A method and device for online monitoring of gaseous peroxide content

Abstract

The present invention discloses an online monitoring method and device for gaseous peroxide content. This method, based on a wet chemical method for gas diffusion, absorption, and capture and fluorescence spectroscopy detection technology, enables real-time online detection of gaseous peroxide content. A multi-turn non-metallic tube trap is used for sampling. An absorption liquid forms a liquid film on the tube wall. The gas components to be measured diffuse and transfer mass at the gas-liquid interface. After sufficient contact and absorption with the absorption liquid, gas-liquid separation is achieved at the other end of the trap. Para-hydroxyphenylacetic acid is used as a peroxide derivative liquid. Under the catalytic action of hemin chloride, fluorescent dimers are generated. Fluorescence is generated under irradiation with light of a characteristic wavelength. The fluorescence intensity is measured using a flow cuvette and a spectrometer, and the peroxide content of the gas to be measured is converted. The corresponding online monitoring device of the present invention utilizes a multi-channel peristaltic pump to precisely control trace solutions, reducing routine maintenance. The device can be applied to the rapid, online, and continuous measurement of gaseous peroxides in the atmosphere of various environmental sites.

Description

Technical Field

[0001] The present invention belongs to the field of environmental monitoring technology, relates to online monitoring technology of ambient air quality and gaseous pollutant emissions from pollution sources, and in particular to an online monitoring method and device for gaseous peroxide content. Background Art

[0002] Peroxides are an important class of chemical products with diverse functions, including bleaching, oxidation, disinfection, and sterilization. They are widely used in various fields, including industry, medicine, and food hygiene. Furthermore, due to their strong oxidizing properties, peroxides can deplete antioxidants in the body, reducing the body's antioxidant capacity. They can also damage DNA in organisms, leading to gene mutations and potentially causing various diseases. Long-term exposure to high concentrations of peroxides can irritate the eyes, respiratory tract, and skin. Furthermore, when their concentration in the air exceeds a certain level, they can adversely affect the growth of plants and microorganisms, as well as human health. Therefore, accurate monitoring of peroxide concentrations in ambient air and at pollution sources is crucial to public health.

[0003] Currently, common methods for monitoring gaseous peroxides include laser absorption spectroscopy, spectrophotometry, chemiluminescence, titration, and enzyme-catalyzed derivatization fluorescence. Laser absorption spectroscopy offers excellent accuracy and minimizes interference factors, but its high cost limits its application. Spectrophotometry primarily includes titanium tetrachloride spectrophotometry and iodide ion oxidation spectrophotometry. Titanium tetrachloride spectrophotometry is the standard method for determining gaseous hydrogen peroxide in the national occupational health standard, "Determination of Oxygenates in Workplace Air (GBZ / T 160.32-2004)." However, both spectrophotometric methods are offline and cannot achieve online continuous monitoring. The same applies to titration. Chemiluminescence is gentle, rapid, instrument-simplified, and lacks blanks, but it also suffers from drawbacks such as poor selectivity and low sensitivity. Enzyme-catalyzed derivatization fluorescence method has become a common method for detecting gaseous peroxides in ambient air due to its advantages of low detection limit, simple operation and high sensitivity. The principle of this method is that under the enzyme-catalyzed reaction, peroxide oxidizes non-fluorescent substrates into fluorescent dimers. Among the existing detection methods, para-hydroxyphenylacetic acid (PHPAA) is the preferred fluorescence indicator substrate. The enzymes selected are peroxidase, horseradish peroxidase (HRP) and hemin. The peroxidase-catalyzed reaction is stable and has a high fluorescence coefficient, but the cost of peroxidase is high. The HRP-catalyzed method is relatively low in cost and has a high fluorescence coefficient compared to peroxidase, but the HRP stock solution is easily denatured and inactivated, and has poor stability. In addition, since the optimal reaction pH value of HRP (5.8) is significantly different from the optimal pH value of fluorescence detection (11), an additional pump is required to transport the buffer to adjust the pH. The optimal reaction pH value of Hemin-catalyzed reaction is consistent with the fluorescence detection value, so the experimental system can reduce one pump. The cost of Hemin is much lower than that of the other two enzymes, and the stock solution is relatively stable. Therefore, this method is relatively simple to use, low in cost, and more suitable for field observation.

[0004] The hydrogen peroxide gas concentration analyzer from Piccaro, a US company, is an online hydrogen peroxide detection instrument based on the near-infrared laser cavity ring-down method. While this instrument offers high sensitivity and accuracy, it is also expensive and requires high maintenance. The hydrogen peroxide analyzer from AeroLaser, a German company, is an online peroxide detection instrument based on the enzyme-catalyzed derivatization fluorescence method. Using peroxidase-catalyzed derivatization, this instrument offers advantages such as low detection limits, high sensitivity, high selectivity, and rapid online detection. However, this method and instrument still suffer from limitations such as baseline drift, frequent maintenance, and high reagent costs.

[0005] Chinese patent application publications CN103604772A, "Method and Apparatus for Measuring Gas-Phase H2O2 Concentration Using Tunable Laser Absorption Spectroscopy," and CN114279996A, "Gas-Phase Hydrogen Peroxide Concentration Detection System Based on Off-Axis Integrating Cavity," employ laser absorption spectroscopy detection technology. Using a near-infrared tunable laser as a light source, the laser passes through a test environment filled with gaseous hydrogen peroxide. The concentration of gaseous hydrogen peroxide is determined based on the linear relationship between the gaseous hydrogen peroxide concentration and the second harmonic peak. This method avoids interference from other gas spectral lines on the measured gas, but the equipment is relatively large and costly, and it also suffers from limited detection accuracy. Summary of the Invention

[0006] In order to overcome the shortcomings of the above-mentioned prior art, the present invention provides a method and device for online monitoring of gaseous peroxide content. Based on a wet chemical method of gas diffusion absorption capture and fluorescence spectroscopy detection technology, the method and device can realize real-time online detection of gaseous peroxide content. The method can be applied to the on-site online continuous monitoring of gaseous peroxide concentration in a variety of environments.

[0007] The principle of this invention is to combine wet chemical methods and fluorescence spectroscopy for online monitoring of gaseous peroxides in ambient air, providing a novel measurement technology for online measurement of gaseous peroxides. During the sampling process, air, driven by a vacuum diaphragm pump, passes through a trap formed by multiple turns of a spiral non-metallic tube. An absorption liquid also enters the trap from the same end, where it forms a liquid film on the tube wall due to liquid tension. Due to the increased gas-liquid interface in the trap, gaseous components in the air diffuse and transfer across the interface, fully contacting and absorbing the absorption liquid. Gas-liquid separation is then achieved at the other end of the trap. Para-hydroxyphenylacetic acid (PHPAA) is used as a derivatizing liquid for gaseous peroxides. In an alkaline environment at pH 10, the peroxide solution and PHPAA undergo a derivatization reaction catalyzed by hemin (hemin) to produce the fluorescent dimer 2,2'-dihydroxy-biphenyl-5,5'-diacetic acid, which emits fluorescence at a characteristic wavelength (400 nm) when illuminated by a 320 nm light source. A liquid sample that has absorbed the component to be tested (gaseous peroxide) undergoes a derivatization reaction and then enters a flow cuvette. When the component to be tested is at a low concentration, under illumination from an LED light source with a wavelength of 320nm, the concentration of the component to be tested is proportional to the fluorescence intensity of the characteristic wavelength emitted by the component. Based on the fluorescence intensity, online monitoring of the gaseous peroxide content can be achieved. The present invention also provides an online monitoring device for gaseous peroxides in ambient air that utilizes the principle of wet gas diffusion capture. This device uses a multi-channel peristaltic pump to precisely control trace solutions, reduce routine maintenance, and achieve rapid, online, and continuous measurement of gaseous peroxides in the atmosphere.

