A method for the analytical determination of 4-hydroxybutyl vinyl ether

Abstract

This invention relates to the field of analytical chemistry and fine chemical product quality testing technology, and discloses an analytical method for the determination of 4-hydroxybutyl vinyl ether. The method involves mixing the sample to be tested with an end-group stabilizing and protective solution containing a weakly basic buffer component, a peroxide elimination component, and a metal ion complexing component. A hydroxyl-selective derivatizing reagent is then added to form a derivatized product that can be identified by chromatographic detection. An internal standard with similar chromatographic retention behavior and distinguishable detection signals is introduced for correction. Finally, the content is calculated by liquid chromatography or liquid chromatography-mass spectrometry. This method can reduce structural changes of the vinyl ether end groups during pretreatment, enhance the detection response of the target analyte, and improve quantitative consistency in complex organic matrices.

Description

Technical Field

[0001] This invention relates to the field of analytical chemistry and fine chemical product quality testing technology, and discloses an analytical method for the determination of 4-hydroxybutyl vinyl ether. Background Technology

[0002] 4-Hydroxybutylvinyl ether (HBE) is a class of alcohol ether compounds containing both hydroxyl and vinyl ether end groups. It is commonly used in fine chemical synthesis, polymerization modification, as a functional monomer, or as a reactive intermediate. These substances have relatively small molecular weights and are highly polar. The vinyl ether end groups are sensitive to acidic impurities, moisture, peroxides, and metal residues. Hydrolysis, addition, oxidation, or slight polymerization may occur during sample storage, dilution, filtration, injection, and detection. Current quality control methods typically involve directly diluting 4-hydroxybutylvinyl ether samples with organic solvents, performing simple filtration, and then detecting them in a gas chromatography or liquid chromatography system. The target peak is then identified based on retention time, and the content is calculated using external standard, normalization, or internal standard methods. This method is concise and suitable for finished samples with few components, a stable matrix, and a high target analyte content. However, its pretreatment process usually does not include protective measures for the vinyl ether end groups, nor does it specifically address the weak response or peak instability caused by the hydroxyl group.

[0003] In relatively similar conventional technical solutions, gas chromatography typically relies on the sample evaporating into the column and separating according to differences in boiling point and polarity, followed by peak area recording using a flame ionization detector or thermal conductivity detector. Liquid chromatography typically uses reversed-phase columns, hydrophilic interaction columns, or mixed-mode columns, with an aqueous and organic mobile phase to separate 4-hydroxybutylvinyl ether, 1,4-butanediol, hydroxybutyraldehyde, butanediol monoether byproducts, and stabilizer residues. Because 4-hydroxybutylvinyl ether lacks a strong UV absorption structure, its response is weak when directly detected using conventional UV light. When using differential refractive index or evaporative light scattering, the detection results are easily affected by mobile phase composition, solvent background, and matrix residues. Some methods employ derivatization to enhance the detection signal; however, existing derivatization methods usually react directly with the hydroxyl group, failing to control the effects of slight acidity, moisture, metal ions, or oxidizing impurities on the vinyl ether end groups before derivatization. Therefore, the target analyte may have already undergone structural changes before derivatization.

[0004] The main technical problem with existing analytical methods is that when 4-hydroxybutylvinyl ether (4-HBE) is determined in complex organic matrices, the vinyl ether end groups are easily degraded by trace amounts of acid, peroxides, metal ions, or moisture during pretreatment and detection. Furthermore, its hydroxyl structure leads to insufficient direct detection response and its retention behavior is easily interfered with by polar impurities, resulting in the target peak area not accurately reflecting the original 4-HBE content in the sample. This problem cannot be solved simply by changing the chromatographic column or adjusting the detector, as the target ether may have undergone chemical structural changes before entering chromatographic separation; nor can it be solved solely by ordinary internal standard correction, as the internal standard can only correct for injection and instrument fluctuations, not compensate for chemical losses of the target ether during sample processing. Therefore, it is necessary to establish an analytical method that integrates vinyl ether end group stability, enhanced hydroxyl response, and internal standard process correction to ensure that the measured results reflect the true content of 4-HBE in the sample. Summary of the Invention

[0005] To address the shortcomings of existing technologies in the determination of 4-hydroxybutylvinyl ether in complex organic matrices, such as susceptibility to structural changes induced by trace amounts of acid, peroxides, metal ions, or moisture, insufficient direct detection response due to the hydroxyl structure, and susceptibility to interference from polar impurities in retention behavior, which prevent the target peak signal from accurately reflecting the original content of 4-hydroxybutylvinyl ether in the sample, this invention provides an analytical method for the determination of 4-hydroxybutylvinyl ether.

[0006] To address the aforementioned technical problems, this invention provides an analytical method for determining 4-hydroxybutylvinyl ether, comprising the following technical features: mixing the sample to be tested with an end-group stabilizing and protecting solution to obtain a stabilized sample solution, wherein the end-group stabilizing and protecting solution comprises a weakly basic buffer component, a peroxide elimination component, and a metal ion complexing component; adding a hydroxyl-selective derivatizing reagent to the stabilized sample solution to form a derivatized product that can be chromatographically detected and identified by the hydroxyl groups of 4-hydroxybutylvinyl ether, thereby obtaining a derivatized sample solution; adding an internal standard that has similar chromatographic retention behavior to 4-hydroxybutylvinyl ether and whose detection signal is distinguishable to the sample to be tested, the stabilized sample solution, or the derivatized sample solution to obtain an internal standard correction sample solution; performing chromatographic separation and detection on the internal standard correction sample solution, collecting the target peak signal corresponding to the derivatized product and the internal standard peak signal corresponding to the internal standard, and calculating the content of 4-hydroxybutylvinyl ether in the sample to be tested based on the correspondence between the target peak signal and the internal standard peak signal.

