JP4938429B2 - Impurity analysis method and apparatus - Google Patents

Description

  The present invention relates to a method and apparatus for analyzing the concentration of impurities contained in a liquid, and in particular, impurities of extremely high purity ultrapure water and process water used for electronic industry applications and pharmaceutical applications. It is suitable for concentration analysis.

  When an extremely pure liquid such as ultrapure water or process water is used in an industrial facility such as a semiconductor factory or a power plant, it is important to control the purity of the liquid, in other words, to monitor the impurity concentration.

Conventionally, as a method for analyzing such impurity concentration, a method using absorption analysis as disclosed in Patent Document 1 is known. In this method, a part of the liquid flowing in the ultrapure water or process water line is branched from the line and passed through the porous membrane, and the amount of impurities trapped in a concentrated state by the porous membrane is measured by a surface analyzer. Measure.
JP 2001-153855 A

  Since the method described in Patent Document 1 uses a surface analyzer, a high concentration is required for the porous membrane. Therefore, expensive equipment including this porous membrane is required. Furthermore, the time required for the concentration, the exchange work of the porous membrane, and the like reduce the analysis efficiency. In addition, it is difficult to dramatically improve the analysis accuracy by this method.

  On the other hand, the analysis of the impurities is required to be performed online (that is, without stopping the line of ultrapure water or the like).

  In view of such circumstances, an object of the present invention is to provide a method and apparatus that can efficiently and accurately analyze the concentration of impurities contained in ultrapure water, process water, or the like.

As means for solving the above problems, the present invention provides a method for measuring impurities contained in a liquid flowing through a predetermined line, wherein a part of the liquid flowing through the line is branched from the line. The measurement object is introduced into the sampling unit provided in advance and flows into the absorption analysis unit consisting of a straight pipe included in the sampling unit, and the liquid that is introduced into the sampling unit and flows through the absorption analysis unit. The operation of irradiating excitation light having a wavelength that matches the light absorption characteristics of the impurity along the flow direction of the liquid in the absorption analysis section, and the photothermal effect of the impurity is generated by irradiation of the excitation light in the liquid measurement target region in the absorption analysis unit to an operation that irradiates along another measurement beam from the excitation light in the flow direction of the liquid in the pumping light coaxial with the Operation and for detecting the phase change of the measurement light transmitted through the constant region of interest, on the basis of the detection result is intended to include operation and for calculating the impurity concentration in the liquid.

Further, the present invention is an apparatus for measuring impurities contained in a liquid flowing through a predetermined line, comprising an absorption analysis unit that is branched from the line and comprises a straight pipe, and flows through the line irradiating a portion is introduced flowed sampling unit to the absorption analysis of the liquid, the excitation light along the flow direction of the liquid the absorption analysis portion relative to the flow Ru liquid is introduced into the sampling section With respect to the measurement target region in the absorption analysis unit in which the photothermal effect of the impurities is caused by irradiation of the excitation light in the liquid, the measurement light different from the excitation light is coaxial with the excitation light and the excitation light irradiation system. a measuring light irradiation system that irradiates along the flow direction of the liquid, and a phase change detector for detecting a phase change of the measurement light transmitted through the measurement target region, based on a detection signal of the phase change detector There are those in which a signal processing unit for outputting a measurement signal for the impurity concentration in the liquid.

In these methods and apparatuses, a part of the liquid flowing in a predetermined line is introduced into the sampling unit and is flowed to the absorption analysis unit consisting of a straight pipe included in the sampling unit, and the flow direction with respect to this liquid Excitation light is irradiated along . This excitation light causes a photothermal effect on the impurities in the liquid. Then, the measurement target region in the absorption analysis unit that exhibits the photothermal effect is irradiated with measurement light different from the excitation light along the flow direction of the liquid coaxially with the excitation light, and the measurement light is refracted. The rate varies with the photothermal effect. Since this change in refractive index causes a change in the phase of the measurement light, it is possible to grasp the degree of the photothermal effect, that is, the absorbance of the excitation light, based on the detection result of the phase change of the measurement light. As a result, the weight of impurities contained in the liquid and the concentration in the liquid can be measured.

  Therefore, unlike the above-described prior art, the method and apparatus do not require a high concentration treatment, and the impurity concentration in the liquid can be analyzed efficiently and with high accuracy. In addition, the impurities can be analyzed online without stopping the flow of liquid in the line.

  Note that the present invention is not intended to exclude one that performs a process of concentrating the liquid before irradiation with the excitation light and measurement light. However, even when the concentration treatment is performed, a simple one is sufficient for the treatment, unlike a method using a conventional surface analyzer. Further, the analysis accuracy is further improved by the concentration process.

  In the method, when the impurity to be measured includes a metal or a metal ion, light having a specific wavelength is obtained by chemically reacting with the impurity in a liquid branched from the line before irradiating the excitation light. More preferably, the excitation light is irradiated with light having a wavelength that can be absorbed by the complex. Thereby, even when the impurity contains a metal or a metal ion, the analysis according to the present invention can be performed.

  The impurity made of the metal or metal ion may not have light absorption characteristics for any wavelength in the ultraviolet region, visible region, and infrared region. No effect can be expected. However, when the reagent is added to this impurity and the two chemically react to generate a complex having the property of absorbing the excitation light, it is possible to obtain light absorption and photothermal effects by this complex. . And the density | concentration of the said impurity can be measured using this photothermal effect.

