Online monitoring method and device for gaseous peroxide content in ambient air

Abstract

This invention discloses an online monitoring method and device for the content of gaseous peroxides in ambient air. Based on a wet chemical method of gas diffusion absorption trapping and fluorescence spectroscopy detection technology, this invention uses a multi-turn wound non-metallic tube trap for sampling. The absorbent forms a liquid film on the tube wall, and the gaseous components to be measured diffuse and transfer mass at the gas-liquid interface. After sufficient contact and absorption with the absorbent, gas-liquid separation is achieved at the other end of the trap. Using p-hydroxyphenylacetic acid as a peroxide derivative, a fluorescent dimer is generated under the catalysis of heme chloride. This dimer fluoresces under characteristic wavelength light irradiation. The fluorescence intensity is measured using a flow cuvette and a photomultiplier tube, and the peroxide content of the gaseous components is calculated. The corresponding online monitoring device of this invention uses a multi-channel peristaltic pump for precise control of trace solutions, reducing daily maintenance. It can be applied to the rapid, online, and continuous measurement of gaseous peroxides in various environmental environments.

Description

Technical Field

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

[0002] Peroxides are an important class of chemical products with multiple functions such as bleaching, oxidation, disinfection, and sterilization, and are widely used in various fields including industry, medicine, and food hygiene. However, due to their strong oxidizing properties, peroxides can deplete the body's antioxidant capacity, leading to decreased antioxidant capacity. They may also cause DNA damage, resulting in gene mutations and further contributing to various diseases. Long-term exposure to high concentrations of peroxides can irritate the eyes, respiratory tract, and skin. 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 for 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 good accuracy and minimal interference, but its high cost limits its application. Spectrophotometry mainly includes two methods: 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 Oxides in Workplace Air (GBZ / T 160.32-2004)". However, both of these spectrophotometric methods are offline and cannot achieve continuous online monitoring; the same applies to titration. Chemiluminescence is mild, rapid, and uses simple instruments, and it does not have a blank period, but it also suffers from poor selectivity and low sensitivity. Enzyme-catalyzed derivatization fluorescence method has become a commonly used 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 catalysis of enzymes, peroxides oxidize non-fluorescent substrates into fluorescent dimers. Among the existing detection methods, p-hydroxyphenylacetic acid (PHPAA) is the preferred fluorescent indicator substrate. The selected enzymes are peroxidase, horseradish peroxidase (HRP), and hemin chloride. The reaction catalyzed by peroxidase is stable and has a high fluorescence coefficient, but peroxidase is expensive. The method catalyzed by HRP is relatively cheaper and has a high fluorescence coefficient than peroxidase, but the HRP stock solution is prone to denaturation and inactivation, and its stability is poor. Moreover, since the optimal reaction pH of HRP (5.8) differs greatly from the optimal pH of fluorescence detection (11), an additional pump is needed to deliver buffer solution to adjust the pH. The optimal reaction pH of Hemin catalysis is consistent with the fluorescence detection value, so the experimental system can reduce one pump. Furthermore, the cost of Hemin is much lower than the other two enzymes, and the stock solution is relatively stable. Therefore, this method has a relatively simple device, low cost, and is more suitable for field observation.

[0004] The hydrogen peroxide gas concentration analyzer from Picaro (USA) is an online detection instrument for hydrogen peroxide based on the near-infrared laser cavity ring-down method. This instrument offers high sensitivity and accuracy, but is expensive and requires high maintenance costs. The hydrogen peroxide analyzer from AeroLaser (Germany) is an online detection instrument for peroxides based on an enzyme-catalyzed derivatization fluorescence method. While this instrument offers advantages such as low detection limits, high sensitivity, high selectivity, and relatively rapid online detection, the method and instrument still suffer from drawbacks such as baseline drift, frequent maintenance, and high reagent costs.

[0005] Chinese patent applications 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. A near-infrared tunable laser is used as the light source to pass through a test environment filled with gas-phase hydrogen peroxide. The concentration of gas-phase hydrogen peroxide is obtained based on the linear relationship between the gas-phase hydrogen peroxide concentration and the second harmonic peak value. 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] To overcome the shortcomings of the prior art, the present invention provides an online monitoring method and device for the content of gaseous peroxides in ambient air. Based on the wet chemical method of gas diffusion absorption and capture and fluorescence spectroscopy detection technology, it realizes real-time online detection of gaseous peroxide content and can be applied to online continuous monitoring of gaseous peroxide concentration in various environments.

[0007] The principle of this invention is as follows: This invention employs a combination of 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 sampling, air is drawn through a trap formed by a multi-turn spiral non-metallic tube under the action of a vacuum diaphragm pump. The absorbent also enters the trap from the same end, forming a liquid film on the tube wall due to liquid tension. Because the gas-liquid interface increases in the trap, the gaseous components of the air diffuse and transfer mass between the interfaces, achieving full contact and absorption with the absorbent. Gas-liquid separation is then achieved at the other end of the trap. Using p-hydroxyphenylacetic acid (PHPAA) as the derivatizing agent for gaseous peroxides, the peroxide solution reacts with PHPAA in an alkaline environment (pH=10) under the catalysis of hemin chloride (Hemin) to generate a fluorescent dimer, 2,2'-dihydroxy-biphenyl-5,5'-diacetic acid, which produces fluorescence at a characteristic wavelength (400nm) under irradiation with a 320nm light source. The liquid sample, having absorbed the analyte (gaseous peroxide), undergoes a derivatization reaction and then enters a flow cuvette. When the analyte is at a low concentration, under illumination from a 320nm LED light source, the concentration of the analyte is directly proportional to the fluorescence intensity of its emitted characteristic wavelength. Online monitoring of the gaseous peroxide content can be achieved based on the fluorescence intensity. This invention also provides an online monitoring device for gaseous peroxides in ambient air utilizing the principle of wet gas diffusion trapping. It employs a multi-channel peristaltic pump for precise control of trace solutions, reducing daily maintenance and enabling rapid, online, and continuous measurement of gaseous peroxides in the atmosphere.

[0008] The technical solution provided by this invention is:

[0009] An online monitoring method for the content of gaseous peroxides in ambient air includes a measurement process, a zeroing process, and a calibration process, wherein the measurement process includes 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 the absorbent for gaseous peroxides. The absorbent and the gas to be tested are passed through the trap. In the trap, the gaseous peroxides in the gas to be tested are absorbed by the absorbent that forms a liquid film on the tube wall, and a liquid phase sample to be tested is obtained.

[0011] 2) Reaction process: Another multi-turn wound non-metallic tube is used as the derivatization reaction trap. An alkaline solution containing heme chloride and p-hydroxyphenylacetic acid is used as the derivatizing liquid. The liquid sample to be tested and the derivatizing liquid are introduced into the reaction trap. The peroxide in the liquid sample to be tested reacts with p-hydroxyphenylacetic acid under the catalysis of heme chloride to generate fluorescent dimer 2,2'-dihydroxy-biphenyl-5,5'-diacetic acid, thus obtaining the fluorescent dimer sample to be tested.

