voltage conversion resistor;
The reference-side current-voltage conversion circuit has a reference-side current-voltage conversion resistor;
A mercury atomic absorption spectrometer in which the respective current-voltage conversion resistors and the respective digital potentiometers have a temperature coefficient of 25 ppm / ° C. or less. In the mercury atomic absorption spectrometer as described in any one of Claims 1-4,
A mercury atomic absorption spectrometer in which the measurement side amplification circuit and the reference side amplification circuit have both functions of amplification and attenuation. In the mercury atomic absorption spectrometer as described in any one of Claims 1-5,
The control means individually transmits control pulses having variable pulse numbers to the measurement-side gain adjustment digital potentiometer and the reference-side gain adjustment digital potentiometer, and the individual transmission that is the number of the individually transmitted control pulses. The resistance values of the measurement-side gain adjustment digital potentiometer and the reference-side gain adjustment digital potentiometer are varied according to the number of pulses, and the individual transmission pulse numbers are monitored to transmit the measurement-side or reference-side transmission. A mercury atomic absorption spectrometer that generates an abnormal signal indicating that the output current of the detector is greater than or equal to a maximum rated value when the number of pulses is less than or equal to a predetermined number. A mercury atomic absorption analyzer according to any one of claims 1 to 6,
A mercury vaporizer that vaporizes mercury in the sample and introduces it into the mercury atomic absorption spectrometer as a measurement gas;
Mercury analysis system equipped with.

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