[0008] The technical solution provided by the present invention is:

[0009] An online monitoring method for gaseous peroxide content includes a measurement process, a zeroing process, and a calibration process, wherein the measurement process includes the following steps 1) to 3):

[0010] 1) Sampling process: A multi-turn non-metallic tube is used as a trap, and potassium hydrogen phthalate solution is used as an absorption liquid for gaseous peroxides. The absorption liquid and the gas to be tested containing gaseous peroxides are passed through the trap. In the trap, the gaseous peroxides are absorbed by the absorption liquid forming a liquid film on the tube wall, thereby obtaining a liquid sample to be tested;

[0011] 2) Reaction process: Using another multi-turn wound non-metallic tube as a derivatization reaction well, using an alkaline solution containing hemin and p-hydroxyphenylacetic acid as a derivatization liquid, the liquid sample to be tested and the derivatization liquid are allowed to enter the reaction well, and the peroxide in the liquid sample and the p-hydroxyphenylacetic acid undergo a derivatization reaction under the catalytic action of the hemin to produce a fluorescent dimer 2,2'-dihydroxy-biphenyl-5,5'-diacetic acid, thereby obtaining a fluorescent dimer test sample;

[0012] 3) Detection process: The fluorescent dimer sample to be tested is placed into a flow cuvette. The characteristic wavelength excitation light generated by the light source is absorbed by the fluorescent dimer component to be tested, and emits fluorescence of the characteristic wavelength. The intensity of the fluorescence signal is detected by a spectrometer.

[0013] 4) The zeroing process is performed before the measurement process. During the zeroing process, air is first passed through the peroxide removal device to obtain zero gas. Then, the zero gas is used as the test gas to undergo the sampling process, reaction process, and detection process of steps 1) to 3) above. The optical signal intensity obtained by the spectrometer is the zero-point optical signal intensity;

[0014] 5) The calibration process is to prepare a series of peroxide standard solutions with gradient concentrations to replace the absorption solution in the sampling process, and to measure the zero air obtained by passing the air through the peroxide removal device through the above steps 1) to 3) to obtain the fluorescence signal intensity of the peroxide standard solution;

[0015] 6) Calculation of peroxide content in the gas to be measured: The zero-point light signal intensity and the fluorescence signal intensity of the peroxide standard solution are obtained in steps 4) and 5). Since the component to be measured is at a low concentration, the concentration of the peroxide is proportional to the fluorescence intensity of the characteristic wavelength emitted by it when the incident light intensity remains unchanged. The liquid phase peroxide concentration can be calculated based on the relationship between fluorescence signal intensity and concentration shown in Equation 1:

[0016]

[0017] In formula 1, I f is the fluorescence signal intensity, I f0is the zero-point light signal intensity, K is the coefficient, and c is the concentration of peroxide; according to the zeroing process, I f0 The concentration c of the peroxide standard solution obtained by the calibration process and its fluorescence signal intensity I f , calculate the coefficient K; thus, using the obtained coefficient K, for the liquid phase sample to be tested, the fluorescence signal intensity can be measured by the spectrometer according to step 3), and the peroxide concentration in the sample, ie, the liquid phase peroxide concentration, can be calculated using formula 1.

[0018] In addition, the liquid phase peroxide concentration needs to be converted to the gas phase peroxide concentration, that is, the peroxide content in the gas to be tested. The peroxide concentration in the liquid phase sample to be tested can be converted to the gaseous peroxide content in the gas to be tested using Formula 2:

[0019]

[0020] In formula 2, c peroxide Represents the concentration of gaseous peroxides (in μg / m 3 ), c [peroxide] represents the concentration of liquid peroxide (in μg / L), F l is the liquid flow rate in the trap (in mL / min), F g is the gas flow rate in the trap (in L / min), and γ is the capture efficiency of the trap for gaseous peroxides in the gas to be tested.

[0021] Preferably, in step 3), a UV LED light source with a central wavelength of 320 nm is used. The spectrometer simultaneously detects the intensity of the fluorescence signal and obtains the intensity of the incident light signal generated by the light source, and calibrates the incident light intensity. The fluorescence emitted by the sample to be tested is quantified using a characteristic wavelength of 400 nm.

[0022] Furthermore, the capture trap and reaction trap both use a PFA tube that is wound around a cylindrical aluminum block in multiple turns, and the temperature of the capture trap and reaction trap is precisely controlled by a temperature control device.

[0023] In one embodiment of the present invention, the absorption liquid is a 5 mM potassium hydrogen phthalate solution with a pH of 6; the derivatization liquid is a solution containing 0.4 mM p-hydroxyphenylacetic acid and 0.01 mM hemin in an ammonium chloride / ammonia aqueous buffer solution with a pH of 10.

[0024] The sampling process of step 1) converts the gaseous peroxide in the sampled sample into a liquid sample to be tested. During the sampling process, the gas to be tested passes through the capture trap under the action of a vacuum diaphragm pump, and the absorption liquid also enters the capture trap from the same end. The absorption liquid forms a liquid film on the tube wall by relying on liquid tension. Since the gas-liquid interface in the capture trap increases, the gas components diffuse and transfer mass between the interfaces, fully contact and absorb with the absorption liquid, and then achieve gas-liquid separation at the other end of the capture trap. At the same time, the sampling temperature is stabilized at 10°C by a temperature control device to avoid interference from outdoor temperature differences and ensure the stability of the capture efficiency during the sampling process.

[0025] In step 2, the reaction uses hydroxyphenylacetic acid (PHPAA) as a peroxide derivatization solution. The peroxide solution (liquid phase sample to be tested) and PHPAA undergo a derivatization reaction in an alkaline environment of pH 10, catalyzed by hemin (hemin), to produce the fluorescent dimer 2,2'-dihydroxy-biphenyl-5,5'-diacetic acid. This produces 400nm fluorescence when illuminated by a 320nm light source. A PFA tubing wrapped multiple times around a cylindrical heat-conducting aluminum block serves as the derivatization reaction well. A temperature control device maintains the reaction temperature at 40°C, accelerating the derivatization reaction and improving reaction stability and detection limits. The reaction well is also designed to shield from light to prevent the effects of light on reaction stability.

[0026] During the sampling process, the liquid sample absorbs the component to be tested (peroxide), undergoes derivatization during the reaction process to generate fluorescent dimers, and then enters the flow cuvette during the detection process in step 3). The characteristic wavelength excitation light generated by the light source is absorbed by the fluorescent dimers of the component to be tested, and emits 400nm wavelength fluorescence in all directions, which is detected by the spectrometer at the optical path exit perpendicular to the incident direction of the excitation light. The present invention uses an ultraviolet LED light source with a central wavelength of 320nm. The spectrometer simultaneously obtains the incident light signal intensity while detecting the fluorescence signal intensity, and corrects the incident light intensity to avoid interference with the detection results due to LED attenuation.

[0027] Calibration is required each time the absorption and derivatization solutions are replaced. During calibration, air is first passed through a peroxide removal device to obtain zero air, and the zero-point optical signal intensity is measured. The absorption solution from step 1) is then replaced with a laboratory-prepared peroxide standard solution with a gradient concentration. The zero air is then measured using the measurement process from steps 1) to 3) to obtain the fluorescence signal intensity of the peroxide standard solution.

[0028] Furthermore, to achieve online monitoring of the concentration of gaseous hydrogen peroxide in the test gas, the liquid sample obtained by sampling in step 1) above can be divided into two channels. The reaction process in step 2) adopts a dual-channel setting, that is, two parallel derivatization reaction wells are set up, one of which causes a derivatization reaction between a derivatization liquid without catalase and one liquid sample to be tested, and the other causes a derivatization reaction between a derivatization liquid containing catalase and the other liquid sample to be tested. The detection process in step 3) also adopts a dual-channel setting, that is, two parallel detection devices are set up to respectively detect the fluorescent signals emitted by the test samples after the derivatization reaction in the two channels. In step 6), the total peroxide content measured in one channel is subtracted from the content of organic peroxides other than hydrogen peroxide measured in the other channel to obtain the hydrogen peroxide content in the sample.

