A method for detecting the content of sodium docusate by high performance liquid chromatography

Abstract

This invention provides a high-performance liquid chromatography (HPLC) method for detecting sodium docusate content, relating to the field of pharmaceutical analysis, including sample preparation and detection. Sample preparation involves accurately weighing and grinding acetaminophen / vitamin C effervescent tablets into powder, adding a mixed alcohol-EDTA composite solvent, and ultrasonically dispersing. Then, a bifunctional modified limiting medium, mesoporous silica dispersion, is added, followed by vortexing, centrifugation, and membrane filtration to obtain the test sample. Detection involves performing HPLC on the test sample, using an organic phase and an aqueous phase; wherein the organic phase is acetonitrile, and the aqueous phase is a mixed ionic liquid system. This method is effective for detecting sodium docusate content in compound preparations such as acetaminophen / vitamin C effervescent tablets, and has advantages such as high specificity, simplicity, speed, high sensitivity, accuracy, and reliability.

Description

Technical Field

[0001] This invention relates to the field of pharmaceutical analysis technology, and in particular to a high-performance liquid chromatography method for detecting sodium docusate content. Background Technology

[0002] Docusate sodium (chemical name: sodium dioctyl sulfosuccinate), as an anionic surfactant, is widely used as a solubilizer, emulsifier, and humectant in pharmaceutical excipients, and also as a main component in constipation treatment drugs. It reduces the surface tension of feces, allowing water and fat to penetrate more easily, softening and loosening hardened stools, thus making them easier to pass. Due to the long-chain alkyl and sulfonic acid groups in its chemical structure and its unique polarity, docusate sodium exhibits unusual retention behavior on reversed-phase chromatography columns (weak retention under pure reversed-phase conditions), making it susceptible to interference from other excipients in the formulation.

[0003] Currently, there are reports on the detection of docusate sodium content in existing technologies. For example, Chinese patent document CN119000932A discloses a method and application for the detection of docusate sodium related substances. It uses a chromatographic column packed with octadecylsilane-bonded silica gel and an acetonitrile-aqueous phase containing quaternary ammonium salt ion-pairing reagent system as the mobile phase. By synergistically combining the concentration of acetonitrile, the type of ion pair, and the concentration of ion pairs, ion-pair high-performance liquid chromatography is used to detect ionic related substances of docusate sodium. However, this method is mainly for active pharmaceutical ingredients (the matrix composition is mostly pure target substances and a small amount of process impurities). For complex formulations containing multiple excipients (such as tablets, capsules, etc.), the matrix effect is significant, and direct application can easily lead to deviations in detection results or interference of chromatographic peaks. Chinese patent document CN116840374A discloses a method for detecting docusate sodium content in salicylic acid ear wash. This method establishes a detection method for docusate sodium in salicylic acid ear wash and can determine the content of docusate sodium in docusate sodium preparations. However, the matrix used in this method is relatively simple (the matrix composition is mostly docusate sodium, salicylic acid, solvent, preservative, etc.). Directly applying this method to the detection of docusate sodium content in complex matrices is not only difficult but also prone to problems such as detection structure deviation or chromatographic peak interference, resulting in inaccurate detection results. Therefore, it is not advisable to directly use the above-mentioned docusate sodium detection method for compound preparations such as acetaminophen and vitamin C effervescent tablets. Due to the overlap and interference of compound preparations, high-salt effervescent matrix, easily oxidized components, surfactants, and enzymes, problems such as retention drift, peak distortion, matrix interference, inaccurate quantification, and rapid column efficiency decay are easily encountered, affecting the detection results. Summary of the Invention

[0004] To address the problems existing in the prior art, the present invention aims to provide a high-performance liquid chromatography (HPLC) method for detecting the content of sodium docusate. This method is used to detect the sodium docusate content in compound preparations such as acetaminophen and vitamin C effervescent tablets (the matrix includes sodium docusate, acetaminophen, vitamin C, citric acid or sodium bicarbonate, lactose, PVP, sweeteners, disintegrants, etc.). It has the advantages of high specificity, simplicity, speed, high sensitivity, accuracy and reliability, thereby ensuring that the quality of compound preparations is effectively controlled.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] A high-performance liquid chromatography method for the determination of sodium docusate content, comprising: Sample preparation: Accurately weigh and grind acetaminophen and vitamin C effervescent tablets into powder, add mixed alcohol-EDTA composite solvent, and ultrasonically disperse; then, add bifunctional modified limiting medium mesoporous silica dispersion, and perform vortex oscillation, centrifugation, and membrane filtration in sequence to obtain the test sample; Detection: The test sample was analyzed by high performance liquid chromatography. The mobile phase included an organic phase and an aqueous phase. The organic phase was acetonitrile with a volume percentage of 30%–40%, and the aqueous phase was a mixed ionic liquid system. The column flow rate was 0.8–1.2 mL / min, the column temperature was 30±2℃, the detection wavelength was 210±2 nm, the injection volume was 18–22 μL, and the run time was 15±0.5 min.

[0007] Based on further optimization of the above scheme, the specific preparation method of the mixed alcohol-EDTA composite solvent is as follows: Anhydrous ethanol, tert-butanol and deionized water are mixed in a volume ratio of 0.95-1.05:0.95-1.05:17.1-18.9, and then EDTA-2Na (disodium ethylenediaminetetraacetate, CAS: 139-33-3) is added. The mass-volume ratio of EDTA-2Na to the mixed solvent (i.e., the mixed solvent composed of anhydrous ethanol, tert-butanol and deionized water) is 0.2g:1000mL. The mixture is magnetically stirred at 300-400rpm for 7-9min at room temperature (i.e., 25±1℃) to obtain the final product.

[0008] Based on further optimization of the above scheme, the mass-volume ratio of the acetaminophen vitamin C effervescent tablet powder to the mixed alcohol-EDTA composite solvent is 1.5g:25mL (1.5g of acetaminophen vitamin C effervescent tablet contains 1-5mg of docusate sodium); the ultrasonic dispersion is specifically performed by ultrasonication at 180-200W power and 38-40kHz frequency for 1.5-2.5min.

[0009] Based on further optimization of the above scheme, the specific preparation method of the bifunctional modified limiting medium mesoporous silica is as follows: first, the mesoporous silica is activated and then added to anhydrous toluene. The mixture is stirred at 280–320 rpm for 28–32 min under a nitrogen atmosphere. Then, octadecyltrichlorosilane (CAS: 112-04-9) is added, and the mixture is stirred at 280–320 rpm for 3.5–4.5 h under a nitrogen atmosphere at 78–82 °C. The mass-to-volume ratio of mesoporous silica, anhydrous toluene, and octadecyltrichlorosilane is 1 g: 100 mL: 2 mL. After stirring, the mixture is then... Centrifuge at 500–12500 rpm for 9–11 min, discard the supernatant, wash the precipitate 3–4 times with anhydrous toluene, and vacuum dry at 58–62 °C and -0.08–-0.09 MPa for 11.5–12.5 h to obtain modified mesoporous silica. Then, add anhydrous toluene to the modified mesoporous silica and stir at 280–320 rpm for 28–32 min under nitrogen atmosphere. Next, add γ-glycidoxypropyltrimethoxysilane (KH-560, CAS: 2530-83-8) and stir under nitrogen atmosphere at 108–112 °C. The mixture was refluxed and stirred at 300–400 rpm for 5.5–6.5 h. The mass-to-volume ratio of modified mesoporous silica, anhydrous toluene, and γ-glycidoxypropyltrimethoxysilane was 1 g:100 mL:3 mL. After stirring, the mixture was centrifuged at 11500–12500 rpm for 9–11 min. The supernatant was discarded, and the precipitate was washed 4–5 times with anhydrous ethanol. The precipitate was then vacuum-dried at 58–62 °C and -0.08–-0.09 MPa for 11.5–12.5 h to obtain the activated intermediate. Finally, the activated intermediate was added to 0.1 mol / L PE... In a G-2000 aqueous solution (pH 8.0±0.1, containing 0.5% triethylamine catalyst), the mixture was stirred at 350-450 rpm for 3.5-4.5 h at 58-62 °C. The mass-to-volume ratio of the activated intermediate to the PEG-2000 aqueous solution was 1 g: 100 mL. After stirring, the mixture was centrifuged at 11500-12500 rpm for 9-11 min. The supernatant was discarded, and the precipitate was washed 3-4 times with ultrapure water. The precipitate was then vacuum dried at 58-62 °C and -0.08--0.09 MPa for 11.5-12.5 h and ground into powder to obtain the final product.