  Further, in the method according to the present invention, the liquid branched from the line is allowed to flow through a specific portion of the sampling unit at a predetermined flow rate, and the liquid flowing through the specific portion is irradiated with the excitation light, thereby It is possible to monitor the concentration continuously in real time. In this method, the impurity concentration is calculated based on the weight of the impurity in the liquid obtained from the detection result and the flow rate of the liquid.

  Even in such a case, it is possible to analyze impurities including metals or metal ions by using the above-described reagents. Specifically, prior to the operation of irradiating the excitation light, a reagent that generates a complex that absorbs light having a specific wavelength by chemically reacting with the impurity in the liquid flowing through the specific portion is added to the liquid. Adding and mixing at a flow rate corresponding to the flow rate, irradiating light having a wavelength that can be absorbed by the complex as the excitation light, the weight of impurities in the liquid obtained from the detection result, the flow rate of the liquid, and the reagent The impurity concentration in the liquid may be calculated based on the addition flow rate of the liquid.

  On the other hand, in the apparatus, when analyzing impurities containing metal or metal ions, the sampling unit is provided with an absorption analysis unit that is irradiated with the excitation light and the measurement light, and an upstream side of the absorption analysis unit. And a colored part that is added to and mixed with a reagent that generates a complex that absorbs light having a specific wavelength by chemically reacting with the impurity, and the excitation light irradiation system includes What is necessary is just to irradiate the liquid introduce | transduced into the said absorption-analysis part from the coloring part with the light of the wavelength which the said complex can absorb as said excitation light.

Further, in the device, wherein the sampling unit, Ri connected to the line, a branch pipe that includes the absorption analysis unit and a flow rate regulator for regulating the flow rate of the liquid flowing through the branch pipe to a particular flow, If the signal processing device calculates the impurity concentration in the liquid based on the weight of the impurity in the liquid obtained from the detection result and the flow rate of the liquid adjusted by the flow rate adjustment unit The concentration of the impurities can be continuously monitored in real time.

  Then, when analyzing impurities including metal or metal ions in this apparatus, the branch pipe includes an absorption analyzer that irradiates the liquid flowing in the branch pipe with the excitation light and the measurement light. A colored portion located upstream of the absorption analysis portion, and the colored portion contains a reagent that generates a complex that absorbs light having a specific wavelength by chemically reacting with the impurities. A reagent addition unit that is added and mixed at a flow rate corresponding to the flow rate is connected, and the excitation light irradiation system irradiates the liquid flowing through the absorption analysis unit with light having a wavelength that can be absorbed by the complex as the excitation light. The signal processing device calculates the impurity concentration in the liquid based on the weight of the impurity in the liquid obtained from the detection result, the flow rate of the liquid, and the addition flow rate of the reagent. It may be any configuration.

  In the apparatus according to the present invention, the excitation light irradiation system irradiates light whose intensity is periodically modulated as the excitation light, and the signal processing apparatus synchronizes with the period of the intensity modulation. It is preferable to take in the detection signal.

  In this apparatus, since the detection signal changes in the same period as the intensity modulation of the excitation light, capturing the detection signal at a timing synchronized with the period affects the influence of noise having no frequency component of the excitation light. It is possible to measure only the phase change (ie, refractive index change) while removing. This improves the S / N ratio of the phase change measurement.

  As the phase change detection device, a spectroscopic optical system that splits the reference light from the measurement light and causes the reference light to interfere with the measurement light transmitted through the measurement target region, and the intensity of the interfered light are detected. Those including a photodetector are preferred. In addition, each of the light reflection units includes a light reflection unit disposed in a posture opposite to the positions on both sides of the measurement target region, and a light detector, and each of the light reflection units transmits the measurement target region. The measurement light is reciprocated by reflecting a part of the light to the light reflection part of the other party, and the light detector has at least one light reflection part of the light reflection part on the side opposite to the measurement target region. A sensor that receives the transmitted measurement light and detects its intensity is also suitable. This apparatus can realize highly accurate impurity analysis using multiple reflection of measurement light between the light reflecting portions.

  Furthermore, the phase change detection device in the latter analyzer further includes a distance adjustment mechanism that adjusts the distance between the light reflecting portions in a direction that maintains the resonance state of the light reciprocating between the two light reflecting portions. preferable. The adjustment of the distance between the light reflecting portions by the distance adjusting mechanism maintains the resonance state of light reciprocating between the light reflecting portions, thereby effectively increasing the measurement accuracy of the phase change.

  As described above, the present invention makes it possible to efficiently and accurately analyze the concentration of impurities contained in ultrapure water, process water, and the like.

  A first embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 shows the overall configuration of an impurity analyzer according to this embodiment. This apparatus is for analyzing impurities contained in a liquid (for example, ultrapure water or process water) flowing through a predetermined line 1, a branch pipe 2 branched from the line 1, and the branch pipe 2 And a tank 3 connected to the end. And the said branch piping 2 has the introducing | transducing part 2a, the coloring part 2b, and the light absorption analysis part 2c in an order from the upstream.

  The introduction part 2 a is provided with a main valve 4 and a flow rate adjustment part 5. The main valve 4 is opened and closed in order to switch on and off the introduction of the liquid into the branch pipe 2. The flow rate adjusting unit 5 adjusts the flow rate of the liquid flowing through the branch pipe 2.

