A gas sampling device and detection method for detecting formamide content in a floor mat

Abstract

The present application belongs to the technical field of analysis and detection, and particularly relates to a gas sampling device and a detection method for detecting the content of formamide in a floor mat. The formamide sample in the floor mat is sampled by using the simple and portable gas sampling device. The sampling device is provided with a thermal desorption tube. After sampling is completed, the sample can be directly detected by thermal desorption, which greatly simplifies the sampling and detection operations. The present application has the beneficial effects that: the gas sampling device is provided with a constant temperature box and a sampling assembly with a flow meter and a timing function, which can simulate the release of formamide in the floor mat product under different temperatures and different storage times, and explore the release rules of formamide in the floor mat under different conditions; and the sampling device is provided with multiple gas collection bags, which can simultaneously collect multiple sets of gas samples in the same temperature environment, and has large sampling amount and high detection accuracy.

Description

Technical Field

[0001] This invention belongs to the field of analytical testing technology, specifically relating to a gas sampling device and testing method for detecting formamide content in floor mats. Background Technology

[0002] Children's crawling mats are soft, brightly colored, and attractive. They not only protect infants and toddlers but also allow parents to teach their babies about various colors and patterns. They are widely used in nurseries, kindergartens, and other places, and their quality is a matter of great concern.

[0003] However, in the production of floor mats, some manufacturers, in order to control costs while improving the softness and comfort of the mats, often use formamide-based foaming agents to enhance the foaming effect and reduce the weight of the mats. In EU regulations, formamide is listed as a substance with reproductive toxicity and is included in the REACH list of substances of very high concern. Numerous studies have shown that formamide has embryotoxicity and teratogenicity; after skin contact, inhalation, or ingestion, it can affect the central nervous system and reproductive system. Therefore, the harm caused by excessive formamide in floor mats should not be underestimated. Accurate detection of formamide content in floor mats and understanding its migration and release patterns during use are crucial.

[0004] Currently, there are no domestic standards that set limits on the formamide content in floor mats, nor are there specific experimental methods for investigating the migration and release patterns of formamide in floor mats. Instead, environmental chamber sampling is often used to investigate the migration and release of indoor pollutants such as sofas and mattresses. However, environmental chambers are bulky, require heating and humidification equipment, place extremely high demands on laboratories, and are expensive.

[0005] Furthermore, there is relatively little research on the release patterns of formamide in floor mats made of different materials. The release methods and rates of formamide in floor mats are currently unclear. Formamide introduced during the production process of floor mats can be slowly released into the environment during storage and use, thus entering the human body and causing harm to human health.

[0006] Studying the long-term release patterns of formamide in floor mats is beneficial for understanding its persistent harm to the environment and human body. Based on the release patterns, corresponding models can also be established to predict the migration concentration and residual amount of formamide after a certain period of time. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention provides a gas sampling device and detection method for detecting the formamide content in floor mats.

[0008] The present invention provides a method for detecting formamide content in floor mats, comprising the following steps:

[0009] Pretreatment of S1 gas sampling device: Clean N2 is used to pre-clean the gas collection bag of the gas sampling device. After cleaning, the gas in the gas collection bag is emptied by a flow pump. At the same time, the thermal desorption tube in the gas sampling device is aged to ensure that there are no pollutants left in the tube.

[0010] The gas sampling device includes a gas collection bag, a thermal desorption tube, and a sampling assembly connected in sequence, and also includes a constant temperature box and a controller for placing the gas collection bag and providing a constant temperature environment.

[0011] Pre-treatment of S2 floor mat products: Cut the floor mat products into 10cm×20cm small pieces and put them into the air collection bag after cleaning in S1;

[0012] S3 uses a gas sampling device to collect formamide from the floor mat: First, 4L of clean nitrogen gas is filled into a 10L gas collection bag. After filling, the filling port is closed, so that the gas collection bag has a load capacity of 10m. 2 / m 3 Then, formamide in the floor mat product is collected at a specific temperature. The temperature is adjustable from 20 to 100°C. At the same time, the flow meter connected to the thermal desorption tube is set to delay opening for 1 hour to 30 days. When the preset delay opening time is reached, the gas supply pipe connected to the thermal desorption tube is opened. The volatile organic compounds released from the floor mat in the gas collection bag are adsorbed on the thermal tube through the gas supply pipe. At this time, the flow meter is turned on and the gas in 2L floor mat is collected at a rate of 100 to 450 mL / min.