[0010] Based on further optimization of the above scheme, the specific steps for activating the mesoporous silica are as follows: Mesoporous silica (particle size 5μm, average pore size 6nm, specific surface area not less than 600m²) is activated. 2 (g) was vacuum dried at 118–122℃ and -0.08–-0.09 MPa for 11.5–12.5 h.

[0011] Based on further optimization of the above scheme, the specific preparation method of the bifunctional modified limiting medium mesoporous silica dispersion is as follows: before use, anhydrous ethanol-water solution with bifunctional modified limiting medium mesoporous silica is mixed in a volume ratio of 1:1 to prepare a dispersion of 10 mg / mL, and ultrasonicated at 180-200 W power and 38-40 kHz frequency for 4.5-5.5 min to obtain the dispersion.

[0012] Based on further optimization of the above scheme, the volume ratio of the bifunctional modified limiting medium mesoporous silica dispersion to the mixed alcohol-EDTA composite solvent is 3:25; the vortex oscillation is specifically performed at a speed of 2400-2600 rpm for 55-65 s at room temperature; the centrifugation separation is specifically performed at a speed of 11500-12500 rpm for 4-6 min; the membrane filtration is specifically performed by discarding the supernatant after centrifugation, adding an 80% methanol-water eluent (i.e., a methanol-water volume ratio of 80:20) to the precipitate, and then adding the eluent to the mixed alcohol-EDTA composite solvent. The volume ratio of the DTA composite solvent is 1:10. Vortex for 55-65 seconds, centrifuge again, and take all the supernatant. Repeat the above steps once, and combine the two supernatants. Use 80% methanol-water eluent to make up to 1 / 5 of the volume of the mixed alcohol-EDTA composite solvent (for example, if the mixed alcohol-EDTA composite solvent is 25 mL, make up to 5 mL). Filter the solution after making up to 1 / 5 of the volume of the mixed alcohol-EDTA composite solvent through a 0.45 μm organic phase filter membrane (nylon material). Discard part of the initial filtrate (the initial filtrate is generally 3 / 5 of the volume of the final solution, i.e., 3 mL), and retain the subsequent filtrate for testing.

[0013] Based on further optimization of the above scheme, in the high performance liquid chromatography detection, the chromatographic column used is an Agilent ZORBAX SB-Aq, 250mm×4.6mm, 5μm.

[0014] Based on further optimization of the above scheme, the mixed ionic liquid system includes potassium dihydrogen phosphate (KH2PO4), 1-butyl-3-methylimidazolium chloride (CAS: 79917-90-1), 1-methyl-3-octylimidazolium chloride (CAS: 629-150-0), and hydroxypropyl-β-cyclodextrin (CAS: 128446-35-5), with concentrations of 19.5–20.5 mmol / L, 2.8–3.2 mmol / L, 1.8–2.2 mmol / L, and 4.8–5.2 mmol / L, respectively.

[0015] Based on further optimization of the above scheme, the specific preparation method of the mixed ionic liquid system is as follows: First, add the corresponding molar amounts of potassium dihydrogen phosphate, 1-butyl-3-methylimidazolium chloride, 1-methyl-3-octylimidazolium chloride, and hydroxypropyl-β-cyclodextrin to a clean beaker in sequence, then add ultrapure water to the beaker (the amount of ultrapure water added is 80% of the prepared volume, i.e., if preparing a 1L mixed ionic liquid system, first add 800mL of ultrapure water), and stir at 300-400rpm for 20-24min in a water bath at 38-42℃; then, at room temperature, add 1-2mL / Add 85% phosphoric acid (chromatographic grade) dropwise at a rate of 400–500 rpm while stirring continuously until the pH of the solution reaches 4 ± 0.05. Then, dilute the pH-adjusted solution to volume with ultrapure water, seal the bottle tightly, and shake it upside down 20–25 times to ensure complete and homogeneous mixing. Finally, filter the diluted aqueous phase through a 0.22 μm aqueous phase filter membrane (polyethersulfone PES or acetate-nitrocellulose mixed ester MCE), collect the filtrate, and sonicate it for 15–20 min at room temperature, 200–240 W power, and 38–40 kHz frequency to obtain the final product.

[0016] The following are the technical effects of this solution: This invention utilizes a mixed alcohol-EDTA composite solvent consisting of anhydrous ethanol, tert-butanol, and EDTA-2Na to extract sodium docusate from a compound preparation (i.e., acetaminophen vitamin C effervescent tablets). This method not only completely dissolves sodium docusate and prevents its re-aggregation (sodium docusate is an anionic surfactant that easily forms micelles in aqueous solution, leading to incomplete extraction), but also effectively avoids interference from trace metal ions in vitamin C with the detection of sodium docusate (such as Fe in vitamin C). 3+ Cu 2+Oxidative degradation of substances like lactose and PVP produces colored impurities and various oxidation products. These products exhibit strong absorption in the 210–220 nm UV region, severely interfering with the detection of docusate sodium. Simultaneously, by modifying the limiting medium, mesoporous silica, with bifunctional modification, not only are large molecular excipients such as lactose, PVP, and disintegrants effectively excluded, but docusate sodium is also selectively retained. This achieves a synergistic effect of matrix removal and target enrichment, effectively avoiding interference from large molecular interfering substances and high-salt components, and improving detection sensitivity. Furthermore, by mixing ionic liquids with the hydroxypropyl-β-cyclodextrin system, the retention behavior of sodium docusate was improved through the synergistic effect of different alkyl chain ionic liquids (i.e., imidazole ionic liquids are positively charged and form neutral ion pairs with the sulfonic acid groups of sodium docusate, increasing the hydrophobicity of sodium docusate; 1-butyl-3-methylimidazolium chloride can quickly form ion pairs with sodium docusate, improving the ion pair formation efficiency; 1-methyl-3-octyl imidazolium chloride enhances the retention of sodium docusate on the chromatographic column and improves the peak shape). Combined with the inclusion selectivity of cyclodextrin, interfering components such as acetaminophen, vitamin C, and citric acid / sodium bicarbonate were effectively separated, avoiding peak distortion and co-elution.

[0017] In summary, this invention, through the extraction of sodium docusate samples and the improvement of ionic liquids, ensures the complete release and stability of the target analyte, avoids oxidation interference, removes matrix interfering substances, enriches the target analyte, and simultaneously separates residual small molecule interfering substances to achieve precise quantification. This results in high specificity (no interference from blank solvent, blank excipient, or negative sample at the sodium docusate main peak position), high sensitivity, excellent accuracy (recovery rate between 98% and 102%, repeatability RSD less than 2.0%), good durability, and simple and convenient operation for the detection of sodium docusate in compound formulations. Attached Figure Description

[0018] Figure 1 This is a chromatogram of the high performance liquid chromatography results in Example 1 of the present invention.

[0019] Figure 2 This is a chromatogram of the high performance liquid chromatography results in Example 2 of the present invention.

