A headspace color reaction device, method and application for volatile component colorimetric determination

Abstract

The present application belongs to the technical field of detection equipment, and discloses a headspace color development reaction device, method and application for colorimetric determination of volatile components. The device comprises a top cover, a bottle body, a detection mechanism and a solution pool. The top of the bottle body is provided with a bottle cavity in a vertical direction from top to bottom. The top cover is arranged at the top opening of the bottle body in cooperation with the bottle body, and can lock the top opening of the bottle body. The detection mechanism is connected to the lower surface of the top cover and can be suspended in the upper part of the bottle cavity through the top cover, so as to detect the air composition in the upper part of the bottle cavity. The solution pool is arranged at the bottom of the bottle cavity. After the color development reaction of the volatile components and the color development solution is completed, the colorimetric reaction pool can be directly moved from the headspace bottle to the general rectangular colorimetric tank of the colorimetric instrument for colorimetric analysis. The device is provided with a volume scale required for constant volume, and can replace the colorimetric tube or the volumetric flask to complete the constant volume, transfer to the colorimetric dish and other processes.

Description

Technical Field

[0001] This invention belongs to the field of detection equipment technology, and in particular to a headspace colorimetric reaction device, method and application for the colorimetric determination of volatile components. Background Technology

[0002] Colorimetric determination of volatile components is a widely used analytical method. Existing methods include absorption-colorimetry and distillation-colorimetry, but they suffer from problems such as complex device structure, time-consuming and cumbersome operation, low sensitivity, and difficulty in achieving batch analysis.

[0003] Volatile components refer to substances that are gaseous at room temperature or when heated, or that easily change from liquid or solid to gaseous states. Although gas chromatography has been widely used in volatile component analysis, colorimetric methods, including ultraviolet-visible spectrophotometry and visual colorimetry, still play an important role due to their low cost, simplicity, and speed. Visual colorimetry, which involves naked-eye observation, is only suitable for screening and cannot meet the accuracy and reliability requirements of food quality and safety, environmental monitoring, and medical biological testing. Spectrophotometry, on the other hand, offers significantly higher accuracy and precision than visual colorimetry, and its instruments are widely available. As an accurate and reliable analytical method commonly used in various fields, it is widely adopted in industry standards and specifications.

[0004] Unlike liquid chromatography, colorimetric reactions of volatile components require pretreatment separation to separate the volatile components from the numerous interfering components in the sample matrix. For solid or liquid samples, existing technologies employ thermal volatilization-solution absorption colorimetry, such as the publicly disclosed rapid colorimetric method for detecting chlorothalonil in fruits and vegetables; or distillation separation-colorimetry, such as the publicly disclosed low-temperature distillation flask and distillation system for rapid determination of ammonia nitrogen in complex water quality (CN206304769U), a portable sample pretreatment device for rapid methanol detection in fruit wine and other samples (CN218381981U), and a distillation-colorimetric method for formaldehyde detection in edible fungi (CN103267735A). These technologies suffer from problems such as large processing device size, complex structure, and cumbersome operation. They are insufficient to meet the needs of rapid, large-scale on-site processing. Furthermore, issues such as volatile component volatilization and pyrolysis losses further limit the improvement of reliability.

[0005] Headspace chromatography uses a sealed vial containing a solid or liquid extractant in the headspace. Heating the sample at the bottom of the vial releases volatile components from the sample matrix, which then enter the headspace and are extracted by the extractant. The extracted components are then transferred to a gas chromatograph for analysis. Headspace colorimetry, combining headspace chromatography with colorimetry, is a currently popular invention and research area. This mainly includes headspace single-droplet colorimetry and headspace paper-based colorimetry. In headspace colorimetry, microdroplets of a colorimetric solution or a paper-based material loaded with the solution are directly suspended in the headspace region to react with the volatile components. However, both headspace single-droplet and headspace paper-based colorimetry cannot be matched with the cuvette 3-5 of a spectrophotometer for accurate and reliable subsequent spectrophotometric measurements. Subsequent colorimetric measurements can only be performed visually or via mobile phone. Measurement errors due to volume changes caused by the evaporation of the colorimetric solution during heating are difficult to detect. To ensure the accuracy and reliability of measurements, and addressing the aforementioned issues, the publicly disclosed inventions and research, such as CN114965329B, employ a specially designed spectrophotometer and fiber optic spectrophotometer to solve the problem of accurate measurement. The technical solution involves inserting a specially designed spectrophotometer containing a colorimetric solution into a headspace vial. After a droplet forms below the spectrophotometer and undergoes a colorimetric reaction with volatile components, the suspended droplet is drawn into the cuvette of the specially designed fiber optic spectrophotometer for colorimetric analysis. However, this invention requires a specially designed fiber optic spectrophotometer, which is difficult to widely adopt. It also fails to solve the instability of single droplet suspension, increases the complexity of the device structure, and adds to the operational process and difficulty, thus limiting the practical application value of this method.