[0013] Detection of S4 formamide: After sampling, remove the thermal desorption tube from the gas sampling device, immediately seal the thermal desorption tube, and empty the remaining gas in the gas collection bag. Then, place the thermal desorption tube of the gas sampling device on the gas chromatograph-mass spectrometer for on-machine testing and analysis.

[0014] In this invention, a gas collection bag is used in conjunction with a thermal desorption tube to sample the floor mat product. Therefore, there is no significant limitation on the sampling volume, and a large amount of gas sample can be collected, with a gas sample collection volume of up to 2L. Thus, when cutting the floor mat, it can be cut into floor mat samples with a relatively large surface area. This operation not only helps to increase the concentration of the floor mat sample to be tested, but also improves the detection accuracy.

[0015] Preferably, in step S3, 2L of gas containing pollutants is collected in the gas bag into the thermal desorption tube at a flow rate of 200±20mL / min.

[0016] Through extensive experiments, the inventors have verified that the flow rate of gas sample collection has a significant impact on the adsorption effect of the thermal desorption tube. When the collection flow rate is too slow, it will result in significant time consumption and affect the detection efficiency. However, if the flow rate is set too fast, the gas sample to be tested will not be completely adsorbed in the thermal desorption tube, making it difficult for the thermal desorption tube to capture the target organic matter, thus affecting its detection accuracy. When the collection is carried out at a flow rate of 200±20mL / min, the thermal desorption tube has the best adsorption effect on the pollutant gas sample in the gas bag.

[0017] In step S3 of this invention, formamide in the floor mat is collected at 20–100°C. Simultaneously, the flow meter is set to delay activation for 1 hour to 30 days. On one hand, the gas collection bag containing the floor mat to be tested is heated by the heating unit in the gas sampling device, which can simulate the release amount and release pattern of formamide in the floor mat under different seasonal temperature conditions. On the other hand, setting the flow meter to delay activation for different times, such as 1 hour to 30 days, can more realistically simulate the release of formamide in the floor mat after different placement times. More comprehensive and three-dimensional data can be obtained on the release pattern of formamide in the same floor mat product with changes in temperature and time.

[0018] Furthermore, the load-bearing capacity of the gas collection bag is set at 10m. 2 / m 3 This load-bearing capacity takes into account the most stringent conditions, namely simulating the maximum contact between a child of 0.5m to 1m height and the floor mat.

[0019] In step S4, when there is only one gas collection bag in the gas sampling device, after the collection is completed, the thermal desorption tube can be taken out first, and then placed directly on the gas chromatograph-mass spectrometer for testing, and the remaining gas in the gas collection bag can be emptied.

[0020] When the gas sampling device has multiple gas collection bags, after the collection is completed, the thermal desorption tubes can be taken out, sealed and numbered sequentially, and the remaining gas in the gas collection bags can be emptied. Then, the thermal desorption tubes of the gas sampling device can be tested and analyzed on the machine.

[0021] Preferably, in S4, the detection conditions of the gas chromatograph-mass spectrometer are as follows: gas chromatograph-mass spectrometer, model 7890B-5977A, Agilent Technologies, USA, column DB624, 60m×0.250mm, carrier gas is helium, and the resolution temperature is 270℃.

[0022] In addition, the present invention also provides a gas sampling device for detecting the formamide content in floor mats, comprising a gas collection bag, a thermal desorption tube, and a sampling component connected in sequence, and further comprising a constant temperature box and a controller for placing the gas collection bag and providing a constant temperature environment.

[0023] The gas collecting bag is provided with an air inlet and an air outlet, and a control valve is provided at both the air inlet and the air outlet. The top of the gas collecting bag is provided with an opening for placing the test sample, and a sealing element is provided at the opening. The bottom of the gas collecting bag is provided with a first magnetic strip.

[0024] Preferably, the control valve is a solenoid valve connected to the controller, and the first magnetic strip and the second magnetic strip are solenoid strips connected to the controller.