  Specifically, the flow rate adjusting unit 5 includes a valve device 5a including an electric control unit, a flow meter 5b, and a timer 5c. The flow meter 5b measures the liquid flow rate on the downstream side of the valve device 5a. The timer 5c inputs a command signal to the valve device 5a periodically at a predetermined time interval for a fixed time period (for example, only 1 minute of 1 hour). The valve device 5a is opened only when a command signal is received from the timer 5c, and at the same time, the target opening is calculated based on the measurement signal from the flow meter 5b, and only the target opening is opened. This target opening is calculated so that the liquid flow rate measured by the flow meter 5b approaches the preset target flow rate.

  A reagent addition unit 6 is connected to the coloring unit 2b. This reagent addition part 6 is for adding a reagent for enabling the analysis to the liquid in the colored part 2b when the impurity contains a metal or metal ion having no light absorption property. . As this reagent, a reagent that forms a complex that absorbs light having a specific wavelength by chemically reacting with an impurity composed of the metal or metal ion is used.

  The reagent adding unit 6 includes a reagent tank 6a for storing the reagent, a valve device 6b including an electric control unit, and a flow meter 6c. The valve device 6b is interposed between the reagent tank 6a and the coloring unit 2b, and adjusts the flow rate of the reagent supplied from the reagent tank 6a to the coloring unit 2b. The flow meter 6c measures the reagent flow rate downstream of the valve device 6b. The valve device 6b calculates a target reagent addition flow rate based on the liquid flow rate measured by the flow meter 5c, and further a target opening for bringing the reagent addition flow rate measured by the flow meter 6c closer to the target reagent addition flow rate. Is calculated, and only the target opening degree is opened.

  The colored portion 2b and the reagent adding portion 6 can be omitted as appropriate depending on the type of impurities. For example, when the impurity to be analyzed is composed only of organic molecules that absorb in the ultraviolet region, no particular coloring operation is required. In addition, the type of reagent to be used is appropriately selected depending on the type of impurity. For example, when the impurity is Fe (II), a nitrosophenol reagent is suitable as the reagent. This nitrosophenol reagent reacts with the Fe (II) to generate a complex ion having an absorption wavelength region of 700 to 800 nm.

  A check valve 7 is provided on each of the upstream side and the downstream side of the colored portion 2b. In other words, the portion sandwiched between the check valves 7 corresponds to the colored portion 2b. The check valve 7 on the upstream side of the check valves 7 prevents the liquid or reagent in the coloring part 2b from flowing back to the introduction part 2a side, and the check valve 7 on the downstream side absorbs light absorption described later. The liquid in the analysis unit 2c is prevented from flowing back to the coloring unit 2b side.

  The absorbance analysis unit 2c is provided on the downstream side of the coloring unit 2b, and is constituted by a straight piping portion in the illustrated example. As shown in FIG. 2, the specific portion of the tube wall of the absorption analyzer 2c is formed as an optical entrance window 8A and an exit window 8B by a material having a property of transmitting excitation light Le and measurement light Lm, which will be described in detail later. Composed. An absorption analysis facility is arranged in the vicinity of the absorption analysis unit 2c. This facility includes an excitation light irradiation system 10, a measurement light irradiation system 20, a photodetector 36 and a signal processing device 50.

  The excitation light irradiation system 10 is for irradiating the liquid flowing through the absorption analyzer 2c with the excitation light Le from the incident window 8A from a specific direction (an oblique direction in the example shown in FIG. 2). A light source 12 and a modulation mechanism 14 are provided.

  As the excitation light source 12, for example, a xenon lamp that outputs white light or a mercury lamp that outputs ultraviolet light is preferably used. As the wavelength, a wavelength that can be absorbed by the impurity or the complex generated in the colored portion 2b is selected. The light emitted from the excitation light source 12 is split by a not-shown spectroscopic mechanism and is incident on the modulation mechanism 14. The modulation mechanism 14 is made of, for example, a chopper, and generates excitation light Le suitable for an absorption analysis described later by periodically modulating the intensity of the light.

  The measurement light irradiation system 20 emits measurement light Lm for measuring a change in refractive index due to the photoelectric effect on the measurement target region AS where the photoelectric effect due to the impurities or the complex absorbing the excitation light Le occurs. Irradiation.

  The measurement light irradiation system 20 has a measurement light source 22. For the measurement light source 22, for example, a He—Ne laser generator with an output of 1 mW is used. The light emitted from the measurement light source 22 first passes through the λ / 2 wavelength plate 23, and the λ / 2 wavelength plate 23 adjusts the polarization plane of the light. The adjusted light is incident on the polarization beam splitter 24. The polarization beam splitter 24 splits the light into two polarized lights orthogonal to each other, specifically, the reference light Lr and the measurement light Lm.

  The reference light Lr is subjected to optical frequency shift (frequency conversion) by the acousto-optic modulator 25A, then reflected by the mirror 26A and input to the polarization beam splitter 28. The measurement light Lm is subjected to optical frequency shift (frequency conversion) by the acousto-optic modulator 25B, and then reflected by the mirror 26B and input to the polarization beam splitter 28. The reference light Lr and the measurement light Lm are combined by the splitter 28, and the combined light is guided to the deflection beam splitter 30.