[0020] Figure 3 This is a chromatogram of the high performance liquid chromatography results in Example 3 of the present invention. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly described below. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0022] Example 1: A high-performance liquid chromatography method for the determination of sodium docusate content, comprising: Sample preparation: Accurately weigh and grind acetaminophen and vitamin C effervescent tablets into powder, then add mixed alcohol-EDTA composite solvent. The mass-volume ratio of acetaminophen and vitamin C effervescent tablet powder to mixed alcohol-EDTA composite solvent is 1.5g:25mL (1.5g acetaminophen and vitamin C effervescent tablet contains 1-5mg of docusate sodium). The mixture is ultrasonically dispersed for 2.5min at 180W power and 38kHz frequency. Then, a bifunctional modified limiting medium mesoporous silica dispersion was added, with a volume ratio of 3:25 between the bifunctional modified limiting medium mesoporous silica dispersion and the mixed alcohol-EDTA composite solvent (i.e., 3 mL of the bifunctional modified limiting medium mesoporous silica dispersion was used). The mixture was then subjected to vortexing, centrifugation, and membrane filtration to obtain the test sample. Specifically, the vortexing was performed at 2400 rpm for 65 seconds at room temperature; the centrifugation was performed at 11500 rpm for 6 minutes; and the membrane filtration was performed by discarding the supernatant after centrifugation and adding an 80% methanol-water eluent (i.e., a methanol-water volume ratio of 80:2) to the precipitate. 0), the volume ratio of the eluent to the mixed alcohol-EDTA composite solvent is 1:10, vortex for 65s (vortex speed is the same as above), centrifuge again (centrifugation parameters are the same as above), take all the supernatant, repeat the above steps once, and combine the two supernatants. Use 80% methanol-water eluent to make up to 1 / 5 of the mixed alcohol-EDTA composite solvent (for example, if the mixed alcohol-EDTA composite solvent is 25mL, then make up to 5mL). Filter the solution after making up to 1 / 5 of the volume using a 0.45μm organic phase filter membrane (nylon material), discard part of the initial filtrate (the initial filtrate is generally 3 / 5 of the volume of the final solution, i.e., 3mL), and retain the subsequent filtrate for detection.

[0023] The specific preparation method of the mixed alcohol-EDTA composite solvent is as follows: Anhydrous ethanol, tert-butanol and deionized water are mixed in a volume ratio of 0.95:0.95:17.1, and then EDTA-2Na (disodium ethylenediaminetetraacetate, CAS: 139-33-3) is added. The mass-volume ratio of EDTA-2Na to the mixed solvent (i.e., the mixed solvent composed of anhydrous ethanol, tert-butanol and deionized water) is 0.2g:1000mL. The mixture is magnetically stirred at 300rpm for 9min at room temperature (i.e., 25±1℃) to obtain the final product.

[0024] The specific preparation method of bifunctional modified confined medium mesoporous silica is as follows: First, mesoporous silica (particle size 5μm, average pore size 6nm, specific surface area not less than 600m²) is prepared. 2 / g) was vacuum dried at 118℃ and -0.08MPa for 12.5h to obtain activated mesoporous silica. The activated mesoporous silica was added to anhydrous toluene and stirred at 280rpm for 32min under nitrogen atmosphere. Then, octadecyltrichlorosilane (CAS: 112-04-9) was added and stirred at 280rpm for 4.5h under nitrogen atmosphere and 78℃. The mass-volume ratio of mesoporous silica, anhydrous toluene, and octadecyltrichlorosilane was 1g:100mL:2mL. After stirring, the mixture was centrifuged at 11500 rpm for 11 min, the supernatant was discarded, and the precipitate was washed three times with anhydrous toluene. It was then vacuum dried at 58 °C and -0.08 MPa for 12.5 h to obtain modified mesoporous silica. Next, the modified mesoporous silica was added to anhydrous toluene, and the mixture was stirred at 280 rpm for 32 min under a nitrogen atmosphere. Then, γ-glycidoxypropyltrimethoxysilane (KH-560, CAS: 2530-83-8) was added, and the mixture was stirred at 108 °C under a nitrogen atmosphere. The mixture was refluxed and stirred at 300 rpm for 6.5 h. The mass-to-volume ratio of modified mesoporous silica, anhydrous toluene, and γ-glycidoxypropyltrimethoxysilane was 1 g:100 mL:3 mL. After stirring, the mixture was centrifuged at 11500 rpm for 11 min, the supernatant was discarded, and the precipitate was washed four times with anhydrous ethanol and then vacuum dried at 58 °C and -0.08 MPa for 12.5 h to obtain the activated intermediate. Finally, the activated intermediate was added to 0.1 mol / L PEG-2000. In an aqueous solution (pH 8.0 ± 0.1, containing 0.5% triethylamine catalyst), the mixture was stirred at 350 rpm for 4.5 h at 58 °C. The mass-to-volume ratio of the activation intermediate to the PEG-2000 aqueous solution was 1 g: 100 mL. After stirring, the mixture was centrifuged at 11500 rpm for 11 min, the supernatant was discarded, and the precipitate was washed three times with ultrapure water. The precipitate was then vacuum-dried at 58 °C and -0.08 MPa for 12.5 h and ground into powder to obtain the bifunctional modified limiting medium mesoporous silica. Before use, the bifunctional modified limiting medium mesoporous silica was mixed with anhydrous ethanol-water solution at a volume ratio of 1:1 to prepare a dispersion of 10 mg / mL. This dispersion was then sonicated at 180 W power and 38 kHz frequency for 5.5 min to obtain the bifunctional modified limiting medium mesoporous silica dispersion.

[0025] Reference solution: Accurately weigh 25 mg of docusate sodium reference standard, place it in a 50 mL volumetric flask, dissolve it in methanol and dilute to the mark, shake well to obtain a 500 μg / mL reference stock solution; accurately measure an appropriate amount of the stock solution and dilute it with 80% methanol-water solution to prepare a series of reference solutions with concentrations of 0.2 μg / mL, 0.5 μg / mL, 2 μg / mL, 5 μg / mL, 10 μg / mL and 20 μg / mL, and prepare them immediately before use.

[0026] Detection: The test sample will be analyzed by high-performance liquid chromatography, specifically as follows: Column: Agilent ZORBAX SB-Aq, 250 mm × 4.6 mm, 5 μm; Detection wavelength: 210nm; Column temperature: 30℃; Column flow rate: 1 mL / min; Injection volume: 20 μL; Running time: 15 minutes; Mobile phase: Organic phase: acetonitrile; Aqueous phase: mixed ionic liquid system; Organic phase to aqueous phase volume ratio: 30%:70%. The mixed ionic liquid system includes potassium dihydrogen phosphate (KH2PO4), 1-butyl-3-methylimidazolium chloride (CAS: 79917-90-1), 1-methyl-3-octylimidazolium chloride (CAS: 629-150-0), and hydroxypropyl-β-cyclodextrin (CAS: 128446-35-5), with concentrations of 19.5 mmol / L, 2.8 mmol / L, 1.8 mmol / L, and 4.8 mmol / L, respectively. The specific preparation method is as follows: First, add the corresponding molar amounts of potassium dihydrogen phosphate, 1-butyl-3-methylimidazolium chloride, 1-methyl-3-octylimidazolium chloride, and hydroxypropyl-β-cyclodextrin to a clean beaker in sequence. Then, add ultrapure water to the beaker (the amount of ultrapure water added is 80% of the prepared volume, i.e., if preparing a 1L mixed ionic liquid system, add 800mL of ultrapure water first). Stir at 300rpm for 24min in a water bath at 38℃. Then, add the mixture dropwise at a rate of 1mL / min at room temperature. Add 85% phosphoric acid (chromatographic grade) dropwise while stirring at 400 rpm until the solution pH is 4 ± 0.05. Then, dilute the pH-adjusted solution to volume with ultrapure water, seal the bottle tightly, and shake it upside down 20 times to ensure complete mixing. Finally, filter the diluted aqueous phase through a 0.22 μm aqueous phase filter membrane (polyethersulfone PES or acetate-nitrocellulose mixed ester MCE), collect the filtrate, and sonicate it for 20 min at room temperature, 200 W power, and 38 kHz frequency to obtain the final product.