[0007] The 4-hydroxybutylvinyl ether molecule contains both vinyl ether terminal groups and aliphatic hydroxyl groups. Vinyl ether terminal groups are prone to addition, hydrolysis, oxidation, or polymerization under slightly acidic, oxidizing, or metal ion-involved conditions. The aliphatic hydroxyl groups, in turn, cause strong hydrogen bonding and weak direct detection response in polar systems. This scheme maintains the sample processing system in an environment unfavorable to the induction reaction of vinyl ether terminal acids through a weakly basic buffer component, reduces the inductive effect of residual oxidants on the vinyl ether terminal groups through a peroxide elimination component, and reduces side reactions involving metal ions through a metal ion complexing component, thus stabilizing the target analyte before derivatization. Subsequently, a hydroxyl-selective derivatizing reagent selectively derivatizes the hydroxyl groups in 4-hydroxybutylvinyl ether, transforming the target analyte from a small molecule with a weak direct response into a chromatographically detectable derivatized product. The internal standard exhibits similar chromatographic retention behavior and distinguishable detection signals to 4-hydroxybutylvinyl ether, undergoing the same or similar pretreatment and detection procedures as the sample, and is used to establish the correspondence between the target peak signal and the internal standard peak signal. The above process is carried out in the order of stabilization, derivatization, internal standard correction and chromatographic separation and detection. Each step is connected to the next, so that chemical stability control, response identification and quantitative correction are in the same measurement process.

[0008] Furthermore, in the above technical solution, the weakly alkaline buffer component in the end-group stabilizing protective liquid is selected from one or more of amine buffer components, ammonium salt buffer components, carbonate buffer components, and borate buffer components; the peroxide elimination component is selected from one or more of sulfites, thiosulfates, ascorbic acid salts, and hindered phenolic compounds; and the metal ion complexing component is selected from one or more of aminocarboxylic acid complexing agents, hydroxycarboxylic acid complexing agents, phosphonic acid complexing agents, and polyamine complexing agents.

[0009] In practice, amine buffer components, ammonium salt buffer components, carbonate buffer components, and borate buffer components can all serve as components of a weakly basic buffer system, preventing the sample from being in a state that promotes the induction of vinyl ether terminal acid reactions during dilution, mixing, and settling. Sulfites, thiosulfates, ascorbic acid salts, and hindered phenolic compounds can participate in the consumption of oxidative residues or the termination of free radical chain processes, reducing the impact of peroxides on vinyl ether terminal groups. Aminocarboxylic acid complexing agents, hydroxycarboxylic acid complexing agents, phosphonic acid complexing agents, and polyamine complexing agents can form complexes with metal ions, reducing the degree of free participation of metal ions in the sample system. When these three types of components coexist in the terminal group stabilizing and protecting solution, the sample treatment system simultaneously covers three sources of influence: acid-induced, oxidation-induced, and metal ion-induced, forming a foundation for stabilization treatment targeting vinyl ether terminal groups.

[0010] Furthermore, in the above technical solution, the hydroxyl-selective derivatizing agent is a derivatizing agent capable of undergoing esterification, carbamate esterification, carbonate esterification, or silanization reactions with aliphatic hydroxyl groups, and the derivatizing agent contains ultraviolet absorbing groups, fluorescent responsive groups, or mass spectrometry-recognizable fragment groups.

[0011] In practice, the aliphatic hydroxyl groups in 4-hydroxybutylvinyl ether can serve as derivatization reaction sites, forming corresponding derivatized products with hydroxyl-selective derivatizing reagents capable of esterification, carbamate esterification, carbonate esterification, or silanization. When the derivatizing reagent contains UV-absorbing groups, fluorescent responsive groups, or mass spectrometry-recognizable fragment groups, the derivatized target analyte can generate a detection signal distinct from that of free small molecules in chromatographic detection. This treatment does not alter the end groups of the vinyl ether as the basis for target structure recognition; rather, it utilizes the reactivity of the hydroxyl groups in the molecule to introduce detectable recognition units, allowing the target analyte to enter a recognizable and integrable chromatographic detection state after end group stabilization.

[0012] Furthermore, in the above technical solution, the internal standard is selected from one of isotopically labeled 4-hydroxybutylvinyl ether, isotopically labeled hydroxyalkylvinyl ether, structurally similar hydroxy ether compounds, and structurally similar vinyl ether compounds, and the internal standard and 4-hydroxybutylvinyl ether form an internal standard derivative product with distinguishable detection signals under the same derivatization conditions.

[0013] In practice, isotopically labeled 4-hydroxybutylvinyl ether has a high structural correspondence with the target analyte. Isotopically labeled hydroxyalkylvinyl ethers, structurally similar hydroxy ether compounds, and structurally similar vinyl ether compounds exhibit similar chromatographic retention and derivatization behaviors to the target analyte, allowing them to undergo sample stabilization, derivatization, and detection processes alongside the target analyte. The internal standard forms an internal standard derivatized product under the same derivatization conditions, and this product has a distinguishable detection signal from the derivatized product of 4-hydroxybutylvinyl ether. This allows the target peak signal and the internal standard peak signal to be collected separately during the same chromatographic separation and detection process. Through this setup of similar processing behaviors and distinguishable signals, the internal standard can be used to characterize common fluctuations during sample processing and instrument detection.