  The deflecting beam splitter 30 reflects the measurement light Lm by 90 ° toward the absorption analyzer 2c, while allowing the reference light Lr to pass therethrough. The reference light Lr passes through the quarter-wave plate 37, is reflected by the mirror 38 by 180 °, and returns to the polarization beam splitter 30 through the quarter-wave plate 37 again. At this time, the quarter wavelength plate 37 rotates the polarization plane of the reference light Lr by 90 ° in total. Accordingly, the reference light Lr is reflected by 90 ° on the side opposite to the absorption analyzing unit 2c by the polarizing beam splitter 30. Then, the light is input to the photodetector 36 through the polarizing plate 35.

  The measurement light Lm reflected by 90 ° by the polarization beam splitter 30 is incident on the measurement target region AS through the quarter-wave plate 32, the condenser lens 33, and the incident window 8A of the absorption analyzer 2c. The measurement light Lm passes through the measurement target area AS and the emission window 8B on the back side thereof, is reflected by a mirror 34 by 180 °, passes through the measurement target area AS again, and passes through the ¼ wavelength plate 32 to transmit the polarized light. Return to the beam splitter 30. At this time, since the measurement light Lm passes back and forth through the quarter-wave plate 32, its plane of polarization rotates by 90 °. The measurement light Lm that has undergone the rotation operation of the deflecting surface passes through the polarization beam splitter 30 as it is, merges with the reference light Lr, and travels toward the polarizing plate 35 and the photodetector 36.

  Here, the entrance window 8A and the exit window 8B each have a material and a size capable of allowing the transmission of each light. As the material, for example, quartz or PDMS (polydimethylsiloxane) is suitable.

  In the polarizing plate 35, the reference light Lr and the measurement light Lm interfere with each other, and the light detector 36 converts the light intensity of the interference light into an electric signal (detection signal). That is, the measurement light irradiation system 20 splits the light emitted from the measurement light source 22 into the measurement light Lm and the reference light Lr, and the measurement light Lm that passes through the reference light Lr and the measurement target region AS. And the optical detector 36 constitutes a phase change detection device.

  The detection signal of the photodetector 36 is input to the signal processing device 40. The signal processing device 40 captures the detection signal at a timing synchronized with the period of the modulation operation of the modulation mechanism 14. That is, sampling is performed periodically.

  Based on the sampled detection signal, the signal processing device 40 calculates a phase change of the measurement light Lm, that is, a phase change caused by the measurement light Lm passing through the liquid. Further, the signal processing device 40 creates data regarding the temporal change of the phase change, and automatically changes the refractive index and further the impurity concentration in the liquid based on the data, as will be described later. Calculate to The principle is as follows.

  The intensity S1 of the interference light is expressed by the following equation (1).

S1 = C1 + C2 · cos (2π · fb · t + φ) (1)
In this equation, C1 and C2 are constants determined by the optical system such as the polarizing beam splitter and the transmittance of the liquid, φ is a phase difference due to the difference between the optical path length of the reference light Lr and the optical path length of the measurement light Lm, and fb Is a frequency difference between the reference light Lr and the measurement light Lm. This equation (1) indicates that the change in the phase difference φ is based on a change in the interference light intensity S1 (that is, when the excitation light Le is not irradiated or when the light intensity is low and when the light intensity is high). Indicates that it is desired.

  When the intensity of the excitation light Le is periodically modulated at the frequency f by the modulation operation of the modulation mechanism 14 (for example, chopper rotation), the refractive index of the liquid and the optical path length of the measurement light Lm change at the frequency f, respectively. To do. On the other hand, since the optical path length of the reference light Lr is constant, the phase difference φ also changes with the frequency f. Therefore, in order to measure (calculate) the change of the phase difference φ with respect to the component of the frequency f (the same period component as the intensity modulation period of the excitation signal), the sampling timing of the detection signal can be synchronized with the modulation operation. It is possible to measure only the refractive index change of the liquid while removing the influence of noise having no frequency f component. This measurement improves the S / N ratio of the measurement of the phase difference φ.

  When the excitation light source 12 is a laser diode or LED, the modulation can be performed by controlling the power source of the excitation light source 12 with an electric circuit.

  The direction of the optical axis of the excitation light Le can be set as appropriate. For example, by using a dichroic mirror 44 as shown in FIG. 3, it is possible to irradiate the excitation light Le and the measurement light Lm coaxially along the liquid flow direction in the absorption analyzer 2c. The dichroic mirror 44 has a characteristic of transmitting the excitation light Le as it is and reflecting the measurement light Lm by 90 °. This characteristic makes it possible to make the optical axes of the light beams Le and Lm the same even when the emission direction of the excitation light Le from the irradiation systems 10 and 20 differs from the emission direction of the measurement light Lm by 90 °. This coaxial irradiation enables irradiation along the flow direction of the liquid. This irradiation extends the measurement optical path length (the length of the measurement target area AS) in the absorbance analysis unit 2c, and improves the analysis accuracy. For this irradiation, the incident side optical window 8A is provided at one of the upstream end and the downstream end of the absorption analysis section 2c, and the output side optical window 8B is provided at the other end.

  Next, an impurity analysis method executed in the impurity analyzer shown in FIGS. 1 and 2 will be described.

