JP2009019886A - Mercury atomic fluorescence analyzer - Google Patents

Abstract

An object of the present invention is to provide a mercury atomic fluorescence analyzer capable of obtaining an accurate and accurate analytical value even when repeatedly measuring immediately after measurement when measuring a sample containing a high concentration of mercury.
A mercury atomic fluorescence spectrometer 1 includes a mercury lamp 10 that emits light 11 in the ultraviolet and visible regions, a flow cell 20 through which a gaseous sample S passes, and a light beam 11 from the mercury lamp 10 into the flow cell 20. A sample-side detector 30 that detects the intensity of mercury fluorescence 12 emitted from the gaseous sample S that is irradiated and passes through the flow cell 20, and a reference-side detector that detects the intensity of the light beam 11 emitted from the mercury lamp 10. 40, a net output value which is an output value obtained by subtracting a base output value which is an output value when the sample side detector 40 is not measured from a signal output value which is an output value of the sample side detector 30, and a reference side detector The output correction means 50 corrects the output value of the sample-side detector 30 with the output value of 40.
[Selection] Figure 1

Description

  The present invention includes a sample-side detector and a reference-side detector, corrects the output value of the sample-side detector by calculating the output value of both detectors, and affects the residual mercury in the sample remaining in the apparatus. The present invention relates to a mercury atomic fluorescence analyzer for removing water.

  Conventionally, mercury analysis by atomic fluorescence has been performed. Mercury by flowing a gaseous sample into a flow cell made of quartz glass, irradiating the sample with ultraviolet rays generated from a mercury lamp, and detecting the fluorescence intensity of mercury generated from mercury atoms present in the sample with a detector. Quantitative analysis has been conducted.

  As shown in FIG. 5, the conventional mercury atomic fluorescence analyzer is generated by flowing a gaseous sample S through a flow cell 20 made of quartz glass and irradiating the sample S with ultraviolet rays 11 emitted from the mercury lamp 10. The intensity of the mercury fluorescence 12 is amplified by a photomultiplier tube 70, and the photocurrent is converted into a voltage signal by a current / voltage conversion circuit 71 formed of an operational amplifier. This voltage signal is input to the signal processing unit 80, subjected to A / D conversion and then subjected to signal processing, and displayed on the display 85 as a signal intensity profile indicating the amount of mercury in the sample.

  As shown in FIG. 6, the signal voltage profile of the current / voltage conversion circuit 71 shows that the scattered light from the mercury lamp 10 is incident on the photomultiplier tube 70 even when mercury is not present in the flow cell 20. The base voltage Vb, which is a signal voltage at the time of non-measurement, becomes a raised voltage, and at the time of sample measurement, a signal voltage corresponding to the intensity of mercury fluorescence generated from the sample in the flow cell 20 is superimposed on the base voltage Vb. Signal voltage Vs. Further, when the same sample is measured for the case where the light quantity of the mercury lamp 10 is reduced by 20% and the case where the light quantity is not diminished (the light quantity is 100%) and the signal intensity profiles are compared, as shown in FIG. Compared with the signal intensity profile J (solid line), the intensity of the signal intensity profile K (broken line) when the amount of light is reduced by 20% is lowered. As described above, when the amount of ultraviolet light 11 emitted from the mercury lamp 10 irradiated on the sample S increases, the intensity of the mercury fluorescence 12 generated from the sample S increases, and the mercury lamp 10 irradiated on the sample S emits. When the amount of ultraviolet light 11 decreases, the intensity of mercury fluorescence 12 generated from the sample S decreases. Therefore, it is necessary for the mercury atomic fluorescence analyzer to compensate for the change in the amount of the ultraviolet rays 11 emitted from the mercury lamp 10.

  For this reason, in the conventional apparatus, in order to solve these problems, the value calculated by the equation (1) is used as the signal intensity Is. FIG. 7 shows a profile obtained by signal processing using the equation (1), and the baseline of the signal intensity is located at 0 point. Further, since the signal processing is performed using the equation (1), the signal voltage Vs and the base voltage Vb change at the same rate even if the amount of light from the mercury lamp changes, and the signal intensity Is does not change.