[0027] Example 2: A high-performance liquid chromatography method for the determination of sodium docusate content, comprising: Sample preparation: Accurately weigh and grind acetaminophen and vitamin C effervescent tablets into powder, then add mixed alcohol-EDTA composite solvent. The mass-volume ratio of acetaminophen and vitamin C effervescent tablet powder to mixed alcohol-EDTA composite solvent is 1.5g:25mL (1.5g acetaminophen and vitamin C effervescent tablet contains 1-5mg of docusate sodium). The mixture is ultrasonically dispersed at 190W power and 39kHz frequency for 2min. Then, a bifunctional modified limiting medium mesoporous silica dispersion was added, with a volume ratio of 3:25 between the bifunctional modified limiting medium mesoporous silica dispersion and the mixed alcohol-EDTA composite solvent (i.e., 3 mL of the bifunctional modified limiting medium mesoporous silica dispersion was used). The mixture was then subjected to vortexing, centrifugation, and membrane filtration to obtain the test sample. Specifically, the vortexing was performed at 2500 rpm for 60 seconds at room temperature; the centrifugation was performed at 12000 rpm for 5 minutes; and the membrane filtration was performed by discarding the supernatant after centrifugation and adding an 80% methanol-water eluent (i.e., a methanol-water volume ratio of 80:2) to the precipitate. 0), the volume ratio of the eluent to the mixed alcohol-EDTA composite solvent is 1:10, vortex for 60s (vortex speed is the same as above), centrifuge again (centrifugation parameters are the same as above), take all the supernatant, repeat the above steps once, and combine the two supernatants. Use 80% methanol-water eluent to make up to 1 / 5 of the mixed alcohol-EDTA composite solvent (for example, if the mixed alcohol-EDTA composite solvent is 25mL, then make up to 5mL). Filter the solution after making up to 1 / 5 of the volume using a 0.45μm organic phase filter membrane (nylon material), discard part of the initial filtrate (the initial filtrate is generally 3 / 5 of the volume of the final solution, i.e., 3mL), and retain the subsequent filtrate for detection.

[0028] The specific preparation method of the mixed alcohol-EDTA composite solvent is as follows: anhydrous ethanol, tert-butanol and deionized water are mixed in a volume ratio of 1:1:18, and then EDTA-2Na (disodium ethylenediaminetetraacetate, CAS: 139-33-3) is added. The mass-volume ratio of EDTA-2Na to the mixed solvent (i.e., the mixed solvent composed of anhydrous ethanol, tert-butanol and deionized water) is 0.2g:1000mL. The mixture is magnetically stirred at 350rpm for 8min at room temperature (i.e., 25±1℃) to obtain the final product.

[0029] The specific preparation method of bifunctional modified confined medium mesoporous silica is as follows: First, mesoporous silica (particle size 5μm, average pore size 6nm, specific surface area not less than 600m²) is prepared. 2 / g) was vacuum dried at 120℃ and -0.085MPa for 12h to obtain activated mesoporous silica. The activated mesoporous silica was added to anhydrous toluene and stirred at 300rpm for 30min under nitrogen atmosphere. Then, octadecyltrichlorosilane (CAS: 112-04-9) was added and stirred at 300rpm for 4h under nitrogen atmosphere and 80℃. The mass-volume ratio of mesoporous silica, anhydrous toluene, and octadecyltrichlorosilane was 1g:100mL:2mL. After mixing, the mixture was centrifuged at 12000 rpm for 10 min, the supernatant was discarded, and the precipitate was washed three times with anhydrous toluene. It was then vacuum dried at 60℃ and -0.085 MPa for 12 h to obtain modified mesoporous silica. Next, the modified mesoporous silica was added to anhydrous toluene and stirred at 300 rpm for 30 min under a nitrogen atmosphere. Then, γ-glycidoxypropyltrimethoxysilane (KH-560, CAS: 2530-83-8) was added, and the mixture was stirred at 110℃ under a nitrogen atmosphere. The mixture was refluxed and stirred at 350 rpm for 6 h. The mass-to-volume ratio of modified mesoporous silica, anhydrous toluene, and γ-glycidoxypropyltrimethoxysilane was 1 g:100 mL:3 mL. After stirring, the mixture was centrifuged at 12000 rpm for 10 min, the supernatant was discarded, and the precipitate was washed four times with anhydrous ethanol and then vacuum dried at 60 °C and -0.085 MPa for 12 h to obtain the activated intermediate. Finally, the activated intermediate was added to 0.1 mol / L PEG-200. In an aqueous solution (pH 8.0 ± 0.1, containing 0.5% triethylamine catalyst), the mixture was stirred at 400 rpm for 4 h at 60 °C. The mass-to-volume ratio of the activation intermediate to the PEG-2000 aqueous solution was 1 g: 100 mL. After stirring, the mixture was centrifuged at 12000 rpm for 10 min, the supernatant was discarded, and the precipitate was washed three times with ultrapure water. The precipitate was then vacuum-dried at 60 °C and -0.085 MPa for 12 h and ground into powder to obtain the bifunctional modified limiting medium mesoporous silica. Before use, the bifunctional modified limiting medium mesoporous silica was mixed with an anhydrous ethanol-water solution at a volume ratio of 1:1 to prepare a 10 mg / mL dispersion. This dispersion was then sonicated at 190 W power and 39 kHz frequency for 5 min to obtain the bifunctional modified limiting medium mesoporous silica dispersion.

[0030] Reference solution: Accurately weigh 25 mg of docusate sodium reference standard, place it in a 50 mL volumetric flask, dissolve it in methanol and dilute to the mark, shake well to obtain a 500 μg / mL reference stock solution; accurately measure an appropriate amount of the stock solution and dilute it with 80% methanol-water solution to prepare a series of reference solutions with concentrations of 0.2 μg / mL, 0.5 μg / mL, 2 μg / mL, 5 μg / mL, 10 μg / mL and 20 μg / mL, and prepare them immediately before use.

[0031] Detection: The test sample will be analyzed by high-performance liquid chromatography, specifically as follows: Column: Agilent ZORBAX SB-Aq, 250 mm × 4.6 mm, 5 μm; Detection wavelength: 210nm; Column temperature: 30℃; Column flow rate: 1 mL / min; Injection volume: 20 μL; Running time: 15 minutes; Mobile phase: Organic phase: acetonitrile; Aqueous phase: mixed ionic liquid system; Organic phase to aqueous phase volume ratio: 35%:65%. The mixed ionic liquid system includes potassium dihydrogen phosphate (KH2PO4), 1-butyl-3-methylimidazolium chloride (CAS: 79917-90-1), 1-methyl-3-octylimidazolium chloride (CAS: 629-150-0), and hydroxypropyl-β-cyclodextrin (CAS: 128446-35-5), with concentrations of 20 mmol / L, 3 mmol / L, 2 mmol / L, and 5 mmol / L, respectively. The specific preparation method is as follows: First, add the corresponding molar amounts of potassium dihydrogen phosphate, 1-butyl-3-methylimidazolium chloride, 1-methyl-3-octylimidazolium chloride, and hydroxypropyl-β-cyclodextrin to a clean beaker in sequence. Then, add ultrapure water to the beaker (the amount of ultrapure water added is 80% of the prepared volume, i.e., if preparing a 1L mixed ionic liquid system, add 800mL of ultrapure water first). Stir at 350rpm for 22min in a water bath at 40℃. Then, add the mixture dropwise at a rate of 1.5mL / min at room temperature. 85% phosphoric acid (chromatographic grade) was added dropwise while stirring at 450 rpm until the pH of the solution reached 4 ± 0.05. Then, the pH-adjusted solution was brought to volume with ultrapure water, the stopper was tightened, and the solution was shaken upside down 22 times to ensure complete mixing. Finally, the aqueous phase was filtered through a 0.22 μm aqueous phase filter membrane (polyethersulfone PES or acetate-nitrocellulose mixed ester MCE), the filtrate was collected, and ultrasonically degassed for 17.5 min at room temperature, 220 W power, and 39 kHz frequency to obtain the final product.