[0012] 3) Detection process: The fluorescent dimer sample is introduced into a flow cuvette. The characteristic wavelength excitation light generated by the light source is absorbed by the fluorescent dimer of the sample and emits fluorescence of the characteristic wavelength. At the light path exit perpendicular to the incident light direction, the fluorescence signal is converted into an electrical signal by a photomultiplier tube to measure the fluorescence signal intensity. At the same time, the incident light signal intensity is obtained by a spectrometer in the direction of incident light and the incident light intensity is corrected.

[0013] 4) The zeroing process is carried out 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 gas to be measured and goes through the sampling process, reaction process and detection process in steps 1) to 3) above. The light signal intensity obtained is the zero point light signal intensity.

[0014] 5) The calibration process involves preparing a series of peroxide standard solutions with gradient concentrations to replace the absorbent in the sampling process. The zero gas obtained by passing air through the peroxide removal device is then subjected to the measurement process described in steps 1) to 3) above to obtain the fluorescence signal intensity of the peroxide standard solution.

[0015] 6) Calculation of peroxide content in the gas to be tested: Steps 4) and 5) yield the zero-point light signal intensity and the fluorescence signal intensity of the peroxide standard solution. Since the analyte is at a low concentration, the concentration of peroxide is proportional to the fluorescence intensity of its emitted characteristic wavelength when the incident light intensity remains constant. The concentration of liquid-phase peroxide can be calculated according to the fluorescence signal intensity versus concentration relationship shown in Equation 1.

[0016]

[0017] In Equation 1, I f I represents the fluorescence signal intensity. f0 Where I is the zero-point optical signal intensity, K is a coefficient, and c is the concentration of peroxide; based on the zero-calibration process, I... f0 The concentration c of the peroxide standard solution obtained during the calibration process and its fluorescence signal intensity I. f The coefficient K is calculated. Therefore, using the obtained coefficient K, for the liquid phase sample to be tested, the concentration of peroxide in the sample, i.e. the concentration of liquid phase peroxide, can be calculated using Equation 1 based on the fluorescence signal intensity obtained in step 3).

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

[0019]

[0020] In Equation 2, c peroxide Represents the concentration of gaseous peroxides (unit: μg / m³). 3 ), c [peroxide] F represents the concentration of liquid phase peroxide (in μg / L). l F represents the liquid flow rate in the trap (in mL / min). g γ represents the gas flow rate in the trap (in L / min), and γ represents the trapping efficiency of the trap in capturing gaseous peroxides in the gas to be tested.

[0021] Preferably, in step 3), an ultraviolet LED light source with a center wavelength of 320nm is used during the detection process. The spectrometer acquires the incident light signal intensity generated by the light source while the photomultiplier tube detects the fluorescence signal intensity, and corrects the incident light intensity. For the fluorescence emitted by the sample to be tested, 400nm is selected as the characteristic wavelength for quantification.

[0022] Furthermore, both the trap and the reaction trap employ PFA tubes wound in multiple turns around a cylindrical aluminum block, and the temperature of the trap and the reaction trap is precisely regulated by a temperature control device.

[0023] In one embodiment of the present invention, the absorbent is a 5 mM potassium hydrogen phthalate solution with pH = 6; the derivatizing solution is a solution containing 0.4 mM p-hydroxyphenylacetic acid and 0.01 mM heme chloride prepared with an ammonium chloride / ammonia buffer solution with pH = 10.

[0024] Step 1) of the sampling process converts gaseous peroxides in the sample into a liquid sample. During sampling, the gas to be tested passes through the trap under the action of a vacuum diaphragm pump, and the absorbent also enters the trap from the same end. The absorbent forms a liquid film on the tube wall due to liquid surface tension. Because the gas-liquid interface increases in the trap, gas components diffuse and transfer mass between the interfaces, making full contact with the absorbent for absorption. Gas-liquid separation is then achieved at the other end of the trap. Simultaneously, a temperature control device stabilizes the sampling temperature at 10℃ to avoid interference from outdoor temperature differences and ensure the stability of the collection efficiency during the sampling process.

[0025] In step 2), hydroxyphenylacetic acid (PHPAA) is used as the derivatization solution for the peroxide. The peroxide solution (liquid-phase sample) reacts with PHPAA in an alkaline environment (pH=10) under the catalysis of hemin chloride to generate a fluorescent dimer, 2,2'-dihydroxy-biphenyl-5,5'-diacetic acid, which produces fluorescence at a wavelength of 400 nm under irradiation with a 320 nm light source. A PFA tube wound in multiple turns around a cylindrical thermally conductive aluminum block serves as the derivatization reaction trap. A temperature control device can stabilize the reaction temperature at 40 °C, accelerating the derivatization reaction and improving its stability and detection limit. The reaction trap is also designed to shield the reaction from light to prevent its influence on reaction stability.

[0026] During sampling, the liquid sample containing the analyte (peroxide) undergoes derivatization to generate a fluorescent dimer. This dimer is then introduced into a flow cuvette during the detection process in step 3). The characteristic wavelength excitation light generated by the light source is absorbed by the fluorescent dimer, which emits fluorescence at a wavelength of 400 nm. At the exit of the light path perpendicular to the incident light direction, a photomultiplier tube converts the fluorescence signal into an electrical signal to measure the fluorescence intensity. The incident light signal intensity is detected by a spectrometer positioned along the incident direction. This invention uses a 320 nm ultraviolet LED light source and acquires the incident light signal intensity simultaneously with the photomultiplier tube's fluorescence signal intensity detection using a spectrometer. The incident light intensity is then corrected to avoid interference from LED attenuation on the detection results.

[0027] Each time the prepared absorbent and derivatizing solutions are changed, a calibration process is required. During the calibration process, air is first passed through a peroxide removal device to obtain zero gas, and the zero-point light signal intensity is measured; then the absorbent in step 1) is replaced with a peroxide standard solution of gradient concentration prepared in the laboratory, and the zero gas is measured through the measurement process from step 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 phase test sample obtained in step 1) can be divided into two paths. The reaction process in step 2) adopts a dual-channel setting, that is, two parallel derivatization reaction traps are set. One trap allows the derivatization solution without catalase to react with one liquid phase test sample, and the other trap allows the derivatization solution containing catalase to react with the other liquid phase test sample. The detection process in step 3) also adopts a dual-channel setting, that is, two parallel detection devices are set to detect the fluorescence signals emitted by the test samples after the two derivatization reactions respectively. In step 6), the total peroxide content measured by one channel is subtracted from the content of organic peroxides other than hydrogen peroxide measured by the other channel to obtain the hydrogen peroxide content in the sample.