[0014] Furthermore, in the above technical solution, the chromatographic separation and detection adopts liquid chromatography or liquid chromatography-mass spectrometry, and the chromatographic separation and detection adopts chromatographic conditions capable of separating 4-hydroxybutylvinyl ether derivatives, internal standards or internal standard derivatives, 1,4-butanediol derivatives, hydroxybutyraldehyde derivatives, butanediol monoether derivatives and stabilizer residues.

[0015] In practice, liquid chromatography (LC) can separate derivatives based on differences in polarity, hydrophobicity, hydrogen bonding ability, and spatial structure. LC-MS can further identify derivatives by utilizing identifiable fragments or differences in mass response. 4-hydroxybutylvinyl ether derivatives, internal standards or their derivatives, 1,4-butanediol derivatives, hydroxybutyraldehyde derivatives, butanediol monoether derivatives, and stabilizer residues differ in their derivatization groups, number of hydroxyl groups, ether bond structure, or residue properties. After separation under chromatographic conditions, they can form corresponding retention behaviors and detection signals. This chromatographic separation and detection step follows the aforementioned stabilization and derivatization steps, allowing the processed target analyte and related impurities to be distinguished within the same detection system.

[0016] Furthermore, in the above technical solution, the end-group stabilizing protective liquid also includes an aqueous dilution medium and an organic co-solvent medium. The weakly alkaline buffer component is dissolved in the aqueous dilution medium. The peroxide elimination component and the metal ion complexing component are dispersed or dissolved in the mixed medium formed by the aqueous dilution medium and the organic co-solvent medium. The sample to be tested is mixed with the end-group stabilizing protective liquid and then subjected to solid-liquid separation or membrane filtration.

[0017] In practice, the aqueous dilution medium provides a dissolution environment for the weakly basic buffer component, enabling it to play a uniform acid-base regulation role in the sample processing system. The organic solubilizing medium helps 4-hydroxybutyl vinyl ether and organic matrix components form a miscible state with the end-group stabilizing protective solution, allowing the peroxide elimination component and metal ion complexing component to contact oxidizing residues and metal ions in the sample within the mixed medium. After the sample to be tested is mixed with the end-group stabilizing protective solution, solid-liquid separation or membrane filtration is performed to separate insoluble particles, aggregates, or suspended matter from the sample solution entering the chromatographic detection, allowing subsequent derivatization and chromatographic separation detection to be carried out in a more homogeneous liquid phase system.

[0018] Furthermore, in the above technical solution, the hydroxyl-selective derivatizing reagent is prepared into a derivatization reaction solution with an anhydrous organic solvent before the derivatization reaction. After the stabilized sample solution is mixed with the derivatization reaction solution, a binding acid component or a catalytic component is added. The binding acid component is selected from one or more of tertiary amine compounds, pyridine compounds, and carbonate compounds. The catalytic component is selected from one or more of acylation catalysts, organic base catalysts, and silanization catalysts.

[0019] In practice, anhydrous organic solvents provide a derivatization reaction medium with less water interference for the hydroxyl-selective derivatization reagent, reducing the possibility of water competing with the derivatization reagent for the reaction. After the stabilized sample solution is mixed with the derivatization reaction solution, the acid-binding component can accept acidic byproducts or intermediate acidic components generated during the derivatization process, keeping the derivatization reaction system in a state suitable for hydroxyl derivatization; the catalytic component can promote hydroxyl derivatization processes such as acylation, carbonate esterification, carbamate esterification, or silanization. Tertiary amine compounds, pyridine compounds, and carbonate compounds serve as acid-binding components, while acylation catalysts, organic base catalysts, and silanization catalysts serve as catalytic components. Together with the aforementioned end-group stabilization treatment, they define the actual working mode of the derivatization reaction.

[0020] Furthermore, in the above technical solution, the internal standard is added to the test sample before mixing with the end-group stabilizing and protective solution, or is added to the stabilizing sample solution before mixing with the hydroxyl-selective derivatizing reagent. The internal standard and 4-hydroxybutyl vinyl ether undergo stabilization and derivatization treatments together.

[0021] In practice, when the internal standard is added before the sample to be tested is mixed with the end-group stabilizing and protective solution, it can undergo the complete process of sample stabilization, derivatization, and chromatographic separation and detection along with the target analyte. When the internal standard is added before the stabilized sample solution is mixed with the hydroxyl-selective derivatizing reagent, it can undergo the derivatization and subsequent detection processes along with the target analyte. Since the internal standard and 4-hydroxybutylvinyl ether have similar chromatographic retention behaviors and distinguishable detection signals, and can form internal standard derivatized products under the same derivatization conditions, their response relationship when undergoing stabilization and derivatization treatments together can reflect the changes in sample transfer, derivatization reaction, and detection response in the same batch of treatments.

[0022] Furthermore, in the above technical solution, the liquid chromatography detection uses a reversed-phase column, a hydrophilic interaction column, or a mixed-mode column for separation. The mobile phase includes an aqueous phase component and an organic phase component. The aqueous phase component contains a volatile buffer salt or an organic acid salt, and the organic phase component is selected from one or more of methanol, acetonitrile, and isopropanol.

[0023] In practice, reversed-phase columns can achieve retention separation based on differences in the hydrophobicity of derivatized products, hydrophilic interaction columns can separate based on differences in polarity and hydrogen bonding caused by hydroxyl groups, ether bonds, and derivatized groups, and mixed-mode columns can combine multiple retention effects to distinguish target derivatized products and related impurities. The aqueous and organic components in the mobile phase jointly regulate the distribution of target derivatized products, internal standards or internal standard derivatized products, and related impurities between the stationary and mobile phases. Volatile buffer salts or organic acid salts maintain the ionic state and peak shape stability in the chromatographic system. Methanol, acetonitrile, and isopropanol, as organic phase components, are used to adjust elution capacity and separation selectivity, ensuring that the liquid chromatography detection matches the aforementioned derivatized sample solution.