  In FIG. 1, when the main valve 4 is opened, a part of the liquid flowing through the line 1 flows into the branch pipe 2. This valve opening may be performed manually, or may be performed by an automatic opening / closing device that is linked to ON / OFF of the switch.

  The flow rate of the liquid flowing into the branch pipe 2 is adjusted by the flow rate adjusting unit 5. Specifically, the valve device 5b of the flow rate adjusting unit 5 periodically allows the liquid to flow for a predetermined time based on a command signal of the timer 5c, and adjusts the flow rate to a target flow rate. This adjustment stabilizes the flow rate of the liquid in the colored portion 2b and the light absorption analysis portion 2c on the downstream side.

  In the colored portion 2b, a reagent is added from the reagent adding portion 6 to the liquid flowing through the colored portion 2b. The reagent addition flow rate is adjusted to a flow rate suitable for the liquid flow rate by the action of the valve device 6b. When the reagent is mixed with the liquid in the colored portion 2b, the reagent chemically reacts with the metal or metal ion that is an impurity in the liquid, that is, a complex suitable for absorption analysis, that is, light having a specific wavelength. To form a complex that absorbs The formation of this complex enables absorption analysis even when the impurity contains a metal or a metal ion.

  In this embodiment, a reagent is added to the liquid flowing in the colored portion 2b. However, the colored portion according to the present invention may temporarily store the liquid in a stationary state. Good. Such a coloring operation in a stationary state can be realized, for example, by closing the on-off valves using on-off valves instead of the check valves 7. In this case, the closing of each on-off valve is maintained for a predetermined reaction time after the addition of the reagent is started. After the reaction time elapses, the downstream on-off valve is opened, and the liquid containing the complex generated by the addition of the reagent is introduced into the next absorption analysis unit 2c. As means for promoting the reaction, it is effective to adjust the temperature of the reaction region with a heater or the like, or to promote the mixing of the liquid and the reagent by rotating the stirring blade.

  In the absorption analysis unit 2c, the excitation light Le is irradiated from the excitation light irradiation system 10 shown in FIG. 2 to the liquid flowing through the absorption analysis unit 2c. The wavelength of the excitation light Le is a wavelength that can be absorbed by the complex. Therefore, the excitation light Le is absorbed with a degree corresponding to the amount of the complex in the liquid. That is, the complex absorbs the excitation light Le and exhibits a photothermal effect by this absorption.

  On the other hand, the measurement light Lm is irradiated from the measurement light irradiation system 20 to the measurement target region AS where the photothermal effect occurs. The measurement light Lm passes through the measurement target area AS, is reflected upward by the mirror 34, and further passes through the measurement target area AS. In the measurement target region AS, the refractive index changes according to the amount of heat generated by the photothermal effect, and the phase difference φ changes according to the refractive index. Therefore, the measurement light Lm returning to the measurement light irradiation system 20 and the measurement light Lm The intensity of interference light with the reference light Lr in the light irradiation system 20 changes according to the amount of heat generated by the photothermal effect. A detection signal corresponding to the interference light intensity is generated by the photodetector 36 of the measurement light irradiation system 20 and input to the signal processing device 40.

  The signal processing device 40 captures the detection signal at a sampling period synchronized with the modulation operation of the modulation mechanism 14. Based on this detection signal, the change in the refractive index of the liquid due to the photothermal effect is calculated. This change in refractive index corresponds to the absorbance of the complex contained in the liquid and thus the amount of the original impurity. Therefore, it is possible to calculate the weight of impurities contained in the liquid (solvent) per unit volume, that is, the impurity concentration, based on the change in refractive index, the flow rate of the liquid, and the addition flow rate of the reagent. It is. The signal processing device 40 creates a measurement signal for such an impurity concentration and outputs the measurement signal to a display device or storage device (not shown) or a warning device for an operation operator as necessary.

  Note that the conversion from the detection signal to the weight of the impurity can be performed, for example, by using a calibration curve prepared in advance. This calibration curve can be obtained by conducting the above-described absorption analysis on a sample whose absorbance and concentration are known, and examining the relationship between the measurement signal and the absorbance.

  In this apparatus, since the refractive index of the liquid and the detection signal thereof change in the same cycle as the intensity modulation of the excitation light Le, the signal processing device 40 captures the detection signal at a timing synchronized with the cycle. Only the change in the refractive index of the liquid can be measured while removing the influence of noise having no frequency component of the excitation light. This improves the S / N ratio of the phase change measurement.

  In the impurity analysis method described above, a part of the liquid flowing in the line 1 is introduced into the branch pipe 2 constituting the sampling unit, and this is performed by irradiation of the excitation light Le and the irradiation light Lm to the introduced liquid. It is possible to perform analysis online and with high accuracy without stopping the line 1. In addition, unlike the conventional method using a surface analysis apparatus, it is not necessary to perform a particularly high concentration treatment as a pretreatment, so that the analysis is performed efficiently and with a simple configuration.

  In particular, the method of irradiating each liquid Le and Lm and adding the reagent to the liquid flowing through the branch pipe 2 enables continuous analysis in real time. Such a continuous analysis cannot be realized by the above-described conventional method, that is, a method in which a concentration process (that is, batch process) has to be performed once with a porous membrane.

  However, this does not mean that the present invention excludes an embodiment in which the liquid branched from the line 1 is temporarily stored and the absorption analysis or coloring process is performed in a stationary state.

