A method for preparing 1h,1h,2h,2h-nonafluorohexyl functionalized silica and an analysis method for extracting and enriching phthalate compounds

Abstract

The application belongs to but is not limited to the technical field of molecules, and discloses a preparation method of 1H, 1H, 2H, 2H-nonafluorohexyl silicon dioxide and an analysis method for extracting and enriching phthalate compounds by using 1H, 1H, 2H, 2H-nonafluorohexyl functionalized silicon dioxide, which comprises 1H, 1H, 2H, 2H-nonafluorohexyl functionalized silicon dioxide microsphere synthesis, sample preparation, material characterization, d-SPE experiment and condition optimization, gas chromatography condition, methodology research and actual sample analysis. The application successfully synthesizes a new d-SPE material for PAEs extraction, and establishes a related detection method, which has great practical application potential.

Description

Technical Field

[0001] This invention belongs to, but is not limited to, the field of molecular technology, and particularly relates to a method for preparing 1H,1H,2H,2H-nonafluorohexyl functionalized silica and an analytical method for extracting and enriching phthalic acid ester compounds using 1H,1H,2H,2H-nonafluorohexyl functionalized silica. Background Technology

[0002] Phthalate esters (PAEs) are a class of widely used plasticizers, primarily used to improve the flexibility, ductility, and processing properties of polymer materials. They are found in numerous industrial products, including toys, food packaging, medical products, and personal care products. These compounds do not bind to polymers through covalent bonds but rather adhere to the material's framework via intermolecular forces. This allows them to gradually migrate into the environment, posing a potential threat to the ecosystem and human health. Existing research confirms that PAEs may damage the nervous, reproductive, and immune systems. Given the potential risks of PAEs, the U.S. Environmental Protection Agency (USEPA) has listed six PAEs—dibutyl phthalate (DBP), butyl benzyl phthalate (BBP), dimethyl phthalate (DMP), diethyl phthalate (DEP), diisobutyl phthalate (DIBP), and di-n-octyl phthalate (DNOP)—as priority pollutants. China's newly released "National Standard for Restricted Hazardous Substances in Electronic and Electrical Products" also includes DBP, DIBP, BBP, and di(2-ethylhexyl) phthalate (DEHP) in the control list.

[0003] The pollution of water bodies by plastic aggregates (PAEs) is increasingly attracting attention due to factors such as industrial emissions, landfill leachate leakage, and the degradation of plastic products. Studies have shown the presence of PAEs in lakes and rivers, and traces of these compounds have also been found in drinking water and bottled drinking water in some areas. The continuous accumulation of PAEs in human-inhabited areas increases the risk of long-term low-dose exposure, posing a serious threat to public health. Establishing an efficient method for the detection and removal of PAEs in water has significant practical importance and application value.

[0004] Dispersive solid-phase extraction (d-SPE) is a simple and efficient sample pretreatment technique. This method involves fully dispersing the adsorbent in the sample solution to capture the target analyte. The adsorbent is then separated by centrifugation or filtration, and the analyte is eluted from the adsorbent using a suitable eluent, thus achieving analyte enrichment and purification. For PAEs in water samples, an ideal adsorbent needs to possess hydrophilicity, a suitable surface structure, good selectivity, and low cost. Silica, rich in hydroxyl groups, exhibits excellent hydrophilicity and possesses numerous modifiable sites. Its pore structure can also be regulated through specific synthetic methods, making it a superior substrate for preparing adsorbent materials. Surface modification of silica is crucial for achieving efficient adsorption. Commonly used nonpolar modifying groups, such as -C18, significantly reduce the hydrophilicity of the material and exhibit poor tolerance to interference from hydrophobic impurities in complex samples. In recent years, fluorine functional groups have attracted considerable attention in the field of fluoride analysis due to their unique fluorine-fluorine interactions; however, research on their hydrophobic interactions is scarce.