[0029] Based on the above-mentioned online monitoring method for gaseous peroxide content, the present invention also provides an online monitoring device for gaseous peroxide content, including a sampling module, a reaction module, a detection module, a solution delivery module, and a control and data acquisition circuit module. The sampling module is used to sample gaseous peroxides and convert gaseous peroxides in the gas to be tested (such as air) into a liquid phase sample to be tested; the reaction module is used to derivatize the liquid phase sample to be tested, so that the liquid phase sample to be tested containing peroxides undergoes a derivatization reaction with PHPAA in an alkaline environment under a constant temperature and Hemin catalysis to generate a fluorescent dimer sample to be tested, 2,2'-dihydroxy-biphenyl-5,5'-diacetic acid; the detection module is used to detect the intensity of the light signal; the light signal intensity is transmitted from the spectrometer of the detection module to the control and data acquisition circuit module via a data connection line for storage; the solution delivery module is used to accurately distribute the absorption liquid, derivatization liquid and components to be tested, and to deliver the cleaning solution and discharge the waste liquid.

[0030] The sampling module includes a sampling pipeline, a filter membrane, a peroxide removal device, an electromagnetic three-way valve, a trap, a trap temperature control device, a gas-liquid separation and drying device, a mass flow controller, and a vacuum diaphragm pump. The sampling pipeline is divided into two branches at the sample gas inlet, one of which is equipped with a peroxide removal device. The two branches are combined into a gas path leading to the trap through an electromagnetic three-way valve, and the gas path is equipped with a filter membrane. The trap is composed of multiple turns of non-metallic tube (preferably PFA tube) wrapped around a metal block. The trap temperature control device maintains the trap at a constant temperature during operation. The rear end of the trap is equipped with a gas-liquid separation and drying device. The liquid sample to be tested from the trap flows to the reaction module through one pipeline, and the gas is discharged as exhaust gas through another pipeline equipped with a mass flow controller and a vacuum diaphragm pump after drying.

[0031] The reaction module includes a reaction trap and a reaction trap temperature control device. The reaction trap is composed of multiple turns of non-metallic tubes (preferably PFA tubes) wrapped around a metal block. The liquid sample to be tested from the capture trap enters the reaction trap through the pipeline and reacts with the derivative liquid at a constant temperature to generate a fluorescent dimer sample to be tested.

[0032] The detection module is divided into a liquid path part, an optical path part and a detection chamber bracket, wherein the liquid path part includes a flow cuvette, through which the fluorescent dimer sample to be tested coming out of the reaction well passes; the flow cuvette is fixed in the detection chamber bracket, and light can pass through the two adjacent sides of the flow cuvette, while the rest of the area is shielded from light; the optical path part includes an LED light source, a collimating lens, an optical fiber and a spectrometer, wherein the LED light source is located on the light-transmitting side of the flow cuvette, the collimating lens and the optical fiber are fixed on the adjacent light-transmitting side, and the optical fiber is connected to the spectrometer.

[0033] The solution delivery module includes a multi-channel peristaltic pump and a solution delivery pipeline. The absorption liquid is delivered to the capture trap, the derivative liquid and the liquid phase sample to be tested are delivered to the reaction trap, and the fluorescent dimer sample to be tested is delivered to the flow cuvette through each pipeline of the peristaltic pump.

[0034] The control and data acquisition circuit module is electrically connected to the sampling module, the reaction module, the detection module, and the solution delivery module respectively to control the operations of these modules and collect data.

[0035] In one embodiment of the present invention, the peristaltic pump is a four-channel peristaltic pump, the first pipeline of which is connected to the absorption liquid delivery pipeline to deliver the absorption liquid into the capture trap; the second pipeline of the peristaltic pump is connected to the derivative liquid delivery pipeline to deliver the derivative liquid into the liquid phase test sample pipeline at the rear end of the capture trap, and the derivative liquid and the liquid phase test sample coming out of the capture trap are mixed and enter the reaction trap under the action of the third pipeline of the peristaltic pump; the fluorescent dimer test sample coming out of the reaction trap enters the flow cuvette under the action of the fourth pipeline of the peristaltic pump and is then discharged.

[0036] Furthermore, a first bubble removal tee is provided at the junction of the derivative liquid delivery pipeline and the liquid phase sample pipeline at the rear end of the capture trap, and a second bubble removal tee is provided on the pipeline connecting the detection module at the rear end of the reaction trap.

[0037] In another embodiment of the present invention, in order to detect the hydrogen peroxide content in the gas to be tested, two sets of parallel reaction devices are set in the reaction module, including a first reaction well and its temperature control device, a second reaction well and its temperature control device, and the liquid phase sample to be tested coming out of the sampling module is divided into two paths, entering the first reaction well and the second reaction well respectively, wherein the derivatization liquid without catalase in the first reaction well undergoes a derivatization reaction with one path of the liquid phase sample to be tested, and the derivatization liquid containing catalase in the second reaction well undergoes a derivatization reaction with the other path of the liquid phase sample to be tested; the detection module is provided with two sets of parallel detection devices, respectively detecting the fluorescence signals emitted by the two paths of the sample to be tested after the derivatization reaction; the peristaltic pump is a four-channel peristaltic pump, wherein the first pipeline is connected to The absorption liquid delivery pipeline delivers the absorption liquid into the capture trap of the sampling module; the front end of the capture trap of the sampling module is connected to the first pipeline of the peristaltic pump, and the rear end of the pipeline for delivering the liquid-phase sample to be tested is divided into two paths, one path passes through a bubble removal tee and enters the first reaction trap, and the other path passes through another bubble removal tee and enters the second reaction trap; the derivative liquid without catalase and the derivative liquid containing catalase are respectively delivered through the second and third pipelines of the peristaltic pump, and respectively merge with the two liquid-phase samples to be tested from the sampling module through the bubble removal tee; the outlets of the first reaction trap and the second reaction trap are connected to the two detection devices of the detection module after passing through a bubble removal tee, and the outlets of the two detection devices are connected to the fourth pipeline of the peristaltic pump after merging the two flow paths through a tee.

[0038] Preferably, the capture trap is a PFA tube wrapped multiple times around a first aluminum block, one end of which serves as an inlet for the absorption liquid and the gas to be tested, and the other end serves as an outlet for the liquid sample to be tested after the absorption liquid absorbs the gaseous peroxide. The capture trap is located in an insulation chamber and is surrounded by insulation cotton and foam board. The capture trap temperature control device includes a semiconductor refrigeration chip, a first radiator, a fan, and a temperature controller connected via a first thermocouple, wherein the semiconductor refrigeration chip is disposed at one end of the first aluminum block, the first radiator is connected to the semiconductor refrigeration chip, the fan faces the first radiator, and the first thermocouple detects the temperature of the PFA tube wrapped multiple times around the first aluminum block and transmits it to the temperature controller. The reaction trap is a PFA tube wrapped multiple times around a second aluminum block, one end of which serves as an inlet for the derivatization liquid and the liquid sample to be tested, and the other end serves as an outlet for the sample to be tested after the derivatization reaction. The reaction trap temperature control device includes a built-in heating block and a temperature controller connected via a second thermocouple.

[0039] Furthermore, the control and data acquisition circuit includes a data acquisition card with a digital I / O port, which controls the LED light source by controlling the solid-state relay through a Labview program written by a computer, controls the temperature of each module by controlling the solid-state relay through a temperature controller, and collects and outputs the temperature information of each module. The light intensity signal data collected by the spectrometer is output from the USB port of the spectrometer.

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] The present invention provides an online monitoring method and device for gaseous peroxide content, which realizes real-time online detection of gaseous peroxide content based on a wet chemical method of gas diffusion absorption capture and fluorescence spectrum detection technology, and can continuously monitor the gaseous peroxide content on site.

[0042] This invention is an online monitoring technology for gaseous peroxides in ambient air that combines wet chemical methods with fluorescence spectroscopy, providing a novel measurement technology for online measurement of gaseous peroxides in the atmosphere. Compared with existing technologies, the technical advantages of this invention are mainly reflected in the following aspects:

[0043] (1) Combining chemical and optical methods, using the wet gas diffusion capture principle and fluorescence spectroscopy technology, rapid, online and continuous measurement of low-concentration gaseous peroxides in the atmosphere can be achieved. The response speed is fast, the instrument cost is significantly lower than the optical method, and the degree of interference and detection limit are significantly lower than the sensor method.

[0044] (2) Compared with the use of photomultiplier tubes as detectors, the application of spectrometers can simultaneously achieve the correction of incident light intensity and avoid the interference of LED attenuation on the detection results.