    Is = Vs / Vb-1 (1)

  However, in the conventional apparatus, the change in the amount of light emitted from the mercury lamp is compensated. However, when measuring a high concentration of mercury of 100 ng, for example, as shown in FIG. 9, the first measurement value L (solid line) ), The second measurement value M (broken line) after 5 minutes is 10% lower in signal strength. When the signal voltage Vs and the base voltage Vb were measured, the base voltage Vb of the first measurement value was 56 mV, the peak value of the signal voltage Vs was 247 V, and the base voltage Vb of the second measurement value was 62 mV. The peak value of the signal voltage Vs was 246V.

  As a result of calculating the rate of change of each voltage from these measured values, the rate of change of the signal voltage Vs was 0.4%, and the rate of change of the base voltage Vb was 10.7%. It can be seen that the fluctuation of the base voltage Vb is the main factor that reduced the signal intensity by 10%. The base voltage Vb rises in the second measurement because when high-concentration mercury is measured, the mercury in the sample remains in the piping system of the gaseous sample flow path, and the intensity of fluorescence generated by the residual mercury is reduced. I noticed that the photomultiplier tube was detecting it. Therefore, in the conventional apparatus, in order to perform an accurate and accurate measurement, it is impossible to start the next measurement until the residual mercury flows out from the piping flow path in the apparatus and the base voltage becomes stable. There was a problem of requiring a long waiting time of more than a minute.

  The present invention has been made in view of the above-described conventional problems. When measuring a sample containing a high concentration of mercury, a mercury atom capable of obtaining an accurate and accurate analytical value even if it is repeatedly measured immediately after the measurement. An object is to provide a fluorescence analyzer.

  In order to achieve the above object, a mercury atomic fluorescence analyzer of the present invention includes a mercury lamp that emits light in the ultraviolet and visible regions, a flow cell through which a gaseous sample passes, and a light beam from the mercury lamp that is in the flow cell. A sample-side detector that detects the intensity of mercury fluorescence generated from a gaseous sample that passes through the flow cell, a reference-side detector that detects the intensity of light emitted from the mercury lamp, and A net output value that is an output value obtained by subtracting a base output value that is an output value when the sample is not measured by the sample side detector from a signal output value that is an output value of the sample side detector, and an output value of the reference side detector And an output correction means for correcting the output value of the sample side detector. In the present invention, a gaseous sample refers to a vaporized mercury sample obtained by vaporizing a mercury sample contained in a gas sample, a solution sample, or a solid sample by a reduction vaporization method or a heat vaporization method.

  According to the mercury atomic fluorescence spectrometer of the present invention, it is not affected by residual mercury due to a high-concentration sample, and repeated measurement at short intervals from a high-concentration sample to a low-concentration sample can be performed. Accurate and accurate analysis values can be obtained.

  In the mercury atomic fluorescence analyzer of the present invention, the output correction means multiplies the net output value by a ratio between a predetermined standard output value of the reference side detector and an output value of the reference side detector. It is preferable to correct the output value of the sample side detector.

  Hereinafter, a mercury atom fluorescence analyzer according to a first embodiment of the present invention will be described. As shown in FIG. 1, the mercury atomic fluorescence analyzer 1 includes a mercury lamp 10 that emits light 11 in the ultraviolet and visible regions, a flow cell 20 through which a gaseous sample S passes, and a light 11 from the mercury lamp 10. The photomultiplier tube 30 which is a sample-side detector for detecting the intensity of the mercury fluorescence 12 generated from the gaseous sample S irradiated to the flow cell 20 and passing through the flow cell 20, and the output current of the photomultiplier tube 30 are A sample-side current / voltage conversion circuit 31 composed of an operational amplifier that converts the sample-side signal voltage Vs, a photosensor 40 that is a reference-side detector that detects the intensity of the light beam 11 emitted from the mercury lamp 10, A reference-side current / voltage conversion circuit 41 composed of an operational amplifier that converts an output current into a reference-side signal voltage Vr, an input sample-side signal voltage Vs, and a reference-side signal voltage Vr The A / D converter 51 calculates after the A / D conversion, and based on the calculated value, the output correction means 50 for correcting the signal intensity, which is the output value on the sample side, and the display 55 for displaying the signal intensity profile are provided. Have.