[0024] Furthermore, in the above technical solution, the sample to be tested is a finished product of 4-hydroxybutylvinyl ether, a 4-hydroxybutylvinyl ether synthesis reaction solution, a purified intermediate fraction of 4-hydroxybutylvinyl ether, a 4-hydroxybutylvinyl ether storage sample, or an organic matrix sample containing 4-hydroxybutylvinyl ether. The calculation of content includes establishing a correction relationship between 4-hydroxybutylvinyl ether derivatives and internal standards or internal standard derivatives, and using the correction relationship to quantify 4-hydroxybutylvinyl ether in the sample to be tested.

[0025] In practice, 4-hydroxybutylvinyl ether finished products, synthesis reaction solutions, purified intermediate fractions, stored samples, and organic matrix samples containing 4-hydroxybutylvinyl ether may all contain varying degrees of polar impurities, stabilizer residues, reaction byproducts, or interfering components formed during storage. After entering this method, all of these samples are processed according to the procedure of end-group stabilization, selective hydroxyl derivatization, internal standard correction, and chromatographic separation and detection. After establishing the correction relationship between 4-hydroxybutylvinyl ether derivatives and internal standards or internal standard derivatives, this correction relationship is used for the quantification of 4-hydroxybutylvinyl ether in the sample to be tested, allowing for content calculation under the same correction logic for samples from different sources.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0027] 1. After determination using an end-group stabilizing protective solution, a hydroxyl-selective derivatizing reagent, and an internal standard, the sample to be tested is first contacted with a weakly basic buffer component, a peroxide elimination component, and a metal ion complexing component before entering derivatization and chromatographic detection. The acidic traces, oxidizing residues, and metal ions in the sample are controlled to a state that is not easily induced to induce end-group reactions of vinyl ether, thus improving the structural retention of 4-hydroxybutylvinyl ether in the pretreatment stage. Subsequently, the hydroxyl-selective derivatizing reagent forms a derivatized product with the hydroxyl group of the target analyte that can be identified by chromatographic detection, transforming the originally weakly responsive free small molecule into a clearly responsive detection target. The internal standard and the target analyte have similar chromatographic retention behavior and their detection signals are distinguishable. They can both undergo stabilization and derivatization treatments, and the content is calculated from the correspondence between the target peak signal and the internal standard peak signal. The above-mentioned technical means form a continuous determination path of stabilization, derivatization, and correction, which can reduce the superimposed influence of pretreatment degradation, derivatization reaction fluctuations, and injection detection fluctuations on the results, and make the determination of 4-hydroxybutylvinyl ether in finished products, synthetic reaction solutions, purified middle fractions, stored samples, and samples containing organic matrix have better structural authenticity and result consistency.

[0028] 2. Improves the detection and differentiation between 4-hydroxybutylvinyl ether and related impurities. By selecting derivatizing reagents capable of esterification, carbamate esterification, carbonate esterification, or silanization with aliphatic hydroxyl groups, 4-hydroxybutylvinyl ether, 1,4-butanediol, hydroxybutyraldehyde, and butanediol monoethers form derivatized products with varying retention behaviors and detection responses. Combined with reversed-phase columns, hydrophilic interaction columns, or mixed-mode columns, and aqueous phase components containing volatile buffer salts or organic acid salts, and organic phase components containing methanol, acetonitrile, or isopropanol, the target derivatized products, internal standards or internal standard derivatized products, glycol derivatized products, and stabilizer residues can be separated. The aqueous dilution medium and organic solubilizing medium in the end-group stabilizing protection solution also facilitate the homogenization of peroxide-removing components, metal ion-complexing components, and the analyte sample, reducing interference from insoluble substances in subsequent solid-liquid separation or membrane filtration. Therefore, the method can be used for principal component quantification of process samples and quality control samples, and can reduce the influence of co-eluenting, peak tailing and matrix residue on the target peak integral. Detailed Implementation

[0029] The present invention will be further described in detail below with reference to embodiments. Those skilled in the art can reproduce the technical solution of the present invention and achieve its claimed technical effects based on the content disclosed in this specification. It should be noted that the following embodiments are only used to explain the present invention and are not intended to limit the scope of protection of the present invention. Any non-substantial improvements and adjustments made based on the core concept of the present invention should fall within the scope of protection of the present invention.

[0030] Example 1: This example describes an analytical method for the determination of 4-hydroxybutylvinyl ether. The end-group stabilizing protective solution consists of an aqueous dilution medium, an organic solubilizing medium, a weakly basic buffer component, a peroxide elimination component, and a metal ion complexing component. The aqueous dilution medium is purified water, the organic solubilizing medium is acetonitrile, and the volume ratio of purified water to acetonitrile is 60:40. The weakly basic buffer component is a borate buffer component with a concentration of 20 mmol / L and a pH of 8.3. The peroxide elimination component is sodium thiosulfate with a concentration of 2 mmol / L, and the metal ion complexing component is disodium ethylenediaminetetraacetate with a concentration of 1 mmol / L. After mixing all the above components thoroughly, the solution is filtered through a microporous membrane to obtain the end-group stabilizing protective solution.