[0006] A study (Xia Chengyan. Colorimetric Detection of Trivalent Arsenic and Nitrite Based on Platform-Based Headspace-Liquid Heterogeneous Reaction [D]. Sichuan University) proposed a colorimetric mode based on platform-based headspace-liquid heterogeneous reaction. This mode utilizes a glass reaction flask with a side arm and a separable reaction platform resembling a Buchner funnel. A thin layer of sponge is placed at the bottom of the platform, with a central depression to accommodate hydrophobic polytetrafluoroethylene powder, ensuring the stability of the liquid droplets in a spherical shape. During use, the reaction droplets are placed on the powder layer, and the flask opening is sealed with an elastic sealing film. The side arm injects the volatile reaction solution. After the droplets react with the volatile components to produce a colorimetric reaction, visual colorimetric analysis is performed using the naked eye, or the solution is transferred to a multi-well plate of an enzyme-linked immunosorbent assay (ELISA) analyzer for UV-Vis absorption spectroscopy. The advantage of this study lies in using a sponge-hydrophobic polytetrafluoroethylene powder to support the colorimetric solution to solve the droplet suspension instability, and using a multi-well plate of an enzyme-linked immunosorbent assay (ELISA) analyzer instead of a spectrophotometer for subsequent colorimetric analysis. This solves the problems of measurement accuracy and batch processing. However, it cannot be applied to the spectrophotometers commonly equipped in grassroots and field laboratories. In addition, the droplet support platform is too complex and bulky, and the corresponding operation steps are too numerous, making it difficult to meet the requirements of miniaturization, integrity, and ease of operation for batch analysis in the field, which also restricts the practical application value of this method.

[0007] Volatile component analysis is a crucial aspect of food quality and safety, product quality, environmental monitoring, and biomedical research. Spectrophotometry offers significantly higher accuracy and precision than visual colorimetry, and is widely adopted in industry standards and specifications. Its advantages, including low cost, speed, and high accessibility, make it a promising field for volatile component analysis. Based on the advantages of headspace methods, headspace colorimetry remains one of the most active and cutting-edge areas in volatile component analysis. However, existing inventions and research have yielded few headspace colorimetric techniques suitable for spectrophotometers. This limitation hinders the widespread adoption and application of headspace colorimetry. Therefore, developing headspace colorimetric techniques suitable for spectrophotometers holds significant application potential and value.

[0008] To address the problems of the existing technologies, a headspace reactor device with volatile component separation and collection functions is designed for pretreatment in chromatographic analysis. Summary of the Invention

[0009] The purpose of this invention is to overcome the shortcomings of the prior art and provide a headspace colorimetric reaction device, method and application for the colorimetric determination of volatile components.

[0010] The technical solution adopted by this invention to solve its technical problem is: A headspace colorimetric reaction device for the colorimetric determination of volatile components is disclosed. This device enables colorimetric detection of volatile components within the device. The device includes a top cap, a bottle body, a detection mechanism, and a solution tank. The top of the bottle body has a vertically oriented cavity with an opening from top to bottom. The top cap fits into the top opening of the bottle body and can be locked in place. The detection mechanism is connected to the lower surface of the top cap and is suspended above the bottle body cavity via the top cap, enabling the detection of air components in the upper part of the cavity. The solution tank is located at the bottom of the bottle body cavity and can hold the solution containing volatile components to be detected. The detection mechanism performs colorimetric detection. Both the detection mechanism and the bottle body are made of transparent material.

[0011] Furthermore, the bottle body is made of transparent glass, with a diameter of 15-30 mm and a volume of 15mL-40mL; the bottle body is a commercially available small glass bottle suitable for laboratory use.

[0012] Furthermore, the detection mechanism includes a colorimetric cell, a light-transmitting cover plate, a suspension plate, and a fixing plate. The colorimetric cell has a colorimetric groove arranged vertically from top to bottom, and the colorimetric groove is arranged horizontally. The light-transmitting cover plate is arranged vertically, and both sides of the colorimetric cell are tightly fixedly connected to it in the horizontal direction. The height of the light-transmitting cover plate is slightly less than the height of the colorimetric groove, allowing the experimenter to visually inspect the colorimetric groove through the light-transmitting cover plate. The structure of the colorimetric cell and the light-transmitting cover plate allows the colorimetric reaction solution to be contained in the colorimetric groove for detection. The suspension plate is arranged vertically, and its sides are detachably and symmetrically installed on both sides of the longitudinal direction of the colorimetric cell by adhesive or bolts. The upper surface of the suspension plate is connected to the lower surface of the fixing plate, and the upper surface of the fixing plate is detachably connected to the lower surface of the top cover by adhesive or bolts.

[0013] Furthermore, the colorimetric cell has an inverted triangular structure, and the interior of the colorimetric cell is provided with scale lines for the solution. The width of the middle part of the inverted triangular colorimetric cell is greater than the incident light slit of the colorimeter, allowing the incident light to completely enter the colorimetric solution.