  In the present invention, an aspect in which the liquid is concentrated before irradiation with the excitation light and the measurement light is not excluded. Even when this concentration process is performed, a simple process is sufficient, unlike the conventional method using a surface analyzer. Further, the analysis accuracy is further improved by the concentration process.

  Next, the absorption analysis equipment of the impurity analyzer according to the second embodiment will be described with reference to FIG. In the figure, the same elements as those shown in FIG. 2 are denoted by the same reference numerals, and the description thereof is omitted.

  In the second embodiment, the configuration of the excitation light irradiation system 10 is exactly the same as that of the first embodiment. On the other hand, the measurement light irradiation system 20 includes a beam splitter 50, high reflection mirrors 52 </ b> A and 52 </ b> B as a pair of light reflection units, and a distance adjustment mechanism 54 in addition to the measurement light source 22.

  The high reflection mirrors 52A and 52B are arranged at positions facing each other across the measurement target region AS where the excitation light Le is incident. Each of these high reflection mirrors 52A and 52B has a characteristic of reflecting most of incident light (measurement light Lm) and transmitting only a part of the light.

  The distance adjusting mechanism 54 automatically adjusts the distance between the two high reflection mirrors 52 </ b> A and 52 </ b> B, and includes a photodetector 55, a displacement control device 56, and a mirror displacement mechanism 57.

  The mirror displacement mechanism 57 displaces the high reflection mirror 52B of the high reflection mirrors 52A and 52B in a direction in which both mirrors 52A and 52B come in contact with and away from each other in accordance with a control signal input from the displacement control device 56. The photodetector 55 detects the intensity of the measurement light Lm that passes through the high reflection mirror 52B to the side opposite to the measurement target region AS. Based on the detection signal of the photodetector 55, the displacement control device 56 suppresses fluctuations in the detection signal (that is, maintains the resonance state of the light reciprocating between the high reflection mirrors 52A and 52). A control signal for displacing the high reflection mirror 52B is created and input to the mirror displacement mechanism 57.

  The adjustment of the distance between the two high reflection mirrors 52A and 52B by the distance adjusting mechanism 54 improves the measurement accuracy of the phase change by maintaining the resonance state.

  The principle of measurement by the absorption analyzer described above is as follows.

  The light (measurement light Lm) output from the measurement light source 22 is reflected by 90 ° by the beam splitter 50 and reaches the high reflection mirror 52A. The high reflection mirror 52A reflects most of the measurement light Lm but allows only a small amount of transmission. The transmitted part of the measurement light Lm is further transmitted through the measurement target region AS and is incident on the opposite high reflection mirror 52B. Similarly to the high reflection mirror 52A, the high reflection mirror 52B reflects most of the incident measurement light Lm but transmits only a small part of the measurement light Lm.

  Accordingly, a part of the measurement light Lm is repeatedly reflected between the high reflection mirrors 52A and 52B while being repeatedly transmitted through the measurement target region AS, and only a part of the measurement light Lm is reflected by both reflections of the high reflection mirror 52A. , 52B leaks outside. Of these, the light transmitted from the high-reflecting mirror 52A to the side opposite to the measurement target area AS is superimposed with light having different numbers of reciprocations between the mirrors 52A and 52B. This light further becomes reflection-side measurement light L1 superimposed on the light reflected by the high reflection mirror 52A toward the beam splitter 50, passes through the beam splitter 50 as it is, and is input to the photodetector 58.

  The photodetector 58 inputs a detection signal corresponding to the intensity of the input reflection side measurement light L <b> 1 to the signal processing device 60. Similar to the signal processing device 40 according to the first embodiment, the signal processing device 60 captures the detection signal at a timing synchronized with the modulation operation of the modulation mechanism 14, and based on the detection signal, the measurement light Lm Impurity purity is calculated from the change in phase and the change in refractive index.

  Specifically, the calculation principle is as follows. As described above, the reflection-side measurement light L1 is obtained by superimposing measurement light having different numbers of reciprocations between the high-reflection mirrors 52A and 52B. When it matches λ / 2 (n is a positive integer and λ is the wavelength of the measurement light between the two mirrors), the phases of the multiple reflection measurement lights are emphasized synchronously (ie, resonated), and the light The intensity P2 becomes the maximum intensity P2max. On the other hand, when the optical path length L between the mirrors deviates from n · λ / 2, the phase of the multiple reflection measurement light having a larger number of reciprocations between the mirrors is shifted more greatly. As a result, even a slight change in the optical path length L is caused. The intensity of the transmission side measurement light L2 is greatly reduced.

  Here, the reflectivity of each of the high reflection mirrors 52A and 52B is R (R = 0 to 1), and the optical path length between the mirrors satisfying the relationship of L = n · λ / 2 is Ln (= n · λ / 2). ), When the optical path length between the mirrors is Ln, the optical path length range ΔL (hereinafter referred to as the optical path length range) that causes a change in the intensity P2 of the transmission side measurement light L2 around the optical path length Ln. ) Is expressed by the following equation (1).

ΔL = Ln / F
However, F = π · √R / (1-R) (2)
This equation (2) indicates that as the reflectivity R of the high reflection mirrors 52A and 52B is larger, and as the optical path length Ln between the mirrors is shorter, the optical path length range ΔL is reduced and a slight change in optical path length is increased. It shows that it can be measured with sensitivity.