[0031] The internal standard was deuterated 4-hydroxybutylvinyl ether, prepared as a 100 μg / mL solution in acetonitrile. The hydroxyl-selective derivatizing reagent was p-nitrophenyl chloroformate, prepared as a 10 mmol / L derivatization reaction solution in anhydrous acetonitrile; the acid-binding component was triethylamine, prepared as a 20 mmol / L acid-binding solution in anhydrous acetonitrile. 4-hydroxybutylvinyl ether standards were prepared as standard stock solutions in acetonitrile, and then serially diluted with acetonitrile to multiple concentration levels of working standard solutions. The test samples included finished 4-hydroxybutylvinyl ether samples, 4-hydroxybutylvinyl ether synthesis reaction solutions, purified intermediate fractions of 4-hydroxybutylvinyl ether, 4-hydroxybutylvinyl ether storage samples, or organic matrix samples containing 4-hydroxybutylvinyl ether.

[0032] For the determination, take 1.00 mL of the sample solution to be tested, add 0.20 mL of internal standard solution, mix, then add 2.00 mL of end-group stabilizing protection solution, shake to mix for 1 minute, and let stand for 5 minutes to obtain the stabilized sample solution. Filter the stabilized sample solution through a microporous membrane, take 1.00 mL of the filtrate, add 0.50 mL of derivatization reaction solution and 0.10 mL of basal acid solution, and react at 35°C for 15 minutes to obtain the derivatized sample solution. Dilute the derivatized sample solution to 5.00 mL with the mobile phase to obtain the internal standard calibration sample solution.

[0033] Detection was performed using liquid chromatography-mass spectrometry (LC-MS). A reversed-phase column (100 mm long, 2.1 mm inner diameter, 1.7 μm particle size) was used; the column temperature was 35°C; the mobile phase consisted of an aqueous phase (5 mmol / L ammonium acetate solution) and an organic phase (acetonitrile); gradient elution was employed, with the organic phase volume fraction increasing from 35% at 0 min to 80% at 10 min, before returning to initial equilibrium; the flow rate was 0.30 mL / min, and the injection volume was 5 μL. During detection, the target peak signal corresponding to the 4-hydroxybutylvinyl ether derivative and the internal standard peak signal corresponding to the deuterated 4-hydroxybutylvinyl ether internal standard derivative were collected. A calibration relationship was established between the target peak signal and the internal standard peak signal obtained by the same stabilization, derivatization, and chromatographic detection procedure using the standard working solution. This calibration relationship was then used to calculate the content of 4-hydroxybutylvinyl ether in the sample.

[0034] In the above process, the end-group stabilizing and protective solution first comes into full contact with the sample to be tested, so that the slightly acidic residues, oxidizing residues and free metal ions in the sample are controlled before the derivatization reaction; the hydroxyl-selective derivatizing reagent then undergoes a carbonate reaction with the aliphatic hydroxyl groups in the 4-hydroxybutylvinyl ether molecule to form a derivatized product that can be identified by chromatographic detection; the internal standard and the target analyte undergo stabilization treatment, derivatization treatment and chromatographic detection together, and a quantitative correspondence is formed between the target peak signal and the internal standard peak signal.

[0035] Example 2: The difference between this example and Example 1 is that the weakly alkaline buffer component in the end-group stabilizing solution is replaced by a tris(hydroxymethyl)aminomethane buffer component at a concentration of 20 mmol / L and a pH of 8.3. The volume ratio of purified water to acetonitrile, the concentration of sodium thiosulfate, the concentration of disodium ethylenediaminetetraacetate, the type of internal standard, the derivatization reaction solution, the acid binding solution, the stabilization treatment, the derivatization treatment, and the chromatographic separation and detection conditions in the end-group stabilizing solution are all the same as in Example 1.

[0036] Example 3: The difference between this example and Example 1 is that the peroxide elimination component in the end-group stabilizing solution is replaced by sodium ascorbate at a concentration of 2 mmol / L instead of sodium thiosulfate. The volume ratio of purified water to acetonitrile, the concentration and pH of the borate buffer component, the concentration of disodium ethylenediaminetetraacetate, the type of internal standard, the derivatization reaction solution, the acid binding solution, the stabilization treatment, the derivatization treatment, and the chromatographic separation and detection conditions in the end-group stabilizing solution are all the same as in Example 1.

[0037] Example 4: The difference between this example and Example 1 is that the metal ion complexing component in the end-group stabilizing solution is replaced by sodium citrate at a concentration of 1 mmol / L instead of disodium ethylenediaminetetraacetate. The purified water to acetonitrile volume ratio, borate buffer concentration and pH, sodium thiosulfate concentration, internal standard type, derivatization reaction solution, acid binding solution, stabilization treatment, derivatization treatment, and chromatographic separation and detection conditions in the end-group stabilizing solution are all the same as in Example 1.

[0038] Example 5: The difference between this example and Example 1 is that the hydroxyl-selective derivatizing reagent is replaced with phenyl isocyanate instead of p-nitrophenyl chloroformate, and a derivatization reaction solution with a concentration of 10 mmol / L is prepared using anhydrous acetonitrile. The composition of the end-group stabilizing protection solution, the type of internal standard, the acid-binding solution, the stabilization treatment, and the chromatographic separation and detection conditions are the same as in Example 1. For the derivatization treatment, 1.00 mL of the stabilized sample solution filtrate is taken, 0.50 mL of the phenyl isocyanate derivatization reaction solution and 0.10 mL of the triethylamine acid-binding solution are added, and the reaction is carried out at 35 degrees Celsius for 15 minutes to obtain the derivatized sample solution.

