A method for detecting organic phosphates in the atmosphere based on mesoporous materials

Abstract

The present invention provides a method for detecting organic phosphates in the atmosphere based on mesoporous materials. The method comprises: using a sampling tube filled with mesoporous materials to collect atmospheric samples; using a sampling tube filled with mesoporous materials to adsorb targets of different concentrations respectively; performing thermal desorption on the sampling tubes after the above sampling and introducing them into a detection device for detection, drawing a standard curve according to the peak area of ​​the target and its corresponding concentration, and converting the peak area of ​​the target in the atmospheric sample into the standard curve to obtain the content of the target. The present invention uses a sampling tube made of a mesoporous material containing silicon, oxygen and iron as an adsorbent to collect atmospheric samples. The material can effectively adsorb organic phosphates in the atmosphere, and then uses thermal desorption technology to desorb the organic phosphates adsorbed on the sampling tube, and then enters the detector with the carrier gas for analysis, which can realize direct, efficient and rapid detection of organic phosphates in the atmosphere, and the technology is green and low-carbon.

Description

Technical Field

[0001] The invention relates to a method for detecting organic phosphate in the atmosphere based on mesoporous materials. Background Art

[0002] Organophosphate esters (OPEs) are one of the substitutes for brominated flame retardants and are widely added to various daily necessities and commercial products. Since organophosphate esters are mainly combined with polymeric materials in a non-valent form, they inevitably enter the environment through various pathways during their production, use, and disposal. Organophosphate esters have been detected in a variety of media such as water, sediment, atmosphere, dust, and soil. According to epidemiological surveys and toxicological data, some organophosphate esters have endocrine disrupting properties and potential toxicity. Therefore, it is necessary to accurately determine the content of organophosphate esters in environmental media in order to provide basic support for environmental management decisions and the formulation of environmental governance technologies.

[0003] There have been many studies on the analysis methods, pollution characteristics and migration patterns of organophosphates in water, soil and organisms, but there are few analysis methods for organophosphates in the atmosphere. Even if there are methods for detecting organophosphates in the atmosphere, they are often ultrasonic or accelerated solvent extraction-combined solid phase extraction of organophosphates in the atmospheric particle phase. This method has the disadvantages of large amount of organic solvent, cumbersome analysis steps, long time consumption and low recovery rate of target. Therefore, there is an urgent need for a detection method that can directly, quickly, efficiently and environmentally friendly analyze organophosphates in the atmospheric gas phase. Summary of the invention

[0004] The purpose of the present invention is to provide a method for detecting organic phosphates in the atmosphere based on mesoporous materials. The method can directly detect organic phosphates in the atmosphere with high accuracy and good sensitivity.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] A method for detecting organic phosphates in the atmosphere based on mesoporous materials, the method comprising the following steps: step 1, using a sampling tube filled with mesoporous materials to collect atmospheric samples; step 2, configuring a target object into a plurality of standard solutions with different concentration gradients, using the sampling tubes filled with mesoporous materials to respectively adsorb the target objects of different concentrations for sampling; step 3, respectively performing thermal desorption on the sampling tubes after sampling in step 1 and step 2 and entering a detection device with a carrier gas for analysis to obtain spectra of each sample, obtaining a standard curve according to the peak area of ​​the target object in the spectrum corresponding to the standard solution and its corresponding concentration, and then converting the content of the target object in the atmospheric sample according to the peak area of ​​the target object in the spectrum corresponding to the atmospheric sample and the standard curve; wherein the mesoporous material contains silicon, oxygen and iron elements, and the specific surface area of ​​the mesoporous material is 95-120 m 2 / g, an average pore diameter of 40-60nm, and a pore volume of 0.7-0.9mL / g; the target substance is an organic phosphate.

[0007] Preferably, a thermal desorber is used to perform thermal desorption on the sampling tube, and the desorption temperature of the sampling tube is 270-290°C, for example, 275°C, 276°C, 277°C, 278°C, 279°C, 280°C, 281°C, 282°C, 283°C, 284°C, 285°C, etc.

[0008] Preferably, the desorption time of the sampling tube pair is 1 to 15 min, for example, 5 min, 6 min, 7 min, 8 min, 9 min, 10 min, 11 min, 12 min, 13 min, 14 min, 15 min, etc.

[0009] Preferably, the desorption flow rate is 20-100 ml / min, for example, 20 ml / min, 30 ml / min, 40 ml / min, 50 ml / min, 60 ml / min, 70 ml / min, 80 ml / min, 90 ml / min, 100 ml / min, etc.