[0045] (3) In the detection module, the collimating lens fixing frame can be rotated in the horizontal direction by a certain angle, so as to adjust the intensity of the LED incident light entering the spectrometer on the basis of keeping the intensity of the received fluorescence unchanged.

[0046] (4) A PFA tube trap with multiple turns wrapped around a cylindrical aluminum block is used as a gaseous peroxide trap, which has the characteristics of high capture efficiency, small size, simple structure, and can be placed outdoors.

[0047] (5) Accurately control the flow rate of solutions in each pipeline through a multi-channel peristaltic pump with adjustable speed, reducing daily maintenance and data loss caused by aging of the peristaltic pump.

[0048] (6) The temperature controller controls the solid-state relay to achieve precise temperature control of each module, ensuring the stable capture and derivatization reaction of peroxides in the air. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1A structural diagram of a gaseous peroxide online monitoring device provided in Example 1 of the present invention, wherein: 1—first electromagnetic three-way valve; 2—peroxide removal device; 3—second electromagnetic three-way valve; 4—filter membrane; 5—water removal safety bottle; 6—mass flow controller; 7—vacuum diaphragm pump; 8—collection trap; 9—first radiator; 10—semiconductor refrigeration plate; 11—first thermocouple; 12—first aluminum block; 13—reaction trap; 14—second thermocouple; 15—second aluminum block; 16—heating block; 17—detection chamber; 18—LED light source; 19—second radiator; 20—LED fixing bracket (including focusing lens); 21—four-channel peristaltic pump (from right to left, first to fourth pipelines respectively); 22—first bubble removal three-way valve; 22′—second bubble removal three-way valve.

[0050] Figure 2 Schematic diagram of the structure of a capture trap in an online monitoring device for gaseous peroxides provided in Example 1 of the present invention, wherein: 9—first radiator; 10—semiconductor refrigeration plate; 11—first thermocouple; 12—first aluminum block; 23—fan; 24—multi-turn PFA tube; 25—insulation chamber; 26—insulation cotton; 27—foam board; 28—absorption liquid inlet; 29—absorption liquid outlet.

[0051] Figure 3 Schematic diagram of the structure of a detection chamber in an online monitoring device for gaseous peroxides provided in Example 1 of the present invention, wherein: 18—LED light source; 19—second heat sink; 20—LED fixing frame (including focusing lens); 30—test liquid inlet; 31—test liquid outlet; 32—flow cuvette; 33—detection chamber bracket; 34—collimating lens; 35—optical fiber; 36—detection chamber base.

[0052] Figure 4 This is a structural diagram of a device for online monitoring of gaseous hydrogen peroxide content provided in Example 2 of the present invention, wherein: 1—first electromagnetic three-way valve; 2—peroxide removal device; 3—second electromagnetic three-way valve; 4—filter membrane; 5—water removal safety bottle; 6—mass flow controller; 7—vacuum diaphragm pump; 8—capture trap; 13a—first reaction trap; 13b—second reaction trap; 17a—first detection chamber; 17b—second detection chamber; 21'—five-channel peristaltic pump (from right to left, first to fifth pipelines respectively); 22a—third bubble removal tee; 22a'—fourth bubble removal tee; 22b—fifth bubble removal tee; 22b'—sixth bubble removal tee. DETAILED DESCRIPTION

[0053] The present invention will be further described below by way of examples in conjunction with the accompanying drawings, but the scope of the present invention is not limited in any way.

[0054] The present invention provides a method and device for online monitoring of gaseous peroxide content. Based on wet chemical technology using gas diffusion absorption capture and fluorescence spectroscopy detection, this method enables real-time online detection of gaseous peroxide content, enabling on-site continuous online monitoring of gaseous peroxide content. The present invention uses a spectrometer to detect the fluorescence intensity of the derivative and simultaneously corrects for incident light intensity, preventing interference from LED attenuation on the detection results. The present invention also provides an online monitoring device for gaseous peroxides in ambient air, utilizing the principles of wet gas diffusion absorption capture and employing a multi-channel peristaltic pump with adjustable speed to precisely control trace amounts of solution and reduce routine maintenance.

[0055] Example 1

[0056] Figure 1 The structural diagram of the online monitoring device for peroxide content in ambient air provided in this embodiment includes a housing, a sampling module, a reaction module, a detection module, a solution delivery module, and a control and data acquisition circuit module, all of which are housed within the housing. The sampling module is used to sample gaseous peroxides and convert them into a liquid sample to be tested. The reaction module is used to derivatize the liquid sample, causing the peroxide-containing liquid sample to undergo a derivatization reaction with PHPAA in an alkaline environment of pH 10 at a constant temperature and under the catalytic action of Hemin to produce the fluorescent dimer test sample 2,2'-dihydroxy-biphenyl-5,5'-diacetic acid. The detection module is used to detect the intensity of the optical signal, which is transmitted from the spectrometer to a computer via a data cable with a USB port for storage. The solution delivery module is used to accurately distribute the absorption solution, derivatization solution, and test components, as well as to deliver the cleaning solution and discharge the waste liquid.

[0057] The sampling module includes a sampling pipeline, a filter membrane 4, a peroxide removal device 2, a second electromagnetic three-way valve 3, a capture trap 8, a capture trap temperature control device, a gas-liquid separation and drying device (dewatering safety bottle 5), a mass flow controller 6 and a vacuum diaphragm pump 7. The reaction module includes a first bubble removal three-way valve 22, a reaction trap 13 and its temperature control device. The front end of the capture trap 8 of the sampling module is connected to the first pipeline of the four-channel peristaltic pump 21 of the solution delivery module, and the rear end is connected to the first bubble removal three-way valve 22 of the reaction module. The other two ends of the first bubble removal three-way valve 22 are respectively connected to the second and third pipelines of the four-channel peristaltic pump 21. The detection module includes a flow cuvette 32, an LED light source 18, a collimating lens 34 and a spectrometer. The outlet of the reaction trap 13 is connected to the second bubble removal three-way valve 22', then enters the flow cuvette 32 of the detection module, and then is connected to the fourth pipeline of the four-channel peristaltic pump 21 of the solution delivery module. The solution delivery module includes a four-channel peristaltic pump 21: the first pipeline connects the absorption liquid to the sampling module, the second pipeline connects the derivatization liquid to the first bubble removal tee 22 of the reaction module, the third pipeline connects the first bubble removal tee 22 of the reaction module to the reaction well 13, and the fourth pipeline connects to the flow cuvette 32 in the detection module. The control and data acquisition circuit includes a data acquisition card with a digital I / O port. A Labview program written on a computer controls a solid-state relay to control the LED light source 18. A temperature controller controls the solid-state relay to control the temperature of each module, collects and outputs temperature information from each module, and outputs light intensity signal data collected by the spectrometer through the spectrometer's built-in USB port.

[0058] In the sampling module, the sampling pipeline adopts 1 / 8" PFA tube, and a vacuum diaphragm pump 7 is used to extract the air sample and pass it into the capture trap 8. At the same time, a 1 / 16" PFA tube is used to pass a potassium hydrogen phthalate solution with a pH of 6 into the capture trap 8 as a gaseous peroxide absorption liquid. Among them, the core component capture trap 8 adopts 1 / 8" PFA tube and is wound on a cylindrical heat-conducting aluminum block (the first aluminum block 12) with a height of 42mm. At the same time, the sampling temperature is stabilized at 10°C by the capture trap temperature control device, which includes a semiconductor refrigeration plate 10, a first radiator 9, a fan 23 and a temperature controller connected by a first thermocouple 11. Figure 2As shown, a multi-turn PFA tube 24 is wound around the first aluminum block 12, with an absorption liquid inlet 28 (also the gas inlet) at one end and an absorption liquid outlet 29 at the other. The first aluminum block 12 and the multi-turn PFA tube 24 are located in an insulation chamber 25, surrounded by insulation 26 and foam board 27. A semiconductor cooling plate 10 and a first heat sink 9 are located at one end of the first aluminum block 12, with a fan 23 facing the first heat sink 9. A first thermocouple 11 detects the temperature of the multi-turn PFA tube 24 and transmits it to a temperature controller, which controls the operation of the semiconductor cooling plate 10 and fan 23. The trap temperature control device ensures that the components to be measured are captured at a constant temperature, preventing fluctuations in sample capture efficiency caused by temperature changes.