[0039] Example 6: The difference between this example and Example 1 is that the internal standard is replaced by 3-hydroxypropyl vinyl ether instead of deuterated 4-hydroxybutyl vinyl ether, and prepared as an internal standard solution with a concentration of 100 μg / mL using acetonitrile. The composition of the end-group stabilizing protection solution, the derivatization reaction solution, the acid binding solution, the stabilization treatment, the derivatization treatment, and the chromatographic separation and detection conditions are the same as in Example 1. During detection, the target peak signal corresponding to the 4-hydroxybutyl vinyl ether derivatized product and the internal standard peak signal corresponding to the 3-hydroxypropyl vinyl ether internal standard derivatized product were collected, and a correction relationship between the two was established.

[0040] Example 7: The difference between this example and Example 1 is that the timing of adding the internal standard is changed from before mixing the test sample with the end-group stabilizing solution to before mixing the stabilized sample solution with the hydroxyl-selective derivatizing reagent. During the determination, take 1.00 mL of the test sample solution, add 2.00 mL of the end-group stabilizing solution, shake to mix for 1 minute, let stand for 5 minutes and filter. Take 1.00 mL of the filtrate, add 0.20 mL of the internal standard solution, then add 0.50 mL of the derivatization reaction solution and 0.10 mL of the chelating acid solution, and react at 35°C for 15 minutes. The composition of the end-group stabilizing solution, the type of internal standard, the derivatization reaction solution, the chelating acid solution, and the chromatographic separation and detection conditions are all the same as in Example 1.

[0041] Example 8: The difference between this example and Example 1 is that the derivatization temperature was adjusted from 35 degrees Celsius to 25 degrees Celsius. The composition of the end-group stabilizing protection solution, the type of internal standard, the derivatization reaction solution, the acid binding solution, the stabilization time, the derivatization time, and the chromatographic separation and detection conditions are all the same as in Example 1.

[0042] Example 9: The difference between this example and Example 1 is that the derivatization treatment time is adjusted from 15 minutes to 30 minutes. The composition of the end-group stabilizing protection solution, the type of internal standard, the derivatization reaction solution, the acid binding solution, the stabilization treatment, the derivatization treatment temperature, and the chromatographic separation and detection conditions are all the same as in Example 1.

[0043] Example 10: The difference between this example and Example 1 is that the flow rate in the chromatographic separation and detection is adjusted from 0.30 mL / min to 0.25 mL / min. The composition of the end-group stabilizing protection solution, the type of internal standard, the derivatization reaction solution, the acid binding solution, the stabilization treatment, the derivatization treatment, the chromatographic column, the column temperature, the composition of the mobile phase, and the gradient elution conditions are all the same as in Example 1.

[0044] Comparative Example 1: The difference between this comparative example and Example 1 is that sodium thiosulfate is not added to the end-group stabilizing and protecting solution. The volume ratio of purified water to acetonitrile, the concentration and pH of the borate buffer component, the concentration of disodium ethylenediaminetetraacetate, the type of internal standard, the derivatization reaction solution, the acid binding solution, the stabilization treatment, the derivatization treatment, and the chromatographic separation and detection conditions are all the same as in Example 1.

[0045] Comparative Example 2: This comparative example uses a conventional direct dilution method. 1.00 mL of the sample solution was diluted to 5.00 mL with acetonitrile, filtered through a microporous membrane, and directly analyzed by liquid chromatography. No end-group stabilizing agent was added, no hydroxyl-selective derivatization was performed, and no internal standard was added. A reversed-phase column was used, and the mobile phase consisted of an aqueous solution containing 5 mmol / L ammonium acetate and acetonitrile. Gradient elution conditions, column temperature, flow rate, and injection volume were the same as in Example 1. The content of 4-hydroxybutylvinyl ether in the sample was calculated using the external standard method.

[0046] Comparative Example 3: The difference between this comparative example and Example 1 is that the pH of the end-group stabilizing solution was adjusted to 6.0. The volume ratio of purified water to acetonitrile, the concentration of borate buffer component, the concentration of sodium thiosulfate, the concentration of disodium ethylenediaminetetraacetate, the type of internal standard, the derivatization reaction solution, the acid binding solution, the stabilization treatment, the derivatization treatment, and the chromatographic separation and detection conditions in the end-group stabilizing solution are all the same as in Example 1.

[0047] Comparative Example 4: The difference between this comparative example and Example 1 is that, after mixing and filtering the sample with the internal standard and end-group stabilizing solution, no hydroxyl-selective derivatizing reagent or acid-binding component was added. The sample was directly diluted to 5.00 mL with the mobile phase and then analyzed by liquid chromatography-mass spectrometry. The composition of the end-group stabilizing solution, the type of internal standard, the stabilization treatment, and the chromatographic separation and detection conditions were all the same as in Example 1.

[0048] Test method:

[0049] Using the same batch of 4-hydroxybutylvinyl ether finished product samples as the base samples, 1,4-butanediol, hydroxybutyraldehyde, butanediol monoether substances and stabilizer residue standards were added to prepare simulated organic matrix samples.

[0050] All examples and comparative examples used samples of the simulated organic matrix for measurement.

[0051] Spiked recoveries were calculated using known amounts of 4-hydroxybutylvinyl ether standard.

[0052] The relative standard deviation of parallel determinations was calculated by preparing and determining six copies of the same sample consecutively.

[0053] Resolution was calculated based on the chromatographic separation results between the target peak and the 1,4-butanediol-related peak;

[0054] The signal-to-noise ratio of low-content samples was determined using low-content samples that simulated organic matrix samples after dilution.

[0055] The relative deviation of the content of stored samples is calculated as the absolute value of the difference between the content measured after the same sample has been stored in the dark and the initially measured content.

[0056] The test results are shown in Table 1.

[0057] Table 1 Performance test results of each embodiment and comparative example.