[0014] Furthermore, the cap is designed to match the opening at the top of the bottle, and the cap can be detachably and tightly connected to the bottle by screwing on. Alternatively, the top cover includes a cover body and a sealing gasket, with the cover body and the top opening of the bottle body sealed together by the sealing gasket.

[0015] Furthermore, the bottle body material is transparent glass, with a diameter of 15-30 mm and a volume of 15mL-40mL; Alternatively, the colorimetric cell material is one of glass, polypropylene (PP) or polystyrene, with a thickness of 5-1 mm, a width of 10-15 mm, and a height of 30-45 mm. The colorimetric cell contains a triangular cell whose height is 10-25 mm lower than the side wall of the colorimetric cell, and the base angle of the triangle is 15-45 degrees. Alternatively, the light-transmitting cover material is one of optical glass, optical polypropylene (PP) or optical polystyrene, with a width consistent with the colorimetric cell and a height 10-25mm lower than the colorimetric cell. Alternatively, both the suspension plate and the fixing plate are made of polytetrafluoroethylene sheet, and the width of the suspension plate is the same as the thickness of the colorimetric cell.

[0016] The apparatus described above is used in the determination of chemical liquid concentrations in a headspace colorimetric reaction apparatus for the colorimetric determination of volatile components.

[0017] The method of using the headspace colorimetric reaction apparatus for the colorimetric determination of volatile components as described above is characterized by comprising the following steps: Pour the solution to be tested into the bottom of the bottle to form a solution pool. Then assemble the detection mechanism with the top cap. After assembly, insert the detection mechanism into the upper part of the bottle cavity through the top cap, and press or screw the top cap until it is sealed to the bottle. Then let it stand or heat the bottom of the device to allow the volatile components in the solution pool to evaporate and float to the detection mechanism at the top of the bottle. The detection mechanism detects the volatile components. Due to the transparent material, the detection mechanism can be observed visually. When a change is observed in the detection mechanism, it can be removed for the next step of colorimetric detection.

[0018] The method for detecting volatile components using a headspace colorimetric reaction device as described above is characterized by the following steps: (1) Pour an appropriate amount of colorimetric solution into the colorimetric cell, pour an appropriate amount of sample into the solution pool, and then assemble the device; (2) The device is placed on the heating device for heating. The sample in the solution pool at the bottom of the headspace bottle is heated. The volatile components contained in the sample are released from the sample matrix and automatically convection into the top area of ​​the bottle. (3) The volatile components entering the top area of ​​the bottle cavity react with the colorimetric solution stored in the colorimetric cell in the top area of ​​the bottle cavity to generate a colorimetrically detectable colored compound. (4) After heating is complete and stabilized, open the bottle cap, remove the colorimetric cell, and place it directly in the colorimetric instrument. Select the optimized incident light beam for subsequent colorimetric analysis to complete the detection.

[0019] The advantages and positive effects of this invention are as follows: 1. This invention's headspace colorimetric reactor integrates the functions of headspace reaction and colorimetric reaction, allowing volatile components to be released and separated from the sample matrix at the bottom of the headspace vial, and then transferred to the colorimetric reaction cell to react with the colorimetric solution. After the colorimetric reaction of the volatile components with the colorimetric solution is complete, this invention allows the colorimetric reaction cell to be directly moved from the headspace vial to a rectangular cuvette 3-5 commonly used in colorimetric instruments for colorimetric analysis. It is equipped with volume graduations for volume determination, and can replace colorimetric tubes or volumetric flasks to complete processes such as volume determination and transfer to cuvettes.

[0020] 2. The headspace colorimetric reactor of this invention features an inverted triangular reaction tank design. This novel design allows volatile components to smoothly reach the colorimetric solution interface. When using a semi-micro (less than 1 mL) colorimetric solution, it ensures that the volatile components and the colorimetric solution still have a large contact area, and the colorimetric system is easy to mix, effectively solving the efficiency problem of improving gas-liquid colorimetric reactions. It also allows the width of the semi-micro colorimetric solution to be larger than the incident light slit of the colorimeter, ensuring that the incident light completely enters the colorimetric solution to be measured, thus guaranteeing the reliability of colorimetric measurements. The inverted triangular reaction tank design of the colorimetric reactor of this invention allows for the use of semi-micro colorimetric solutions to perform efficient and reliable semi-micro colorimetric reactions and colorimetric determinations of volatile components. This significantly increases the sensitivity of the method and ensures the detection limit and reliability for the determination of low-content target volatile components. Existing methods such as absorption-colorimetry and distillation-colorimetry for volatile components use multiple reaction flasks, colorimetric tubes, or volumetric flasks for multi-step extraction, separation, solution transfer, colorimetric reactions, or volume adjustment processes. The resulting dilution effect makes it difficult to guarantee the sensitivity requirements for the determination of most low-content volatile components.