  The mercury lamp 10 is, for example, a discharge tube in which mercury is enclosed, and emits light in the ultraviolet and visible regions when energized and discharged, and the emitted ultraviolet light includes a mercury resonance line having a wavelength of 253.7 nm. Yes. As shown in FIG. 1, the flow cell 20 and the photosensor 40 are arranged at positions facing each other with the mercury lamp 10 in the middle, and the mercury lamp 10 has a light beam 11 in each of the direction toward the flow cell 20 and the direction toward the photosensor 40. Is radiating. The flow cell 20 has a shape of, for example, a square cylinder, and is formed of synthetic quartz having a vertical dimension of 12 mm, a horizontal dimension of 12 mm, a height of 40 mm, and a thickness of 1 mm. The photomultiplier tube 30 is highly sensitive to ultraviolet rays and is disposed at a position where the light beam 11 of the mercury lamp 10 does not directly enter. The photosensor 40 is sensitive to the light beam 11 in the ultraviolet and visible regions, and is arranged at a position where the light beam of the mercury lamp 10 is directly incident. The output correction means 50 includes an A / D conversion unit 51, a memory unit 53, and a CPU unit 52.

  Next, the operation of the mercury atomic fluorescence analyzer 1 of the first embodiment shown in FIG. 1 will be described. When the mercury atomic fluorescence analyzer 1 is energized, the mercury lamp 10 is turned on and emits light 11 in the ultraviolet and visible regions. The photomultiplier tube 30 detects the intensity of the scattered light of the mercury lamp 10 generated by irradiating the emitted light beam 11 to the flow cell 20, and the sample-side current / voltage conversion circuit 31 detects the detection signal. The signal is output to the output correction means 50 as the signal voltage Vs. On the other hand, the photosensor 40 detects the intensity of the light beam 11 and the reference-side current / voltage conversion circuit 41 outputs the detection signal to the output correcting means 50 as the reference-side signal voltage Vr. The memory unit 53 of the output correction means 50 stores the reference side signal voltage Vr after 30 minutes of energization of the mercury atomic fluorescence analyzer 1 as the reference side reference voltage Vc. The reference-side reference voltage Vc is not limited to the reference-side signal voltage Vr after 30 minutes of energization of the mercury atomic fluorescence analyzer 1, but the reference-side signal voltage Vr after 20 or 40 minutes has passed is appropriately determined according to the purpose of analysis. Just choose.

  When the sample measurement is started, the gaseous sample S is introduced from the sample introduction unit (not shown), but the sample-side signal voltage Vs immediately before the gaseous sample S is introduced into the flow cell 20 is used as the base voltage Vb. Is stored in the memory unit 53. When the gaseous sample S is introduced into the flow cell 20, the sample 11 is irradiated with the light beam 11 from the mercury lamp 10, and a fluorescence 12 of 253.7 nm is generated from the mercury atoms in the sample S. The multiplier tube 30 detects, and the sample side current / voltage conversion circuit 31 outputs the detection signal to the output correction means 50 as the sample side signal voltage Vs. At this time, the photosensor 40 detects the intensity of the light beam 11 of the mercury lamp 10, and the reference side current / voltage conversion circuit 41 outputs the detection signal to the output correction means 50 as the reference side signal voltage Vr. The output correction means 50 uses the following equation (2) for the sample-side signal voltage Vs and the reference-side signal voltage Vr, and the base voltage Vb and the reference-side reference voltage Vc stored in the memory unit 53. The CPU unit 52 calculates and corrects the sample-side output value and outputs the signal intensity Is. A signal intensity profile is displayed on the display 55 based on the output value Is.

Is = (Vs−Vb) × Vc / Vr (2)

  Vs−Vb is a net output value that is an output value obtained by subtracting a base output value Vb that is an output value when the sample side detector 30 is not measuring from a signal output value Vs that is an output value of the sample side detector 30. . Vc / Vr is a ratio between a predetermined reference output value Vc of the reference side detector 40 and an output value Vr of the reference side detector 40.

  FIG. 2 shows a signal intensity profile obtained by measuring the mercury concentration of 100 ng which is a high concentration in the mercury atomic fluorescence analyzer 1 of the first embodiment. The first measurement profile A (solid line) and the second measurement profile B (broken line) after 5 minutes are shown. Both profiles are almost the same. The results of analysis with good reproducibility are also obtained. This is because the photomultiplier tube 30 in which the apparatus 1 of the first embodiment is a sample side detector, a sample side current / voltage conversion circuit 31, a photosensor 40 as a reference side detector, and a reference side current / voltage conversion circuit 41. This is because the output correction means 50 is provided and the output value Vs of the sample-side detector 30 is corrected based on the equation (2), so that it is not affected by residual mercury in the high-concentration sample.