[0058]

[0059] Table 1 shows that, under the conditions of the combined use of end-group stabilizing protective solution, hydroxyl-selective derivatizing reagent, internal standard, and liquid chromatography-mass spectrometry (LC-MS) detection in Example 1, the spiked recovery rate was 99.1%, the relative standard deviation of parallel determinations was 0.72%, the resolution between the target peak and the 1,4-butanediol-related peak was 2.35, the signal-to-noise ratio of low-content samples was 46, and the absolute value of the relative deviation of the content of stored samples was 0.8%. These results indicate that the end-group stabilizing protective solution, composed of a weakly basic buffer component, a peroxide elimination component, and a metal ion complexing component, can control the structural changes of the vinyl ether end groups due to trace amounts of acid, residual oxidants, and metal ions in the early stages of sample processing; the hydroxyl-selective derivatizing reagent causes the target analyte to form a derivatized product that can be identified by chromatographic detection; and the internal standard, after undergoing the same processing procedure as the target analyte, can correct for fluctuations during pretreatment and detection. The above steps, arranged in the order of stabilization, derivatization, and correction detection, avoid the problem that a single detection method cannot simultaneously cover chemical stability, response intensity, and quantitative correction.

[0060] Example 2 replaced the weakly basic buffer component with a tris(hydroxymethyl)aminomethane buffer component; Example 3 replaced the peroxide elimination component with sodium ascorbate; and Example 4 replaced the metal ion complexing component with sodium citrate. The spiked recoveries of all three remained above 97.9%, and the relative standard deviations of parallel determinations did not exceed 1.26%. These results indicate that, provided the end-group stabilizing protectant maintains the simultaneous presence of the three functions of weakly basic buffering, peroxide elimination, and metal ion complexation, the components can be replaced within permissible categories while still maintaining control over the pretreatment stability of 4-hydroxybutylvinyl ether. In Example 5, after replacing the hydroxyl-selective derivatizing reagent with phenyl isocyanate, the spiked recovery was 97.6%, and the signal-to-noise ratio for low-content samples was 44. This indicates that a derivatizing reagent capable of undergoing carbamate esterification with aliphatic hydroxyl groups and introducing detectable recognition groups can also achieve target analyte response recognition. In Example 6, after replacing the internal standard with 3-hydroxypropyl vinyl ether, the spiked recovery rate was 98.0%, and the relative standard deviation of parallel determinations was 1.51%, indicating that internal standards with similar structures and distinguishable detection signals can be used to establish a correction relationship between the target peak signal and the internal standard peak signal.

[0061] Example 7 changed the timing of internal standard addition, Example 8 changed the derivatization temperature, Example 9 changed the derivatization time, and Example 10 changed the chromatographic separation and detection flow rate. The spiked recoveries in all examples were between 98.6% and 99.0%, the relative standard deviations of parallel determinations were all less than 1.22%, and the resolution between the target peak and the 1,4-butanediol-related peak was not less than 2.28. These results indicate that, while maintaining consistency in the end-group stabilizing solution, hydroxyl-selective derivatization reagent, and internal standard correction system, adjusting the timing of internal standard addition, derivatization temperature, derivatization time, and flow rate within the set conditions still allows the method to maintain the detection and identification of the target derivatized product and the chromatographic differentiation of related impurities. Example 10 achieved a resolution of 2.40 at a lower flow rate, indicating that, provided the sample has undergone stabilization and derivatization, the separation between the target peak and polar-related impurities can be further improved by adjusting the flow rate during chromatographic elution.

[0062] Comparative Example 1, with only the peroxide elimination component removed and all other conditions the same as in Example 1, showed a decrease in spiked recovery to 89.5%, an increase in the relative standard deviation of parallel determinations to 5.80%, and an increase in the absolute value of the relative deviation of the stored sample content to 8.7%. This result indicates that in the presence of residual oxidizing background in the sample, the weakly basic buffer component and the metal ion complexing component alone are insufficient to stabilize the vinyl ether end groups. The peroxide elimination component is a key component in the end-group stabilizing and protecting solution for maintaining the structural authenticity of the target analyte. Comparative Example 2 used the conventional direct dilution assay method without end-group stabilization, hydroxyl selective derivatization, or internal standard correction. The spiked recovery was 82.3%, the resolution was 0.92, and the signal-to-noise ratio for low-content samples was 8. This demonstrates that the direct detection method cannot simultaneously address the structural changes, low response, and co-eluenting of related impurities during target analyte processing in complex organic matrices.

[0063] Comparative Example 3 adjusted the pH of the end-group stabilizing solution to 6.0, with other conditions the same as in Example 1. The spiked recovery rate decreased to 75.4%, and the absolute value of the relative deviation of the stored sample content increased to 18.6%. This result indicates that the end-group stabilizing solution needs to be kept weakly alkaline to avoid changes in the vinyl ether end groups induced by acidic conditions during sample processing. Even if the peroxide elimination component, metal ion complexing component, derivatizing reagent, and internal standard are still present, deviations in pH will still cause loss of the target analyte before derivatization. Comparative Example 4 omitted the hydroxyl-selective derivatization step, with other conditions the same as in Example 1. The signal-to-noise ratio of the low-content sample was only 7, and the resolution between the target peak and the 1,4-butanediol-related peak was 1.05, indicating that end-group stabilization and internal standard correction alone cannot solve the problems of insufficient direct detection response and insufficient separation from polarity-related impurities of 4-hydroxybutylvinyl ether. The above comparisons show that the technical effect of this method comes from the continuous combination of end-group stabilization protection, hydroxyl-selective derivatization, and internal standard correction detection, rather than a simple substitution of any single measure.