[0029] Based on the above-mentioned online monitoring method for the content of gaseous peroxides in ambient air, this invention also provides an online monitoring device for the content of gaseous peroxides, 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 them into a liquid sample to be tested in ambient air. The reaction module is used to derivatize the liquid sample to be tested, so that the liquid sample to be tested containing peroxides undergoes a derivatization reaction with PHPAA in an alkaline environment under 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 light signal intensity. The light signal intensity is transmitted from the photomultiplier tube of the detection module to the control and data acquisition circuit module for storage via a data connection line. The solution delivery module is used to accurately deliver the absorption liquid, derivatization liquid, and the sample 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 splits into two branches at the sample gas inlet, one of which is equipped with the peroxide removal device. The two branches merge into a single gas path leading to the trap via an electromagnetic three-way valve, and this gas path is equipped with a filter membrane. The trap is constructed of a non-metallic tube (preferably PFA tube) wound multiple turns around a metal block. The trap temperature control device maintains the trap at a constant temperature during operation. A gas-liquid separation and drying device is located at the rear end of the trap. The liquid sample from the trap flows through a pipeline to the reaction module, while the gas, after drying, is discharged as exhaust gas through another pipeline equipped with a mass flow controller and a vacuum diaphragm pump.

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

[0032] The detection module is divided into a liquid path section, an optical path section, and a detection chamber support. The liquid path section includes a flowing cuvette through which the fluorescent dimer sample from the reaction trap passes. The flowing cuvette is fixed in the detection chamber support, allowing light to pass through its four sides while blocking light from the rest. The optical path section includes an LED light source, a UV concave mirror, a photomultiplier tube, a collimating lens, an optical fiber, and a spectrometer. The LED light source is located on one side of the flowing cuvette, with a collimating lens and an optical fiber on the opposite side, the fiber connecting to the spectrometer. A photomultiplier tube and a UV concave mirror are located on two adjacent sides, respectively. The sample liquid in the flowing cuvette absorbs incident light and emits fluorescence in all directions. This fluorescence is focused by the UV concave mirror and directed to the opposite photomultiplier tube for photo-to-electrical signal conversion. A 400nm center wavelength filter can be installed in front of the photomultiplier tube to filter out stray light.

[0033] The solution delivery module includes a multi-channel peristaltic pump and solution delivery pipelines. The absorbent is delivered into the trap through the pipelines of the peristaltic pump, the derivatized liquid and the liquid phase test sample are delivered into the reaction trap, and the fluorescent dimer test sample is delivered into the flow cuvette.

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

[0035] In one embodiment of the present invention, the peristaltic pump is a four-channel peristaltic pump. Its first line is connected to the absorbent delivery line, which delivers the absorbent into the trap. The second line of the peristaltic pump is connected to the derivatization delivery line, which delivers the derivatization into the liquid phase test sample line at the rear end of the trap. The derivatization and the liquid phase test sample from the trap are mixed and then enter the reaction trap under the action of the third line of the peristaltic pump. The fluorescent dimer test sample from the reaction trap enters the flow cuvette under the action of the fourth line of the peristaltic pump and then is discharged.

[0036] Furthermore, a first degassing tee is installed at the junction of the derivative liquid delivery pipeline and the liquid phase test sample pipeline at the rear end of the trap, and a second degassing tee is installed 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 test gas, two parallel reaction devices are set in the reaction module, including a first reaction trap and its temperature control device, and a second reaction trap and its temperature control device. The liquid test sample from the sampling module is divided into two paths, which enter the first reaction trap and the second reaction trap respectively. The derivatization solution in the first reaction trap, which does not contain catalase, reacts with one path of liquid test sample, and the derivatization solution in the second reaction trap, which contains catalase, reacts with the other path of liquid test sample. The detection module is equipped with two parallel detection devices to detect the fluorescence signals emitted by the test samples after the two derivatization reactions respectively. The peristaltic pump is a four-channel peristaltic pump, wherein the first pipeline is connected to... The absorbent delivery line delivers the absorbent into the trap of the sampling module. The front end of the trap of the sampling module is connected to the first line of the peristaltic pump, and the rear line for delivering the liquid phase test sample is divided into two paths: one path passes through a degassing tee and enters the first reaction trap, and the other path passes through another degassing tee and enters the second reaction trap. The catalase-free derivatized solution and the catalase-containing derivatized solution are delivered through the second and third lines of the peristaltic pump, respectively, and then merged with the two liquid phase test samples from the sampling module through degassing tees. The outlets of the first and second reaction traps are connected to the two detection devices of the detection module through a degassing tee, and the outlets of the two detection devices are connected to the fourth line of the peristaltic pump through a tee that merges the two flow paths.

[0038] Preferably, the trap is a PFA tube wound multiple turns around a first aluminum block, with one end serving as the inlet for the absorbent and the gas to be tested, and the other end serving as the outlet for the liquid sample after the absorbent has absorbed gaseous peroxides. The trap is located in an insulation chamber and surrounded by insulation cotton and foam board. The trap temperature control device includes a semiconductor cooling chip, a first heat sink, a fan, and a temperature controller connected via a first thermocouple. The semiconductor cooling chip is located at one end of the first aluminum block, the first heat sink is connected to the semiconductor cooling chip, the fan faces the first heat sink, and the first thermocouple detects the temperature of the PFA tube wound multiple turns around the first aluminum block and transmits it to the temperature controller. The reaction trap is a PFA tube wound multiple turns around a second aluminum block, with one end serving as the inlet for the derivatization liquid and the liquid sample to be tested, and the other end serving as the outlet for the sample 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 digital I / O ports. A LabVIEW program written on a computer controls the solid-state relay to control the LED light source. A temperature controller controls the solid-state relay to control the temperature of each module. The circuit also collects and outputs the temperature information of each module. The light intensity signal data captured and converted by the photomultiplier tube is collected by the data acquisition card and output through the USB port.

[0040] Compared with the prior art, the beneficial effects of the present invention are:

[0041] This invention provides an online monitoring method and device for the content of gaseous peroxides in ambient air. Based on the wet chemical method of gas diffusion absorption and capture and fluorescence spectroscopy detection technology, it realizes real-time online detection of gaseous peroxide content and can continuously monitor the content of gaseous peroxides on site.

[0042] This invention is an online monitoring technology for gaseous peroxides in ambient air that combines wet chemical methods and fluorescence spectroscopy, providing a novel measurement technique 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] (i) Combining chemical and optical methods, using the principle of wet gas diffusion trapping and fluorescence spectroscopy, we can achieve rapid, online and continuous measurement of low concentrations of gaseous peroxides in the atmosphere. The response speed is faster, the instrument cost is significantly lower than that of optical methods, and the degree of interference is significantly reduced compared with the sensor method.

[0044] (ii) The use of photomultiplier tubes combined with amplification circuits to detect fluorescence intensity improves the sensitivity of gaseous peroxide detection and lowers the detection limit. At the same time, the application of a spectrometer enables the correction of incident light intensity, avoiding interference of LED light source intensity changes on the detection results.

[0045] (III) The PFA tube trap with multiple turns wound around a cylindrical aluminum block is used as a gaseous peroxide trap, which has the characteristics of high trapping efficiency, small size, simple structure and outdoor placement.

[0046] (iv) The flow rate of the solution in each pipeline is precisely controlled by a multi-channel peristaltic pump with adjustable speed, reducing daily maintenance and data loss due to aging of the peristaltic pump.