[0005] Based on the hydrophobic effect of fluorine groups and their excellent water dispersibility under specific conditions, this invention proposes a method for the enrichment and detection of PAEs in water. Researchers first synthesized 1H,1H,2H,2H-nonafluorohexylfunctionalized silica (9F-silica) and used it as an adsorbent for d-SPE to enrich and purify PAEs (including DMP, DEP, DIBP, DBP, BBP, and DNOP) in water. Qualitative and quantitative analysis of the target compounds was then performed using gas chromatography-flame ionization detector (GC-FID). To ensure optimal extraction efficiency, parameters such as adsorption time, desorption time, shaking frequency, salt concentration, and eluent were optimized. The linear range, detection limit, quantitation limit, and repeatability of the established method were evaluated. The results show that this detection method is simple, rapid, low-cost, and environmentally friendly, providing an effective means for the detection of PAEs in environmental water bodies. Summary of the Invention

[0006] To address the problems existing in the prior art, the present invention provides a method for preparing 1H,1H,2H,2H-nonafluorohexyl functionalized silica (9F-silica).

[0007] This invention is achieved by providing a method for preparing 1H,1H,2H,2H-nonafluorohexyl functionalized silica, comprising the following steps:

[0008] Step 1: After vacuum drying of silica, it is mixed with toluene and 1H,1H,2H,2H-nonafluorohexyltriethoxysilane and mechanically stirred.

[0009] Step 2: After heating and reflux reaction, filtration and washing, and vacuum drying, 1H,1H,2H,2H-nonafluorohexyl functionalized silica is obtained.

[0010] Furthermore, the amount of silica used is 22 g, the vacuum drying temperature is 140℃, and the vacuum drying time is 12 h.

[0011] Furthermore, the amount of toluene used is 80 g, and the amount of 1H,1H,2H,2H-nonafluorohexyltriethoxysilane used is 5.0 g.

[0012] Furthermore, the temperature of the heating reflux reaction is 120°C, and the reaction time is 8 hours.

[0013] Furthermore, the vacuum filtration and washing process involves washing with toluene three times, and the vacuum drying process is carried out at a temperature of 100°C for 12 hours.

[0014] Another object of the present invention is to provide an analytical method for extracting and enriching phthalic acid esters using 1H,1H,2H,2H-nonafluorohexyl-functionalized silica, comprising the following steps:

[0015] Prepare working solutions of phthalate compounds or actual water samples;

[0016] The prepared 1H,1H,2H,2H-nonafluorohexyl functionalized silica was used as a dispersed solid-phase extraction adsorbent, mixed with the sample solution, and adsorbed by shaking.

[0017] After adsorption, the mixture was allowed to settle and the supernatant was removed to obtain the extraction material adsorbed with phthalic acid esters.

[0018] Add desorption solution to the extraction material, and after ultrasonic desorption and static sedimentation, take the supernatant;

[0019] Phthalate esters in the supernatant were detected by gas chromatography with flame ionization.

[0020] Furthermore, the phthalate compounds are dimethyl phthalate, diethyl phthalate, diisobutyl phthalate, dibutyl phthalate, butyl benzyl phthalate, and di-n-octyl phthalate.

[0021] Furthermore, the working solution is prepared by diluting the acetonitrile mother liquor of phthalic acid esters with water, wherein the concentration of the acetonitrile mother liquor is 5 mg / mL.

[0022] Furthermore, in the dispersed solid-phase extraction, the amount of 1H,1H,2H,2H-nonafluorohexyl functionalized silica used is 10 mg, the sample solution volume is 25 mL, and the desorption liquid volume is 100 μL.

[0023] Furthermore, the conditions for gas chromatography flame ionization detection include: an RTX-5 column, an injection port temperature of 260°C, a detector temperature of 280°C, a splitless injection mode, an initial column temperature of 110°C, a temperature ramp to 160°C at 30°C / min, a temperature ramp to 260°C at 50°C / min and held for 3.5 min, a total program duration of 8 min, and a nitrogen carrier gas flow rate of 2 mL / min.

[0024] Based on the above technical solutions and the technical problems solved, the advantages and positive effects of the technical solution to be protected by this invention are as follows:

[0025] First, this invention successfully prepared fluorinated silica material (9F-silica) using silica as the matrix material and 1H,1H,2H,2H-nonafluorohexyltriethoxysilane as the functional reagent. Using this material as an adsorbent for dispersive solid-phase extraction (d-SPE), a method combining dispersive solid-phase extraction and gas chromatography / flame ionization detector (d-SPE-GC-FID) was constructed to achieve accurate detection of phthalic acid esters (PAEs) in water.