[0025] The constant temperature box includes a detachably connected box body and a cover. The box body has a cavity for accommodating the gas collection bag. A temperature sensor connected to a controller is embedded in the inner wall of the box body. The side wall of the box body is provided with a heat-conducting layer, a heating layer, and a heat-insulating layer from the inside to the outside. A heating unit connected to the controller is provided in the heating layer. A second magnetic strip is provided on the inner bottom wall of the box body. The second magnetic strip is attracted to the first magnetic strip on the gas collection bag.

[0026] The cover has a through hole running vertically and a protrusion that fits the cavity. The bottom of the protrusion has a horizontally running groove. The gas collection bag can be slidably inserted into and secured in the groove through one side of the groove. The groove has a "T" shaped cross-section.

[0027] In this invention, a constant temperature box is set up, which contains a heating unit, which is an electric heating wire or an electric heating plate. During the actual sampling process, the controller controls the heating unit to heat or stop heating based on the temperature data inside the box cavity monitored by the temperature sensor, thereby achieving a constant temperature effect.

[0028] Furthermore, a transverse sliding groove is provided on the lid of the constant temperature box, allowing the sealing element of the gas collection bag to move laterally left and right along the groove. The "T"-shaped groove also limits the sealing element, preventing it from moving up and down. This ensures that the gas collection bag can only slide left and right in the groove and cannot move up and down, thus suspending the gas collection bag in the internal cavity of the constant temperature box. At the same time, the attraction of the first and second magnetic strips fixes both ends of the gas collection bag, facilitating the release and collection of sample gas in the gas collection bag.

[0029] Furthermore, a first magnetic strip and a second magnetic strip are installed at the bottom of the gas collection bag and on the inner wall of the bottom of the box. During use, the gas sampling device can be magnetized by the controller. When the first and second magnetic strips are energized, they attract each other magnetically. At this time, the bottom of the gas collection bag is stably fixed on the inner bottom wall of the constant temperature box. This avoids the instability of the sampling process caused by the shaking of the gas collection bag due to different sample amounts or different sampling stages, which would affect the accuracy of the sampling data. Conversely, when the gas collection bag needs to be removed after sampling, simply disconnect the power. The magnetism of the first and second magnetic strips disappears, and there is no attraction between them, so the gas collection bag can be easily removed.

[0030] Preferably, the number of grooves is at least one, the number of through holes is at least one, and the number of grooves is equal to the number of gas collection bags, thermal desorption tubes, and sampling components.

[0031] Preferably, the number of grooves is 1 to 3, and the number of through holes is the same as the number of grooves.

[0032] More preferably, there are 3 chutes, 3 matching gas collection bags, and 3 thermal desorption tubes and sampling components connected to the gas collection bags.

[0033] Preferably, in the above-mentioned sampling device, the heating unit is an electric heating wire or an electric heating plate.

[0034] In this invention, one or three parallel swivels can be selected to be set at the bottom of the protrusion of the gas sampling device, depending on the experimental conditions. If three parallel swivels are set, three through holes are set on the cover. The main purpose of the three swivels, the three gas collection bags that are adapted to them, and the thermal desorption tube and sampling components connected to each gas collection bag is to enable the constant temperature chamber to control the temperature of the three gas collection bags at the same time, ensuring the consistency of the sampling environment of the three gas collection bags. At the same time, the sampling components are used to sample the floor mat products in the three gas collection bags at the same time. Three sets of data can be obtained in one experiment, and the average value can be directly taken. This is beneficial to improve the sampling efficiency of gas samples and shorten the gas sampling and collection time.

[0035] As another heating option, preferably, the heating layer of the gas sampling device is provided with a cavity for containing a liquid medium, and the casing is provided with an inlet and an outlet communicating with the cavity. Valves are provided at both the inlet and outlet, allowing cooling liquid to be circulated into the cavity of the heating layer through the inlet and outlet to cool the gas collection bag and prevent the gas sample from evaporating or dissipating during intermittent testing, thus avoiding distortion of the test results.

[0036] The thermal desorption tube has its two ends detachably and sealed to the gas outlet of the gas collection bag and the sampling component, respectively. A check valve is also installed between the thermal desorption tube and the sampling component to prevent gas backflow from affecting the accuracy of the gas sample acquisition data.