[0047] (v) The solid-state relays controlled by the temperature controller achieve precise temperature control of each module, ensuring the stable capture and derivatization reaction of peroxides in the air. Attached Figure Description

[0048] Figure 1The diagram shows the structural composition of an online monitoring device for gaseous peroxides provided in Embodiment 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 cooling chip; 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 mounting bracket (including focusing lens); 21—four-channel peristaltic pump (from right to left, the first pipeline to the fourth pipeline); 22—first de-aeration tee; 22'—second de-aeration tee.

[0049] Figure 2 This is a schematic diagram of the trap structure in an online monitoring device for gaseous peroxides provided in Embodiment 1 of the present invention, wherein: 9—first heat sink; 10—semiconductor cooling chip; 11—first thermocouple; 12—first aluminum block; 23—fan; 24—multi-turn wound PFA tube; 25—insulation chamber; 26—insulation cotton; 27—foam board; 28—absorbent inlet; 29—absorbent outlet.

[0050] Figure 3 This is a schematic diagram of the detection chamber in an online monitoring device for gaseous peroxides provided in Embodiment 1 of the present invention, wherein: 18—LED light source; 19—second heat sink; 20—LED mounting bracket (including focusing lens); 30—test liquid inlet; 31—test liquid outlet; 32—flowing cuvette; 33—detection chamber support; 34—collimating lens; 35—optical fiber; 36—ultraviolet concave mirror; 37—photomultiplier tube; 38—high voltage power supply assembly.

[0051] Figure 4 This is a structural diagram of an online monitoring device for gaseous hydrogen peroxide content provided in Embodiment 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—collection 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, the first pipeline to the fifth pipeline); 22a—third deaerator tee; 22a'—fourth deaerator tee; 22b—fifth deaerator tee; 22b'—sixth deaerator tee. Detailed Implementation

[0052] The present invention will be further described below with reference to the accompanying drawings and embodiments, but the scope of the invention is not limited in any way.

[0053] This invention provides an online monitoring method and device for gaseous peroxide content. Based on wet chemical technology of gas diffusion absorption trapping and fluorescence spectroscopy detection technology, it achieves real-time online detection of gaseous peroxide content, enabling continuous on-site monitoring of gaseous peroxide content. This invention uses a photomultiplier tube to detect the fluorescence intensity of derivatives, and simultaneously employs a spectrometer to correct the incident light intensity, avoiding interference from LED attenuation on the detection results. This invention also provides an online monitoring device for ambient air gaseous peroxides utilizing the wet gas diffusion trapping principle, employing an adjustable-speed multi-channel peristaltic pump for precise control of trace solutions and reducing daily maintenance.

[0054] Example 1

[0055] Figure 1 This embodiment provides a structural diagram of the online monitoring device for ambient air peroxide content, including a housing, a sampling module, a reaction module, a detection module, a solution delivery module, and a control and data acquisition circuit module. All modules are housed within the housing. The sampling module samples gaseous peroxides, converting them into a liquid sample for testing. The reaction module derivatizes the liquid sample, causing the peroxide-containing liquid sample to undergo a derivatization reaction with PHPAA in an alkaline environment (pH=10) under constant temperature and Hemin catalysis to generate a fluorescent dimer sample, 2,2'-dihydroxy-biphenyl-5,5'-diacetic acid. The detection module detects the light signal intensity, which is transmitted from a photomultiplier tube to a computer for storage via a data cable with a USB port. The solution delivery module precisely delivers the absorption liquid, derivatization liquid, and analyte, and also delivers the cleaning solution and discharges waste liquid.

[0056] The sampling module includes a sampling pipeline, a filter membrane 4, a peroxide removal device 2, a second electromagnetic three-way valve 3, a trap 8, a trap temperature control device, a gas-liquid separation and drying device (water-removing safety bottle 5), a mass flow controller 6, and a vacuum diaphragm pump 7. The reaction module includes a first degassing tee 22, a reaction trap 13, and its temperature control device. The front end of the 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 degassing tee 22 of the reaction module. The other two ends of the first degassing tee 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, an ultraviolet concave mirror 36, a photomultiplier tube 37, a filter, a collimating lens 34, and a spectrometer. The outlet of the reaction trap 13 is connected to the second degassing tee 22', then enters the flow cuvette 32 of the detection module, and is then 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 derivatized liquid to the first degassing tee 22 of the reaction module, the third pipeline connects the first degassing tee 22 of the reaction module to the reaction trap 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 digital I / O ports. A LabVIEW program written on a computer controls solid-state relays to control the LED light source 18, and a temperature controller controls the solid-state relays to control the temperature of each module. It also collects and outputs temperature information from each module. The photomultiplier tube captures and converts light intensity signal data, which is collected by the data acquisition card and output through the USB port.

[0057] In the sampling module, the sampling pipeline uses 1 / 8” PFA tubing. An air sample is drawn in using a vacuum diaphragm pump 7 and introduced into the trap 8. Simultaneously, a 1 / 16” PFA tubing is used to introduce a pH=6 potassium hydrogen phthalate solution into the trap 8 as a gaseous peroxide absorbent. The core component, the trap 8, uses 1 / 8” PFA tubing wound around a 42mm high cylindrical thermally conductive aluminum block (first aluminum block 12). The sampling temperature is stabilized at 10°C by a trap temperature control device, which includes a semiconductor cooling chip 10, a first heat sink 9, a fan 23, and a temperature controller connected via a first thermocouple 11. Figure 2As shown, the first aluminum block 12 has a multi-turn PFA tube 24 wound around it, with one end being the absorbent inlet 28 (which is also the gas inlet) and the other end being the absorbent outlet 29. The first aluminum block 12 and the multi-turn PFA tube 24 are located in the insulation chamber 25 and are surrounded by insulation cotton 26 and foam board 27. A semiconductor cooling chip 10 and a first heat sink 9 are installed 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 chip 10 and the fan 23. The trap temperature control device ensures that the analyte is captured at a constant temperature, avoiding fluctuations in sample capture efficiency caused by temperature changes.

[0058] In the reaction module, the derivatization solution and the test solution absorbing peroxide simultaneously enter the reaction trap 13 through the first degassing tee 22, where a derivatization reaction occurs at 40°C to generate a fluorescent dimer. Since this reaction is relatively slow at room temperature, the reaction trap 13 is specifically constructed by winding 1 / 8” PFA tubing around a cylindrical thermally conductive aluminum block (second aluminum block 15) with a height of 22.5 cm. An internal heating block 16 and a temperature controller connected via a second thermocouple 14 maintain the temperature of the reaction trap 13 at 40°C to accelerate the derivatization reaction.