[0021] 4. The headspace colorimetric reactor of this invention integrates multiple reaction processes, including the release of volatile components, mass transfer, and colorimetric reaction at the gas-liquid interface, within a sealed headspace vial. These multiple reaction processes are all automatically carried out under thermal drive, exhibiting a high degree of integration. Its advantage lies in allowing for a single manual operation—sample heating—to separate the target volatile components from the sample matrix and transfer them to the colorimetric solution interface to complete the colorimetric reaction and other pre-colorimetric determination processes. This eliminates the need for multiple heating steps, manual transfer of the sample solution, separation, concentration, and volume adjustment required by existing methods, significantly simplifying the operation process and reducing operational complexity.

[0022] 5. The design of this invention, which places the colorimetric reactor within a headspace reactor, along with the simplified one-step operation process and semi-micro-volume application method, offers advantages. These advantages include the ability to integrate and miniaturize the reactor, simplify the process, and improve method sensitivity. It also allows for the use of multi-position heating modules to achieve batch processing of volatile components. While automated and information-based analytical instruments are increasingly common, sample pretreatment still suffers from low efficiency, cumbersome operation, and time consumption, representing a bottleneck in improving analytical efficiency. This invention overcomes the problems of existing reactors, providing a beneficial solution for the batch processing and analysis of volatile components.

[0023] 6. The present invention is based on a commercially available headspace vial and designs a colorimetric reaction cell compatible with a spectrophotometer universal colorimetric cell 3-5. The colorimetric reaction cell is integrated into a sealed headspace vial. The colorimetric reaction cell is used to load the colorimetric solution. After the colorimetric reaction is completed, it is directly transferred to the spectrophotometer universal colorimetric cell 3-5 for subsequent accurate colorimetric analysis. Furthermore, the colorimetric reaction cell of the present invention abandons the design of existing technologies where droplets are suspended or loaded onto materials such as paper. Instead, it uses a colorimetric reaction cell to load the colorimetric solution, thereby solving the problems of droplet suspension instability in existing technologies. Unlike the method of droplet suspension or loading of gaseous volatile components to contact the colorimetric solution from bottom to top, the present invention uses a colorimetric reaction cell where gaseous volatile components react with the colorimetric solution from top to bottom. Therefore, the present invention is specifically designed to solve the problems of gas-liquid reaction efficiency and mixing uniformity between the semi-micro colorimetric solution and volatile components.

[0024] 7. This invention is significantly superior to the traditional distillation-colorimetric method in terms of field applicability, ease of operation, accuracy, and high sensitivity. Compared with the existing headspace-colorimetric method, this invention not only has better ease of operation, but also better versatility, good practicality, and is easy to promote and popularize. Attached Figure Description

[0025] Figure 1 This is a three-dimensional schematic diagram of the structural connection of the device of the present invention; Figure 2 This is a schematic diagram of the structural connection and assembly process of the detection mechanism 3 in the device of the present invention; Figure 3 This is a schematic diagram of the structural connection and assembly process of the device of the present invention; Figure 4 This is a schematic diagram of the experimental operation method of the device of the present invention, wherein (a) is heating, (b) is reaction, (c) is transferring to the colorimetric tank, and (d) is colorimetric determination; Figure 5 This is a graph showing the effect of heating time on scavenging rate and free radical absorbance in this invention. Detailed Implementation

[0026] The present invention will be further described below with reference to the embodiments. The following embodiments are descriptive and not limiting, and should not be used to limit the scope of protection of the present invention.

[0027] The various experimental operations involved in the specific embodiments are all conventional techniques in the field. For parts not specifically annotated in this document, those skilled in the art can refer to various commonly used reference books, scientific and technological documents or related instructions and manuals prior to the filing date of this invention to carry out the operations.

[0028] A headspace colorimetric reaction apparatus for the colorimetric determination of volatile components, which can perform colorimetric detection of volatile components within the apparatus, such as... Figures 1 to 3 As shown, the device includes a top cover 1, a bottle body 2, a detection mechanism 3, and a solution tank 4. The top cover 1 is tightly and detachably connected to the top of the bottle body 2, and the top cover 1 can lock the bottle body 2. The bottle body 2 includes a bottle body cavity 2-1, a bottle body 2-2, and a bottle body opening 2-3. The bottle body 2-2 is arranged vertically, and the bottle body opening 2-3 is provided at the top of the bottle body 2-2. The bottle body 2-2 is hollow inside, forming the bottle body cavity 2-1. The top cover 1 is tightly and detachably connected to the bottle body opening 2-3, so that the bottle body... The cavity 2-1 is in a sealed environment to ensure that the detection environment is free from interference. The detection mechanism 3 is connected to the lower surface of the top cover 1. The detection mechanism 3 can be suspended in the upper part of the bottle cavity 2-1 through the top cover 1 and can detect the air composition in the upper part of the bottle cavity 2-1. The solution pool 4 is located at the bottom of the bottle cavity 2-1 and can hold the solution with volatile components to be tested. The detection mechanism 3 can perform colorimetric detection. Both the detection mechanism 3 and the bottle 2 are made of transparent material, which is convenient for visual observation.