[0032] Example 3: A high-performance liquid chromatography method for the determination of sodium docusate content, comprising: Sample preparation: Accurately weigh and grind acetaminophen and vitamin C effervescent tablets into powder, then add mixed alcohol-EDTA composite solvent. The mass-volume ratio of acetaminophen and vitamin C effervescent tablet powder to mixed alcohol-EDTA composite solvent is 1.5g:25mL (1.5g acetaminophen and vitamin C effervescent tablet contains 1-5mg of docusate sodium). Sonicate for 1.5min at 200W power and 40kHz frequency. Then, a bifunctional modified limiting medium mesoporous silica dispersion was added, with a volume ratio of 3:25 between the bifunctional modified limiting medium mesoporous silica dispersion and the mixed alcohol-EDTA composite solvent (i.e., 3 mL of the bifunctional modified limiting medium mesoporous silica dispersion was used). The mixture was then subjected to vortexing, centrifugation, and membrane filtration to obtain the test sample. Specifically, the vortexing was performed at 2600 rpm for 55 seconds at room temperature; the centrifugation was performed at 12500 rpm for 4 minutes; and the membrane filtration was performed by discarding the supernatant after centrifugation and adding an 80% methanol-water eluent (i.e., a methanol-water volume ratio of 80:2) to the precipitate. 0), the volume ratio of the eluent to the mixed alcohol-EDTA composite solvent is 1:10, vortex for 55s (vortex speed is the same as above), centrifuge again (centrifugation parameters are the same as above), take all the supernatant, repeat the above steps once, and combine the two supernatants. Use 80% methanol-water eluent to make up to 1 / 5 of the mixed alcohol-EDTA composite solvent (for example, if the mixed alcohol-EDTA composite solvent is 25mL, then make up to 5mL). Filter the solution after making up to 1 / 5 of the volume using a 0.45μm organic phase filter membrane (nylon material), discard part of the initial filtrate (the initial filtrate is generally 3 / 5 of the volume of the final solution, i.e., 3mL), and retain the subsequent filtrate for detection.

[0033] The specific preparation method of the mixed alcohol-EDTA composite solvent is as follows: Anhydrous ethanol, tert-butanol and deionized water are mixed in a volume ratio of 1.05:1.05:18.9, and then EDTA-2Na (disodium ethylenediaminetetraacetate, CAS: 139-33-3) is added. The mass-volume ratio of EDTA-2Na to the mixed solvent (i.e., the mixed solvent composed of anhydrous ethanol, tert-butanol and deionized water) is 0.2g:1000mL. The mixture is magnetically stirred at 400rpm for 7min at room temperature (i.e., 25±1℃) to obtain the final product.

[0034] The specific preparation method of bifunctional modified confined medium mesoporous silica is as follows: First, mesoporous silica (particle size 5μm, average pore size 6nm, specific surface area not less than 600m²) is prepared. 2 / g) was vacuum dried at 122℃ and -0.09MPa for 11.5h to obtain activated mesoporous silica. The activated mesoporous silica was added to anhydrous toluene and stirred at 320rpm for 28min under nitrogen atmosphere. Then, octadecyltrichlorosilane (CAS: 112-04-9) was added and stirred at 320rpm for 3.5h under nitrogen atmosphere and 82℃. The mass-volume ratio of mesoporous silica, anhydrous toluene, and octadecyltrichlorosilane was 1g:100mL:2mL. After stirring, the mixture was centrifuged at 12500 rpm for 9 min, the supernatant was discarded, and the precipitate was washed four times with anhydrous toluene. It was then vacuum dried at 62 °C and -0.09 MPa for 11.5 h to obtain modified mesoporous silica. Next, the modified mesoporous silica was added to anhydrous toluene, and the mixture was stirred at 320 rpm for 28 min under a nitrogen atmosphere. Then, γ-glycidoxypropyltrimethoxysilane (KH-560, CAS: 2530-83-8) was added, and the mixture was stirred at 112 °C under a nitrogen atmosphere. The mixture was refluxed and stirred at 400 rpm for 5.5 h. The mass-to-volume ratio of modified mesoporous silica, anhydrous toluene, and γ-glycidoxypropyltrimethoxysilane was 1 g:100 mL:3 mL. After stirring, the mixture was centrifuged at 12500 rpm for 9 min, the supernatant was discarded, and the precipitate was washed five times with anhydrous ethanol and then vacuum dried at 62 °C and -0.09 MPa for 11.5 h to obtain the activated intermediate. Finally, the activated intermediate was added to 0.1 mol / L PEG-2000. In an aqueous solution (pH 8.0 ± 0.1, containing 0.5% triethylamine catalyst), the mixture was stirred at 450 rpm for 3.5 h at 62 °C. The mass-to-volume ratio of the activation intermediate to the PEG-2000 aqueous solution was 1 g: 100 mL. After stirring, the mixture was centrifuged at 12500 rpm for 9 min, the supernatant was discarded, and the precipitate was washed four times with ultrapure water. The precipitate was then vacuum-dried at 62 °C and -0.09 MPa for 11.5 h and ground into powder to obtain the bifunctional modified limiting medium mesoporous silica. Before use, the bifunctional modified limiting medium mesoporous silica was mixed with anhydrous ethanol-water solution at a volume ratio of 1:1 to prepare a dispersion of 10 mg / mL. This dispersion was then sonicated at 200 W power and 40 kHz frequency for 4.5 min to obtain the bifunctional modified limiting medium mesoporous silica dispersion.

[0035] Reference solution: Accurately weigh 25 mg of docusate sodium reference standard, place it in a 50 mL volumetric flask, dissolve it in methanol and dilute to the mark, shake well to obtain a 500 μg / mL reference stock solution; accurately measure an appropriate amount of the stock solution and dilute it with 80% methanol-water solution to prepare a series of reference solutions with concentrations of 0.2 μg / mL, 0.5 μg / mL, 2 μg / mL, 5 μg / mL, 10 μg / mL and 20 μg / mL, and prepare them immediately before use.

[0036] Detection: The test sample will be analyzed by high-performance liquid chromatography, specifically as follows: Column: Agilent ZORBAX SB-Aq, 250 mm × 4.6 mm, 5 μm; Detection wavelength: 210nm; Column temperature: 30℃; Column flow rate: 1 mL / min; Injection volume: 20 μL; Running time: 15 minutes; Mobile phase: Organic phase: acetonitrile; Aqueous phase: mixed ionic liquid system; Organic phase to aqueous phase volume ratio: 40% : 60%. The mixed ionic liquid system includes potassium dihydrogen phosphate (KH2PO4), 1-butyl-3-methylimidazolium chloride (CAS: 79917-90-1), 1-methyl-3-octylimidazolium chloride (CAS: 629-150-0), and hydroxypropyl-β-cyclodextrin (CAS: 128446-35-5), with concentrations of 20.5 mmol / L, 3.2 mmol / L, 2.2 mmol / L, and 5.2 mmol / L, respectively. The specific preparation method is as follows: First, add the corresponding molar amounts of potassium dihydrogen phosphate, 1-butyl-3-methylimidazolium chloride, 1-methyl-3-octylimidazolium chloride, and hydroxypropyl-β-cyclodextrin to a clean beaker in sequence. Then, add ultrapure water to the beaker (the amount of ultrapure water added is 80% of the prepared volume, i.e., if preparing a 1L mixed ionic liquid system, add 800mL of ultrapure water first). Stir at 400rpm for 20min in a water bath at 42℃. Then, add the mixture dropwise at a rate of 2mL / min at room temperature. Add 85% phosphoric acid (chromatographic grade) dropwise while stirring at 500 rpm until the solution pH is 4 ± 0.05. Then, dilute the pH-adjusted solution to volume with ultrapure water, seal the bottle tightly, and shake it upside down 25 times to ensure complete mixing. Finally, filter the diluted aqueous phase through a 0.22 μm aqueous phase filter membrane (polyethersulfone PES or acetate-nitrocellulose mixed ester MCE), collect the filtrate, and degas it by sonication at room temperature, 240 W power, and 40 kHz frequency for 15 min to obtain the final product.

[0037] Example 4: As another preferred embodiment of the present invention, based on any of the above embodiments 1 to 3, the maintenance of the chromatographic column is also included, specifically: when using it for the first time, it is first rinsed with a methanol-water solution with a volume ratio of 1:1 for 28 to 32 minutes, and then equilibrated with the mobile phase for 58 to 60 minutes; After each day's test, the sample was first rinsed with a trifluoroacetic acid-acetonitrile aqueous solution with a concentration-to-volume ratio of 1:9 for 28-32 minutes, then rinsed with a methanol aqueous solution with a volume ratio of 1:1 for 28-32 minutes, and stored in methanol. Column contamination regeneration: Flush with methanol, dichloromethane and methanol sequentially for 28-32 minutes each, then balance according to the first use procedure.