[0059] The detection module can be divided into a liquid path section, an optical path section, and a detection chamber support. For example... Figure 3As shown, the liquid path includes a flowing cuvette 32. The test liquid, after undergoing a derivatization reaction, enters and exits the cuvette through two threaded interfaces sealed with O-rings (test liquid inlet 30 and test liquid outlet 31) on the top of the flowing cuvette 32. The optical path includes an LED light source 18, an ultraviolet concave mirror 36, a photomultiplier tube 37, a filter, a collimating lens 34, an optical fiber 35, and a spectrometer. The detection chamber support 33 is a near-cubic prism with a cuvette groove on the top surface and light passing through all four sides. The flowing cuvette 32 can be directly fixed in the cuvette groove of the detection chamber support 33. The four sides of the flowing cuvette 32 are quartz light-transmitting windows, allowing ultraviolet light to pass through, while the top is light-shielded. The four sides of the detection chamber support 33 are respectively fixed with an LED holder (including a focusing lens) 20 and an LED light source 18, a filter and a photomultiplier tube 37, a collimating lens 34 and an optical fiber 35, and an ultraviolet concave mirror 36. All fixing points are light-shielded. To avoid excessive heat generation and significant temperature-dependent spectrum fluctuations in the light source, a stable LED light source 18 is used, and a second heat sink 19 is installed on the outside of the LED mounting bracket (including the focusing lens) 20. Based on the frequency characteristics of the LED, a wavelength of 320nm is selected. The light emitted by the LED light source 18 is incident on one side of the detection chamber support 33 onto the flowing cuvette 32. The liquid to be tested in the flowing cuvette 32 absorbs the incident light and emits fluorescence in all directions. After being converged by an ultraviolet concave reflector 36 fixed on the adjacent side of the incident light, it is directed towards a photomultiplier tube 37 opposite the reflector for photo-to-electric signal conversion. A filter with a center wavelength of 400nm is installed in front of the photomultiplier tube 37 to filter out stray light. Simultaneously, the LED incident light is collimated by a collimating lens 34 on the opposite side and coupled into a spectrometer via an optical fiber 35 for detection, in order to correct the LED incident light intensity and avoid the influence of LED attenuation on the detection results.

[0060] In the solution delivery module, the first, second, and third pipelines of the four-channel peristaltic pump 21 are used to accurately deliver the absorbent, the derivative, and the analyte, respectively, while the fourth pipeline is used to discharge the waste liquid.

[0061] The device was used to monitor the content of gaseous peroxides online, and the specific implementation was as follows: a 5 mM potassium hydrogen phthalate solution with pH=6 was prepared as the absorption solution; an ammonium chloride / ammonia buffer solution with pH=10 was prepared; Hemin was dissolved in the ammonium chloride / ammonia buffer solution to prepare a 1 mM Hemin stock solution, which was then stored in the dark and at low temperature; a 40 mM PHPAA stock solution was prepared and stored in the dark and at low temperature; and a derivatization solution was prepared by diluting 10 mL of Hemin stock solution and 10 mL of PHPAA stock solution with ammonium chloride / ammonia buffer solution to a final volume of 1 L.

[0062] During sampling, the second electromagnetic three-way valve 3 switches to sampling mode, and the sample gas directly passes through the filter membrane 4 to remove particulate matter. Under the action of the vacuum diaphragm pump 7, it passes through the trap 8 ( Figure 2 The structure of the trap shown in this embodiment is as follows: Simultaneously, the absorbent liquid enters the multi-turn wound PFA tube 24 under the combined action of the first pipeline of the four-channel peristaltic pump 21 and the airflow, forming a liquid film on the tube wall. The gaseous peroxide component is absorbed and transferred to the liquid phase. The sampling temperature is stabilized at 10°C by the semiconductor cooling chip 10 and the temperature controller. After leaving the trap 8, the airflow first passes through a desiccant-containing water-removing safety bottle 5 to remove moisture from the gas, and then flows to the mass flow controller 6 and the vacuum diaphragm pump 7 to prevent liquid accumulation from damaging the mass flow controller 6 and the vacuum diaphragm pump 7. Under the control of the second pipeline of the four-channel peristaltic pump 21, the degassing tee 22 mixes with the liquid sample to be tested. 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 to undergo a derivatization reaction (the structure of the reaction trap is similar to...). Figure 2 The trap structure shown is basically the same (without a heat sink), and the reaction temperature is kept constant at 40°C. Before entering the detection module, the sample to be tested is passed through the second degassing tee 22' at the rear end of the reaction trap 13 to avoid the influence of air bubbles on the measurement. After removing the air bubbles, the sample to be tested is transported into the detection chamber 17 through the fourth pipeline of the four-channel peristaltic pump 21. Under the specific LED light source 18 at 320nm, the fluorescence signal intensity of the sample to be tested is detected by the photomultiplier tube.

[0063] During zeroing, the second electromagnetic three-way valve 3 is switched into the peroxide removal device 2 channel to obtain zero gas. The zero gas passes through the filter membrane 4 to remove particulate matter, and under the action of the vacuum diaphragm pump 7, it passes through the multi-turn PFA tube 24 in the trap 8. Simultaneously, the absorbent enters the multi-turn PFA tube 24 in the trap 8 under the combined action of the first pipeline of the four-channel peristaltic pump 21 and the airflow. The airflow passes sequentially through the desiccant-containing dehydration safety bottle 5, the mass flow controller 6, and the vacuum diaphragm pump 7 before being discharged. The absorbent and derivative liquids are mixed under the control of the first and second pipelines of the four-channel peristaltic pump 21 and then enter the reaction trap 13. After passing through the second degassing three-way valve 22', it is transported to the detection chamber 17 by the fourth pipeline of the four-channel peristaltic pump 21 for zero-point calibration. Since organic peroxide standard substances are difficult to obtain, hydrogen peroxide standard solution is used for calibration. During liquid phase calibration, similarly, the second electromagnetic three-way valve 3 is switched into the channel of the peroxide removal device 2 to obtain zero gas. A series of hydrogen peroxide standard solutions with gradient concentrations are also provided, switched into the channel by the first electromagnetic three-way valve 1, and enter the multi-turn PFA tube 24 in the trap 8 under the simultaneous action of the first pipeline of the four-channel peristaltic pump 21 and the gas flow. The hydrogen peroxide standard solutions and derivatized solutions sequentially enter the reaction trap 13 and the detection chamber 17 through the same control and reaction steps, and finally, the fluorescence signal intensity is detected. During zeroing and calibration, all controls of the reaction module, detection module, and solution delivery module are the same as during sampling.

[0064] During cleaning, the vacuum diaphragm pump 7 stops working, and the four-channel peristaltic pump 21 starts. The cleaning fluid enters the device under the action of the four-channel peristaltic pump 21 to clean the internal pipelines of the device.

[0065] 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.

[0066] The peroxide solution (liquid-phase sample) undergoes a derivatization reaction with PHPAA in an alkaline environment (pH=10) catalyzed by hemin chloride to generate a fluorescent dimer, 2,2'-dihydroxy-biphenyl-5,5'-diacetic acid, which produces fluorescence at a wavelength of 400 nm under irradiation with a 320 nm light source. After the liquid-phase sample of the analyte (peroxide) undergoes derivatization to generate the fluorescent dimer, it enters a flow cuvette. The characteristic wavelength light generated by a 320 nm ultraviolet LED light source is absorbed by the fluorescent dimer, which emits 400 nm fluorescence in all directions. This fluorescence is detected by a photomultiplier tube at the exit of the light path perpendicular to the incident direction of the light source. The incident light signal intensity is acquired by a spectrometer, and the incident light intensity is corrected to avoid interference from LED attenuation on the detection results.