[0059] In the reaction module, the derivatization solution and the peroxide-absorbing test solution simultaneously enter the reaction well 13 through the first bubble-removing tee 22, where a derivatization reaction occurs at 40°C to produce fluorescent dimers. Because this reaction is slow at room temperature, the reaction well 13 is constructed using 1 / 8" PFA tubing wrapped around a 22.5cm tall cylindrical heat-conducting aluminum block (second aluminum block 15). A built-in heating block 16 and a temperature controller connected via a second thermocouple 14 maintain the temperature of the reaction well 13 at 40°C to accelerate the derivatization reaction.

[0060] The detection module can be divided into a liquid path part, an optical path part and a detection chamber bracket. Figure 3As shown, the liquid path portion includes a flow cuvette 32, and the liquid to be tested that has undergone the derivatization reaction enters and exits the cuvette through two threaded interfaces (the liquid to be tested inlet 30 and the liquid to be tested outlet 31) sealed by O-rings above the flow cuvette 32. The optical path portion includes an LED light source 18, a collimating lens 34, an optical fiber 35, and a spectrometer. The detection chamber bracket 33 is a quasi-cube with a cuvette groove on the top surface and light-permeable adjacent sides. The flow cuvette 32 can be directly fixed in the cuvette groove of the detection chamber bracket 33. Except for the light-transmitting windows on the two adjacent sides that provide LED light and fluorescence to pass through, the rest of the flow cuvette 32 is all light-proof. The light-transmitting windows are all made of quartz material, and ultraviolet light can pass through. The LED light source 18 is fixed to one of the sides of the detection chamber bracket 33, and the collimating lens 34 and the optical fiber 35 are fixed to the adjacent sides of the detection chamber bracket 33. The fixed parts are all light-proof. In order to avoid the light source generating too much heat and the spectrum fluctuating significantly with temperature, the light source adopts a stable LED light source 18, and a second heat sink 19 is provided on the outside of the LED fixing frame (including focusing lens) 20. According to the frequency band characteristics of the LED, the wavelength is selected as 320nm. The LED light is incident on the flow cuvette 32 through one side of the detection chamber bracket 33. The liquid to be tested in the flow cuvette 32 absorbs the incident light and emits fluorescence in all directions. The fluorescence is detected from the other side of the detection chamber bracket 33 (perpendicular to the incident light), and the incident light can also be detected at the same time; the fixing frame of the collimating lens 34 can be rotated a certain angle in the horizontal direction to adjust the intensity of the LED incident light entering the spectrometer on the basis of receiving the unchanged fluorescence intensity; at this time, the fluorescence and a small amount of incident light are collimated by the collimating lens 34 and coupled to the spectrometer by the optical fiber 35, and detected in different bands. The detected incident light signal intensity can be used to calibrate the light intensity of the LED light source 18 to avoid the influence of LED attenuation on the detection results.

[0061] The first, second and third pipelines of the four-channel peristaltic pump 21 in the solution delivery module are respectively used for accurately distributing the absorption liquid, the derivative liquid and the component to be measured, and the fourth pipeline is used for discharging the waste liquid.

[0062] The device is used to monitor the content of gaseous peroxides online, and the specific implementation is as follows: preparing a 5mM potassium hydrogen phthalate solution with a pH of 6 as an absorption liquid; preparing an ammonium chloride / ammonia buffer solution with a pH of 10; dissolving hemin in the ammonium chloride / ammonia buffer solution to prepare a hemin stock solution with a concentration of 1mM, and storing it in the dark and at a low temperature; preparing a 40mM PHPAA stock solution and storing it in the dark and at a low temperature; and preparing a derivatization solution by diluting 10mL of the hemin stock solution and 10mL of the PHPAA stock solution to 1L with the ammonium chloride / ammonia buffer solution.

[0063] During sampling, the second electromagnetic three-way valve 3 switches to the sampling mode, and the sample gas directly passes through the filter membrane 4 to remove particulate matter, and under the action of the vacuum diaphragm pump 7, passes through the trap 8 ( Figure 2 The structure of the capture trap in this embodiment is shown), and at the same time, the absorption liquid enters the multi-turn PFA tube 24 under the simultaneous action of the first pipeline of the four-channel peristaltic pump 21 and the air flow, and forms a liquid film on the tube wall, and the gaseous peroxide component is absorbed and transferred to the liquid phase. The sampling temperature is stabilized at 10°C by the semiconductor refrigeration plate 10 and the temperature controller. After leaving the capture trap 8, the air flow first passes through the water removal safety bottle 5 containing desiccant to remove moisture from the gas, and then flows to the mass flow controller 6 and the vacuum diaphragm pump 7 to prevent the accumulated liquid from damaging the mass flow controller 6 and the vacuum diaphragm pump 7. The derivative liquid is mixed with the liquid phase sample to be tested through the first bubble removal tee 22 under the control of the second pipeline of the four-channel peristaltic pump 21. After mixing, the sample to be tested enters the reaction trap 13 under the control of the third pipeline of the four-channel peristaltic pump 21 for derivatization reaction (the reaction trap structure is the same as Figure 2 The trap structure shown in Figure 1 is essentially the same, but without the heat sink. The reaction temperature is maintained at a constant 40°C. Before entering the detection module, the sample is passed through a second bubble removal tee 22' at the rear end of the reaction trap 13 to prevent bubbles from affecting the measurement. After the bubbles are removed, the sample is transported into the detection chamber 17 via the fourth line of the four-channel peristaltic pump 21. Under the influence of a specific 320nm LED light source 18, the spectrometer detects the fluorescence signal intensity of the sample via optical fiber 35.

[0064] During zero calibration, the second electromagnetic three-way valve 3 engages the peroxide removal device 2 channel to obtain zero air. The zero air passes through the filter membrane 4 to remove particulate matter and, under the action of the vacuum diaphragm pump 7, passes through the multi-turn PFA tubing 24 in the trap 8. Simultaneously, the absorption liquid enters the multi-turn PFA tubing 24 in the trap 8 under the combined action of the first line of the four-channel peristaltic pump 21 and the airflow. The airflow then passes through the desiccant-containing water-removing safety bottle 5, the mass flow controller 6, and the vacuum diaphragm pump 7 before being discharged. The absorption liquid and the derivative liquid are mixed under the control of the first and second lines of the four-channel peristaltic pump 21, respectively, and then enter the reaction trap 13. After passing through the second bubble removal tee 22', they are transported by the fourth line of the four-channel peristaltic pump 21 to the detection chamber 17 for zero calibration. Because organic peroxide standard substances are difficult to obtain, calibration is performed using a standard hydrogen peroxide solution. During liquid phase calibration, the second solenoid three-way valve 3 is similarly used to connect the peroxide removal device 2 to the zero gas channel. A series of standard hydrogen peroxide solutions with gradient concentrations are also provided and connected via the first solenoid three-way valve 1. Driven by the first line of the four-channel peristaltic pump 21 and the airflow, these solutions enter the multi-turn PFA tubing 24 in the trap 8. The standard hydrogen peroxide solutions and the derivative solution follow the same control and reaction steps, sequentially entering the reaction well 13 and detection chamber 17, where the fluorescence signal intensity is finally detected. During zeroing and calibration, all controls for the reaction module, detection module, and solution delivery module remain the same as for sampling.

[0065] During cleaning, the vacuum diaphragm pump 7 stops working, and the four-channel peristaltic pump 21 is turned on. The cleaning liquid enters the device under the action of the four-channel peristaltic pump 21 to clean the pipelines in the device.

[0066] In this embodiment, the flow rates of the first to fourth pipelines of the four-channel peristaltic pump 21 are 0.45 mL / min, 0.15 mL / min, 0.75 mL / min, and 0.27 mL / min, respectively, and the gas flow rate in the trap 8 is 2 L / min.