Claims

1. A method for the analytical determination of 4-hydroxybutylvinyl ether, characterized in that, Includes the following steps: The sample to be tested is mixed with an end-group stabilizing and protective solution to obtain a stabilized sample solution. The end-group stabilizing and protective solution includes a weakly alkaline buffer component, a peroxide elimination component, and a metal ion complexing component. A hydroxyl-selective derivatizing reagent is added to the stabilized sample solution to form a derivatized product that can be detected by chromatography, thereby obtaining a derivatized sample solution; An internal standard with similar chromatographic retention behavior and distinguishable detection signal to 4-hydroxybutylvinyl ether is added to the sample to be tested, the stabilized sample solution, or the derivatized sample solution to obtain an internal standard calibration sample solution. The internal standard calibration sample solution is subjected to chromatographic separation and detection. The target peak signal corresponding to the derivative and the internal standard peak signal corresponding to the internal standard are collected. The content of 4-hydroxybutyl vinyl ether in the sample to be tested is calculated based on the correspondence between the target peak signal and the internal standard peak signal.

2. The analytical method for determining 4-hydroxybutylvinyl ether according to claim 1, characterized in that, The weakly alkaline buffer component in the end-group stabilizing protective solution is selected from one or more of amine buffer components, ammonium salt buffer components, carbonate buffer components, and borate buffer components; the peroxide elimination component is selected from one or more of sulfites, thiosulfates, ascorbic acid salts, and hindered phenolic compounds; and the metal ion complexing component is selected from one or more of aminocarboxylic acid complexing agents, hydroxycarboxylic acid complexing agents, phosphonic acid complexing agents, and polyamine complexing agents.

3. The analytical method for determining 4-hydroxybutylvinyl ether according to claim 1, characterized in that, The hydroxyl-selective derivatizing agent is a derivatizing agent capable of undergoing esterification, carbamate esterification, carbonate esterification, or silanization reactions with aliphatic hydroxyl groups, and the derivatizing agent contains ultraviolet-absorbing groups, fluorescent responsive groups, or mass spectrometry-recognizable fragment groups.

4. The analytical method for determining 4-hydroxybutylvinyl ether according to claim 1, characterized in that, The internal standard is selected from one of isotopically labeled 4-hydroxybutylvinyl ether, isotopically labeled hydroxyalkylvinyl ether, structurally similar hydroxy ether compounds, and structurally similar vinyl ether compounds, and the internal standard and 4-hydroxybutylvinyl ether form an internal standard derivatized product with distinguishable detection signals under the same derivatization conditions.

5. The analytical method for determining 4-hydroxybutylvinyl ether according to claim 1, characterized in that, The chromatographic separation and detection are performed using liquid chromatography or liquid chromatography-mass spectrometry. The chromatographic separation and detection are performed under chromatographic conditions that can separate 4-hydroxybutylvinyl ether derivatives, internal standards or internal standard derivatives, 1,4-butanediol derivatives, hydroxybutyraldehyde derivatives, butanediol monoether derivatives and stabilizer residues.

6. The analytical method for determining 4-hydroxybutylvinyl ether according to claim 2, characterized in that, The end-group stabilizing and protective solution also includes an aqueous dilution medium and an organic co-solvent medium. The weakly alkaline buffer component is dissolved in the aqueous dilution medium. The peroxide elimination component and the metal ion complexing component are dispersed or dissolved in the mixed medium formed by the aqueous dilution medium and the organic co-solvent medium. The sample to be tested is mixed with the end-group stabilizing and protective solution and then subjected to solid-liquid separation or membrane filtration.

7. The analytical method for determining 4-hydroxybutylvinyl ether according to claim 3, characterized in that, The hydroxyl-selective derivatizing reagent is prepared into a derivatization reaction solution with an anhydrous organic solvent before the derivatization reaction. After the stabilized sample solution is mixed with the derivatization reaction solution, a binding acid component or a catalytic component is added. The binding acid component is selected from one or more of tertiary amine compounds, pyridine compounds and carbonate compounds. The catalytic component is selected from one or more of acylation catalysts, organic base catalysts and silanization catalysts.

8. The analytical method for determining 4-hydroxybutylvinyl ether according to claim 4, characterized in that, The internal standard is added to the test sample before mixing with the end-group stabilizing solution, or to the stabilized sample solution before mixing with the hydroxyl-selective derivatizing reagent. The internal standard and 4-hydroxybutyl vinyl ether undergo stabilization and derivatization treatments together.

9. The analytical method for determining 4-hydroxybutylvinyl ether according to claim 5, characterized in that, The liquid chromatography detection uses a reversed-phase column, a hydrophilic interaction column, or a mixed-mode column for separation. The mobile phase includes an aqueous phase component and an organic phase component. The aqueous phase component contains volatile buffer salts or organic acid salts, and the organic phase component is selected from one or more of methanol, acetonitrile, and isopropanol.

10. The analytical method for determining 4-hydroxybutylvinyl ether according to any one of claims 1 to 9, characterized in that, The sample to be tested is a finished product of 4-hydroxybutylvinyl ether, a 4-hydroxybutylvinyl ether synthesis reaction solution, a purified middle fraction of 4-hydroxybutylvinyl ether, a 4-hydroxybutylvinyl ether storage sample, or an organic matrix sample containing 4-hydroxybutylvinyl ether. The calculation of content includes establishing a correction relationship between 4-hydroxybutylvinyl ether derivatives and internal standards or internal standard derivatives, and using the correction relationship to quantify 4-hydroxybutylvinyl ether in the sample to be tested.

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