[0026] This invention utilizes nitrogen adsorption-desorption and thermogravimetric analysis to systematically analyze the 9F-silica material. The results confirm that fluorine functional groups have been successfully grafted onto the silica surface through chemical bonding. Contact angle testing further demonstrates that the 9F-silica material possesses both moderate hydrophilicity and hydrophobicity: its hydrophilicity allows for rapid and uniform dispersion in an aqueous environment, ensuring sufficient contact with the target analyte; its hydrophobicity facilitates the selective adsorption of hydrophobic PAEs, laying the foundation for efficient extraction.

[0027] To maximize extraction efficiency, this invention systematically optimized key parameters of d-SPE, including adsorption time, elution time, shaking frequency, salt concentration, and elution solvent type. Experimental results show that appropriately extending the adsorption time allows the material to fully interact with PAEs, shortening the elution time reduces target analyte loss, increasing the shaking frequency enhances the mass transfer process, and increasing the salt concentration promotes the transfer of PAEs from the aqueous phase to the adsorbent surface through the "salting-out effect." These adjustments all contribute to improving the extraction effect. In the elution solvent screening, by comparing the elution capabilities of various common solvents, acetone was ultimately determined to be the optimal choice, exhibiting the highest desorption efficiency for PAEs adsorbed on the 9F-silica material.

[0028] Method validation results show that the established d-SPE-GC-FID method exhibits excellent performance: the detection limits for six PAEs range from 0.2 to 0.8 μg / mL, and the sensitivity is significantly better than the traditional n-hexane liquid-liquid extraction method. When applied to the analysis of actual lake water samples, the concentration range of PAEs in the lake water determined using the standard addition method was 0.093 to 0.189 μg / mL, demonstrating good practical applicability.

[0029] This invention successfully developed a novel d-SPE adsorbent material suitable for PAE extraction and established a matching high-sensitivity detection method, which has broad application prospects in the field of PAE monitoring in aquatic environments.

[0030] The 1H,1H,2H,2H-nonafluorohexyl functionalized silica prepared in this invention precisely controls the density and spatial arrangement of functional groups, thereby enhancing the multi-molecule recognition mechanism.

[0031] Based on the low surface energy and suitable hydrophobicity of the 1H,1H,2H,2H-nonafluorohexyl segment, a dual synergistic adsorption system combining hydrophobic interaction and van der Waals dispersion forces was constructed by precisely controlling the grafting density of nonafluorohexyl functional groups on the silica gel surface through synthesis temperature and reaction feed ratio. Utilizing the hydrophobic association between the perfluorinated long chain and the hydrophobic benzene ring and alkyl side chain of phthalate esters, combined with the long-distance van der Waals interaction generated by the high polarizability of fluorine atoms, the system accurately identifies the molecular structural characteristics of phthalate esters, significantly improving the selective recognition ability of target analytes and effectively distinguishing polar impurities, short-chain organic acids, and other interfering substances in water.

[0032] This invention has a wide range of applications and strong versatility. The modified material is based on an inert fluorine material surface and a stable silica skeleton, which has excellent structural stability and chemical resistance. Combined with the sample pre-filtration process, it can be adapted to various environmental media such as surface water, industrial wastewater, domestic sewage, and environmental sediment leachate, making it more widely applicable.

[0033] This invention improves detection accuracy and stability by optimizing coupled chromatographic quantitative parameters, matching the extraction characteristics of modified adsorption materials, and systematically optimizing quantitative parameters such as gas chromatography temperature program, carrier gas flow rate, split ratio, and detector temperature. It constructs an integrated optimization system of extraction pretreatment and chromatographic detection, further reducing the detection limit of phthalates, while improving the precision, repeatability, and long-term stability of the detection method.

[0034] Secondly, as supporting evidence of the inventiveness of this invention, it is also reflected in the following important aspects:

[0035] (1) The expected benefits and commercial value of the technical solution of this invention after transformation are as follows:

[0036] This technique is simple to synthesize, and the 1H,1H,2H,2H-nonafluorohexyl functionalized silica gel material produced is inexpensive. In particular, after careful selection, it has good water dispersibility and PAE extraction ability, and can be used for PAE enrichment and detection. It has great application value, social benefits and economic benefits in the field of environmental protection.