  On the other hand, the intensity P1 of the reflection side measurement light L1 is an intensity obtained by subtracting the intensity P2 of the transmission side measurement light L2 from the intensity P1max substantially equal to the original intensity of the measurement light in accordance with the law of conservation of energy (≈ P1max-P2).

  The analysis according to this embodiment is executed by the following procedure, for example, using the above principle.

  Step 1: The initial interval between the high reflection mirrors 52A and 52B is adjusted. Specifically, first, multiple reflection between the high reflection mirrors 52A and 52B is performed in a state where the excitation light Le is not irradiated, and the intensity P1 of the reflection side measurement light L1 at that time is detected by the photodetector 58. Is done. The initial interval between the high reflection mirrors 52A and 52B is set so that the detection intensity P1 matches the minimum intensity P1min (≈P1max−P2max) of the detection signal or an intermediate intensity between the minimum intensity and the maximum intensity P1max. Is adjusted.

  This interval adjustment may be made so that the detection intensity P2 of the light detector 55 on the transmission side matches the maximum intensity P2max of the detection signal or an intermediate intensity between the maximum intensity P2max and the maximum intensity P2max. In that case, when the intensity P2 (signal) detected by the light detector 55 is fluctuating (in this case, the intensity P1 detected by the light detector 58 is also fluctuating), an amount corresponding to the fluctuation is obtained. The displacement control device 56 and the mirror displacement mechanism 57 automatically displace the high reflection mirror 57. That is, the interval between the two high reflection mirrors 52A and 52B is adjusted in a direction to suppress the fluctuation of the detection signal by the photodetector 55. Thereafter, during the measurement, the displacement control device 56 and the mirror displacement mechanism 57 continue to adjust the position of the second high reflection mirror 57.

  Step 2: The excitation light Le intensity-modulated by the modulation mechanism 14 is intermittently applied to the liquid while adjusting the positions of the high reflection mirrors 52A and 52B. At this time, the excitation light Le causes a photothermal effect on the impurities contained in the liquid, and this photothermal effect changes the refractive index of the liquid. This change in refractive index causes a change in the optical path length L between the mirrors. This change greatly changes the detection signal (the detection signal of the intensity of the reflection side measurement light L1) input to the signal processing device 60 by the photodetector 58. This detection signal is stored in a storage unit included in the signal processing device 60.

  Step 3: The signal processing device 60 measures a change in refractive index based on the detection signal. This measurement is performed using, for example, a data table or conversion formula (data table or conversion formula indicating the correspondence between the detection signal and the refractive index change) prepared in advance. From this change in refractive index, the concentration of impurities contained in the liquid is analyzed with high accuracy.

  This measurement can also be performed based on the intensity P2 of the transmission side measurement light L2 detected by the photodetector 55. This is because the sum of the intensity P2 and the intensity P1 of the reflection side measurement light L1 is constant (≈P1max).

  In addition, in the present invention, various optical system arrangement modes can be adopted. The arrangement is not particularly limited as long as the measurement target area AS can be irradiated with the measurement light and the phase change of the measurement light can be detected.

1 is a diagram showing an overall configuration of an impurity analyzer according to a first embodiment of the present invention. It is a figure which shows the light absorption analysis part of the said impurity analyzer. It is a figure which shows the example in which excitation light and irradiation light are irradiated coaxially in the said impurity analyzer. It is a figure which shows the light absorption analysis part of the impurity analyzer which concerns on the 2nd Embodiment of this invention.

Explanation of symbols

Lr Reference light Lm Measurement light Le Excitation light 1 Line 2 Branch pipe 2a Introduction part 2b Coloring part 2c Absorption analysis part 5 Flow rate adjustment part 6 Reagent addition part 10 Excitation light irradiation system 12 Excitation light source 20 Measurement light irradiation system 22 Measurement light source 24, 30 Deflection beam splitter (optical system for spectroscopy)
36 Photo detector 40 Signal processing device 52A, 52B High reflection mirror (light reflection part)
54 Distance adjustment mechanism 58 Photo detector 60 Signal processing device

Claims (12)

