Determination method for sensitizing substance of polyurethane elastomer wearing product

Abstract

The invention provides a method for measuring sensitizing substances of a polyurethane elastomer wearing product. The method comprises the following steps: preparing a standard working solution; shearing the sample, and freezing and crushing the sample through liquid nitrogen to obtain crushed powder; adding the crushed powder into an acetonitrile solution, carrying out vortex mixing, and carrying out ultrasonic extraction in ultrasonic equipment to obtain an ultrasonic extract; eluting and adsorbing the ultrasonic extract through a mixed strong anion exchange reversed-phase solid-phase extraction column, and collecting purified effluent to obtain liquid to be detected; and performing chromatographic detection on the to-be-detected liquid. The liquid nitrogen freezing and crushing are adopted, so that the swelling of the material and the release of heat-sensitive interferents are avoided, and the stability of the components is ensured; the solvent permeation and release are enhanced through the solubility of acetonitrile and the cavitation effect of ultrasonic waves, so that the extraction efficiency and selectivity are improved; purification is carried out through a mixed type strong anion exchange reversed-phase solid-phase extraction column, and interference of a plasticizer and an antioxidant is reduced through selective adsorption.

Description

Technical Field

[0001] This disclosure relates to the technical field of electronic product testing, and in particular to a method for determining sensitizing substances in polyurethane elastomer wearable products. Background Technology

[0002] Wearable electronic products such as smartwatches, headphones, and health monitoring devices contain allergens. These allergenic chemicals in their materials may pose health risks to wearers through migration or release. Polyurethane elastomers, widely used in wearable electronic products due to their excellent physical properties, may contain residual allergens such as methylenediamine, hexamethylenetetramine, diethanolamine, N,N-dimethylacetamide, 2-toluenediamine, and N,N-dimethylpropylene during synthesis or processing. When these products are in close contact with the skin for extended periods, the release of these allergens is accelerated in sweaty and humid environments, thus exacerbating allergic reactions.

[0003] Different substrates exhibit significant differences in their adsorption and release characteristics for sensitizing substances. When extraction methods involve immersion in organic solvents, non-target interfering substances such as plasticizers and antioxidants may be released during the immersion process, as silicone and TPU are solvent-swellable materials, thus affecting the accuracy of the detection.

[0004] For example, the gas chromatography method for detecting trace amounts of N,N-dimethylformamide in synthetic leather disclosed in prior art CN201410202341.7 involves ultrasonic-assisted methanol extraction to extract trace amounts of residual N,N-dimethylformamide from polyurethane synthetic leather. Qualitative analysis using gas chromatography and quantification using an internal standard method are then employed to determine the N,N-dimethylformamide content in the extract. The accuracy of the method is verified by spiking. However, this method cannot avoid the release of non-target interfering substances, such as plasticizers and antioxidants, during the soaking process, thus affecting the accuracy of the detection. Summary of the Invention

[0005] The purpose of this disclosure is to overcome the shortcomings of the prior art and provide a method for determining sensitizing substances in polyurethane elastomer wearable products that avoids interference from swelling and heat sensitivity, reduces interference from plasticizers and antioxidants, and improves detection sensitivity.

[0006] The purpose of this disclosure is achieved through the following technical solution: A method for determining sensitizing substances in polyurethane elastomer wearable products includes the following steps: Prepare standard working solutions of hexamethylenediamine, hexamethylenetetramine, diethanolamine, N,N-dimethylacetamide, 2-toluenediamine, and N,N-dimethylacrylamide; The sample is sheared, and the sheared sample is placed in a crushing container. The sheared sample is then crushed by liquid nitrogen cryogenic crushing to obtain crushed powder. The pulverized powder is added to an acetonitrile solution and vortexed to obtain an extraction mixture; The extraction mixture is placed in an ultrasonic device for ultrasonic extraction to obtain an ultrasonic extract. The ultrasonic extract was eluted and adsorbed through a mixed strong anion exchange reversed-phase solid-phase extraction column, and the purified effluent was collected to obtain the test solution. The test solution is filtered through a filter membrane and then subjected to chromatographic detection.

[0007] In one embodiment, the sample is sheared, the sheared sample is placed in a pulverizing container, and the sheared sample is cryogenically pulverized using liquid nitrogen to obtain pulverized powder, including the following steps: The sample is cut into small pieces to obtain a cut sample; The sheared sample is placed in a crushing container and immersed in liquid nitrogen for 1-3 minutes to allow the sheared sample to become fully brittle. The embrittled sheared sample was mechanically pulverized under conditions of continuous replenishment of liquid nitrogen to maintain low temperature, with a total pulverization time of 3-5 minutes. Collect the pulverized powder.