[0010] Preferably, the cold trap capture temperature of the thermal desorber is -5 to 5°C, for example, -5°C, -4°C, -3°C, -2°C, -1°C, 0°C, 1°C, 2°C, 3°C, 4°C, 5°C, etc.

[0011] Preferably, the cold trap desorption temperature of the thermal desorber is 280-300°C, for example, 280°C, 285°C, 290°C, 295°C, 300°C, etc.

[0012] Preferably, the secondary desorption time is 1 to 5 min, for example, 1 min, 2 min, 3 min, 4 min, 5 min, etc.

[0013] Preferably, the temperature of the transmission line is 280-300° C., for example, 280° C., 285° C., 290° C., 295° C., 300° C., etc.

[0014] Further preferably, the desorption temperature of the sampling tube is 280-285°C.

[0015] Further preferably, the desorption time of the sampling tube is 5 to 10 minutes.

[0016] Further preferably, the cold trap capture temperature is -5 to 0°C.

[0017] More preferably, the cold trap desorption temperature is 290-300°C.

[0018] Preferably, the method further comprises the step of preparing the blank sampling tube: taking a sampling tube made of stainless steel, filling a plurality of the mesoporous materials therein, making the mesoporous materials 10 to 15 mm away from the inlet end of the sampling tube, the length of the mesoporous materials in the sampling tube being 10 to 30 mm, and fixing the two ends of the sampling tube with stainless steel meshes to prevent the adsorbent from falling; aging the filled sampling tube in a nitrogen flow, and immediately sealing the two ends of the sampling tube with polytetrafluoroethylene caps after aging to obtain the blank sampling tube. The length of the mesoporous material in the sampling tube does not exceed the size of the heating zone of the thermal desorber.

[0019] More preferably, the inner diameter of the sampling tube is 4-6 mm, such as 4 mm, 5 mm, 6 mm, etc.

[0020] Preferably, the loading amount of the mesoporous material is 200-400 mg, for example, 200 mg, 250 mg, 300 mg, 350 mg, 400 mg, etc.

[0021] Preferably, the aging temperature is 340-360°C, for example, 340°C, 345°C, 350°C, 355°C, 360°C, etc.

[0022] Preferably, the aging time is 100 to 140 min, for example, 100 min, 110 min, 120 min, 130 min, 140 min, etc.

[0023] Preferably, the nitrogen flow rate is 30 to 70 ml / min, for example, 30 ml / min, 40 ml / min, 50 ml / min, 60 ml / min, 70 ml / min, etc.

[0024] Preferably, in the step 1, the collection includes connecting the blank sampling tube to the gas sampling tube, and collecting air at a flow rate of 100 to 200 ml / min for 10 to 20 minutes.

[0025] Preferably, the mesoporous material is prepared by the following method: dissolving iron salt, aluminum salt, ammonium salt and alkali in water, then mixing with silica aqueous solution, then crystallizing in a vacuum drying oven, and then centrifuging, filtering, washing to neutrality, baking and grinding to obtain the mesoporous material.

[0026] More preferably, the mass ratio of the iron source, aluminum salt, ammonium salt, alkali and silicon dioxide is 1: (0.1-0.5): (2.5-3.5): (4-5): (0.02-0.03).

[0027] More preferably, the mass ratio of the iron source, aluminum salt, ammonium salt, alkali and silicon dioxide is 1: (0.2-0.3): (2.9-3.1): (4.2-4.5): (0.02-0.03).

[0028] According to some preferred embodiments, the silicon dioxide is fed in the form of a silicon dioxide aqueous solution, and the concentration of the silicon dioxide aqueous solution is 40 to 60 mg / L.

[0029] Preferably, the crystallization temperature is 150-200°C.

[0030] Preferably, the crystallization time is 15 to 25 hours.

[0031] Preferably, the baking temperature is 450-600°C.

[0032] Preferably, the baking time is 4 to 6 hours.

[0033] Preferably, the organic phosphate includes one or more of tripropyl phosphate, triisobutyl phosphate, tri-n-butyl phosphate, tri(1-chloro-2-propyl) phosphate and triphenyl phosphate.

[0034] Preferably, the detection limit of the organophosphate is 2.4 to 33.8 ng·m -3 The spiked recoveries were between 72.8% and 123.1%, and the relative standard deviation was less than 11.6%.