[0037] (2) The technical solution of this invention fills a technical gap in the industry both domestically and internationally:

[0038] This invention, based on the regulation and design of fluorinated functionalized materials, fills a gap in the application of D-SPE extraction technology in the field of PAE detection, and is an important supplement to environmental protection and analytical detection technologies.

[0039] (3) The technical solution of the present invention solves a technical problem that people have long wanted to solve but have never been able to solve successfully:

[0040] This invention provides a novel extraction method for PAEs, which solves the problem of the difficulty in dispersing traditional C18 silica gel materials in aqueous solutions, has excellent operational convenience, and thus significantly improves the repeatability of detection. Attached Figure Description

[0041] Figure 1 A flowchart illustrating a method for preparing 1H,1H,2H,2H-nonafluorohexyl functionalized silica provided in an embodiment of the present invention.

[0042] Figure 2 This is a schematic diagram of the d-SPE adsorption and desorption experimental process provided in an embodiment of the present invention;

[0043] Figure 3 The synthesis reaction of 9F-silica material provided in the embodiments of the present invention;

[0044] Figure 4 The adsorption isotherms of SiO2 and 9F-silica provided in the embodiments of the present invention;

[0045] Figure 5 TGA curves of SiO2 and 9F-silica provided for embodiments of the present invention;

[0046] Figure 6 The contact angles between SiO2 and 9F-silica and water provided in embodiments of the present invention;

[0047] Figure 7 The following is a schematic diagram of the peak areas of the six PAEs under different d-SPE experimental conditions provided for embodiments of the present invention: (A) adsorption time, (B) shaking frequency, (C) salt concentration, (D) desorption solvent, (E) desorption time;

[0048] Figure 8 Chromatograms of actual water samples, actual water samples with 1 μg / mL PAEs added, and pure water with 1 μg / mL PAEs added, provided in the embodiments of the present invention. Detailed Implementation

[0049] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0050] like Figure 1 As shown, this embodiment of the invention provides a method for preparing 1H,1H,2H,2H-nonafluorohexyl functionalized silica, comprising the following steps:

[0051] S101, after vacuum drying of silica, it is mixed with toluene and 1H,1H,2H,2H-nonafluorohexyltriethoxysilane and mechanically stirred;

[0052] S102 was subjected to a heating and reflux reaction, followed by filtration, washing, and vacuum drying to obtain 1H,1H,2H,2H-nonafluorohexyl functionalized silica.

[0053] In this embodiment of the invention, the amount of silica used is 22 g, the vacuum drying temperature is 140°C, and the vacuum drying time is 12 h.

[0054] In this embodiment of the invention, the amount of toluene used is 80 g, and the amount of 1H,1H,2H,2H-nonafluorohexyltriethoxysilane used is 5.0 g.

[0055] The embodiment of the present invention provides a heating reflux reaction temperature of 120°C and a reaction time of 8 h.

[0056] The embodiment of the present invention provides that the vacuum filtration washing is performed with toluene washing three times, and the vacuum drying temperature is 100°C and the time is 12 h.

[0057] This invention provides an analytical method for extracting and enriching phthalic acid esters using 1H,1H,2H,2H-nonafluorohexyl-functionalized silica, comprising the following steps:

[0058] Prepare working solutions of phthalate compounds or actual water samples;

[0059] The prepared 1H,1H,2H,2H-nonafluorohexyl functionalized silica was used as a dispersed solid-phase extraction adsorbent, mixed with the sample solution, and adsorbed by shaking.

[0060] After adsorption, the mixture was allowed to settle and the supernatant was removed to obtain the extraction material adsorbed with phthalic acid esters.

[0061] Add desorption solution to the extraction material, and after ultrasonic desorption and static sedimentation, take the supernatant;

[0062] Phthalate esters in the supernatant were detected by gas chromatography with flame ionization.

[0063] The phthalate compounds provided in this invention are dimethyl phthalate, diethyl phthalate, diisobutyl phthalate, dibutyl phthalate, butyl benzyl phthalate, and di-n-octyl phthalate.

[0064] The working solution provided in this embodiment of the invention is prepared by diluting an acetonitrile mother liquor containing phthalic acid esters with water, wherein the concentration of the acetonitrile mother liquor is 5 mg / mL.