[0037] The sampling assembly includes a pump body, a flow meter, and a regulating assembly connected in sequence. The regulating assembly is connected to the thermal desorption tube, and the pump body, flow meter, and regulating assembly are all connected to the controller.

[0038] Preferably, the sampling component is a low-flow air sampler, the pump body is a diaphragm pump, the regulating component is a regulating valve, and a timer connected to the controller is also provided.

[0039] Preferably, the controller includes a display screen mounted on the outer wall of the housing, which can be used to display relevant information such as temperature, time, and sample being tested.

[0040] The beneficial effects of this invention are as follows:

[0041] (1) The method for detecting formamide content in floor mats provided by the present invention has the characteristics of large sample volume and high detection accuracy due to the use of thermal desorption tube for direct sample loading. When the method of the present invention is used for detection, the relative deviation of parallel samples is within 10%, and the spiked recovery rate is within ±20%.

[0042] (2) The present invention provides a gas sampling device for detecting the formamide content in floor mats. The device is equipped with a constant temperature box and a controller. The temperature of the gas collection bag is controlled by the constant temperature box to simulate the release of formamide gas in the floor mat at different temperatures. In addition, by means of the flow meter, timer and other structures set in the sampling component of the gas sampling device, the release of formamide in the floor mat at different delayed sampling times can be further simulated. That is, the detection method of the present invention can obtain the dynamic release pattern of formamide in the floor mat at different temperatures and placement times, which is beneficial to guide consumers on the use of floor mats.

[0043] (3) In the gas sampling device of the present invention, multiple sliding grooves are provided in the constant temperature box, preferably three, and gas collection bags, thermal desorption tubes and sampling components that are matched with them respectively. That is, one device can simultaneously sample three groups of samples, which is beneficial to saving experimental time and the sampling environment has strong consistency, which is beneficial to improving the accuracy of detection.

[0044] (4) The gas sampling device provided by the present invention is simple in structure, portable and easy to use. Attached Figure Description

[0045] Figure 1 The formamide standard curve in the gas chromatography-mass spectrometry system of Example 1 of the present invention has a linearity of 0.999499 and a retention time of 11.204 min.

[0046] Figure 2 This is a gas chromatogram and mass spectrum of formamide collected simultaneously from the three gas collection bags before spiking in Example 1 of the present invention;

[0047] Figure 3 In Example 1 of this invention, the gas chromatogram and mass spectrum of formamide collected simultaneously by three gas collecting bags after spiking;

[0048] Figure 4 Emission rate trend of formamide at different migration times in Example 2 of the present invention;

[0049] Figure 5 Gas chromatograms and mass spectra of formamide at different sampling rates in Comparative Example 1 of the present invention; wherein, from left to right, the sampling rates are 200, 300, and 400 mL / min respectively;

[0050] Figure 6 This is a schematic diagram of the gas sampling device in Embodiment 3 of the present invention;

[0051] Figure 7 This is a schematic diagram of the constant temperature box in the gas sampling device of Embodiment 3 of the present invention;

[0052] Figure 8 This is a cross-sectional view of the constant temperature box body in the gas sampling device of Embodiment 3 of the present invention;

[0053] Figure 9 This is a schematic diagram of the structure of the constant temperature box cover in the gas sampling device of Embodiment 3 of the present invention;

[0054] Figure 10 This is a schematic diagram illustrating the connection principle of the controller in the gas sampling device in the gas collection bag according to Embodiment 3 of the present invention;

[0055] Figure 11 This is a schematic diagram of the gas sampling device in Embodiment 4 of the present invention;

[0056] Figure 12 This is a schematic diagram of the cover structure of the gas sampling device in Embodiment 4 of the present invention;

[0057] Figure 13 This is a schematic diagram of the gas sampling device of the gas collection bag in Embodiment 5 of the present invention;

[0058] In the diagram: 1-Gas collection bag, 11-Air inlet, 12-Air outlet, 13-Sealing element, 14-First magnetic strip, 2-Thermal desorption tube, 3-Sampling component, 4-Constant temperature box, 41-Box body, 411-Temperature sensor, 412-Heat-conducting layer, 413-Heating layer, 414-Insulation layer, 415-Heating unit, 416-Second magnetic strip, 417-Liquid inlet, 418-Liquid outlet, 42-Cover, 421-Through hole, 422-Protrusion, 423-Slide groove, 5-Check valve, 6-Display screen. Detailed Implementation

[0059] To enable those skilled in the art to better understand the present invention, the present invention will now be further described in conjunction with specific embodiments.