[0035] According to some preferred embodiments, the detection equipment is a gas chromatography-mass spectrometer, and the test conditions are as follows: chromatographic column: DB-5MS, 30m×0.25mm×0.32μm; carrier gas is high-purity helium, with a constant flow rate of 0.50-1.5mL·min -1 ; Temperature program: first maintain 55-65℃ for 1-2min, then 15-25℃·min -1 Raise to 150-160℃, then at 5-15℃·min -1 Raise to 260-280℃, maintain for 5-10min, the temperatures of the injection port and mass spectrometer interface are 270-280℃ and 275-285℃ respectively; splitless injection mode; ion source: electron impact ion source, selected ion scanning mode (SIM), the temperatures of the ion source and quadrupole are 220-240℃ and 140-160℃ respectively.

[0036] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0037] The present invention collects air through a sampling tube made of a mesoporous material containing silicon, oxygen and iron, which can effectively adsorb organic phosphates in the atmosphere, and then thermally desorbs the organic phosphates adsorbed on the sampling tube and then introduces them into a detector for detection, thereby achieving direct and effective detection of organic phosphates in the atmosphere, with the advantages of good accuracy, high sensitivity and saving analysis time. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 The results of the optimization of thermal desorption conditions in the embodiment of the present invention are shown in FIG. (a) the amount of the adsorbent (mesoporous material) is optimized; (b) the thermal desorption time is optimized; (c) the cold trap capture temperature is optimized; (d) the cold trap desorption time is optimized;

[0039] Figure 2 The adsorption-thermal desorption response diagram of the adsorbents prepared in Example 1 and Comparative Example 1 of the present invention and the commercial adsorbent to organic phosphates;

[0040] Figure 3 The SEM images of the adsorbents in the present invention, wherein (a) and (c) are the adsorbents prepared in Comparative Example 1, which are spherical with rough surfaces; (b) and (d) are the adsorbents prepared in Example 1, which are irregular block morphologies with agglomerated particles;

[0041] Figure 4 is the EDS spectrum of the adsorbent in the present invention, wherein ZSM5 is the adsorbent prepared in Comparative Example 1; Fe-ZSM5 is the adsorbent prepared in Example 1;

[0042] Figure 5 is an X-ray diffraction diagram, wherein (A) is the adsorbent prepared in Comparative Example 1; (B) is the adsorbent prepared in Example 1; (C) is an amorphous SiO2 standard card;

[0043] Figure 6 is the nitrogen adsorption-desorption isotherm of the adsorbent in Example 1 of the present invention;

[0044] Figure 7 This is a thermogravimetric analysis diagram of FS of the adsorbent in Example 1 of the present invention;

[0045] Figure 8 This is the FTIR graph of the adsorbent in Example 1 of the present invention before and after adsorption of organic phosphate. DETAILED DESCRIPTION

[0046] At present, the detection of organic phosphates in the atmosphere is basically to detect organic phosphates in atmospheric particulate matter. Since this method detects organic phosphates in atmospheric particulate matter, there is a certain deviation from organic phosphates in the atmosphere. The applicant uses a homemade mesoporous material to adsorb organic phosphates in the atmosphere, and then thermally desorbs the organic phosphates, and then introduces them into a detector for detection, thereby achieving direct detection of organic phosphates in the atmosphere. At the same time, the organic combination of mesoporous materials, thermal desorption processes and detection processes improves the accuracy and sensitivity of detection. The scheme of this application is further discussed below.

[0047] According to some preferred embodiments, a method for detecting organic phosphates in the atmosphere based on mesoporous materials specifically comprises the following steps:

[0048] 1) Preparation of mesoporous materials:

[0049] The iron salt, aluminum salt, ammonium salt and alkali are first dissolved in water, then mixed with the silica aqueous solution, and then crystallized in a vacuum drying oven, and then centrifuged, filtered, washed to neutrality, baked, and ground to obtain the mesoporous material;

[0050] 2) Prepare blank sampling tube:

[0051] Take a sampling tube made of stainless steel, fill it with some of the mesoporous materials, make the mesoporous materials 10 to 15 mm away from the inlet end of the sampling tube, the length of the mesoporous materials in the sampling tube is 10 to 30 mm, and fix the two ends of the sampling tube with stainless steel mesh to prevent the adsorbent from falling;

[0052] The filled sampling tube is aged in a nitrogen flow, and both ends of the sampling tube are immediately sealed with polytetrafluoroethylene caps after aging to obtain the blank sampling tube;

[0053] 3) collecting an atmospheric sample using the blank sampling tube;

[0054] 4) The target object is prepared into a plurality of standard solutions with different concentration gradients, and the target objects with different concentrations are adsorbed and sampled using the blank sampling tube;

[0055] 5) The sampling tubes after sampling in the above step 3) and step 4) are respectively subjected to thermal desorption and introduced into the detection equipment for detection to obtain the spectrum of each sample, and a standard curve is obtained according to the peak area of ​​the target object in the spectrum corresponding to the standard solution and its corresponding concentration, and then the content of the target object in the atmospheric sample is converted according to the peak area of ​​the target object in the spectrum corresponding to the atmospheric sample and the standard curve;

[0056] Among them, a thermal desorber is used to perform thermal desorption on the sampling tube, the thermal desorption temperature of the sampling tube (primary) is 270-290°C, the desorption time is 1-15min, the cold trap capture temperature is -5-5°C, the cold trap desorption temperature is 280-300°C, and the cold trap desorption time is 1-5min.