[0067] A peroxide solution (liquid-phase test sample) and PHPAA undergo a derivatization reaction in an alkaline environment of pH 10 under the catalysis of hemin to produce a fluorescent dimer, 2,2'-dihydroxy-biphenyl-5,5'-diacetic acid. This fluorescent dimer emits 400nm fluorescence when illuminated by a 320nm light source. The liquid-phase test sample, the test component (peroxide), undergoes derivatization to produce the fluorescent dimer. The sample then enters the flow cuvette, where the characteristic wavelength of light generated by a UV LED light source with a central wavelength of 320nm is absorbed by the fluorescent dimer and emits 400nm fluorescence in all directions. This fluorescence is detected by a spectrometer at a light path perpendicular to the incident direction of the light source. The spectrometer simultaneously measures the intensity of the incident light signal while detecting the fluorescence signal intensity, and corrects the incident light intensity to prevent interference from LED attenuation on the test results.

[0068] Calculation of peroxide content: When the incident light intensity remains constant, the concentration of peroxide is proportional to the fluorescence intensity at 400nm. The relationship between fluorescence signal intensity and concentration is as follows:

[0069]

[0070] In formula 1, I f is the fluorescence signal intensity, I f0 is the zero-point light signal intensity, K is the coefficient, and c is the concentration of peroxide. f0 and I measured during the calibration process f , and the corresponding c (concentration of hydrogen peroxide in the hydrogen peroxide standard solution) is known, the coefficient K can be calculated by formula 1.

[0071] Using the obtained coefficient K, the fluorescence signal intensity of a sample of ambient air can be measured and the peroxide content in the sample, i.e., the liquid peroxide concentration, can be calculated using Formula 1. The liquid peroxide concentration can then be converted to the gaseous peroxide concentration, i.e., the ambient air peroxide concentration, using the following conversion method:

[0072]

[0073] In formula 2, cperoxide Represents the concentration of gaseous peroxides (in μg / m 3 ), c [peroxide] represents the concentration of liquid peroxide (in μg / L), F l is the liquid flow rate in the trap (in mL / min), F g is the gas flow rate in the trap (in L / min), and γ is the capture efficiency of the trap for gaseous peroxides in the air.

[0074] Example 2

[0075] On the basis of Example 1, a parallel reaction module and a parallel detection module can be added after the absorption module to achieve the measurement of the concentration of hydrogen peroxide, which is the most common peroxide. Figure 4 This is a structural diagram of the online monitoring device for hydrogen peroxide content in ambient air, after adding a dual-channel reaction-detection module in this embodiment. The device includes a housing, a sampling module, two reaction modules, two detection modules, a solution delivery module, and a control and data acquisition circuit module, all of which are housed within the housing. The sampling module, first reaction module, detection module, solution delivery module, and control and data acquisition circuit module serve the same functions as those used in the corresponding device for the single-channel detection method in Example 1. In the second reaction module, a certain concentration of catalase catalyzes the removal of hydrogen peroxide from the liquid sample at a constant temperature. The remaining peroxide in the liquid sample, catalyzed by Hemin, undergoes a derivatization reaction with PHPAA in an alkaline environment at pH 10 to produce the fluorescent dimer test sample, 2,2'-dihydroxy-biphenyl-5,5'-diacetic acid.

[0076] The internal structures of the sampling module, reaction module, and detection module are consistent with the structures of the corresponding device of the single-channel detection method in Example 1. The front end of the capture trap 8 of the sampling module is connected to the second pipeline of the five-channel peristaltic pump 21' of the solution delivery module, and the rear end is connected to the first pipeline of the peristaltic pump. It is then divided into two paths through a tee, one path connected to the third bubble removal tee 22a of the first reaction module, and the other path connected to the fifth bubble removal tee 22b of the second reaction module. The derivative liquid a (without catalase) and the derivative liquid b (containing catalase) are respectively transported through the third and fourth pipelines of the five-channel peristaltic pump 21', and respectively merge with the two absorption liquids from the sampling module through the third bubble removal tee 22a and the fifth bubble removal tee 22b. The other end of the third bubble removal tee 22a is connected to the first reaction well 13a, and the other end of the fifth bubble removal tee 22b is connected to the second reaction well 13b. The outlets of the first reaction well 13a and the second reaction well 13b are respectively connected to the fourth bubble removal tee 22a' and the sixth bubble removal tee 22b', and then enter the first detection chamber 17a and the second detection chamber 17b respectively. The two flow paths are then merged through the tee and connected to the fifth pipeline of the five-channel peristaltic pump 21' of the solution delivery module.

[0077] The control and data acquisition circuit includes a data acquisition card with a digital I / O port. The Labview program written by the computer controls the solid-state relay to control the LED light sources in the first detection chamber 17a and the second detection chamber 17b respectively. The solid-state relay is controlled by the temperature controller to control the temperature of each module, and collects and outputs the temperature information of each module. The spectrometers in the first detection chamber 17a and the second detection chamber 17b respectively collect light intensity signal data and output it from the USB port of the spectrometer.

[0078] The first and second pipelines of the five-channel peristaltic pump 21 ′ in the solution delivery module are used for accurately distributing the absorption liquid, the third and fourth pipelines are used for accurately distributing the derivative liquid a and the derivative liquid b respectively, and the fifth pipeline is used for discharging the waste liquid.

[0079] The device is used to monitor the content of gaseous hydrogen peroxide online, and the specific implementation is as follows: preparing a 5mM potassium hydrogen phthalate solution with a pH of 6 as an absorption liquid; preparing an ammonium chloride / ammonia buffer solution with a pH of 10; dissolving hemin in the ammonium chloride / ammonia buffer solution to prepare a hemin stock solution with a concentration of 1mM, and storing it in the dark and at a low temperature; dissolving catalase in ultrapure water to prepare a catalase stock solution with a concentration of 1mM, and storing it in the dark and at a low temperature; preparing a 40mM PHPAA stock solution, and storing it in the dark and at a low temperature; preparing a derivative solution a by diluting 10mL of the hemin stock solution and 10mL of the PHPAA stock solution to 1L with the ammonium chloride / ammonia buffer solution; and preparing a derivative solution b by diluting 10mL of the hemin stock solution, 10mL of the catalase, and 10mL of the PHPAA stock solution to 1L with the ammonium chloride / ammonia buffer solution.

[0080] During sampling, the capture method and process are the same as those used in Example 1, when using a single-channel device to detect gaseous peroxides. After absorbing the gaseous sample, the absorption liquid is divided into two paths after passing through the first pipeline of the five-channel peristaltic pump 21', one flowing to the first reaction well 13a and the other flowing to the second reaction well 13b. Under the control of the third and fourth pipelines of the five-channel peristaltic pump 21', the derivative liquid a and derivative liquid b are mixed with the liquid sample to be tested through the third and fifth bubble removal tee 22a, 22b, respectively, and then enter the first and second reaction wells 13a, 13b for derivatization reactions, respectively, with the reaction temperature maintained at 40°C. Before entering the detection module, the two paths of the test sample are respectively passed through the fourth bubble removal tee 22a' at the rear end of the first reaction well 13a and the sixth bubble removal tee 22b' at the rear end of the second reaction well 13b to prevent bubbles from affecting the measurement. After removing bubbles, the two test samples enter the first detection chamber 17a and the second detection chamber 17b, respectively. The signal measurement method and process are the same as those used when detecting gaseous peroxides using a single-channel device. After testing, the two flow paths are combined through a three-way connection and then discharged through the fifth pipeline of the five-channel peristaltic pump 21'.

[0081] During zero mark, method and process are basically the same as when using single channel device to detect gaseous peroxide with embodiment 1, except that the first detection chamber 17a and the second detection chamber 17b need to be carried out zero point calibration respectively. Because organic peroxide standard substance is difficult to obtain, the liquid phase calibration process of the first detection chamber 17a and the second detection chamber 17b all uses hydrogen peroxide standard solution to carry out. During liquid phase calibration, the third and fourth pipelines of five-channel peristaltic pump 21 ' all pass into derivative liquid a, and hydrogen peroxide standard solution and derivative liquid a enter two-way reaction-detection channel successively by identical control and reaction step, i.e. channel one (first reaction well 13a, first detection chamber 17a) and channel two (second reaction well 13b, second detection chamber 17b), detect the fluorescence signal intensity of two detection chambers respectively, and two channels are calibrated respectively. During zero mark and calibration, except that the third pipeline of peristaltic pump is changed into passing into derivative liquid a, all the other controls of reaction module, detection module and solution delivery module are identical when sampling.