[0065] In this embodiment of the invention, the amount of 1H,1H,2H,2H-nonafluorohexyl functionalized silica used in the dispersive solid-phase extraction is 10 mg, the sample solution volume is 25 mL, and the desorption liquid volume is 100 μL.

[0066] The conditions provided in this embodiment of the invention for gas chromatography flame ionization detection include: an RTX-5 column, an injection port temperature of 260°C, a detector temperature of 280°C, a splitless injection mode, an initial column temperature of 110°C, a temperature ramp to 160°C at 30°C / min, a temperature ramp to 260°C at 50°C / min and held for 3.5 min, a total program duration of 8 min, and a nitrogen carrier gas flow rate of 2 mL / min.

[0067] like Figure 1 As shown, this embodiment of the invention provides a method for preparing 1H,1H,2H,2H-nonafluorohexyl functionalized silica, comprising the following steps:

[0068] Synthesis of S1: 1H,1H,2H,2H-nonafluorohexyl functionalized silica microspheres;

[0069] S2: Sample preparation;

[0070] S3: Material Characterization;

[0071] S4: d-SPE experiment and condition optimization;

[0072] S5: Gas chromatography conditions;

[0073] S6: Methodological research;

[0074] S7: Actual sample analysis.

[0075] S1 specifically includes:

[0076] Weigh 22 g of SiO2 into a 250 mL three-necked flask and dry it at 140 °C for 12 h. After the system cools, add 80 g of toluene and 5.0 g of 1H,1H,2H,2H-nonafluorohexyltriethoxysilane to the three-necked flask and stir magnetically. Heat under reflux at 120 °C for 12 h. The resulting white solid is washed three times by vacuum filtration with toluene and dried under vacuum at 100 °C for 12 h to obtain 1H,1H,2H,2H-nonafluorohexylfunctionalized silica (9F-silica).

[0077] S2 specifically includes:

[0078] Six PAEs, including DBP, DEP, BBP, DNOP, DMP, and DIBP, were dissolved in acetonitrile to prepare a stock solution of 5.0 mg / mL, and then gradually diluted with water to the required concentration to serve as the working solution. The actual water sample was collected from local lake water and filtered through a 0.22 μm filter membrane before being used for analysis.

[0079] S3 specifically includes:

[0080] Nitrogen adsorption-desorption analysis was performed on SiO2 and 9F-silica using a TriStar II porosity analyzer. The samples were vacuum dried at 120 °C for 12 h before testing. The specific surface area was calculated using the BET method, and the porosity parameters were evaluated from the desorption branches of the isotherms using the BJH model.

[0081] Thermogravimetric analysis was performed on SiO2 and 9F-silica materials using a TG 209 F1 Libra thermal analyzer. The gas conditions were air: 40 mL / min, protective gas N2: 25 mL / min, heating rate: 10 °C / min, and temperature range from 30 °C to 750 °C.

[0082] The contact angles of SiO2 and 9F-silica materials with water were analyzed using a contact angle analyzer.

[0083] S4 specifically includes:

[0084] In the experiment, the effects of adsorption time, shaking frequency, inorganic salt concentration, type of desorption solution, and desorption time on the d-SPE effect were systematically investigated, thereby optimizing the d-SPE method. The experiment was divided into five groups based on the different conditions investigated, each group containing four different condition levels, as shown in the table below. Three parallel d-SPE experiments were conducted under the corresponding conditions in each group. The d-SPE process mainly includes an adsorption step and an elution step, as follows... Figure 2 As shown;

[0085] Table 1 Experimental conditions for solid-phase extraction

[0086]

[0087] First, accurately weigh 10 mg of adsorbent into a 50 mL glass bottle, add 25 mL of phthalic acid ester (PAE) working solution, and then transfer the bottle to a shaker for adsorption according to the set parameters. After adsorption is complete, allow the system to settle for 10 minutes, carefully pour off and remove the supernatant to obtain the PAE-loaded extract. Next, add 100 μL of desorption buffer to the bottle and perform ultrasonic desorption for the set time. After desorption, allow the system to settle for 10 minutes, collect the supernatant, and store it at low temperature for subsequent sample injection and analysis.