[0057] The method of the present invention has at least the following advantages:

[0058] 1. The method of the present invention collects air through a sampling tube made of a homemade mesoporous material, which can effectively adsorb organophosphates in the atmosphere, and desorbs the organophosphates adsorbed on the sampling tube using thermal desorption technology, and then enters the detector with the carrier gas for detection, thereby realizing direct, rapid and effective detection of organophosphates in the atmosphere.

[0059] 2. The method of the present invention has high sensitivity, good accuracy and good reproducibility. The detection limit of various organic phosphates in the atmosphere is 2.4-33.8 ng·m -3 The spike recovery rate is between 72.8% and 123.1%, and the relative standard deviation is less than 11.6%, which can meet the detection requirements.

[0060] 3. The mesoporous material of the present invention has good stability and good adsorption. The preparation method of the mesoporous material is simple, convenient and low-cost. The technology integrates sampling and analysis, is free of organic solvents, and is environmentally friendly, which solves the current difficulties in sampling and analyzing organic phosphates in the atmospheric gas phase.

[0061] The present invention is further described below in conjunction with the examples. However, the present invention is not limited to the following examples. The implementation conditions used in the examples can be further adjusted according to the different requirements of specific use, and the implementation conditions not specified are conventional conditions in the industry. The technical features involved in each embodiment of the present invention can be combined with each other as long as they do not conflict with each other.

[0062] Example 1

[0063] A method for detecting organophosphate esters (OPEs) in the atmosphere based on self-made mesoporous materials comprises the following steps:

[0064] (1) Preparation of mesoporous material (adsorbent): 2.0 mg of ferric chloride, 0.5 mg of aluminum sulfate, 6 mg of tetrapropylammonium bromide, and 8.75 mg of sodium hydroxide were dissolved in 0.3 mL of water, mixed and then slowly added with 1 mL of 50 mg / L silica aqueous solution, stirred at room temperature (25°C ± 5°C) for 2.0 h, and crystallized in a vacuum oven at 180°C for 20 h, then centrifuged and filtered, washed with ultrapure water several times until neutral, and the filter residue was collected and baked in a muffle furnace at 550°C for 5 h. Cooled to room temperature, ground evenly with an agate mortar, and placed in a centrifuge tube for later use.

[0065] (2) Preparation of sampling tube:

[0066] A. Take a stainless steel sampling tube with an inner diameter of 5 mm, fill it with 200 mg of the adsorbent prepared by the method of step (1), the adsorbent is 10-15 mm away from the inlet end of the sampling tube, the length of the adsorbent in the sampling tube is 10-30 mm, and the two ends of the sampling tube are fixed with a 0.05 m stainless steel mesh to prevent the adsorbent from falling;

[0067] B. Aging the filled sampling tube in a nitrogen flow, where the aging temperature is 350°C, the aging time is 120 min, and the nitrogen flow rate is 50 ml / min. After aging, both ends of the sampling tube are immediately sealed with polytetrafluoroethylene caps and stored.

[0068] (3) Atmospheric sample collection: Take a certain amount of target substances: tripropyl phosphate (TPrP), triisobutyl phosphate (TiBP), tri-n-butyl phosphate (TnBP), tri(1-chloro-2-propyl) phosphate (TCPP), triphenyl phosphate (TPhP), prepare 1 μL of a mixed standard solution of 5.0 mg / L each of TPrP, TiBP, TnBP, TCPP and TPhP, inject the mixed standard solution into the blank sampling tube prepared in step (2), and purge the sampling tube with nitrogen at a high flow rate (30 ml / min) for 10 min to allow the solvent in the standard solution to evaporate quickly and remove the original air. Then quickly remove the sampling tube and seal both ends of the sampling tube with sealing caps.

[0069] (4) Sample testing:

[0070] The sampling tube in step (3) is connected to a thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS) instrument for analysis.