[0060] Example 1

[0061] A method for detecting formamide content in floor mats, comprising the following steps:

[0062] Pretreatment of S1 gas sampling device: Clean N2 is used to pre-clean the three gas collection bags in the gas sampling device three times. After cleaning, the gas in the gas collection bags is emptied by a flow pump. At the same time, the thermal desorption tube in the gas sampling device is aged to ensure that there are no pollutants left in the tube.

[0063] Pre-treatment of S2 floor mat products: Cut the floor mat products into three small pieces of 10×20cm, and put them into the three air collection bags after cleaning in S1. The volume of each air collection bag is 10L.

[0064] Formamide collection from S3 floor mat: First, N2 was added at a flow rate of 200 mL / min for 20 minutes, followed by 4 L of N2. After inflation, the inflation port was closed, ensuring the gas collection bag had a load capacity of 10 m. 2 / m 3 The experiment simulated the scenario of a 1-meter-tall child playing on a floor mat. Then, the formamide in the floor mat product was collected at 25°C. At the same time, the flow meter was set to turn on after a 1-hour delay. The amount of formamide released from the floor mat in the air bag was collected after 1 hour. When the preset delay time was reached, the collection continued for 10 minutes. The same operation was performed on 3 air collection bags.

[0065] Detection of S4 formamide: After the collection is completed, the thermal desorption tubes in the gas sampling device are removed, the thermal desorption tubes are immediately sealed, and the remaining gas in the gas collection bag is emptied. Then, the collected thermal desorption tubes are placed on the gas chromatograph-mass spectrometer for on-machine testing and analysis. The final data is the average value of the data collected from the three gas collection bags.

[0066] In S4, the detection conditions were as follows: gas chromatography-mass spectrometry (GC-MS), model 7890B-5977A, Agilent Technologies, USA; column: DB624, 60m × 0.250mm; carrier gas: helium; and resolution temperature: 270℃.

[0067] In addition, a standard solution of the target pollutant, formamide, was prepared, and a standard curve was plotted using gas chromatography-mass spectrometry, as shown in the attached figure. Figure 1 As shown.

[0068] Meanwhile, repeat steps S1 to S4 above, except that in S2, each floor mat sample is spiked with 10 ng of formamide standard solution.

[0069] The relative deviations in formamide content collected by the gas collection bags before and after spiking, as well as the spiking recovery rates, are shown in Table 1 and Appendix. Figures 2-3 As shown.

[0070] Among them, the appendix Figure 2 The attached image shows the gas chromatogram and mass spectrum of formamide collected simultaneously from the three gas collection bags before spiking; Figure 3The images show gas chromatograms and mass spectra of formamide collected simultaneously from three gas collection bags after spiking; from left to right, they are sample 1, sample 2, and sample 3.

[0071] Table 1. Relative deviation and spiked recovery rate of formamide collected from floor mats by the gas sampling device.

[0072]

[0073] As can be seen from the data in Table 1, the relative deviation of each parallel sample is within 10%, and the spiked recovery rate is within ±20%, indicating that the structure of the parallel gas collection bag in the gas sampling device provided by the present invention has high environmental consistency, enabling the present invention to effectively and accurately detect the formamide content in the floor mat.

[0074] Example 2

[0075] Unlike Example 1, in step S3, the delay start time of the flow meter is set to 1d, 2d, 4d, 8d, 15d, and 30d respectively, and the release amount of formamide in the air bag of the mat after being placed for a longer period of time is collected.

[0076] All other operations and conditions are the same as in Example 1.

[0077] The formamide content in the floor mats at different migration times is shown in Table 2 below.

[0078] Furthermore, based on the data in Table 2, a trend diagram of formamide emission rates in the ground mat at different migration times was plotted, as shown in the attached diagram. Figure 4 As shown.

[0079] Table 2. Formamide release amount and release rate in floor mats at different migration times.

[0080] Release amount (ng) 62.87 54.29 55.08 21.24 21.28 13.35 Release rate (ng / d) 62.87 54.29 27.54 5.31 3.04 0.89

[0081] In the table above, the formamide emission rate is calculated as emission amount / collection time.