[0082] During cleaning, the vacuum diaphragm pump 7 stops working, and the five-channel peristaltic pump 21 ′ is turned on. The cleaning liquid enters the device under the action of the five-channel peristaltic pump 21 ′ to clean the pipelines in the device.

[0083] When the dual-channel device is used to detect the concentration of hydrogen peroxide, the flow rates of the first to fifth pipelines of the five-channel peristaltic pump 21 ′ are 0.9 mL / min, 0.9 mL / min, 0.15 mL / min, 0.15 mL / min, and 0.54 mL / min, respectively, and the gas flow rate in the trap 8 is 4 L / min.

[0084] Calculation of hydrogen peroxide content: According to formula 1, the I obtained by the zeroing process of the first detection chamber 17a and the second detection chamber 17b are f0 and I measured during the calibration process f , and the corresponding c (concentration of hydrogen peroxide in the hydrogen peroxide standard solution) is known, the coefficient K can be calculated a and K b When testing the sample, the fluorescence signal intensity of a certain ambient air sample can be obtained. a with If b , where If a is the fluorescence signal of the total peroxide in the sample, If b is the fluorescence signal of the organic peroxide in the sample except hydrogen peroxide, and the coefficient K obtained by formula 1 is a and K b Calculate the total peroxide content c in the liquid sample a and the content of organic peroxides other than hydrogen peroxide c b , the difference c a -c bThis is the hydrogen peroxide content in the liquid sample. The liquid hydrogen peroxide concentration is then converted to the gaseous hydrogen peroxide concentration, which is the ambient air hydrogen peroxide concentration. The conversion method is as follows:

[0085]

[0086] In formula 3, c H2O2 Represents the concentration of gaseous hydrogen peroxide (in μg / m 3 ), c [H2O2] represents the concentration of liquid hydrogen peroxide (in μg / L), F l is the liquid flow rate in the trap (in mL / min), F g is the gas flow rate in the trap (in L / min), and γ is the capture efficiency of the trap for gaseous hydrogen peroxide in the air.

[0087] It should be noted that the purpose of disclosing the embodiments is to facilitate a further understanding of the present invention. However, those skilled in the art will appreciate that various substitutions and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the present invention should not be limited to the contents disclosed in the embodiments, and the scope of protection claimed by the present invention shall be determined by the scope defined in the claims.

Claims

1. An online monitoring method for gaseous peroxide content, comprising a measurement process, a zeroing process, and a calibration process, comprising the following steps: 1) Sampling process: A multi-turn non-metallic tube is used as a trap, and potassium hydrogen phthalate solution is used as the absorption liquid for gaseous peroxides. The absorption liquid and the gas to be tested containing gaseous peroxides are passed through the trap. In the trap, the gaseous peroxides are absorbed by the absorption liquid forming a liquid film on the tube wall, obtaining a liquid phase sample to be tested; 2) Reaction process: Another multi-turn wound non-metallic tube is used as a derivatization reaction well, and an alkaline solution containing hemin and p-hydroxyphenylacetic acid is used as a derivatization liquid. The liquid phase test sample and the derivatization liquid are allowed to enter the reaction well. The peroxide in the liquid phase test sample and the p-hydroxyphenylacetic acid undergo a derivatization reaction under the catalytic action of the hemin to generate a fluorescent dimer 2,2'-dihydroxy-biphenyl-5,5'-diacetic acid, thereby obtaining a fluorescent dimer test sample; 3) Detection process: The fluorescent dimer sample to be tested enters the flow cuvette. The 320 nm excitation light generated by the light source is absorbed by the fluorescent dimer component to be tested, and emits fluorescence of a characteristic wavelength. The fluorescence signal intensity is detected by a spectrometer. 4) The zeroing process is performed before the measurement process. During zeroing, air is first passed through the peroxide removal device to obtain zero gas. Then, the zero gas is used as the test gas and the sampling process, reaction process, and detection process of steps 1) to 3) above are carried out. The optical signal intensity obtained by the spectrometer is the zero-point optical signal intensity. 5) The calibration process involves preparing a series of peroxide standard solutions with gradient concentrations to replace the absorption solution used in the sampling process. The zero air obtained by passing air through the peroxide removal device is measured in steps 1) to 3) above to obtain the fluorescence signal intensity of the peroxide standard solution. 6) Calculation of peroxide content in the gas to be tested: First, calculate the liquid phase peroxide concentration based on the relationship between fluorescence signal intensity and concentration shown in formula 1: Formula 1 In formula 1, I f is the fluorescence signal intensity, I f0 is the zero-point light signal intensity, K is the coefficient, and c is the concentration of peroxide; according to the zeroing process, I f0 The concentration c of the peroxide standard solution obtained by the calibration process and its fluorescence signal intensity I f , calculate the coefficient K; Then, the liquid peroxide concentration is converted into the gaseous peroxide content in the gas to be measured using Formula 2: Formula 2 In formula 2, c peroxide Represents the concentration of gaseous peroxides in μg / m 3 ; c [peroxide] represents the concentration of liquid peroxide, in μg / L; F l is the liquid flow rate in the trap, in mL / min; F g is the gas flow rate in the trap, in L / min; γ is the capture efficiency of the trap for gaseous peroxides in the air.

2. The online monitoring method according to claim 1, wherein: During the detection, an ultraviolet LED light source with a central wavelength of 320 nm is used. The spectrometer obtains the intensity of the incident light signal generated by the light source while detecting the intensity of the fluorescence signal, and corrects the incident light intensity.

3. The online monitoring method according to claim 1, wherein: The absorption liquid is a 5 mM potassium hydrogen phthalate solution with a pH of 6; the derivatization liquid is a solution containing 0.4 mM p-hydroxyphenylacetic acid and 0.01 mM hemin prepared with an ammonium chloride / ammonia buffer solution with a pH of 10.

4. The online monitoring method according to claim 1, wherein: The temperature of the capture trap and reaction trap is precisely controlled by a temperature control device. The sampling temperature of the capture trap is stabilized at 10 °C, and the reaction temperature of the reaction trap is stabilized at 40 °C.

5. The online monitoring method according to any one of claims 1 to 4, characterized in that: This method is used to achieve online monitoring of gaseous hydrogen peroxide concentration. The liquid sample to be tested is divided into two channels. The reaction process in step 2) adopts a dual-channel setting, that is, two parallel derivatization reaction wells are set up, one of which allows a derivatization reaction between a derivatization liquid without catalase and one liquid sample to be tested, and the other allows a derivatization reaction between a derivatization liquid containing catalase and the other liquid sample to be tested. The detection process in step 3) also adopts a dual-channel setting, that is, two parallel detection devices are set up to respectively detect the fluorescent signals emitted by the two test samples after the derivatization reaction. In step 6), the total peroxide content measured in one channel is subtracted from the content of organic peroxides other than hydrogen peroxide measured in the other channel to obtain the hydrogen peroxide content in the sample.