[0071] Among them, the conditions of thermal desorber TD-100 (Markers, UK) were as follows: sampling tube desorption temperature 280°C, desorption time 5 min, desorption flow rate 50 mL / min; cold trap capture temperature -5°C, cold trap desorption temperature 290°C, cold trap desorption time 3 min, transmission line temperature 280°C;

[0072] Quantitative analysis was performed using a gas chromatography-mass spectrometer (Agilent 7890GC-5973NMS) and a DB-5MS capillary column (30 m × 0.25 mm × 0.32 μm, Agilent). The carrier gas was high-purity helium at a constant flow rate of 1.0 mL min -1 . Temperature program: first maintain 60℃ for 1min, then increase the temperature by 20℃·min -1 Raise to 160℃, then increase the temperature by 10℃·min -1The temperature was raised to 270°C and maintained for 5 min. The injection port and mass spectrometer interface temperatures were 275°C and 280°C, respectively. Splitless injection was used. Electron impact (EI) ion source, selected ion scanning mode (SIM), ion source and quadrupole temperatures were 230°C and 150°C, respectively.

[0073] The retention time and qualitative and quantitative ions of each chemical are shown in Table 1.

[0074] Table 1

[0075]

[0076] In this example, the peak area of ​​TPrP is about 1.2×10 5 The peak area of ​​TiBP is about 5.5×10 5 The peak area of ​​TnBP is about 4.3×10 5 The peak area of ​​TCPP is about 1.2×10 5 The peak area of ​​TPhP is about 2.5×10 5 .

[0077] Example 2

[0078] This embodiment is substantially the same as embodiment 1, except that: this embodiment studies the peak areas of various targets when the sampling tube desorption temperature is 280°C, the desorption time is 10 min, the desorption flow rate is 50 ml / min, the cold trap capture temperature is 0 degrees, the cold trap desorption temperature is 280°C, and the adsorbent loading is 100 mg, 150 mg, 250 mg and 300 mg, as shown in FIG. Figure 1 (a) shown.

[0079] The study found that as the adsorbent loading increases, more targets are adsorbed, and the peak area of ​​each target increases. However, when the adsorbent loading is higher than 200 mg, the peak area of ​​each target remains basically unchanged, and the longer it takes to reach adsorption equilibrium, the longer the adsorption equilibrium time will be. Under the condition of fixed adsorption time and flow rate, continuing to increase the adsorbent loading will extend the adsorption equilibrium time. Therefore, the optimal amount of adsorbent is 200 mg.

[0080] Example 3

[0081] This embodiment is substantially the same as Embodiment 1, except that:

[0082] This example studies the peak areas of various targets when the adsorbent dosage is 200 mg, the sampling tube desorption temperature is 280°C, the desorption flow rate is 50 ml / min, the cold trap capture temperature is 0 degrees, the cold trap desorption temperature is 280°C, and the desorption time is 1 min, 5 min, 10 min, 15 min and 20 min. Figure 1 (b) as shown.

[0083] The study found that when the desorption time was reduced to 1 min, the peak areas of the five organophosphates decreased significantly. This may be because the target was desorbed from the mesoporous material surface and into the gas phase. When the desorption time was short, the desorption process was in a non-equilibrium state, resulting in insufficient desorption.

[0084] When the desorption time increases, the peak area of ​​each target increases, but surprisingly, when the desorption time is greater than 5 min, the peak area of ​​the target tends to decrease. Therefore, the optimal desorption time is 5 min.

[0085] Example 4

[0086] This embodiment is substantially the same as Embodiment 1, except that:

[0087] This example studies the peak areas of various targets when the adsorbent dosage is 200 mg, the desorption time of the sampling tube is 5 min, the desorption flow rate is 50 ml / min, the cold trap desorption temperature is 280 ° C, and the cold trap capture temperatures are -10 ° C, -5 ° C, 0 ° C, and 10 ° C, respectively. Figure 1 (c) as shown.

[0088] The study found that as the cold trap temperature increased, the peak area of ​​each target showed an upward trend, but when the cold trap temperature was higher than -5°C, the peak area of ​​each target showed a downward trend. Therefore, the optimal cold trap temperature is -5°C.

[0089] Example 5

[0090] The difference between this embodiment and embodiment 1 is that:

[0091] This example studies the effect of the cold trap desorption temperatures of 270°C, 280°C, and 300°C on the peak areas of each target when the adsorbent dose is 200 mg, the desorption time of the sampling tube is 5 min, the desorption flow rate is 50 ml / min, and the cold trap capture temperature is -5°C. Figure 1 (d) as shown.

[0092] The study found that as the cold trap desorption temperature increased, the peak area of ​​each target showed an upward trend, but when the cold trap desorption temperature was higher than 290°C, the peak area of ​​each target tended to remain unchanged. Therefore, the optimal cold trap desorption temperature is 290°C.