[0082] Table 2 and appendices Figure 4 The results showed that the release rate of formamide in the floor mats decreased overall with the extension of migration time. The release amount and release rate of formamide in the floor mats were significantly higher in the period of 1 to 10 days. After 10 days, the release amount of formamide in the floor mats decreased significantly. Therefore, when people buy floor mat products, they can place the floor mat products outdoors for ventilation for about 10 days before placing them indoors for use. This can largely avoid the peak release period of volatile organic compounds such as formamide in new floor mat products and reduce harm to children or adults.

[0083] Comparative Example 1

[0084] Repeat steps S1 to S4 of Example 1. The difference from Example 1 is that in step S3, the three gas collection bags are set with different flow rates, and the flow rates of the flow meters are set to 200 mL / min, 300 mL / min, and 400 mL / min, respectively.

[0085] Table 3 shows the release of formamide from the floor mat at different sampling flow rates.

[0086] Meanwhile, the gas chromatograms and mass spectra of formamide at different sampling rates are attached. Figure 5 As shown, Figure 5 From left to right, the sampling rates are 200, 300, and 400 mL / min, respectively.

[0087] Table 3. Formamide release (ng) from floor mats at different sampling flow rates.

[0088] Formamide release (ng) 2.80 2.71 2.68

[0089] The data in Table 3 show that the concentration of formamide decreases with increasing sampling flow rate. This is because when the sampling rate is too fast, such as 300 mL / min or 400 mL / min, the formamide volatilized from the mat cannot be adsorbed by the filling material in the adsorption tube in time, resulting in the loss of volatilized formamide and thus reducing the accuracy of detection. When the flow rate is 200 mL / min, the release of formamide is the highest. It can be seen that at this sampling rate, the filling material in the thermal desorption tube has the best adsorption effect on formamide, and the detection accuracy is further improved.

[0090] Example 3

[0091] As shown in the attached document Figure 6 The gas sampling device shown is used to sample formamide in the floor mat.

[0092] A gas sampling device includes a gas collection bag 1, a thermal desorption tube 2, a sampling component 3 connected in sequence via a gas delivery pipe, a constant temperature box 4 for placing the gas collection bag 1 and providing a constant temperature environment, and a controller.

[0093] like Figure 6 As shown, the gas collecting bag 1 is provided with an air inlet 11 and an air outlet 12, and both the air inlet 11 and the air outlet 12 are provided with control valves. The control valves are solenoid valves connected to the controller. The top of the gas collecting bag 1 is provided with an opening for placing the test sample. A sealing element 13 is provided at the opening. After the sample to be tested is placed through the opening, the opening is closed by the sealing element 13. The bottom of the gas collecting bag 1 is provided with a first magnetic strip 14. The first magnetic strip 14 is an electromagnetic strip connected to the controller. The controller controls the magnetization of the first magnetic strip 14.

[0094] As attached Figure 7As shown, the constant temperature box 4 is a rectangular box, which includes a detachably connected box body 41 and a lid 42, as shown in the attached figure. Figure 7 As shown, the box body 41 has a cavity for accommodating the gas collecting bag 1. A temperature sensor 411 connected to a controller is embedded in the inner wall of the box body 41. From the inside out, the side wall of the box body 41 has a heat-conducting layer 412, a heating layer 413, and an insulation layer 414. The heating layer 413 is a sandwich layer located between the heat-conducting layer 412 and the insulation layer 414, and a heating unit 415 connected to the controller is installed within this sandwich layer. The heating unit 415 is an electric heating wire or an electric heating element. The controller uses the temperature data monitored by the temperature sensor 411 inside the box body cavity to control the heating unit 415 to heat or stop heating, thereby achieving a constant temperature effect. The insulation layer 414 is provided with insulation material, such as heat-insulating fiber or heat-insulating cotton, to prevent heat loss and improve temperature stability. For better control, the heat-conducting layer 412 is made of a heat-conducting material, such as thermally conductive silicone. The inner bottom wall of the box body 41 is provided with a second magnetic strip 416 that attracts the first magnetic strip 14. The second magnetic strip 416 is an electromagnetic strip connected to the controller. That is, the controller can control the magnetization of the first magnetic strip 14 and the second magnetic strip 416 to fix the bottom of the gas collection bag 1. When the first magnetic strip 14 and the second magnetic strip 416 are energized, the resulting magnetism attracts each other. At this time, the bottom of the gas collection bag 1 is stably fixed on the inner bottom wall of the box body, avoiding the instability caused by shaking that affects the accuracy of the sampling data. When the gas collection bag 1 needs to be removed, simply disconnect the power supply. The magnetism of the first magnetic strip 14 and the second magnetic strip 416 disappears, and there is no attraction between them, so the gas collection bag 1 can be easily removed.