A method for measuring impurities contained in a liquid flowing through a predetermined line,
A part of the liquid flowing through the line is branched from the line and introduced into a sampling unit provided in advance, and the flow is made to flow through an absorption analysis unit consisting of a straight pipe included in the sampling unit ,
The liquid introduced into the sampling unit and flowing through the absorption analysis unit is irradiated with excitation light having a wavelength that matches the light absorption characteristics of the impurity to be measured along the flow direction of the liquid in the absorption analysis unit. Operation,
With respect to the measurement target region in the absorption analysis unit where the photothermal effect of the impurities occurs in the liquid when irradiated with the excitation light, measurement light different from the excitation light is coaxial with the excitation light along the flow direction of the liquid. Operation to irradiate,
An operation for detecting a phase change of the measurement light transmitted through the measurement target region;
And an operation of calculating an impurity concentration in the liquid based on the result of the detection. The impurity analysis method according to claim 1, wherein the impurity analysis method comprises a metal or a metal ion.
Before the operation of irradiating the excitation light, the liquid may be mixed with a reagent that generates a complex that absorbs light having a specific wavelength by chemically reacting with the impurities in the liquid branched from the line.
The operation of irradiating the excitation light is to irradiate light having a wavelength that can be absorbed by the complex as the excitation light. The impurity analysis method according to claim 1,
An operation of flowing a liquid branched from the line to a specific portion of the sampling unit at a predetermined flow rate;
The operation of irradiating the excitation light is to irradiate the liquid flowing through the specific portion with the excitation light,
The operation of calculating the impurity concentration in the liquid is to calculate the impurity concentration in the liquid based on the weight of the impurity in the liquid obtained from the detection result of the phase change and the flow rate of the liquid. An impurity analysis method characterized by the above. The impurity analysis method according to claim 3, wherein the impurity analysis method comprises a metal or a metal ion.
Prior to the operation of irradiating the excitation light, a reagent that generates a complex that absorbs light having a specific wavelength by chemically reacting with the impurities in the liquid flowing through the specific portion is a flow rate corresponding to the flow rate of the liquid. Including adding and mixing in
The operation of irradiating the excitation light is to irradiate light having a wavelength that can be absorbed by the complex as the excitation light.
The operation of calculating the impurity concentration in the liquid calculates the impurity concentration in the liquid based on the weight of the impurity in the liquid obtained from the detection result, the flow rate of the liquid, and the addition flow rate of the reagent. An impurity analysis method characterized by being a thing. An apparatus for measuring impurities contained in a liquid flowing through a predetermined line,
A sampling unit that branches from the line and includes an absorption analysis unit made of a straight pipe, wherein a part of the liquid flowing through the line is introduced and flowed to the absorption analysis unit ;
An excitation light irradiation system for irradiating excitation light along the flow direction of the liquid to the absorption analysis portion flows Ru liquid is introduced into the sampling unit,
With respect to the measurement target region in the absorption analysis unit where the photothermal effect of the impurities occurs in the liquid when irradiated with the excitation light, measurement light different from the excitation light is coaxial with the excitation light along the flow direction of the liquid. a measuring light irradiation system that irradiates Te,
A phase change detection device for detecting a phase change of the measurement light transmitted through the measurement target region;
An impurity analyzer comprising: a signal processing device that outputs a measurement signal for the impurity concentration in the liquid based on a detection signal of the phase change detection device. The impurity analysis apparatus according to claim 5, wherein the apparatus is for analyzing impurities containing metal or metal ions,
The sampling unit is provided on the upstream side of the absorption analysis unit where the excitation light and the measurement light are irradiated, and absorbs light having a specific wavelength by chemically reacting with the impurities. A coloring part in which a reagent for forming a complex is added and mixed in the liquid,
The excitation light irradiation system irradiates, as the excitation light, light having a wavelength that can be absorbed by the complex with respect to a liquid introduced from the colored portion into the absorption analysis portion. The impurity analyzer according to claim 5, wherein
The sampling unit includes Ri connected to the line, a branch pipe that includes the absorption analysis unit and a flow rate regulator for regulating the flow rate of the liquid flowing through the branch pipe to a particular flow,
The signal processing device calculates the impurity concentration in the liquid based on the weight of the impurity in the liquid obtained from the detection signal of the phase change detection device and the flow rate of the liquid adjusted by the flow rate adjusting unit. Impurity analyzer characterized by being a thing. The apparatus for analyzing impurities according to claim 7, wherein the apparatus is for analyzing impurities containing metal or metal ions.
The impurities are metals or metal ions;
The branch pipe includes an absorption analysis unit in which the excitation light and the measurement light are irradiated with respect to the liquid flowing in the branch pipe, and a coloring unit located on the upstream side of the absorption analysis unit,
A reagent that adds to the colored part a reagent that forms a complex that absorbs light having a specific wavelength by chemically reacting with the impurities in the liquid flowing through the colored part at a flow rate corresponding to the flow rate of the liquid. The additive part is connected,
The excitation light irradiation system irradiates, as the excitation light, light having a wavelength that can be absorbed by the complex with respect to the liquid flowing through the absorption analysis unit.
The signal processing device calculates the impurity concentration in the liquid based on the weight of the impurity in the liquid obtained from the detection signal of the phase change detection device, the flow rate of the liquid, and the addition flow rate of the reagent. An impurity analyzer characterized by being. In the impurity analyzer in any one of Claims 5-8,
The excitation light irradiation system irradiates light whose intensity is periodically modulated as the excitation light,
The impurity analyzer according to claim 1, wherein the signal processor captures a detection signal of the phase change detector at a timing synchronized with a period of the intensity modulation. In the impurity analyzer in any one of Claims 5-9,
The phase change detection device detects the intensity of light after the interference, and a spectroscopic optical system that separates the reference light from the measurement light and causes the reference light to interfere with the measurement light transmitted through the measurement target region. An impurity analyzer including a photodetector. In the impurity analyzer in any one of Claims 5-9,
The phase change detection device includes a light reflection unit disposed in a posture facing each other on both sides of the measurement target region, and a photodetector, and each of the light reflection units includes the measurement target. The measurement light is reciprocated by reflecting a part of the measurement light transmitted through the region to the other light reflection unit, and the photodetector detects at least one of the light reflection units as the measurement target region. An impurity analyzer characterized by receiving measurement light transmitted to the opposite side of the electrode and detecting its intensity. The impurity analyzer according to claim 11, wherein
The phase change detection device further includes a distance adjusting mechanism that adjusts a distance between the light reflecting portions in a direction in which a resonance state of light reciprocating between the two light reflecting portions is maintained.

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