[0093] Example 6

[0094] S1. The indoor air outlet 1 and the outdoor air 1 and the air 2 of a furniture processing enterprise are sampled using the sampling tube prepared in step (2) of Example 1, wherein the sampling flow rate is 100 mL / min and the sampling time is 20 min. After the air sample is collected by the sampling tube, a thermal desorber is connected to thermally desorb the OPEs adsorbed on the sampling tube, and then the air is introduced into the gas phase inlet of the GC-MS instrument for analysis.

[0095] The working conditions of the thermal desorber are as follows: sampling tube desorption temperature 280°C, desorption time 5 min, desorption flow rate 50 mL / min; cold trap capture temperature -5°C, cold trap desorption temperature 290°C, desorption time 3 min, transmission line temperature 280°C;

[0096] The operating conditions of the GC-MS instrument are shown in Example 1.

[0097] S2. Prepare 1.0 μL of each of five organophosphate mixed standard solutions at five concentration levels: 1.0 mg / L, 5.0 mg / L, 20 mg / L, 50 mg / L, and 100 mg / L. Inject the mixed standard solutions into the blank sampling tubes prepared in step (2) of Example 1. Purge the sampling tubes with nitrogen at a high flow rate (30 ml / min) for 10 min. Quickly remove the sampling tubes and seal both ends of the sampling tubes with sealing caps.

[0098] The sampling tube was connected to a thermal desorber for analysis by a thermal desorption-GC-MS instrument. The working conditions of the thermal desorption-GC-MS instrument were as described in S1.

[0099] S3. Draw the working curve:

[0100] The peak area of ​​the standard solution at each concentration was obtained according to S2, and then a standard curve was established according to the corresponding relationship between the concentration of each target and the corresponding peak area. The results are shown in Table 2.

[0101] Table 2 Quantitative curves, correlation coefficients and detection limits (ng) of five organophosphates

[0102]

[0103] As can be seen from the table above, this method has a wide linear range (1-100 ng). When the air is sampled at a flow rate of 100 ml / min for 10 min, the detection limit of the target in the air is in the range of 2.4 to 33.8 ng / m 3 , are both low, the linear regression equation of this method is good, R 2 All above 0.99.

[0104] S4. For each sample in S1, 1.0 μL spike recovery experiment was performed at 5.0 mg / L, 20 mg / L, and 100 mg / L, respectively. The parallel determination was performed 3 times. The determination results are shown in Table 3.

[0105] Table 3 Actual sample spike recovery (%) and relative standard deviation (%)

[0106]

[0107]

[0108] The recoveries of five kinds of organophosphates in the atmosphere were all between 72.8% and 123.1%, and the relative standard deviations (RSDs) were between 1.2% and 11.6%. This method can meet the actual detection needs of organophosphates in the atmosphere with reliable accuracy and precision.

[0109] S5. Calculate the actual content of each target in the sample in S1 according to the standard curve of S3. From the results, it can be seen that alkyl organophosphates are 100% detected in the atmosphere, chloroalkyl organophosphates and aromatic organophosphates are detected at a lower rate in the atmospheric gas phase, and the total organophosphate content in the indoor atmosphere of the enterprise is slightly higher than that in the outdoor atmosphere.

[0110] Comparative Example 1

[0111] The difference from Example 1 is that the adsorbent is different.

[0112] The preparation method of the adsorbent of this comparative example is as follows: 0.5 mg aluminum sulfate, 6 mg tetrapropylammonium bromide, and 8.75 mg sodium hydroxide are dissolved in 0.3 mL water, and after mixing, 1 mL of 50 mg / L silica aqueous solution is slowly added, stirred at room temperature (25°C ± 5°C) for 2.0 h, and crystallized in a vacuum drying oven at 180°C for 20 h, then centrifuged and filtered, washed with ultrapure water for multiple times until neutral, and the filter residue is collected and baked in a muffle furnace at 550°C for 5 h. Cool to room temperature, grind evenly with an agate mortar, and place in a centrifuge tube for later use.

[0113] The comparative examples also used commercial adsorbents, which included Tenax TA, Carbograph 2TD, and Sulficarb.

[0114] 1 μL of a mixed standard solution containing 5.0 g / L of TPrP, TiBP, TnBP, TCPP and TPhP was prepared, and the mixed standard solution was injected into the sampling tubes made of the above different adsorbents, and the S2 method in Example 6 was used for testing and analysis. The relevant structures are shown in FIG. Figure 2As shown, FS is the adsorbent prepared in Example 1, NFS is the adsorbent prepared in Comparative Example 1, and the organic phosphates corresponding to each adsorbent are TPrP, TiBP, TnBP, TCPP and TPhP from left to right.