[0038] Comparative Example 1: A high-performance liquid chromatography (HPLC) detection method, comprising: Sample preparation: Accurately weigh and grind acetaminophen and vitamin C effervescent tablets into powder, then add a mixed alcohol-EDTA composite solvent. The mass-to-volume ratio of the acetaminophen and vitamin C effervescent tablet powder to the mixed alcohol-EDTA composite solvent is 1.5g:25mL (1.5g of acetaminophen and vitamin C effervescent tablet contains 1-5mg of docusate sodium). The mixture is ultrasonically dispersed at 190W power and 39kHz frequency for 2 minutes. Then, the mixture is sequentially subjected to vortexing, centrifugation, and membrane filtration to obtain the test sample. The methods for vortexing, centrifugation, and membrane filtration are consistent with those in Example 2.

[0039] The specific preparation of the mixed alcohol-EDTA composite solvent is the same as in Example 2.

[0040] Reference solution: Accurately weigh 25 mg of docusate sodium reference standard, place it in a 50 mL volumetric flask, dissolve it in methanol and dilute to the mark, shake well to obtain a 500 μg / mL reference stock solution; accurately measure an appropriate amount of the stock solution and dilute it with 80% methanol-water solution to prepare a series of reference solutions with concentrations of 0.2 μg / mL, 0.5 μg / mL, 2 μg / mL, 5 μg / mL, 10 μg / mL and 20 μg / mL, and prepare them immediately before use.

[0041] Detection: The test sample will be analyzed by high-performance liquid chromatography, specifically as follows: Column: Agilent ZORBAX SB-Aq, 250 mm × 4.6 mm, 5 μm; Detection wavelength: 210nm; Column temperature: 30℃; Column flow rate: 1 mL / min; Injection volume: 20 μL; Running time: 15 minutes; Mobile phase: organic phase: acetonitrile; aqueous phase: mixed ionic liquid system; organic phase to aqueous phase volume ratio 35%:65%; the mixed ionic liquid system is the same as in Example 2.

[0042] Comparative Example 2: A high-performance liquid chromatography (HPLC) detection method, comprising: Sample preparation: Accurately weigh and grind acetaminophen and vitamin C effervescent tablets into powder, then add a mixed alcohol-EDTA composite solvent. The mass-to-volume ratio of the acetaminophen and vitamin C effervescent tablet powder to the mixed alcohol-EDTA composite solvent is 1.5g:25mL (1.5g of acetaminophen and vitamin C effervescent tablet contains 1-5mg of docusate sodium). The mixture is ultrasonically dispersed at 190W power and 39kHz frequency for 2 minutes. Then, a mesoporous silica dispersion is added, with a volume ratio of the mesoporous silica dispersion to the mixed alcohol-EDTA composite solvent of 3:25 (i.e., 3mL of mesoporous silica dispersion is used). The mixture is then subjected to vortexing, centrifugation, and membrane filtration to obtain the test sample. The methods for vortexing, centrifugation, and membrane filtration are consistent with those in Example 2.

[0043] The specific preparation of the mixed alcohol-EDTA composite solvent is the same as in Example 2.

[0044] Reference solution: Accurately weigh 25 mg of docusate sodium reference standard, place it in a 50 mL volumetric flask, dissolve it in methanol and dilute to the mark, shake well to obtain a 500 μg / mL reference stock solution; accurately measure an appropriate amount of the stock solution and dilute it with 80% methanol-water solution to prepare a series of reference solutions with concentrations of 0.2 μg / mL, 0.5 μg / mL, 2 μg / mL, 5 μg / mL, 10 μg / mL and 20 μg / mL, and prepare them immediately before use.

[0045] Detection: The test sample will be analyzed by high-performance liquid chromatography, specifically as follows: Column: Agilent ZORBAX SB-Aq, 250 mm × 4.6 mm, 5 μm; Detection wavelength: 210nm; Column temperature: 30℃; Column flow rate: 1 mL / min; Injection volume: 20 μL; Running time: 15 minutes; Mobile phase: organic phase: acetonitrile; aqueous phase: mixed ionic liquid system; organic phase to aqueous phase volume ratio 35%:65%; the mixed ionic liquid system is the same as in Example 2.

[0046] Comparative Example 3: A high-performance liquid chromatography (HPLC) detection method, comprising: Sample preparation: Accurately weigh and grind acetaminophen and vitamin C effervescent tablets into powder, then add a mixed alcohol-EDTA composite solvent. The mass-to-volume ratio of the acetaminophen and vitamin C effervescent tablet powder to the mixed alcohol-EDTA composite solvent is 1.5g:25mL (1.5g of acetaminophen and vitamin C effervescent tablet contains 1-5mg of docusate sodium). The mixture is ultrasonically dispersed at 190W power and 39kHz frequency for 2 minutes. Then, a mesoporous silica dispersion is added as a modification medium. The volume ratio of the mesoporous silica dispersion to the mixed alcohol-EDTA composite solvent is 3:25 (i.e., 3mL of the mesoporous silica dispersion is used). The mixture is then subjected to vortexing, centrifugation, and membrane filtration to obtain the test sample. The methods for vortexing, centrifugation, and membrane filtration are consistent with those in Example 2.

[0047] The specific preparation of the mixed alcohol-EDTA composite solvent is the same as in Example 2.

[0048] The specific preparation method of the modified medium mesoporous silica is as follows: First, mesoporous silica (particle size 5μm, average pore size 6nm, specific surface area not less than 600m²) is prepared. 2 / g) was vacuum dried at 120℃ and -0.085MPa for 12h to obtain activated mesoporous silica. The activated mesoporous silica was added to anhydrous toluene and stirred at 300rpm for 30min under nitrogen atmosphere. Then, octadecyltrichlorosilane (CAS: 112-04-9) was added and stirred at 300rpm for 4h under nitrogen atmosphere and 80℃. The mass-volume ratio of mesoporous silica, anhydrous toluene, and octadecyltrichlorosilane was 1g:100mL:2mL. After stirring, the mixture was centrifuged at 12000rpm for 10min, the supernatant was discarded, and the precipitate was washed three times with anhydrous toluene and then heated at 60℃ and -0.085MPa. Modified mesoporous silica was obtained by vacuum drying at 0.085 MPa for 12 h. Finally, the modified mesoporous silica was added to a 0.1 mol / L PEG-2000 aqueous solution (pH 8.0 ± 0.1, containing 0.5% triethylamine catalyst), and stirred at 400 rpm for 4 h at 60 °C. The mass-to-volume ratio of modified mesoporous silica to PEG-2000 aqueous solution was 1 g: 100 mL. After stirring, the mixture was centrifuged at 12000 rpm for 10 min, the supernatant was discarded, and the precipitate was washed three times with ultrapure water. It was then vacuum dried at 60 °C and -0.085 MPa for 12 h and ground into powder to obtain the modified medium mesoporous silica. Before use, the modified medium mesoporous silica was mixed with an anhydrous ethanol-water solution at a volume ratio of 1:1 to prepare a 10 mg / mL dispersion, and sonicated at 190 W power and 39 kHz frequency for 5 min to obtain the modified medium mesoporous silica dispersion.

[0049] Reference solution: Accurately weigh 25 mg of docusate sodium reference standard, place it in a 50 mL volumetric flask, dissolve it in methanol and dilute to the mark, shake well to obtain a 500 μg / mL reference stock solution; accurately measure an appropriate amount of the stock solution and dilute it with 80% methanol-water solution to prepare a series of reference solutions with concentrations of 0.2 μg / mL, 0.5 μg / mL, 2 μg / mL, 5 μg / mL, 10 μg / mL and 20 μg / mL, and prepare them immediately before use.

[0050] Detection: The test sample will be analyzed by high-performance liquid chromatography, specifically as follows: Column: Agilent ZORBAX SB-Aq, 250 mm × 4.6 mm, 5 μm; Detection wavelength: 210nm; Column temperature: 30℃; Column flow rate: 1 mL / min; Injection volume: 20 μL; Running time: 15 minutes; Mobile phase: organic phase: acetonitrile; aqueous phase: mixed ionic liquid system; organic phase to aqueous phase volume ratio 35%:65%; the mixed ionic liquid system is the same as in Example 2.