[0008] In one embodiment, the frozen sample is pulverized to 100nm-200nm.

[0009] In one embodiment, the vortex mixing time is 2 min to 5 min, and the vortex mixing speed is 2000 r / min to 3000 r / min.

[0010] In one embodiment, the ultrasonic extraction temperature is 38°C-44°C, and the ultrasonic extraction time is 50 min-80 min.

[0011] In one embodiment, the ultrasonic extractant is eluted and adsorbed in a hybrid strong anion exchange reversed-phase solid-phase extraction column to obtain a purified effluent, comprising the following steps: The hybrid strong anion exchange reversed-phase solid-phase extraction column was activated using acetonitrile; The ultrasonic extraction solution was transferred to an activated mixed-type strong anion exchange reversed-phase solid-phase extraction column, and the flow rate was controlled to allow the solution to flow down naturally. Acetonitrile was added to the mixed-type strong anion exchange reversed-phase solid-phase extraction column for elution, and the purified effluent was collected.

[0012] In one embodiment, the preparation of a standard working solution of hexamethylenediamine, hexamethylenetetramine, diethanolamine, N,N-dimethylacetamide, 2-toluenediamine, and N,N-dimethylacrylamide includes the following steps: The accurately weighed hexamethylenediamine, hexamethylenetetramine, diethanolamine, N,N-dimethylacetamide, 2-toluenediamine, and N,N-dimethylacrylamide standard substances were completely dissolved in isopropanol and then diluted to volume to prepare a primary standard stock solution. The primary standard stock solutions of hexamethylenediamine, hexamethylenetetramine, diethanolamine, N,N-dimethylacetamide, 2-toluenediamine, and N,N-dimethylacrylamide were diluted to volume with tetrahydrofuran, dimethyl sulfoxide, or dichloromethane to obtain standard working solutions.

[0013] In one embodiment, before detecting the test solution, the ultrasonic extract is eluted and adsorbed by passing the ultrasonic extract through a solid-phase extraction column. After collecting the purified effluent, the method further includes the following steps: The purified effluent is dried by nitrogen blowing to obtain an effluent mixture; The effluent mixture was redissolved in an acetic acid-acetonitrile solution to obtain the test solution.

[0014] In one embodiment, the pore size of the filter membrane is 0.20 μm-0.25 μm.

[0015] In one embodiment, the chromatographic conditions for the chromatographic detection are as follows: Column: C18 (100 mm, 2.1 μm); Column oven: 40℃; Flow rate: 0.3 mL / min; Injection volume: 5 μL; Mobile phase A: 100% acetonitrile; Mobile phase B: 0.1% formic acid solution.

[0016] Compared with the prior art, this disclosure has at least the following advantages: The aforementioned method for determining sensitizing substances in polyurethane elastomer wearable products employs liquid nitrogen cryogenic pulverization technology for sample pretreatment. This process embrittles and pulverizes the sample at extremely low temperatures, avoiding material swelling and the release of heat-sensitive interfering substances caused by mechanical friction or solvent contact, thus ensuring the representativeness of the sample and the stability of the original components. The method leverages the excellent solubility of acetonitrile in target amine sensitizing substances and enhances solvent penetration and release through the cavitation effect of ultrasound, resulting in high and rapid extraction efficiency. This establishes an efficient and synergistic extraction and purification process, significantly improving the extraction efficiency and selectivity of target amine sensitizing substances. Purification is achieved using a mixed-type strong anion exchange reversed-phase solid-phase extraction column, which selectively adsorbs plasticizers and antioxidants while eluting sensitizing substances, reducing interference from plasticizers and antioxidants and effectively improving the sensitivity of subsequent chromatographic detection. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of this disclosure, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this disclosure and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a flowchart illustrating the operation of a method for determining sensitizing substances in a polyurethane elastomer wearable product according to an embodiment. Figures 2 to 7 The ion extraction diagram is shown in the chromatographic detection example. Detailed Implementation

[0019] To facilitate understanding of this disclosure, a more complete description will be given below with reference to the accompanying drawings, which illustrate preferred embodiments of the present disclosure. However, this disclosure can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure.