[0115] The study found that the peak areas of TCPP and TPhP measured by the adsorbent prepared by the method of Example 1 were greater than those of the three commercial adsorbents, and the peak areas of TPrP, TiBP and TnBP were greater than those of Carbograph 2TD and Sulficarb, and were comparable to the adsorbent Tenax TA. At the same time, the peak areas of all target substances of the adsorbent were much greater than those of the adsorbent prepared in Comparative Example 1, proving that iron doping can improve the adsorption performance of the material for OPEs.

[0116] The adsorbent prepared by the invention has a simple synthesis method, cheap raw materials, low cost, can replace commercial adsorbents, and has good application prospects.

[0117] The present invention also conducted morphology and performance studies on the adsorbents prepared in Example 1 and Comparative Example 1, as follows.

[0118] 1) The surface morphology and chemical element composition of the adsorbent were analyzed using a Quanta FEG scanning electron microscope with an energy dispersive spectrometer. The adsorbent was freeze-dried and tested under the following conditions: HV 20.00kV WD 9.6mm magnification 1000x det ETD mode SEQuanta FEG. The results are as follows: Figure 3 As shown, (a) and (c) are adsorbents prepared in Comparative Example 1, and (b) and (d) are adsorbents prepared in Example 1.

[0119] EDS test results are as follows Figure 4 And as shown in Table 3.

[0120] Table 3

[0121]

[0122] Depend on Figure 4 As shown in Table 3, the adsorbent prepared in Comparative Example 1 mainly contains silicon and oxygen, while the adsorbent prepared in Example 1 contains a small amount of iron in addition to silicon and oxygen. The crystal structures of the two adsorbents are analyzed using X-ray diffraction patterns ( Figure 5 ), it was found that the adsorbent prepared in Example 1 had new peaks at 33.15°, 35.61°, 49.48° and 54.09°, which were consistent with the standard card 33-0664, indicating that the Fe element was doped into the material and existed mainly in the form of iron oxide. The broad peak at 22.15° was similar to the amorphous silica structure in the standard card. Figure 5(A) is the adsorbent prepared in Comparative Example 1, (B) is the adsorbent prepared in Example 1, and (C) is an amorphous SiO2 standard card.

[0123] 2) Nitrogen adsorption and desorption characterization

[0124] The specific surface area ( Figure 6 ) and pore size. The BET adsorption isotherm shows a hysteresis loop in the range of P / P0=0.8 to 0.98, showing type IV, which indicates that the material has mesoporous capillary condensation.

[0125] The BET specific surface area is 105.9 m 2 / g, the material has an average pore diameter of 49.6nm and a pore volume of 0.823mL / g, which are mainly distributed in the mesopores and micropores.

[0126] 3) Analyze the thermal stability of materials using a thermogravimetric analyzer

[0127] The aging temperature of the sampling tube is generally as high as 350°C, so the filler in the sampling tube is required to have good thermal stability. The thermogravimetric analysis of the adsorbent obtained by implementation 1 is shown in Figure 7. When the temperature is raised to 150°C, the mass loss of the material is about 0.7%, mainly due to the loss of water. As the temperature rises to 350°C, the mass loss of the material is only about 0.1%, which shows that it is stable under the aging temperature, the material has no significant mass loss, and is basically stable.

[0128] Since the adsorption performance of the adsorbent for OPEs will affect the recovery rate of the target by adsorption-thermal desorption, in order to explore the possible adsorption mechanism of the material for OPEs, the surface functional groups of the material before and after OPEs adsorption were analyzed by FTIR. The results are shown in Figure 8 FTIR before and after adsorption at 3439cm -1 and 1634cm -1 There are symmetric stretching and bending vibrations of the OH bond at 1106 cm -1 and 472cm -1 There is Si-Ocm -1 Key symmetrical stretch, 477cm -1 and 552cm -1 There is stretching vibration of Fe-O bond of Fe2O3, 801cm -1 There is symmetric stretching of the AlO4 tetrahedral unit.