[0088] S5 specifically includes:

[0089] This gas chromatography-flame ionization detector (GC-FID) test was performed using an Agilent 7890A gas chromatograph, and the specific chromatographic parameters were set as follows:

[0090] The chromatographic column used was an RTX-5 capillary column; the injection port and detector temperatures were both set to 260℃; the injection mode was splitless; the temperature program was as follows: initial temperature 110℃, first increased to 160℃ at a rate of 30℃ / min, then switched to a rate of 50℃ / min to increase to 260℃ and held for 3.5 minutes; nitrogen was used as the carrier gas, and the flow rate was controlled at 2 mL / min.

[0091] S6 specifically includes:

[0092] To comprehensively evaluate the performance of the established detection method, the linear range, accuracy, precision, limit of detection (LOD), and limit of quantitation (LOQ) were systematically validated. Under optimized experimental conditions, the linear relationship between the chromatographic peak area and concentration of six phthalic acid esters (PAEs) was clarified by detecting a series of standard samples of dimethyl phthalate (DMP), dibutyl phthalate (DBP), butyl benzyl phthalate (BBP), diethyl phthalate (DEP), diisobutyl phthalate (DIBP), and di-n-octyl phthalate (DNOP). The LOD and LOQ were calculated for the six PAEs using the formulas LOD = 3 × signal-to-noise ratio (S / N) and LOQ = 10 × signal-to-noise ratio (S / N), respectively. Parallel experiments were conducted at a concentration level of 1 μg / mL to further validate the precision and reliability of the detection method.

[0093] Specifically, S7 includes:

[0094] Under the determined optimized conditions, extraction and detection were performed on the prepared actual water samples, the actual water samples spiked with 1 μg / mL, and the 1 μg / mL LPAES working solution. Each sample was measured in triplicate.

[0095] Evidence related to the technical effects obtained by the embodiments of the present invention.

[0096] 1. Material Characterization

[0097] The fluorination of silica is achieved by utilizing the silanol groups on its surface to form Si-O-Si bonds with 1H,1H,2H,2H-nonafluorohexyltriethoxysilane, as shown in the reaction... Figure 3 As shown. The SiO2 and the resulting 9F-silica material were characterized by BET, TGA and contact angle.

[0098] Table 2 Specific surface area, pore size, and pore volume of SiO2 and 9F-silica

[0099]

[0100] The specific surface area and pore size of SiO2 and 9F-silica were characterized by BET nitrogen adsorption-desorption analysis, and the results are as follows: Figure 4 As shown in Table 2, both SiO2 and 9F-silica exhibit typical type IV isotherms, indicating a saturation adsorption plateau upon reaching adsorption saturation and a hysteresis loop during desorption, suggesting that both materials possess a mesoporous structure. Figure 4 Compared to SiO2, 9F-silica exhibits reduced surface area, pore volume, and pore size, indicating that 1H,1H,2H,2H-nonafluorohexyl groups have been successfully bonded to the SiO2 surface (Table 2).

[0101] SiO2 and 9F-silica were characterized by thermogravimetric analysis (TGA) and differential thermogravimetric analysis (DTGA), and their TGA and DTG curves are shown below. Figure 5 As shown, compared with SiO2 (weight loss rate 4.13%), 9F-silica exhibits more significant thermal weight loss (weight loss rate reaching 10.33%). This is due to the combustion consumption of organic chains bonded to the SiO2 surface, indicating that 1H,1H,2H,2H-nonafluorohexyl has been successfully modified onto SiO2.

[0102] The contact angles between SiO2 and 9F-silica materials and water were determined by contact angle testing, and the hydrophilicity and hydrophobicity of the materials were characterized. The results are as follows: Figure 6 As shown, the contact angle between SiO2 and water is only 36.6°, which stems from the abundant silanol groups on the material surface, giving it good hydrophilicity. After introducing fluorine groups, the contact angle between 9F-silica and water increases to 117.8°, indicating that 9F-silica has a certain degree of hydrophobicity compared to SiO2. Conventional C... 18Modified silica often has a contact angle with water greater than 150°, exhibiting stronger hydrophobicity, which is detrimental to its dispersion in water. 9F-silica, however, possesses suitable hydrophilicity and hydrophobicity, enabling it to disperse effectively in water and enrich PAEs through hydrophobic interactions, thereby improving extraction efficiency.