[0095] As attached Figures 8-9 As shown, the cover 42 is provided with a through hole 421 extending vertically and a protrusion 422 that matches the cavity. A sealing bushing (not shown in the figure) is provided at the through hole 421. The gas supply pipe connected to the gas outlet 12 of the gas collection bag 1 extends through the through hole 421 and connects to the thermal desorption pipe 2. The sealing bushing can effectively prevent heat from escaping through the through hole. A transversely extending groove 423 is provided at the bottom of the protrusion 422. The gas collection bag 1 can be slidably inserted into and secured in the groove 423 through one side of the groove 423. The cross-section of the groove 423 is shown in the figure. The gas collecting bag 1 is T-shaped, and the sealing element 13 can move laterally left and right along the slide groove 423. The T-shaped slide groove 423 can limit the sealing element 13 to prevent it from moving up and down. That is, the gas collecting bag 1 can only slide left and right in the slide groove 13 and cannot move up and down. This allows the gas collecting bag 1 to be suspended in the internal cavity of the constant temperature box 4. At the same time, with the attraction of the first magnetic strip 14 and the second magnetic strip 416, both the upper and lower ends of the gas collecting bag 1 are fixed, which facilitates the release and collection of sample gas in the gas collecting bag 1.

[0096] The two ends of the thermal desorption tube 2 are detachably and sealed to the gas outlet 12 of the gas collection bag 1 and the sampling component 3, respectively. At the same time, a check valve 5 is provided between the thermal desorption tube 2 and the sampling component 3 to prevent gas backflow from affecting the accuracy of gas sample collection data.

[0097] The sampling component 3 includes a pump body, a flow meter, and a regulating component connected in sequence. The regulating component is connected to the thermal desorption tube 2. The pump body, flow meter, and regulating component are all connected to the controller. Specifically, the sampling component 3 is a low-flow air sampler, the pump body is a diaphragm pump, the regulating component is a regulating valve, and a timer connected to the controller is also provided.

[0098] The controller includes a display screen 6 mounted on the outer wall of the casing. The display screen 6 can be used to display relevant information such as temperature, time, and sample information. The connection principle of the controller in the sampling device is shown in the attached figure. Figure 10 As shown.

[0099] Example 4

[0100] As attached Figure 11 As shown, unlike Embodiment 3, the heating layer 413 of the gas sampling device is provided with a cavity for containing liquid medium, and the box body 41 is provided with an inlet 417 and an outlet 418 communicating with the cavity. Valves are provided at both the inlet 417 and the outlet 418, and cooling liquid can be circulated into the cavity of the heating layer 413 through the inlet 417 and the outlet 418 to cool the gas collection bag 1, so as to avoid the volatilization and dissipation of gas sample during the intermittent process of intermittent detection, thereby causing the detection results to be distorted.

[0101] Furthermore, as attached Figure 12 As shown, the cover 42 of the constant temperature box 4 is provided with three through holes 421, and the bottom of the protrusion 422 is provided with three transverse through grooves 423, which can simultaneously fix the three gas collection bags 1. Correspondingly, the number of gas collection bags 1 is consistent with the number of thermal desorption tubes 2 and sampling components 3.

[0102] Example 5

[0103] As attached Figure 13 As shown, descriptions of parts that are no different from those in Embodiment 3 are omitted in the figures, and the same reference numerals are used.

[0104] As attached Figure 13 As shown, in the gas sampling device of this embodiment, the constant temperature box 4 is an elliptical box. The elliptical box is closer to the shape of the gas collection bag 1, which can improve its uniform heating effect. It is also simple in structure, lightweight and portable, and expands the scope of application. Compared with traditional ovens or environmental chambers, it has the advantages of being lightweight, portable and easy to use.