[0051] Comparative Example 4: A high-performance liquid chromatography (HPLC) detection method, comprising: Sample preparation: Accurately weigh and grind acetaminophen and vitamin C effervescent tablets into powder, then add a mixed alcohol-EDTA composite solvent. The mass-to-volume ratio of the acetaminophen and vitamin C effervescent tablet powder to the mixed alcohol-EDTA composite solvent is 1.5g:25mL (1.5g of acetaminophen and vitamin C effervescent tablet contains 1-5mg of docusate sodium). The mixture is ultrasonically dispersed at 190W power and 39kHz frequency for 2 minutes. Then, an activation medium, mesoporous silica dispersion, is added. The volume ratio of the activation medium, mesoporous silica dispersion, to the mixed alcohol-EDTA composite solvent is 3:25 (i.e., 3mL of the activation medium, mesoporous silica dispersion, is used). The mixture is then subjected to vortexing, centrifugation, and membrane filtration to obtain the test sample. The methods for vortexing, centrifugation, and membrane filtration are consistent with those in Example 2.

[0052] The specific preparation of the mixed alcohol-EDTA composite solvent is the same as in Example 2.

[0053] The specific preparation method of the activated medium mesoporous silica is as follows: First, mesoporous silica (particle size 5μm, average pore size 6nm, specific surface area not less than 600m²) is prepared. 2 / g) was vacuum dried at 120℃ and -0.085MPa for 12h to obtain activated mesoporous silica. The activated mesoporous silica was added to anhydrous toluene and stirred at 300rpm for 30min under nitrogen atmosphere. Then, γ-glycidoxypropyltrimethoxysilane (KH-560, CAS: 2530-83-8) was added, and the mixture was refluxed at 350rpm for 6h under nitrogen atmosphere and 110℃. The mass-to-volume ratio of modified mesoporous silica, anhydrous toluene, and γ-glycidoxypropyltrimethoxysilane was 1g:100mL:3mL. After stirring, the mixture was centrifuged at 12000rpm for 10min, the supernatant was discarded, and the solution was purified using anhydrous... The precipitate was washed four times with ethanol and then vacuum dried at 60℃ and -0.085MPa for 12 h to obtain the activated intermediate. Finally, the activated intermediate was added to a 0.1 mol / L PEG-2000 aqueous solution (pH 8.0±0.1, containing 0.5% triethylamine catalyst) and stirred at 400 rpm for 4 h at 60℃. The mass-to-volume ratio of the activated intermediate to the PEG-2000 aqueous solution was 1 g: 100 mL. After stirring, the mixture was centrifuged at 12000 rpm for 10 min, the supernatant was discarded, and the precipitate was washed three times with ultrapure water and then vacuum dried at 60℃ and -0.085MPa for 12 h. The precipitate was then ground into powder to obtain the activated medium mesoporous silica. Before use, an anhydrous ethanol-water solution with activated mesoporous silica was mixed in a volume ratio of 1:1 to prepare a dispersion of 10 mg / mL. The dispersion was then sonicated at 190 W power and 39 kHz frequency for 5 min to obtain the activated medium mesoporous silica dispersion.

[0054] Reference solution: Accurately weigh 25 mg of docusate sodium reference standard, place it in a 50 mL volumetric flask, dissolve it in methanol and dilute to the mark, shake well to obtain a 500 μg / mL reference stock solution; accurately measure an appropriate amount of the stock solution and dilute it with 80% methanol-water solution to prepare a series of reference solutions with concentrations of 0.2 μg / mL, 0.5 μg / mL, 2 μg / mL, 5 μg / mL, 10 μg / mL and 20 μg / mL, and prepare them immediately before use.

[0055] Detection: The test sample will be analyzed by high-performance liquid chromatography, specifically as follows: Column: Agilent ZORBAX SB-Aq, 250 mm × 4.6 mm, 5 μm; Detection wavelength: 210nm; Column temperature: 30℃; Column flow rate: 1 mL / min; Injection volume: 20 μL; Running time: 15 minutes; Mobile phase: organic phase: acetonitrile; aqueous phase: mixed ionic liquid system; organic phase to aqueous phase volume ratio 35%:65%; the mixed ionic liquid system is the same as in Example 2.

[0056] Comparative Example 5: A high-performance liquid chromatography (HPLC) detection method, comprising: Sample preparation: Acetaminophen and vitamin C effervescent tablets were accurately weighed, ground into powder, and then added to an ethanol-EDTA composite solvent. The mass-to-volume ratio of the acetaminophen and vitamin C effervescent tablet powder to the ethanol-EDTA composite solvent was 1.5 g: 25 mL (1.5 g of acetaminophen and vitamin C effervescent tablets contained 1-5 mg of docusate sodium). The mixture was ultrasonically dispersed at 190 W power and 39 kHz frequency for 2 min. Then, a bifunctional modified limiting medium mesoporous silica dispersion was added. The volume ratio of the bifunctional modified limiting medium mesoporous silica dispersion to the ethanol-EDTA composite solvent was 3:25 (i.e., 3 mL of the bifunctional modified limiting medium mesoporous silica dispersion was used). The mixture was then subjected to vortexing, centrifugation, and membrane filtration to obtain the test sample. The specific preparation method, vortexing, centrifugation, and membrane filtration of the bifunctional modified limiting medium mesoporous silica were consistent with those in Example 2.

[0057] The specific preparation method of the ethanol-EDTA composite solvent is as follows: Anhydrous ethanol and deionized water are mixed at a volume ratio of 1:18, and then EDTA-2Na (disodium ethylenediaminetetraacetate, CAS: 139-33-3) is added. The mass-volume ratio of EDTA-2Na to the mixed solvent (i.e., the mixed solvent composed of anhydrous ethanol and deionized water) is 0.2g:1000mL. The mixture is magnetically stirred at 350rpm for 8min at room temperature (i.e., 25±1℃) to obtain the final product.

[0058] Reference solution: Accurately weigh 25 mg of docusate sodium reference standard, place it in a 50 mL volumetric flask, dissolve it in methanol and dilute to the mark, shake well to obtain a 500 μg / mL reference stock solution; accurately measure an appropriate amount of the stock solution and dilute it with 80% methanol-water solution to prepare a series of reference solutions with concentrations of 0.2 μg / mL, 0.5 μg / mL, 2 μg / mL, 5 μg / mL, 10 μg / mL and 20 μg / mL, and prepare them immediately before use.

[0059] Detection: The test sample will be analyzed by high-performance liquid chromatography, specifically as follows: Column: Agilent ZORBAX SB-Aq, 250 mm × 4.6 mm, 5 μm; Detection wavelength: 210nm; Column temperature: 30℃; Column flow rate: 1 mL / min; Injection volume: 20 μL; Running time: 15 minutes; Mobile phase: organic phase: acetonitrile; aqueous phase: mixed ionic liquid system; organic phase to aqueous phase volume ratio 35%:65%; the mixed ionic liquid system is the same as in Example 2.

[0060] Comparative Example 6: A high-performance liquid chromatography (HPLC) detection method, comprising: Sample preparation: The steps are the same as in Example 2.

[0061] Reference solution: Accurately weigh 25 mg of docusate sodium reference standard, place it in a 50 mL volumetric flask, dissolve it in methanol and dilute to the mark, shake well to obtain a 500 μg / mL reference stock solution; accurately measure an appropriate amount of the stock solution and dilute it with 80% methanol-water solution to prepare a series of reference solutions with concentrations of 0.2 μg / mL, 0.5 μg / mL, 2 μg / mL, 5 μg / mL, 10 μg / mL and 20 μg / mL, and prepare them immediately before use.