[0103] 2. Optimization of extraction conditions

[0104] In the d-SPE process, adsorption time, shaking frequency, inorganic salt concentration, type of desorption solution, and desorption time all affect the extraction efficiency. Here, the d-SPE method was systematically optimized from these aspects, using the peak area of ​​PAEs as an indicator.

[0105] 2.1 Adsorption time investigation

[0106] Adsorption time is a key factor determining the extraction loading of the target analyte by the adsorbent. Insufficient adsorption time makes it difficult for the system to reach adsorption equilibrium, resulting not only in low enrichment recovery but also reduced method reproducibility. This study prioritized investigating the effect of adsorption time on extraction efficiency during condition optimization. Figure 7 As shown in A, the chromatographic peak areas of all PAEs gradually increase with the extension of adsorption time, and reach the peak value at 50 min. Therefore, 50 min is selected as the optimal adsorption time.

[0107] 2.2 Examination of shaking frequency

[0108] The shaking frequency can regulate the contact between the adsorbent and the analyte; suitable shaking conditions can promote sufficient contact between the two phases, thereby improving extraction efficiency. Figure 7 As shown in Figure B, the peak areas of the six PAEs generally increase with increasing shaking frequency. Specifically, DMP and BBP reach their maximum peak areas at a shaking rate of 75 r / min, while the other four PAEs achieve their optimal responses at 100 r / min. The samples showed good repeatability under all shaking speed conditions, which may be attributed to the suitable hydrophilicity / hydrophobicity of this fluorocarbon modified material. Taking all factors into consideration, 75 r / min was ultimately selected as the optimal shaking frequency.

[0109] 2.3. Salt Concentration Investigation

[0110] Salt concentration can significantly modulate the ionic strength of the system, thereby altering the wettability and charge distribution of the adsorbent surface. In some extraction systems, the addition of salt can also affect the activity of surface functional groups by adjusting the system pH, further influencing the adsorption process. For fluorocarbon materials and PAEs systems, increased salt concentration typically promotes salting-out repulsion of water molecules from the adsorbent surface, effectively enhancing the adsorption and enrichment capacity of the target analyte. Figure 7 As shown in C, the peak areas of the six PAEs gradually increased with the increase of NaCl salt concentration, and reached the peak value at a concentration of 100 ug / mL. Therefore, 100 ug / mL was selected as the optimal NaCl salt concentration for the system.

[0111] 2.4 Investigation of Eluent Types

[0112] The eluent not only needs to achieve complete elution of the target analyte from the adsorbent, but also should have good compatibility with the subsequent gas chromatography (GC) analysis system. This study selected three common organic solvents—methanol, acetonitrile, and acetone—and systematically investigated their extraction performance as desorption solvents. Figure 7 As shown in D, all three solvents can effectively achieve the desorption and elution of PAEs, with acetone showing the best elution effect.

[0113] 2.5 Desorption Time Examination

[0114] Desorption time directly affects the elution efficiency of the target analyte on the adsorbent surface, thus significantly impacting the overall recovery rate of the method. Figure 7 As shown in Figure E, the peak areas of all six PAEs reached their maximum values ​​at a desorption time of 10 min. With further extension of the desorption time, the peak areas of each target analyte generally showed a decreasing trend. This may be because the solvent becomes more volatile with prolonged desorption time, leading to a decrease in efficiency. Therefore, 10 min was selected as the optimal desorption time.

[0115] Based on the above results, the optimal conditions for d-SPE are as follows: 10 mg of 9F-silica and 25 mL of water sample containing PAEs were added to a glass bottle, and the NaCl concentration was controlled at 100 μg / mL. The glass bottle was placed on a shaker and shaken at 75 r / min for 50 min. Then, the system was allowed to stand for 10 min, and the supernatant was removed to obtain the adsorbent material with adsorbed PAEs. This material was mixed with 100 μL of acetone and then sonicated for 10 min. The desorbed solution was filtered through a 0.22 μm filter membrane and stored at 4 °C for GC detection.