[0067] Peroxide content calculation: When the incident light intensity remains constant, the concentration of peroxide is directly proportional to the fluorescence intensity emitted at 400 nm. The relationship between fluorescence signal intensity and concentration is as follows:

[0068]

[0069] In Equation 1, I f I represents the fluorescence signal intensity. f0 Let I be the zero-point optical signal intensity, K be a coefficient, and c be the concentration of peroxide. Based on the zero-calibration process, I... f0 I obtained from the calibration process f Given the corresponding c (the concentration of hydrogen peroxide in the standard hydrogen peroxide solution), the coefficient K can be calculated using Equation 1.

[0070] Using the obtained coefficient K, the peroxide content in a sample of ambient air can be calculated using Equation 1 by measuring the fluorescence signal intensity of the sample. This is the liquid-phase peroxide concentration. The liquid-phase peroxide concentration is then converted to the gaseous-phase peroxide concentration, which is the ambient air peroxide concentration. The conversion method is as follows:

[0071]

[0072] In Equation 2, c peroxideRepresents the concentration of gaseous peroxides (unit: μg / m³). 3 ), c [peroxide] F represents the concentration of liquid phase peroxide (in μg / L). l F represents the liquid flow rate in the trap (in mL / min). g γ represents the gas flow rate in the trap (in L / min), and γ represents the trap's efficiency in capturing gaseous peroxides in the air.

[0073] Example 2

[0074] Based on 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, the most common peroxide. Figure 4 This is a structural diagram of the online monitoring device for ambient air hydrogen peroxide content after adding a dual-channel reaction-detection module in this embodiment. It 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 housed within the housing. The sampling module, first reaction module, detection module, solution delivery module, and control and data acquisition circuit module have the same purpose as those in the device corresponding to 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-phase sample at a constant temperature. The remaining peroxides in the liquid-phase sample undergo a derivatization reaction with PHPAA in an alkaline environment (pH=10) under Hemin catalysis to generate a fluorescent dimer, 2,2'-dihydroxy-biphenyl-5,5'-diacetic acid, as the sample.

[0075] The internal structures of the sampling module, reaction module, and detection module are all consistent with those in the device corresponding to the single-channel detection method in Example 1. The front end of the trap 8 of the sampling module is connected to the first 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. Then, it is divided into two paths via a tee: one path connects to the third degassing tee 22a of the first reaction module, and the other path connects to the fifth degassing tee 22b of the second reaction module. Derivatized solution a (without catalase) and derivatized solution b (containing catalase) are delivered via the third and fourth pipelines of the five-channel peristaltic pump 21', respectively, and merge with the two absorption solutions from the sampling module via the third degassing tee 22a and the fifth degassing tee 22b, respectively. The other end of the third degassing tee 22a is connected to the first reaction trap 13a, and the other end of the fifth degassing tee 22b is connected to the second reaction trap 13b. The outlets of the first reaction trap 13a and the second reaction trap 13b are respectively connected to the fourth degassing tee 22a' and the sixth degassing tee 22b', and then enter the first detection chamber 17a and the second detection chamber 17b respectively. After the two flow paths are merged through the tee, they are connected to the fifth pipeline of the five-channel peristaltic pump 21' of the solution delivery module.

[0076] The control and data acquisition circuit includes a data acquisition card with digital I / O ports. A LabVIEW program written on a computer controls solid-state relays to control the LED light sources in the first detection chamber 17a and the second detection chamber 17b respectively. A temperature controller controls the solid-state relays to control the temperature of each module and collects and outputs the temperature information of each module. The photomultiplier tubes in the first detection chamber 17a and the second detection chamber 17b respectively capture and convert fluorescence intensity signals, which are collected by the data acquisition card and output through the USB port.

[0077] In the solution delivery module, the first and second pipelines of the five-channel peristaltic pump 21' are used for precise delivery of the absorbent liquid, the third and fourth pipelines are used for precise delivery of derivative liquid a and derivative liquid b, respectively, and the fifth pipeline is used for discharging waste liquid.

[0078] The device was used to monitor the content of gaseous hydrogen peroxide online, and the specific implementation was as follows: a 5 mM potassium hydrogen phthalate solution with pH=6 was prepared as the absorption solution; an ammonium chloride / ammonia buffer solution with pH=10 was prepared; Hemin was dissolved in the ammonium chloride / ammonia buffer solution to prepare a 1 mM Hemin stock solution, which was then stored in the dark and at low temperature; catalase was dissolved in ultrapure water to prepare a 1 mM catalase stock solution, which was then stored in the dark and at low temperature; a 40 mM PHPAA stock solution was prepared and stored in the dark and at low temperature; derivatization solution a was prepared by diluting 10 mL of Hemin stock solution and 10 mL of PHPAA stock solution with ammonium chloride / ammonia buffer solution to a final volume of 1 L; and derivatization solution b was prepared by diluting 10 mL of Hemin stock solution, 10 mL of catalase, and 10 mL of PHPAA stock solution with ammonium chloride / ammonia buffer solution to a final volume of 1 L.

[0079] During sampling, the collection method and procedure are the same as those used in Example 1 when detecting gaseous peroxides using a single-channel device. After absorbing the gaseous sample, the absorbent liquid is divided into two streams after passing through the first pipeline of the five-channel peristaltic pump 21': one stream flows to the first reaction trap 13a, and the other flows to the second reaction trap 13b. Derivatized liquids a and b, under the control of the third and fourth pipelines of the five-channel peristaltic pump 21', are mixed with the liquid sample through the third degassing tee 22a and the fifth degassing tee 22b, respectively, and then enter the first and second reaction traps 13a and 13b, respectively, for derivatization reactions. The reaction temperature is kept constant at 40°C. Before entering the detection module, the two sample streams are respectively introduced into the fourth degassing tee 22a' at the rear end of the first reaction trap 13a and the sixth degassing tee 22b' at the rear end of the second reaction trap 13b to avoid the influence of air bubbles on the measurement. After removing air bubbles, the two test samples enter the first detection chamber 17a and the second detection chamber 17b, respectively. The signal measurement method and procedure are the same as when using a single-channel device to detect gaseous peroxides. After the test is completed, the two flow paths are merged through a three-way valve and the waste liquid is discharged through the fifth pipeline of the five-channel peristaltic pump 21'.

[0080] During zeroing, the method and process are basically the same as those used in Example 1 when detecting gaseous peroxides using a single-channel device. The difference is that zero-point calibration needs to be performed on the first detection chamber 17a and the second detection chamber 17b separately. Since organic peroxide standard materials are difficult to obtain, hydrogen peroxide standard solution is used for the liquid phase calibration process of both the first detection chamber 17a and the second detection chamber 17b. During liquid phase calibration, the third and fourth pipelines of the five-channel peristaltic pump 21' are both purged with derivatizing solution a. The hydrogen peroxide standard solution and derivatizing solution a are sequentially introduced into the two reaction-detection channels through the same control and reaction steps, namely channel one (first reaction trap 13a, first detection chamber 17a) and channel two (second reaction trap 13b, second detection chamber 17b), respectively, to detect the fluorescence signal intensity of the two detection chambers and calibrate the two channels separately. During zeroing and calibration, except that the third pipeline of the peristaltic pump is changed to be purged with derivatizing solution a, all other controls of the reaction module, detection module, and solution delivery module are the same as during sampling.