6. An online monitoring device for gaseous peroxide content, for implementing the online monitoring method for gaseous peroxide content according to any one of claims 1 to 4, comprising a sampling module, a reaction module, a detection module, a solution delivery module, and a control and data acquisition circuit module, wherein: The sampling module samples gaseous peroxides and converts gaseous peroxides in the gas to be tested into a liquid sample to be tested. The sampling module includes a sampling pipeline, a filter membrane, a peroxide removal device, an electromagnetic three-way valve, a capture trap, a capture trap temperature control device, a gas-liquid separation and drying device, a mass flow controller, and a vacuum diaphragm pump. The sampling pipeline is divided into two branches at the sample gas inlet, one of which is provided with a peroxide removal device. The two branches are merged into an air path leading to the capture trap through an electromagnetic three-way valve, and the air path is provided with a filter membrane; the capture trap is composed of a non-metallic tube wrapped around a metal block with multiple turns, and the capture trap temperature control device maintains the capture trap at a constant temperature during operation; the rear end of the capture trap is provided with a gas-liquid separation and drying device, and the liquid sample to be tested from the capture trap flows to the reaction module through a pipeline, and the gas is discharged as tail gas through another pipeline provided with a mass flow controller and a vacuum diaphragm pump after drying; The reaction module includes a reaction trap and a reaction trap temperature control device. The reaction trap is composed of a non-metallic tube wrapped around a metal block in multiple turns. The liquid sample to be tested from the capture trap enters the reaction trap through the pipeline and reacts with the derivatization liquid at a constant temperature to generate a fluorescent dimer sample to be tested. The detection module is divided into a liquid path part, an optical path part and a detection chamber bracket, wherein the liquid path part includes a flow cuvette, through which the fluorescent dimer sample to be tested from the reaction well passes; the flow cuvette is fixed in the detection chamber bracket, and light can pass through the two adjacent sides of the flow cuvette, while the rest of the area is shielded from light; the optical path part includes an LED light source, a collimating lens, an optical fiber and a spectrometer, wherein the LED light source is located on the light-transmitting side of the flow cuvette, the collimating lens and the optical fiber are fixed to the adjacent light-transmitting side, and the optical fiber is connected to the spectrometer; The solution delivery module includes a multi-channel peristaltic pump and a solution delivery pipeline. Through each pipeline of the peristaltic pump, the absorption liquid is delivered to the capture trap, the derivative liquid and the liquid phase sample to be tested are delivered to the reaction trap, the fluorescent dimer sample to be tested is delivered to the flow cuvette, and the waste liquid is discharged; The control and data acquisition circuit module is electrically connected to the sampling module, the reaction module, the detection module, and the solution delivery module respectively to control the operations of these modules and collect data.

7. The online monitoring device according to claim 6, characterized in that: The peristaltic pump is a four-channel peristaltic pump, wherein the first pipeline of the peristaltic pump is connected to the absorption liquid delivery pipeline to deliver the absorption liquid into the capture trap; the second pipeline of the peristaltic pump is connected to the derivative liquid delivery pipeline to deliver the derivative liquid into the liquid-phase test sample pipeline at the rear end of the capture trap; the derivative liquid and the liquid-phase test sample coming out of the capture trap are mixed and then enter the reaction trap under the action of the third pipeline of the peristaltic pump; the fluorescent dimer test sample coming out of the reaction trap enters the flow cuvette under the action of the fourth pipeline of the peristaltic pump and is then discharged; and a first bubble removal tee is provided at the junction of the derivative liquid delivery pipeline and the liquid-phase test sample pipeline at the rear end of the capture trap, and a second bubble removal tee is provided on the pipeline connecting the rear end of the reaction trap to the detection module.

8. An online monitoring device for gaseous hydrogen peroxide concentration, used to implement the online monitoring method according to claim 5, comprising a sampling module, a reaction module, a detection module, a solution delivery module, and a control and data acquisition circuit module, wherein: The sampling module samples gaseous peroxides and converts gaseous peroxides in the gas to be tested into a liquid sample to be tested. The sampling module includes a sampling pipeline, a filter membrane, a peroxide removal device, an electromagnetic three-way valve, a capture trap, a capture trap temperature control device, a gas-liquid separation and drying device, a mass flow controller, and a vacuum diaphragm pump. The sampling pipeline is divided into two branches at the sample gas inlet, one of which is provided with a peroxide removal device. The two branches are merged into an air path leading to the capture trap through an electromagnetic three-way valve, and the air path is provided with a filter membrane; the capture trap is composed of a non-metallic tube wrapped around a metal block with multiple turns, and the capture trap temperature control device maintains the capture trap at a constant temperature during operation; the rear end of the capture trap is provided with a gas-liquid separation and drying device, and the liquid sample to be tested from the capture trap flows to the reaction module through a pipeline, and the gas is discharged as tail gas through another pipeline provided with a mass flow controller and a vacuum diaphragm pump after drying; The reaction module includes a reaction trap and a reaction trap temperature control device. The reaction trap is composed of multiple turns of non-metallic tubes wrapped around a metal block. The liquid phase sample to be tested from the capture trap enters the reaction trap through the pipeline and reacts with the derivative liquid at a constant temperature to generate a fluorescent dimer sample to be tested; the detection module is divided into a liquid path part, an optical path part and a detection chamber bracket, wherein the liquid path part includes a flow cuvette, and the fluorescent dimer sample to be tested from the reaction trap passes through the flow cuvette; the flow cuvette is fixed in the detection chamber bracket, and light can pass through the two adjacent sides of the flow cuvette, while the rest of the area is shielded from light; the optical path part includes an LED light source, a collimating lens, an optical fiber and a spectrometer. The LED light source is located on the light-transmitting side of the flow cuvette, and the collimating lens and the optical fiber are fixed on the adjacent light-transmitting side. The optical fiber is connected to the spectrometer; The solution delivery module includes a multi-channel peristaltic pump and a solution delivery pipeline. Through each pipeline of the peristaltic pump, the absorption liquid is delivered to the capture trap, the derivative liquid and the liquid phase sample to be tested are delivered to the reaction trap, the fluorescent dimer sample to be tested is delivered to the flow cuvette, and the waste liquid is discharged; The control and data acquisition circuit module is electrically connected to the sampling module, reaction module, detection module, and solution delivery module, respectively, to control the operation of these modules and collect data; it is characterized in that the reaction module is provided with two sets of parallel reaction devices, including a first reaction well and its temperature control device, a second reaction well and its temperature control device, the liquid phase sample to be tested coming out of the sampling module is divided into two paths, entering the first reaction well and the second reaction well respectively, wherein the derivative liquid without catalase in the first reaction well undergoes a derivatization reaction with one path of the liquid phase sample to be tested, and the derivative liquid containing catalase in the second reaction well undergoes a derivatization reaction with the other path of the liquid phase sample to be tested; the detection module is provided with two sets of parallel detection devices, respectively detecting the fluorescence signals emitted by the two paths of the sample to be tested after the derivatization reaction; the peristaltic pump is a five-channel peristaltic pump, wherein the second pipeline is connected to the absorption liquid delivery pipeline to deliver the absorption liquid into the capture trap of the sampling module;The front end of the sampling module's capture trap is connected to the second line of the peristaltic pump, and the rear end is connected to the first line of the peristaltic pump. A tee then splits the line carrying the liquid sample into two: one line passes through a de-bubble tee before entering the first reaction trap, and the other line passes through another de-bubble tee before entering the second reaction trap. The catalase-free and catalase-containing derivative liquids are transported through the third and fourth lines of the peristaltic pump, respectively, and then pass through the de-bubble tee to merge with the two liquid sample lines from the sampling module. The outlets of the first and second reaction traps each pass through a de-bubble tee before connecting to the two detection devices of the detection module. The outlets of the two detection devices are then connected to the fifth line of the peristaltic pump, joining the two flow paths through a tee.

9. The online monitoring device according to claim 7 or 8, characterized in that: The capture trap is a PFA tube wrapped around a first aluminum block in multiple turns, one end of which is the inlet for the absorption liquid and the gas to be tested, and the other end is the outlet for the liquid phase sample to be tested after the absorption liquid absorbs the gaseous peroxide; the capture trap is located in an insulation chamber and is surrounded by insulation cotton and foam boards; the capture trap temperature control device includes a semiconductor refrigeration plate, a first radiator, a fan and a temperature controller connected through a first thermocouple, wherein the semiconductor refrigeration plate is arranged at one end of the first aluminum block, the first radiator is connected to the semiconductor refrigeration plate, the fan faces the first radiator, and the thermocouple detects the temperature of the PFA tube wrapped around the first aluminum block in multiple turns and transmits it to the temperature controller.

10. The online monitoring device according to claim 7 or 8, characterized in that: The reaction trap is a PFA tube wrapped multiple times around a second aluminum block, one end of which is the inlet for the derivatization liquid and the liquid-phase sample to be tested, and the other end is the outlet for the sample to be tested after the derivatization reaction; the reaction trap temperature control device includes a built-in heating block and a temperature controller connected via a second thermocouple.

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