[0116] 2.6 Methodological Research

[0117] Table 3. Linear range, linear equation, and R0 for the method on six PAEs. 2 LOD and LOQ

[0118]

[0119] To investigate the linear range, LOD, and LOQ of the method, dSPE-GC-FID detection was performed using working solutions of PAEs at specific concentration ranges. As shown in the table above, the linear range was 0.5 μg / mL to 200 μg / mL (R² > 0.999). The LOD range of PAEs was 0.2–0.8 μg / mL, and the LOQ was 0.6–2.9 μg / mL, indicating that the method has high sensitivity.

[0120] 2.7 Analysis of Actual Samples

[0121] Table 4. Content and relative standard deviation of six PAEs in actual water samples

[0122]

[0123] The content of PAEs in actual water samples is usually low. Therefore, a standard PAE solution of 1 μg / mL was added to the actual water sample to quantify the concentration of PAEs in the water sample. The results showed that the concentrations of DEP, DIBP, DBP, and BBP ranged from 0.093 to 0.189 μg / mL, while DMP and DNOP were not detected, as shown in Table 4.

[0124] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions, and improvements made by those skilled in the art within the scope of the technology disclosed in the present invention, and within the spirit and principles of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing 1H,1H,2H,2H-nonafluorohexyl functionalized silica, characterized in that, Includes the following steps: Step 1: After vacuum drying of silica, it is mixed with toluene and 1H,1H,2H,2H-nonafluorohexyltriethoxysilane and mechanically stirred. Step 2: After heating and reflux reaction, filtration and washing, and vacuum drying, 1H,1H,2H,2H-nonafluorohexyl functionalized silica is obtained.

2. The preparation method according to claim 1, characterized in that, The amount of silica used is 22 g, the vacuum drying temperature is 140℃, and the vacuum drying time is 12 h.

3. The preparation method according to claim 1, characterized in that, The amount of toluene used is 80 g, and the amount of 1H,1H,2H,2H-nonafluorohexyltriethoxysilane used is 5.0 g.

4. The preparation method according to claim 1, characterized in that, The temperature of the heating reflux reaction is 120°C, and the reaction time is 8 hours.

5. The preparation method according to claim 1, characterized in that, The filtration and washing process involves washing with toluene three times, and the vacuum drying process is carried out at a temperature of 100°C for 12 hours.

6. An analytical method for extracting and enriching phthalic acid ester compounds using 1H,1H,2H,2H-nonafluorohexyl functionalized silica, which implements the preparation method of 1H,1H,2H,2H-nonafluorohexyl functionalized silica as described in any one of claims 1-5, characterized in that, Includes the following steps: Prepare working solutions of phthalate compounds or actual water samples; The 1H,1H,2H,2H-nonafluorohexyl functionalized silica prepared by any one of claims 1 to 5 is used as a dispersed solid-phase extraction adsorbent, mixed with the sample solution, and adsorbed by shaking. After adsorption, the mixture was allowed to settle and the supernatant was removed to obtain the extraction material adsorbed with phthalic acid esters. Add desorption solution to the extraction material, and after ultrasonic desorption and static sedimentation, take the supernatant; Phthalate esters in the supernatant were detected by gas chromatography with flame ionization.

7. The analytical method according to claim 6, characterized in that, The phthalate compounds are dimethyl phthalate, diethyl phthalate, diisobutyl phthalate, dibutyl phthalate, butyl benzyl phthalate, and di-n-octyl phthalate.

8. The analytical method according to claim 6, characterized in that, The working solution is prepared by diluting the acetonitrile mother liquor of phthalic acid esters with water, wherein the concentration of the acetonitrile mother liquor is 5 mg / mL.

9. The analytical method according to claim 6, characterized in that, In the dispersive solid-phase extraction, the amount of 1H,1H,2H,2H-nonafluorohexyl functionalized silica used was 10 mg, the sample solution volume was 25 mL, and the desorption liquid volume was 100 μL.

10. The analytical method according to claim 6, characterized in that, The conditions for gas chromatography flame ionization detection include: an RTX-5 column, an injection port temperature of 260°C, a detector temperature of 280°C, a splitless injection mode, an initial column temperature of 110°C, a temperature ramp to 160°C at 30°C / min, a temperature ramp to 260°C at 50°C / min and held for 3.5 min, a total program duration of 8 min, and a nitrogen carrier gas flow rate of 2 mL / min.

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