[0029] Preferably, the bottle body 2 is made of transparent glass, with a diameter of 15-30 mm and a volume of 15mL-40mL; the bottle body 2 is a commercially available small glass bottle suitable for laboratory use.

[0030] The method of using the headspace colorimetric reaction apparatus for the colorimetric determination of volatile components as described above includes the following steps: Pour the solution to be tested into the solution pool 4 at the bottom of bottle 2. Then assemble the detection mechanism 3 with the top cover 1. After assembly, insert the detection mechanism 3 into the upper part of the bottle cavity 2-1 in bottle 2 through the top cover 1. Press or screw the top cover 1 until the top cover 1 and bottle 2 are sealed. Then let it stand or heat the bottom of the device so that the volatile components in the solution pool 4 evaporate and float to the detection mechanism 3 at the top of bottle 2. The detection mechanism 3 detects the volatile components. Due to the transparent material, the detection mechanism 3 can be observed visually. When the detection mechanism 3 changes, it can be removed for the next step of colorimetric detection.

[0031] This invention integrates headspace reaction and colorimetric reaction functions, allowing volatile components to be released and separated from the sample matrix at the bottom of the headspace vial, and then transferred to the detection unit 3 for colorimetric reaction. After the colorimetric reaction between the volatile components and the colorimetric solution is complete, the detector can be directly moved from the device to a rectangular colorimetric cell commonly used in colorimetric instruments for colorimetric analysis.

[0032] like Figure 2As shown, in this embodiment, the detection mechanism 3 includes a colorimetric cell 3-1, a light-transmitting cover plate 3-2, a suspension plate 3-3, a fixing plate 3-4, a colorimetric tank 3-5, and a ventilation window 3-6. The colorimetric tank 3-5 is disposed within the colorimetric cell 3-1, extending downwards from the upper surface of the colorimetric cell 3-1, and is longitudinally continuous. The light-transmitting cover plate 3-2 is vertically disposed, and is tightly fixed to both sides of the colorimetric cell 3-1. The top of the light-transmitting cover plate 3-2 is lower than the top of the colorimetric tank 3-5, and is higher than the colorimetric tank 3-5 in the front-back direction. The purpose of being lower than the colorimetric tank 3-5 is to form a gas passage channel above the colorimetric cell 3-1, allowing the passing gas to be absorbed by the colorimetric solution in the cell below, thus producing a gas flow. The colorimetric reaction occurs; the light-transmitting cover 3-2 allows the experimenter to visually inspect the colorimetric tank. The colorimetric tank 3-5 between the colorimetric tank body 3-1 and the light-transmitting cover 3-2 can hold the colorimetric solution. The hanging plate 3-3 is set vertically, and its sides are detachably and symmetrically installed on both horizontal sides of the upper part of the colorimetric tank body 3-1 by adhesive or bolts. The upper surface of the hanging plate 3-3 is connected to the lower surface of the fixing plate 3-4, and the upper surface of the fixing plate 3-4 is detachably connected to the lower surface of the top cover 1 by adhesive or bolts. The colorimetric tank body 3-1, the hanging plate 3-3, and the fixing plate 3-4 form a ventilation window 3-6, through which volatile components can enter the colorimetric tank 3-5 and react with the colorimetric solution in the colorimetric tank 3-5, facilitating operation.

[0033] The detection mechanism 3 can be detachably connected to the top cover 1 via the fixing plate 3-4, which facilitates the disassembly of the detection mechanism 3. By pouring the colorimetric solution into the colorimetric cell 3-5, a colorimetric reaction can be carried out with the solution containing volatile components to be tested. The hanging plate 3-3 can hang the colorimetric cell 3-1 to perform component detection on the headspace. By adjusting the height of the hanging plate 3-3, it can be adjusted according to different solutions to be tested, which facilitates the colorimetric reaction and improves convenience.

[0034] Preferably, the colorimetric cell 3-5 has an inverted triangular structure, and the colorimetric cell 3-5 is provided with a scale line for the solution (not shown in the figure) inside, which facilitates the filling of the liquid and the control of the dosage. The width of the middle part of the colorimetric cell 3-5 with the inverted triangular structure is larger than the incident light slit of the colorimeter, allowing the incident light to completely enter the colorimetric solution.

[0035] In this embodiment, the structural connection between the top cover 1 and the bottle opening 2-3 can refer to the structural design of the bottle mouth and bottle cap of drinking mineral water. The top cover 1 and the bottle opening 2-3 are tightly and detachably connected. The cap 1-1 can be detachably and tightly connected to the bottle 2 by screwing. Or, such as Figure 3As shown, the top cover 1 includes a cover body 1-1 and a sealing gasket 1-2. The cover body 1-1 and the bottle opening 2-3 are sealed together by the sealing gasket 1-2, so that the top cover 1 and the bottle opening 2-3 can be better sealed to prevent the leakage of volatile gases and affect the health of the experimental personnel. The sealing gasket 1-2 can be a mature product or technology such as a sealing gasket in the existing technology.