[0062] Detection: The test sample will be analyzed by high-performance liquid chromatography, specifically as follows: Column: Agilent ZORBAX SB-Aq, 250 mm × 4.6 mm, 5 μm; Detection wavelength: 210nm; Column temperature: 30℃; Column flow rate: 1 mL / min; Injection volume: 20 μL; Running time: 15 minutes; Mobile phase: Organic phase: acetonitrile; Aqueous phase: mixed ionic liquid system; Organic phase to aqueous phase volume ratio: 35%:65%. The mixed ionic liquid system includes potassium dihydrogen phosphate (KH₂PO₄), tetrapropylammonium chloride, tetrabutylammonium chloride, and hydroxypropyl-β-cyclodextrin (CAS: 128446-35-5), with concentrations of 20 mmol / L, 3 mmol / L, 2 mmol / L, and 5 mmol / L, respectively. The specific preparation method is as follows: First, the corresponding molar amounts of potassium dihydrogen phosphate, tetrapropylammonium chloride, tetrabutylammonium chloride, and hydroxypropyl-β-cyclodextrin are sequentially added to a clean beaker. Then, ultrapure water is added to the beaker (80% of the prepared volume; i.e., if preparing a 1 L mixed ionic liquid system, 800 mL of ultrapure water is added first). The mixture is stirred at 350 rpm for 22 min in a 40 °C water bath. Then, 85% phosphoric acid (color) is added dropwise at a rate of 1.5 mL / min at room temperature. (Spectroscopically pure) water was added dropwise while stirring at 450 rpm until the pH of the solution reached 4 ± 0.05. Then, the pH-adjusted solution was brought to volume with ultrapure water, the stopper was tightened, and the solution was shaken upside down 22 times to ensure complete mixing. Finally, the aqueous phase was filtered through a 0.22 μm aqueous phase filter membrane (polyethersulfone PES or cellulose acetate-nitrocellulose mixed ester MCE), the filtrate was collected, and ultrasonically degassed for 17.5 min at room temperature, 220 W power, and 39 kHz frequency to obtain the final product.

[0063] The detection results of Examples 1 to 3 and Comparative Examples 1 to 6 are shown in the table below:

[0064] As shown in the table above, the present invention addresses the problems of high matrix interference and low recovery rate in traditional pretreatment methods by using bifunctional modified mesoporous silica as the limiting medium, which possesses both hydrophilic exclusion on the outer surface and hydrophobic adsorption on the inner surface. The mixed alcohol-EDTA solvent treatment perfectly matches the amphiphilic structure of sodium docusate, improving extraction efficiency and eliminating metal ion interference. The imidazole ionic liquid combines ion-pairing and silanol masking effects, resulting in more symmetrical peaks, lower background noise, and higher separation. Through the synergistic effect of the methods described in the embodiments, the present invention significantly improves the extraction efficiency, purification level, and chromatographic separation performance of sodium docusate, thereby achieving high sensitivity, good accuracy, and good durability in the detection of sodium docusate.

Claims

1. A high-performance liquid chromatography method for the detection of sodium docusate, characterized in that: include: Sample preparation: Accurately weigh and grind acetaminophen and vitamin C effervescent tablets into powder, add mixed alcohol-EDTA composite solvent, and ultrasonically disperse; Then, add the bifunctional modified limiting medium mesoporous silica dispersion, and perform vortex oscillation, centrifugation, and membrane filtration in sequence to obtain the test sample; Detection: The test sample was analyzed by high performance liquid chromatography. The mobile phase included an organic phase and an aqueous phase. The organic phase was acetonitrile with a volume percentage of 30%–40%, and the aqueous phase was a mixed ionic liquid system. The column flow rate was 0.8–1.2 mL / min, the column temperature was 30±2℃, the detection wavelength was 210±2 nm, the injection volume was 18–22 μL, and the run time was 15±0.5 min.

2. The high-performance liquid chromatography method for detecting sodium docusate content according to claim 1, characterized in that: The specific preparation method of the mixed alcohol-EDTA composite solvent is as follows: anhydrous ethanol, tert-butanol and deionized water are mixed in a volume ratio of 0.95-1.05:0.95-1.05:17.1-18.9, and then EDTA-2Na is added. The mass-volume ratio of EDTA-2Na to the mixed solvent is 0.2g:1000mL. The mixture is magnetically stirred at 300-400rpm for 7-9min at room temperature to obtain the final product.

3. A high-performance liquid chromatography method for detecting sodium docusate content according to claim 1 or 2, characterized in that: The mass-to-volume ratio of the acetaminophen vitamin C effervescent tablet powder to the mixed alcohol-EDTA composite solvent is 1.5g:25mL; the ultrasonic dispersion is specifically performed by ultrasonication at a power of 180-200W and a frequency of 38-40kHz for 1.5-2.5min.

4. A high-performance liquid chromatography method for detecting sodium docusate content according to claim 2 or 3, characterized in that: The specific preparation method of the bifunctional modified limiting medium mesoporous silica is as follows: First, the mesoporous silica is activated and then added to anhydrous toluene. The mixture is stirred at 280–320 rpm for 28–32 min under a nitrogen atmosphere. Then, octadecyltrichlorosilane is added, and the mixture is stirred at 280–320 rpm for 3.5–4.5 h under a nitrogen atmosphere at 78–82 °C for 3.5–4.5 h. The mass-to-volume ratio of mesoporous silica, anhydrous toluene, and octadecyltrichlorosilane is 1 g: 100 mL: 2 mL. After stirring, the mixture is heated at 11500–12500 °C. Centrifuge at rpm for 9–11 min, discard the supernatant, wash the precipitate 3–4 times with anhydrous toluene, and vacuum dry at 58–62 °C and -0.08–-0.09 MPa for 11.5–12.5 h to obtain modified mesoporous silica. Then, add anhydrous toluene to the modified mesoporous silica and stir at 280–320 rpm for 28–32 min under nitrogen atmosphere. Next, add γ-glycidoxypropyltrimethoxysilane and stir at 300–400 rpm under nitrogen atmosphere at 108–112 °C. The mixture was rapidly refluxed and stirred for 5.5–6.5 h. The mass-to-volume ratio of modified mesoporous silica, anhydrous toluene, and γ-glycidoxypropyltrimethoxysilane was 1 g:100 mL:3 mL. After stirring, the mixture was centrifuged at 11500–12500 rpm for 9–11 min. The supernatant was discarded, and the precipitate was washed 4–5 times with anhydrous ethanol. The precipitate was then vacuum-dried at 58–62 °C and -0.08–-0.09 MPa for 11.5–12.5 h to obtain the activated intermediate. Finally, 0.1 mol of the activated intermediate was added... In a 1 / L PEG-2000 aqueous solution, the mixture was stirred at 350–450 rpm at 58–62 °C for 3.5–4.5 h. The mass-to-volume ratio of the activated intermediate to the PEG-2000 aqueous solution was 1 g: 100 mL. After stirring, the mixture was centrifuged at 11500–12500 rpm for 9–11 min. The supernatant was discarded, and the precipitate was washed 3–4 times with ultrapure water. The precipitate was then vacuum dried at 58–62 °C and -0.08–-0.09 MPa for 11.5–12.5 h and ground into powder to obtain the final product.

5. The high-performance liquid chromatography method for detecting sodium docusate content according to claim 4, characterized in that: The specific steps for activating the mesoporous silica are as follows: vacuum drying the mesoporous silica at 118-122℃ and -0.08--0.09MPa for 11.5-12.5 hours.

6. The high-performance liquid chromatography method for detecting sodium docusate content according to claim 4, characterized in that: The specific preparation method of the bifunctional modified limiting medium mesoporous silica dispersion is as follows: before use, anhydrous ethanol-water solution with bifunctional modified limiting medium mesoporous silica is mixed in a volume ratio of 1:1 to prepare a dispersion of 10 mg / mL, and then sonicated at 180-200 W power and 38-40 kHz frequency for 4.5-5.5 min to obtain the dispersion.

7. The high-performance liquid chromatography method for detecting sodium docusate content according to claim 1, characterized in that: In the high-performance liquid chromatography (HPLC) detection, an Agilent ZORBAX SB-Aq column was used, 250 mm × 4.6 mm, 5 μm.

8. The high-performance liquid chromatography method for detecting sodium docusate content according to claim 1, characterized in that: The mixed ionic liquid system includes potassium dihydrogen phosphate, 1-butyl-3-methylimidazolium chloride, 1-methyl-3-octylimidazolium chloride, and hydroxypropyl-β-cyclodextrin, with concentrations of 19.5–20.5 mmol / L, 2.8–3.2 mmol / L, 1.8–2.2 mmol / L, and 4.8–5.2 mmol / L, respectively.

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