[0081] During cleaning, the vacuum diaphragm pump 7 stops working, and the five-channel peristaltic pump 21' starts. The cleaning fluid enters the device under the action of the five-channel peristaltic pump 21' to clean the internal pipelines of the device.

[0082] When using a dual-channel device to detect hydrogen peroxide concentration, the flow rates of the first to fifth lines 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.

[0083] Hydrogen peroxide content calculation: According to Equation 1, I is obtained from the zeroing process of the first detection chamber 17a and the second detection chamber 17b respectively. f0 I obtained from the calibration process f Given the corresponding c (the concentration of hydrogen peroxide in the hydrogen peroxide standard solution), the coefficient K can be calculated. a and K b When testing samples, the fluorescence signal intensity of a sampled ambient air can be obtained. a with If b , where, If a If represents the fluorescence signal of total peroxides in the sample. b The fluorescence signals of organic peroxides other than hydrogen peroxide in this sample are obtained by using Equation 1 with the coefficient K obtained above. a and K b The total peroxide content c in the liquid phase sample was calculated. a and the content of organic peroxides other than hydrogen peroxide (c) b The difference c a -c b This represents the hydrogen peroxide content in the liquid sample. The liquid phase hydrogen peroxide concentration is then converted to a gaseous phase hydrogen peroxide concentration, which is the ambient air hydrogen peroxide concentration. The conversion method is as follows:

[0084]

[0085] In Equation 3, c H2O2 Represents the concentration of gaseous hydrogen peroxide (unit: μg / m³). 3 ), c [H2O2] F represents the concentration of hydrogen peroxide in the liquid phase (in μg / L). l F represents the liquid flow rate in the trap (in mL / min). g γ represents the gas flow rate in the trap (in L / min), and γ represents the trap's efficiency in capturing gaseous hydrogen peroxide from the air.

[0086] It should be noted that the purpose of disclosing the embodiments is to help further understand the present invention. However, those skilled in the art will understand 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 content disclosed in the embodiments, and the scope of protection of the present invention is defined by the scope of the claims.

Claims

1. An online monitoring method for gaseous peroxide content, comprising a measurement process, a zeroing process, and a calibration process, including 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 absorbent for gaseous peroxides. The absorbent and the gas to be tested are passed through the trap. In the trap, the gaseous peroxides in the gas to be tested are absorbed by the absorbent that forms a liquid film on the tube wall, and a liquid sample to be tested is obtained. 2) Reaction process: Another multi-turn wound non-metallic tube is used as the derivatization reaction trap. An alkaline solution containing heme chloride and p-hydroxyphenylacetic acid is used as the derivatizing liquid. The liquid sample to be tested and the derivatizing liquid are introduced into the reaction trap. The peroxide in the liquid sample to be tested reacts with p-hydroxyphenylacetic acid under the catalysis of heme chloride to generate fluorescent dimer 2,2'-dihydroxy-biphenyl-5,5'-diacetic acid, thus obtaining the fluorescent dimer sample to be tested. 3) Detection process: The fluorescent dimer sample is introduced into a flow cuvette. The 320 nm excitation light generated by the light source is absorbed by the fluorescent dimer of the sample and emits fluorescence of a characteristic wavelength. At the exit of the light path perpendicular to the incident light direction, the fluorescence signal is converted into an electrical signal by a photomultiplier tube to measure the fluorescence signal intensity. At the same time, the incident light signal intensity is obtained by a spectrometer in the direction of incident light and the incident light intensity is corrected. 4) The zeroing process is performed before the measurement process. During zeroing, air is first passed through a peroxide removal device to obtain zero gas. Then, the zero gas is used as the gas to be measured and goes through the sampling process, reaction process and detection process in steps 1) to 3) above. The light signal intensity obtained is the zero-point light signal intensity. 5) The calibration process involves preparing a series of peroxide standard solutions with gradient concentrations to replace the absorbent in the sampling process. The zero gas obtained by passing air through the peroxide removal device is then subjected to the measurement process described 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 according to the fluorescence signal intensity and concentration relationship shown in Equation 1: Formula 1 In Equation 1, I f I represents the fluorescence signal intensity. f0 Where I is the zero-point optical signal intensity, K is a coefficient, and c is the concentration of peroxide; based on the zero-calibration process, I... f0 The concentration c of the peroxide standard solution obtained during the calibration process and its fluorescence signal intensity I. f The coefficient K is calculated. Then, the concentration of liquid peroxides is converted into the content of gaseous peroxides in the gas to be tested using Equation 2: Formula 2 In Equation 2, c peroxide This represents the concentration of gaseous peroxides, in μg / m³. 3 ; c [peroxide] Represents the concentration of liquid phase peroxides, in μg / L; F l F represents the liquid flow rate in the trap, expressed in mL / min. g γ represents the gas flow rate in the trap, expressed in L / min; γ represents the trap's efficiency in capturing gaseous peroxides from the air.

2. The online monitoring method as described in claim 1, characterized in that, During the detection, an ultraviolet LED light source with a center wavelength of 320 nm was used. While the photomultiplier tube detected the fluorescence signal intensity, the incident light signal intensity generated by the light source was obtained through a spectrometer, and the incident light intensity was corrected.

3. The online monitoring method as described in claim 1, characterized in that, The absorption solution is a 5 mM potassium hydrogen phthalate solution with pH=6; the derivatization solution is a solution containing 0.4 mM p-hydroxyphenylacetic acid and 0.01 mM heme chloride, prepared with an ammonium chloride / ammonia buffer solution with pH=10.

4. The online monitoring method as described in claim 1, characterized in that, The temperature of the trap and the reaction trap is precisely controlled by a temperature control device. The sampling temperature of the trap is stabilized at 10 ℃, and the reaction temperature of the reaction trap is stabilized at 40 ℃.

5. The online monitoring method as described in any one of claims 1 to 4, characterized in that, This method enables online monitoring of gaseous hydrogen peroxide concentration. The liquid sample to be tested is divided into two streams. The reaction process in step 2) adopts a dual-channel setup, i.e., two parallel derivatization reaction traps are set up. One trap allows the derivatization solution without catalase to react with one stream of liquid sample, while the other trap allows the derivatization solution containing catalase to react with the other stream of liquid sample. The detection process in step 3) also adopts a dual-channel setup, i.e., two parallel detection devices are set up to detect the fluorescence signals emitted by the samples after the two derivatization reactions. In step 6), the total peroxide content measured by one channel is subtracted from the content of organic peroxides other than hydrogen peroxide measured by the other channel to obtain the hydrogen peroxide content in the sample.