[0129] The above detailed description of the present invention is intended to enable persons familiar with the art to understand the contents of the present invention and implement them. It does not limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for detecting organic phosphates in the atmosphere based on mesoporous materials, characterized in that: The method comprises the following steps: Step 1: Collect atmospheric samples using a sampling tube filled with mesoporous materials; Step 2: The target object is prepared into a plurality of standard solutions with different concentration gradients, and sampling tubes filled with mesoporous materials are used to adsorb the target objects with different concentrations for sampling; Step 3, thermally desorbing the sampling tubes after sampling in step 1 and step 2 respectively and entering the detection equipment with the carrier gas for analysis to obtain the spectrum of each sample, and obtaining a standard curve according to the peak area of ​​the target object in the spectrum corresponding to the standard solution and its corresponding concentration, and then converting the content of the target object in the atmospheric sample according to the peak area of ​​the target object in the spectrum corresponding to the atmospheric sample and the standard curve; The mesoporous material contains silicon, oxygen and iron elements, and the specific surface area of ​​the mesoporous material is 95-120 m 2 / g, an average pore size of 40-60 nm, and a pore volume of 0.7-0.9 mL / g. The mesoporous material is prepared by the following method: dissolving iron salt, aluminum salt, ammonium salt and alkali in water, and then mixing them with a silica aqueous solution, and then crystallizing them in a vacuum drying oven, and then centrifuging, filtering, washing to neutrality, baking, and grinding to obtain the mesoporous material. The mass ratio of the iron salt, aluminum salt, ammonium salt, alkali and silica is 1: (0.1-0.5): (2.5-3.5): (4-5): (0.02-0.03), the crystallization temperature is 150-200°C, the time is 15-25h, and the baking temperature is 450-600°C, and the time is 4-6 h; The target substance is an organic phosphate.

2. The method for detecting organic phosphates in the atmosphere based on mesoporous materials according to claim 1, characterized in that: The sampling tube is thermally desorbed using a thermal desorber, wherein the desorption temperature of the sampling tube is 270-290°C, the desorption time is 1-15 min, the desorption flow rate is 20-100 mL / min, the cold trap capture temperature is -5-5°C, the cold trap desorption temperature is 280-300°C, the secondary desorption time is 1-5 min, and the transmission line temperature is 280-300°C.

3. The method for detecting organic phosphates in the atmosphere based on mesoporous materials according to claim 2, characterized in that: The desorption temperature of the sampling tube is 280-285°C, the desorption time is 5-10 min, the cold trap capture temperature is -5-0°C, and the cold trap desorption temperature is 290-300°C.

4. The method for detecting organic phosphates in the atmosphere based on mesoporous materials according to claim 1, characterized in that: The method further comprises the step of preparing the sampling tube: Take a sampling tube made of stainless steel, fill it with some of the mesoporous materials, make the mesoporous materials 10-15 mm away from the inlet end of the sampling tube, the length of the mesoporous materials in the sampling tube is 10-30 mm, and fix the two ends of the sampling tube with stainless steel mesh to prevent the adsorbent from falling; The filled sampling tube is aged in a nitrogen flow, and both ends of the sampling tube are immediately sealed with polytetrafluoroethylene caps after aging to obtain the sampling tube.

5. The method for detecting organic phosphates in the atmosphere based on mesoporous materials according to claim 4, characterized in that: The inner diameter of the sampling tube is 4-6 mm; and / or, The loading amount of the mesoporous material is 200-400 mg; and / or, The aging temperature of the sampling tube is 340-360° C., the aging time is 100-140 min, and the nitrogen flow rate is 30-70 mL / min.

6. The method for detecting organic phosphates in the atmosphere based on mesoporous materials according to claim 1, characterized in that: The organic phosphate includes one or more of tripropyl phosphate, triisobutyl phosphate, tri-n-butyl phosphate, tri(1-chloro-2-propyl) phosphate and triphenyl phosphate.

7. The method for detecting organic phosphates in the atmosphere based on mesoporous materials according to claim 1 or 6, characterized in that: The detection limit of the organophosphate is 2.4~33.8 ng·m -3 The spiked recoveries were between 72.8% and 123.1%, and the relative standard deviation was less than 11.6%.

8. The method for detecting organic phosphates in the atmosphere based on mesoporous materials according to claim 1, characterized in that: The detection equipment is a gas chromatography-mass spectrometer, and the test conditions are: Chromatographic column: DB-5MS, 30m×0.25mm×0.32μm, The carrier gas is high-purity helium with a constant flow rate of 0.50~1.5 mL·min -1 , Program temperature rise: first maintain 55~65℃ for 1~2 min, then 15~25℃·min -1 Raise to 150~160℃, then at 5~15℃·min -1 Raise to 260~280℃, maintain for 5~10min, the injection port and mass spectrometer interface temperature are 270~280℃ and 275~285℃ respectively; splitless injection mode; Ion source: electron bombardment ion source, selected ion scanning mode (SIM), ion source and quadrupole temperatures were 220~240℃ and 140~160℃ respectively.

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