Claims

1. A gas sampling device for detecting formamide content in floor mats, characterized in that, It includes a gas collection bag (1), a thermal desorption tube (2), and a sampling assembly (3) connected in sequence, as well as a constant temperature box (4) for placing the gas collection bag (1) and providing a constant temperature environment and a controller; The gas collection bag (1) is provided with an air inlet (11) and an air outlet (12). A control valve is provided at both the air inlet (11) and the air outlet (12). The top of the gas collection bag (1) is provided with an opening for inserting the test sample. A sealing element (13) is provided at the opening. The bottom of the gas collection bag (1) is provided with a first magnetic strip (14). The constant temperature box (4) includes a detachably connected box body (41) and a cover (42). The box body (41) is provided with a cavity for accommodating the gas collection bag (1). A temperature sensor (411) connected to the controller is embedded in the inner wall of the box body (41). The side wall of the box body (41) is provided with a heat-conducting layer (412), a heating layer (413), and a heat-insulating layer (414) from the inside to the outside. A heating unit (415) connected to the controller is provided in the heating layer (413). The inner bottom wall of the cover (42) is provided with a second magnetic strip (416), which attracts the first magnetic strip (14) on the gas collection bag (1); the cover (42) is provided with a through hole (421) that runs vertically through the cover and a protrusion (422) that matches the cavity. The bottom of the protrusion (422) is provided with a horizontally through groove (423). The gas collection bag (1) can be slid into and locked in the groove (423) through one side of the groove (423). The cross-section of the groove (423) is "T" shaped. The thermal desorption tube (2) is detachably and sealed at both ends to the outlet (12) of the gas collection bag (1) and the sampling component (3); The sampling component (3) includes a pump body, a flow meter, and a regulating component connected in sequence. The regulating component is connected to the thermal desorption tube (2), and the pump body, the flow meter, and the regulating component are all connected to the controller.

2. The gas sampling device for detecting formamide content in floor mats as described in claim 1, characterized in that, The heating layer (413) is provided with a receiving cavity for containing liquid medium, and the box body (41) is provided with a liquid inlet (417) and a liquid outlet (418) communicating with the receiving cavity.

3. The gas sampling device for detecting formamide content in floor mats as described in claim 1, characterized in that, A check valve (5) is provided between the thermal desorption tube (2) and the sampling component (3).

4. A gas sampling device for detecting formamide content in floor mats as described in claim 1, characterized in that, The control valve is connected to the controller. The control valve is a solenoid valve. The first magnetic strip (14) and the second magnetic strip (416) are solenoid strips connected to the controller.

5. A method for detecting the formamide content in floor mats using the sampling device described in any one of claims 1 to 4, characterized in that, Includes the following steps: Pretreatment of S1 gas sampling device: Clean N2 is used to pre-clean the gas collection bag of the gas sampling device. After cleaning, the gas in the gas collection bag is emptied by a pump. At the same time, the thermal desorption tube in the gas sampling device is aged. Pre-treatment of S2 floor mat products: Cut the floor mat products into 10 cm × 20 cm small pieces and put them into the air collection bag after cleaning in S1; Formamide collection from S3 floor mats: First, 4 L of clean nitrogen gas was filled into a 10 L gas collection bag. After filling, the air inlet was closed, so that the gas collection bag had a load capacity of 10 m. 2 / m 3 Then, formamide in the floor mat product is collected at a specific temperature, which is an adjustable temperature range of 20 to 100°C. At the same time, the flow meter connected to the thermal desorption tube is set to delay opening for 1 hour to 30 days. When the preset delay opening time is reached, the gas supply pipe connected to the thermal desorption tube is opened. The volatile organic compounds released by the floor mat in the gas collection bag are adsorbed on the thermal desorption tube through the gas supply pipe. At this time, the flow meter is turned on and the gas released by the floor mat is collected at a rate of 100 to 450 mL / min. The gas collection volume is 2L. Detection of S4 formamide: After sampling, remove the thermal desorption tube from the gas sampling device, seal the thermal desorption tube, and empty the remaining gas in the gas collection bag. Then, place the thermal desorption tube of the gas sampling device on the gas chromatograph-mass spectrometer for on-machine testing and analysis.

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