6. An online monitoring device for the content of gaseous peroxides, used to implement the online monitoring method for the content of gaseous peroxides 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, converting them into a liquid sample. It 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 splits into two branches at the sample gas inlet, one of which is equipped with the peroxide removal device. The two branches merge into a single gas path leading to the trap via an electromagnetic three-way valve, and this gas path is equipped with a filter membrane. The trap consists of a non-metallic tube wound multiple turns around a metal block. The trap temperature control device maintains the trap at a constant temperature during operation. A gas-liquid separation and drying device is located at the rear of the trap. The liquid sample from the trap flows through a pipeline to the reaction module, while the gas, after drying, is discharged as exhaust gas through another pipeline equipped with a mass flow controller and a vacuum diaphragm pump. The reaction module includes a reaction trap and a reaction trap temperature control device. The reaction trap is composed of a non-metallic tube wound around a metal block. The liquid sample to be tested from the trap enters the reaction trap through the tube and reacts with the derivatizing liquid at a constant temperature to generate a fluorescent dimer sample to be tested. The detection module is divided into a liquid path section, an optical path section, and a detection chamber support. The liquid path section includes a flowing cuvette through which the fluorescent dimer sample to be tested exits the reaction trap. The flowing cuvette is fixed in the detection chamber support, allowing light to pass through its four sides while blocking light from the rest. The optical path section includes an LED light source, an ultraviolet concave mirror, a photomultiplier tube, a collimating lens, an optical fiber, and a spectrometer. The LED light source is located on one side of the flowing cuvette, with a collimating lens and an optical fiber on the opposite side. The optical fiber connects to the spectrometer. A photomultiplier tube and an ultraviolet concave mirror are respectively located on two adjacent sides. The ultraviolet concave mirror focuses the fluorescence emitted by the sample to be tested and directs it to the opposite photomultiplier tube for photo-to-electric signal conversion. The solution delivery module includes a multi-channel peristaltic pump and solution delivery pipelines. The absorbent is delivered into the trap through the pipelines of the peristaltic pump, the derivatized liquid and the liquid phase test sample are delivered into the reaction trap, the fluorescent dimer test sample is delivered into 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, and controls the operation of these modules and acquires data.

7. The online monitoring device as described in claim 6, characterized in that, The peristaltic pump is a four-channel peristaltic pump. Its first line is connected to the absorbent delivery line, which delivers the absorbent into the trap. The second line of the peristaltic pump is connected to the derivatization delivery line, which delivers the derivatization into the liquid phase test sample line at the rear end of the trap. The derivatization and the liquid phase test sample from the trap are mixed and then enter the reaction trap under the action of the third line of the peristaltic pump. The fluorescent dimer test sample from the reaction trap enters the flow cuvette under the action of the fourth line of the peristaltic pump and then is discharged. A first degassing tee is set at the junction of the derivatization delivery line and the liquid phase test sample line at the rear end of the trap, and a second degassing tee is set on the line connecting the detection module at the rear end of the reaction trap.

8. An online monitoring device for the content of gaseous peroxides, used to implement the online monitoring method of 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, converting them into a liquid sample. It 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 splits into two branches at the sample gas inlet, one of which is equipped with the peroxide removal device. The two branches merge into a single gas path leading to the trap via an electromagnetic three-way valve, and this gas path is equipped with a filter membrane. The trap consists of a non-metallic tube wound multiple turns around a metal block. The trap temperature control device maintains the trap at a constant temperature during operation. A gas-liquid separation and drying device is located at the rear of the trap. The liquid sample from the trap flows through a pipeline to the reaction module, while the gas, after drying, is discharged as exhaust gas through another pipeline equipped with a mass flow controller and a vacuum diaphragm pump. The reaction module includes a reaction trap and a reaction trap temperature control device. The reaction trap is composed of a non-metallic tube wound around a metal block. The liquid sample to be tested from the trap enters the reaction trap through the tube and reacts with the derivatizing liquid at a constant temperature to generate a fluorescent dimer sample to be tested. The detection module is divided into a liquid path section, an optical path section, and a detection chamber support. The liquid path section includes a flowing cuvette through which the fluorescent dimer sample to be tested exits the reaction trap. The flowing cuvette is fixed in the detection chamber support, allowing light to pass through its four sides while blocking light from the rest. The optical path section includes an LED light source, a UV concave mirror, a photomultiplier tube, a collimating lens, an optical fiber, and a spectrometer. The LED light source is located on one side of the flowing cuvette, with a collimating lens and an optical fiber on the opposite side. The optical fiber connects to the spectrometer. A photomultiplier tube and a UV concave mirror are respectively located on two adjacent sides. The UV concave mirror focuses the fluorescence emitted by the sample to be tested and directs it to the opposite photomultiplier tube for photo-to-electric signal conversion. The solution delivery module includes a multi-channel peristaltic pump and solution delivery pipelines. The peristaltic pump delivers the absorbent liquid into the trap, the derivatized liquid and the liquid sample to be tested into the reaction trap, and the fluorescent dimer sample to be tested into the flowing cuvette, while discharging waste liquid. 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 acquire data. The reaction module is characterized by having two parallel reaction devices, including a first reaction trap and its temperature control device, and a second reaction trap and its temperature control device. The liquid sample from the sampling module is divided into two paths, entering the first and second reaction traps respectively. In the first reaction trap, a derivatized solution without catalase reacts with one of the liquid sample paths, while in the second reaction trap, a derivatized solution containing catalase reacts with the other liquid sample path. The detection module has two parallel detection devices that detect the fluorescence signals emitted by the two samples after the derivatization reactions.The peristaltic pump is a five-channel peristaltic pump. The second line connects to the absorbent delivery line, sending the absorbent into the trap of the sampling module. The trap of the sampling module is connected from the front end to the second line of the peristaltic pump and from the rear end to the first line. A tee then divides the line carrying the liquid sample into two paths: one path passes through a degassing tee before entering the first reaction trap, and the other path passes through another degassing tee before entering the second reaction trap. The catalase-free and catalase-containing degassing solutions are delivered via the third and fourth lines of the peristaltic pump, respectively, and then merged with the two liquid sample lines from the sampling module via degassing tees. The outlets of the first and second reaction traps each pass through a degassing tee and are connected to two detection devices of the detection module. The outlets of the two detection devices are merged via a tee and then connected to the fifth line of the peristaltic pump.

9. The online monitoring device as described in claim 7 or 8, characterized in that, The trap is a PFA tube wound in multiple turns around a first aluminum block. One end is the inlet for the absorbent and the gas to be tested, and the other end is the outlet for the liquid sample after the absorbent has absorbed the gaseous peroxide. The trap is located in an insulation chamber and is surrounded by insulation cotton and foam board. The temperature control device of the trap includes a semiconductor cooling chip, a first heat sink, a fan, and a temperature controller connected by a first thermocouple. The semiconductor cooling chip is located at one end of the first aluminum block, the first heat sink is connected to the semiconductor cooling chip, the fan faces the first heat sink, and the thermocouple detects the temperature of the PFA tube wound in multiple turns around the first aluminum block and transmits it to the temperature controller.

10. The online monitoring device as described in claim 7 or 8, characterized in that, The reaction trap is a PFA tube wound in multiple turns on a second aluminum block. One end of the tube is the inlet for the derivatization liquid and the liquid sample to be tested, and the other end is the outlet for the sample to be tested after the derivatization reaction. The temperature control device of the reaction trap includes a built-in heating block and a temperature controller connected by a second thermocouple.

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