[0036] like Figure 4 As shown, the method for detection using the headspace colorimetric reaction device for colorimetric determination of volatile components as described above specifically includes the following steps: (1) Pour an appropriate amount of colorimetric solution into colorimetric cell 3-5, pour an appropriate amount of sample into solution cell 4, and then assemble the device; (2) The device is placed on the heating device for heating. The sample in the solution pool 4 at the bottom of the headspace bottle is heated. The volatile components contained in the sample are released from the sample matrix and automatically convection into the top area of ​​the bottle 2. (3) The volatile components entering the top area of ​​the bottle cavity 2-1 react with the colorimetric solution stored in the colorimetric tank 3-5 in the top area of ​​the bottle cavity 2-1 to generate a colorimetrically detectable colored compound. (4) After heating is completed and stabilized, open the top cover 1, remove the colorimetric cell 3-1, and place it directly in the colorimetric instrument. Select the optimized incident light beam for subsequent colorimetric analysis to complete the detection.

[0037] Preferably, the bottle body 2 is made of transparent glass, with a diameter of 15-30 mm and a volume of 15 mL-40 mL. The colorimetric cell 3-1 is made of glass, polypropylene (PP) or polystyrene, with a thickness of 5-1 mm, a width of 10-15 mm, and a height of 30-45 mm. The triangular cell inside the colorimetric tank 3-5 is 10-25 mm lower than the side wall of the colorimetric cell 3-1, and the base angle of the triangle is 15-45 degrees. The light-transmitting cover plate 3-2 is made of optical glass, optical polypropylene (PP) or optical polystyrene, with a width consistent with the colorimetric cell 3-1 and a height 10-25 mm lower than the colorimetric cell 3-5. Both the suspension plate 3-3 and the fixing plate 3-4 are made of polytetrafluoroethylene sheet, and the width of the suspension plate 3-3 is the same as the thickness of the colorimetric cell 3-1.

[0038] Because this device utilizes the property of volatile gases to rise after evaporation for colorimetric detection, by replacing the solution in the colorimetric cell 3-5, the concentration of some special chemical liquids that are not convenient to be directly chemically reacted can also be determined. By adding the corresponding liquid to the colorimetric cell 3-5 to make it react, the concentration of the liquid in the bottle can be determined, such as concentrated sulfuric acid, concentrated hydrochloric acid, etc.

[0039] Therefore, the apparatus described above can be applied to the determination of chemical liquid concentrations in headspace colorimetric reaction apparatuses used for the colorimetric determination of volatile components.

[0040] Preferably, the present invention utilizes a shallow-hole multi-position metal bath heating module, which facilitates the placement of multiple headspace colorimetric reactors, enabling the processing of multiple samples simultaneously. The shallow-hole heating module ensures that heating is focused on the headspace sample specimen, heating the specimen at the bottom of the headspace vial. Volatile components contained in the specimen are released from the sample matrix, rise automatically into the headspace region through convection, and react with the colorimetric solution stored in the inverted triangular cell to generate a colorimetrically measurable colored compound. The inverted triangular design increases the contact area between the volatile components and the colorimetric solution, which is beneficial for improving reaction efficiency.

[0041] Example 1 This embodiment provides a method for evaluating the free radical scavenging ability of active volatile components using the present invention. Materials and reagents used: 1. Mixed standard sample of volatile components: Take 2.5 mL of natural volatile standards with free radical scavenging ability (HPLC ≥ 98%), 1.25 mL each of linalool, geraniol, and β-caryophyllene. Mix them in a volumetric flask and store at 4 °C.

[0042] 2. Blank matrix of Pu-erh tea: Take 100 g of raw Pu-erh tea, place it in an oven, heat it at 60 ℃ for 12 h to remove the volatile components of the sample, and obtain a blank sample matrix. Place it in a ground glass bottle, seal it, and store it at 4 ℃.

[0043] 3. 2,2′-Azido-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) free radical solution: Solution A: Place 5.0 mg K₂S₂O₈ into a 10.0 mL colorimetric tube and add 7.5 mL of pure water; Solution B: Place 15.0 mg of ABTS reagent into another 10 mL colorimetric tube and add 4.0 mL of pure water, then sonicate for 3 min. After mixing, take 4.0 mL of each solution A and B, mix and seal, and store at 4 °C with shaking in the dark for 12-16 h. Before use, dilute with pure water approximately 50 times to adjust the absorbance A to 0.7 ± 0.002.

[0044] 4. Preparation of simulated active samples: Take the prepared Pu-erh tea blank matrix, crush it to below 100 mesh, transfer 1.0 g of sample into a headspace vial, use a microsyringe to add 0.1 mL of volatile component mixed standard sample to the Pu-erh tea blank matrix in the headspace vial, shake to mix, seal and place at 4 ℃ for 24 h, and at the same time use the blank sample matrix without volatile component mixed standard sample as the blank sample.