  In addition, the result of having investigated about the influence of the light quantity change of the mercury lamp 10 in the apparatus 1 of 1st Embodiment is shown in FIG. As shown in FIG. 3, the measurement profile C (solid line) when the light quantity of the mercury lamp is irradiated by 100% coincides with the measurement profile D (dashed line) when the light quantity decreases by 20%. As described above, in the apparatus 1 of the first embodiment, the reference-side signal voltage Vr after 30 minutes has passed after energization is stored as the reference voltage Vc, and the output correction unit 50 performs correction using the above-described equation (2). Since the light quantity change of the mercury lamp 10 is compensated, both signal intensities Is at the time of sample measurement can be made the same.

  A mercury atomic fluorescence analyzer that is a second embodiment of the present invention will be described. As shown in FIG. 4, in the device 2 of the second embodiment, a half mirror 60 for transmitting and reflecting the light beam 11 of the mercury lamp 10 is added to the device 1 of the first embodiment, and the mercury lamp 10 and the reference side detector are added. The arrangement of the photosensor 40 is different from that of the apparatus 1 of the first embodiment, and the other configurations are the same. Only the different configurations will be described below. The light beam 11 from the mercury lamp 10 is divided into a transmitted light beam 11 a and a reflected light beam 11 b by the half mirror 60, the transmitted light beam 11 a is irradiated on the flow cell 20, and the reflected light beam 11 b is incident on the photosensor 40. The half mirror 60 uses a synthetic quartz plate and is fixed so as to have an incident angle of 45 ° with respect to the light beam 11 from the mercury lamp 10.

  Since the device 2 of the second embodiment also includes the photosensor 40 that is a reference-side detector, the reference-side current / voltage conversion circuit 41, and the output correction means 50, the same operation as the device 1 of the first embodiment. An effect can be obtained.

  In the above embodiment, the non-dispersion type mercury atom fluorescence analyzer has been described. However, a wavelength dispersion type mercury atom fluorescence analyzer may be used. Moreover, although the apparatus which measures by a batch system was demonstrated, the effect similar to the apparatus of embodiment can be acquired also by the apparatus which measures by a continuous system, flowing a gaseous sample to a flow cell.

1 is a schematic block diagram of a mercury atomic fluorescence analyzer that is a first embodiment of the present invention. FIG. It is the signal intensity profile of the high concentration sample by the same apparatus. It is the signal intensity profile which investigated the influence of the light quantity change of the mercury lamp by the same apparatus. It is a schematic block diagram of the mercury atom fluorescence analyzer which is 2nd Embodiment of this invention. It is a schematic block diagram of the conventional mercury atom fluorescence analyzer. It is the profile of the signal voltage by the same apparatus. It is the profile of the signal strength by the same apparatus. It is the signal intensity profile which investigated the influence of the light quantity change of the mercury lamp by the same apparatus. It is the signal intensity profile of the high concentration sample by the same apparatus.

Explanation of symbols

1, 2 Mercury atomic fluorescence analyzer 10 Mercury lamp 11 Light beam (ultraviolet light)
12 Mercury fluorescence 20 Flow cell 30 Sample-side detector (photomultiplier tube)
40 Reference side detector (photo sensor)
50 Output correction means S Sample

Claims (2)

A mercury lamp emitting ultraviolet and visible light;
A flow cell through which a gaseous sample passes;
A sample-side detector for detecting the intensity of mercury fluorescence generated from the gaseous sample passing through the flow cell by irradiating the flow cell with light from the mercury lamp;
A reference detector for detecting the intensity of light emitted from the mercury lamp;
A net output value that is an output value obtained by subtracting a base output value that is an output value when the sample of the sample side detector is not measured from a signal output value that is an output value of the sample side detector, and an output of the reference side detector Output correction means for correcting the output value of the sample side detector based on the value;
Mercury atomic fluorescence spectrometer.   2. The sample-side detector according to claim 1, wherein the output correction unit multiplies the net output value by a ratio between a predetermined reference output value of the reference-side detector and an output value of the reference-side detector. Mercury atom fluorescence analyzer that corrects the output value of.

Images