[0045] For detailed implementation procedures, please refer to [link / reference]. Figure 4 The process includes two steps: headspace-color development and colorimetry. (1) Headspace-color development process: The device used includes the present invention and headspace vials containing simulated active samples and blank samples respectively. Take 0.5 mL of ABTS free radical solution with an absorbance (A) of 0.7 (hereinafter referred to as 0.7 ABTS free radical solution) and place it in the colorimetric cell. Place the detection mechanism in the upper part of the vial body. Seal the vial body with the top cap. Place the sealed device on the heating device. Heat the bottom of the device at 70°C. The active simulated sample or the blank sample without active substances, the volatile components in the sample mixed with the standard components are released from the sample matrix, and rise automatically to the upper part of the vial body through convection and enter the headspace area. Through the scavenging reaction with the ABTS free radicals stored in the inverted triangular colorimetric cell 3-5, the green ABTS is generated. (2) During the colorimetric determination process, the detection mechanism that has completed the headspace-colorimetric reaction is removed and placed directly in the rectangular groove colorimetric cell of a conventional colorimetric instrument to measure the absorbance of ABTS free radicals after the scavenging reaction (A1), and at the same time, the absorbance value (A0) without blank sample is measured, and the ABTS free radical scavenging activity (E) of the volatile components is calculated. The formula is as follows: (E(%)=(A1-A0)×100 / A0).

[0046] The preferred heating temperature is 70℃, according to Figure 5 The effect of heating time on free radical absorbance and scavenging rate was investigated, with a preferred heating time of 30 min.

[0047] The results are shown in Table 1. Table 1 shows the ABTS radical scavenging results of the active simulant sample. The standard values ​​in the table are the results of direct scavenging of 0.7 mL ABTS radical solution (0.5 mL) by a mixed standard sample (0.1 mL) without headspace processing. As can be seen from the table, the relative standard deviations of the results in this implementation case are within acceptable ranges compared to the standard values, meeting the analytical requirements. Under the condition that the ratio of the simulated active sample amount to the 0.7 mL ABTS radical solution amount is consistent, the results of this implementation case are significantly better than the conventional distillation-colorimetric method control in both accuracy and precision.

[0048] Table 1. Results of ABTS radical scavenging in active simulated samples

[0049] Table 2 summarizes the technical features of this invention and its differences from other methods and inventions through this implementation case. Compared with other methods and disclosed inventions, this invention has three unique features: (1) Apparatus: The headspace separation and colorimetric reaction device are integrated into one unit, and the device is compact; (2) Process: The headspace separation and colorimetric reaction are completed in one step in the headspace colorimetric reactor, and the process does not require transfer and dilution, avoiding volatilization loss and solution transfer error; (3) Colorimetric mode: The designed rectangular headspace colorimetric cell is adapted to the universal rectangular colorimetric cell of the colorimeter, allowing direct placement into the colorimeter for colorimetric comparison.

[0050] Table 2. Comparison of the differences between this invention and other methods and inventions.

[0051] Based on the above-mentioned unique design, this invention is significantly superior to the traditional distillation-colorimetric method in three dimensions: field applicability, ease of operation, accuracy, and high sensitivity. Compared with the existing headspace-colorimetric method, this invention not only has better ease of operation, but also better versatility, good practicality, and is easy to promote and popularize.

[0052] Although embodiments of the invention have been disclosed for illustrative purposes, those skilled in the art will understand that various substitutions, variations, and modifications are possible without departing from the spirit and scope of the invention and the appended claims. Therefore, the scope of the invention is not limited to the contents disclosed in the embodiments.

Claims

1. A headspace colorimetric reaction apparatus for the colorimetric determination of volatile components, characterized in that: The device is capable of colorimetric detection of volatile components within the device. The device includes a top cover (1), a bottle body (2), a detection mechanism (3), and a solution pool (4). The top of the bottle body (2) has a vertical opening from top to bottom to form a bottle cavity (2-1). The top cover (1) is fitted to the bottle body (2) at the top opening of the bottle body (2) and can lock the top opening of the bottle body (2). The detection mechanism (3) is connected to the lower surface of the top cover (1) and can be suspended above the bottle cavity (2-1) through the top cover (1) to detect the air components in the upper part of the bottle cavity (2-1). The solution pool (4) is located at the bottom of the bottle cavity (2-1) and can hold the solution containing volatile components to be tested. The detection mechanism (3) can perform colorimetric detection. Both the detection mechanism (3) and the bottle body (2) are made of transparent material.

2. The apparatus according to claim 1, characterized in that: The bottle body (2) is made of transparent glass, with a diameter of 15-30 mm and a volume of 15mL-40mL.

3. The apparatus according to claim 1, characterized in that: The testing mechanism (3) includes a colorimetric cell (3-1), a light-transmitting cover plate (3-2), a suspension plate (3-3), and a fixing plate (3-4). The colorimetric cell (3-1) has a colorimetric groove (3-5) arranged vertically from top to bottom, and the colorimetric groove (3-5) is arranged horizontally. The light-transmitting cover plate is arranged vertically, and both sides of the colorimetric cell (3-1) are tightly fixed and connected to the light-transmitting cover plate (3-2). The height of the light-transmitting cover plate (3-2) is slightly less than the height of the colorimetric groove (3-5), allowing the experimenter to pass through the light-transmitting cover plate (3-2). Visual inspection is performed inside the colorimetric tank. The structure of the colorimetric tank body (3-1) and the light-transmitting cover plate (3-2) is designed so that the colorimetric tank (3-5) can hold the colorimetric reaction solution for testing. The hanging plate (3-3) is set vertically. The sides of the hanging plate (3-3) are detachably and symmetrically installed on both sides of the longitudinal direction of the colorimetric tank body (3-1) by adhesive or bolts. The upper surface of the hanging plate (3-3) is connected to the lower surface of the fixing plate (3-4). The upper surface of the fixing plate (3-4) is detachably connected to the lower surface of the top cover (1) by adhesive or bolts.

4. The apparatus according to claim 3, characterized in that: The colorimetric cell (3-5) has an inverted triangular structure and is equipped with scale lines for the solution inside. The width of the middle part of the inverted triangular colorimetric cell (3-5) is greater than the incident light slit of the colorimeter, allowing the incident light to completely enter the colorimetric solution.

5. The apparatus according to claim 1, characterized in that: The cap (1-1) is matched with the top opening of the bottle (2), and the cap (1-1) can be detachably and tightly connected to the bottle (2) by screwing. Alternatively, the top cover (1) includes a cover body (1-1) and a sealing gasket (1-2), with the top opening of the cover body (1-1) and the bottle body (2) sealed together by the sealing gasket (1-2).

6. The apparatus according to any one of claims 1 to 5, characterized in that: The bottle body (2) is made of transparent glass, with a diameter of 15-30 mm and a volume of 15mL-40mL; Alternatively, the colorimetric cell (3-1) is made of glass, polypropylene (PP) or polystyrene, with a thickness of 5-1 mm, a width of 10-15 mm, and a height of 30-45 mm. The triangular cell inside the colorimetric tank (3-5) is 10-25 mm lower than the side wall of the colorimetric cell (3-1), and the base angle of the triangle is 15-45 degrees. Alternatively, the light-transmitting cover plate (3-2) may be made of optical glass, optical polypropylene (PP) or optical polystyrene, with a width consistent with the colorimetric cell body (3-1) and a height 10-25 mm lower than the colorimetric tank (3-5). Alternatively, the suspension plate (3-3) and the fixing plate (3-4) are both made of polytetrafluoroethylene sheet, and the width of the suspension plate (3-3) is the same as the thickness of the colorimetric cell body (3-1).

7. The method of using the headspace colorimetric reaction apparatus for colorimetric determination of volatile components as described in any one of claims 1 to 6, characterized in that: Includes the following steps: Pour the solution to be tested into the bottom of the bottle (2) to form a solution pool (4). Then assemble the detection mechanism (3) with the top cover (1). After assembly, insert the detection mechanism (3) into the upper part of the bottle cavity (2-1) in the bottle (2) through the top cover (1). Press or twist the top cover (1) until the top cover (1) and the bottle (2) are sealed. Then let it stand or heat the bottom of the device so that the volatile components in the solution pool (4) evaporate and float to the detection mechanism (3) in the upper part of the bottle (2). The detection mechanism (3) detects the volatile components. Due to the transparent material, the detection mechanism (3) can be observed visually. When the detection mechanism (3) changes, remove the detection mechanism (3) and proceed to the next step of colorimetric detection.

8. The application of the apparatus according to any one of claims 1 to 6 in the determination of the concentration of chemical liquids in a headspace colorimetric reaction apparatus for the colorimetric determination of volatile components.

9. The method for detection using the headspace colorimetric reaction apparatus for colorimetric determination of volatile components as described in any one of claims 1 to 6, characterized in that: Includes the following steps: (1) Pour an appropriate amount of colorimetric solution into the colorimetric cell (3-5), pour an appropriate amount of sample into the solution pool (4), and then assemble the device; (2) The device is placed on the heating device for heating. The sample in the solution pool (4) at the bottom of the headspace bottle is heated. The volatile components contained in the sample are released from the sample matrix and automatically convection into the top area of ​​the bottle (2). (3) The volatile components entering the top region of the bottle cavity (2-1) react with the colorimetric solution stored in the colorimetric tank (3-5) in the top region of the bottle cavity (2-1) to generate a colorimetrically measurable colored compound; (4) After heating is complete and stabilized, open the bottle cap, remove the colorimetric cell (3-1), and place it directly in the colorimetric instrument. Select the optimized incident light beam for subsequent colorimetric analysis to complete the detection.

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