[0020] It should be noted that when an element is referred to as being "fixed to" another element, it can be directly attached to the other element or there may be an intervening element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of this disclosure. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0022] To better understand the technical solutions and beneficial effects of this disclosure, the following detailed description is provided in conjunction with specific embodiments: This invention relates to a method for determining sensitizing substances in polyurethane elastomer wearable products, comprising the following steps: preparing standard working solutions of hexamethylenediamine, hexamethylenetetramine, diethanolamine, N,N-dimethylacetamide, 2-toluenediamine, and N,N-dimethylacrylamide; shearing the sample, placing the sheared sample in a pulverizing container, and pulverizing the sheared sample by liquid nitrogen cryogenic pulverization to obtain pulverized powder; adding the pulverized powder to an acetonitrile solution and vortexing to obtain an extraction mixture; subjecting the extraction mixture to ultrasonic extraction in an ultrasonic device to obtain an ultrasonic extract; eluting and adsorbing the ultrasonic extract through a mixed-type strong anion exchange reversed-phase solid-phase extraction column, collecting the purified effluent to obtain the test solution; and filtering the test solution through a filter membrane for chromatographic detection.

[0023] The aforementioned method for determining sensitizing substances in polyurethane elastomer wearable products employs liquid nitrogen cryogenic pulverization technology for sample pretreatment. This process embrittles and pulverizes the sample at extremely low temperatures, avoiding material swelling and the release of heat-sensitive interfering substances caused by mechanical friction or solvent contact, thus ensuring the representativeness of the sample and the stability of the original components. The method leverages the excellent solubility of acetonitrile in target amine sensitizing substances and enhances solvent penetration and release through the cavitation effect of ultrasound, resulting in high and rapid extraction efficiency. This establishes an efficient and synergistic extraction and purification process, significantly improving the extraction efficiency and selectivity of target amine sensitizing substances. Purification is achieved using a mixed-type strong anion exchange reversed-phase solid-phase extraction column, which selectively adsorbs plasticizers and antioxidants while eluting sensitizing substances, reducing interference from plasticizers and antioxidants and effectively improving the sensitivity of subsequent chromatographic detection.

[0024] Please see Figure 1 The present invention provides a method for determining sensitizing substances in a polyurethane elastomer wearable product, comprising the following steps: S101 is used to prepare standard working solutions of hexamethylenediamine, hexamethylenetetramine, diethanolamine, N,N-dimethylacetamide, 2-toluenediamine, and N,N-dimethylacrylamide. It is understood that by preparing standard working solutions using these standard substances, a quantitative baseline is established, providing accurate qualitative and quantitative data for subsequent instrument detection. This ensures the method can simultaneously detect multiple amine-sensitizing substances, improving detection efficiency.

[0025] S103 shears the sample to obtain a sheared sample. The sheared sample is then placed in a pulverizing container and pulverized using liquid nitrogen cryogenic pulverization to obtain a pulverized powder. Understandably, the sample is embrittled in the cryogenic environment of liquid nitrogen, and the mechanical shearing force breaks the sample, avoiding the degradation of heat-sensitive substances or material swelling due to frictional heating. This maintains the stability of the original sample components and prevents the release of plasticizers, antioxidants, and other interfering substances due to thermal effects during room temperature pulverization, thus reducing the introduction of non-target substances at the source.

[0026] S105 involves adding the pulverized powder to an acetonitrile solution and vortexing it to obtain an extraction mixture. It is understood that acetonitrile can efficiently extract polar and moderately polar sensitizers.

[0027] S107 involves placing the extraction mixture into an ultrasonic device for ultrasonic extraction to obtain an ultrasonic extract. The cavitation effect of ultrasound enhances solvent penetration and accelerates the release of the target analyte from the matrix. It is understood that the cavitation effect generated by ultrasound in a liquid can create strong shock waves and microjets, effectively disrupting the physical structure of the polyurethane matrix, allowing acetonitrile solvent to penetrate more fully into the sample, greatly improving the extraction efficiency and rate of sensitizing substances. Simultaneously, the low-temperature environment during the ultrasonic process further prevents the decomposition of heat-sensitive target substances.

[0028] S109 elutes the ultrasonically extracted solution through a mixed-type strong anion exchange reversed-phase solid-phase extraction column, collecting the purified effluent to obtain the analyte. Understandably, the mixed packing material in the mixed-type strong anion exchange reversed-phase solid-phase extraction column selectively adsorbs plasticizers and antioxidants in the sample matrix. Amines, due to their weak interaction with the packing material under these conditions, pass rapidly through the extraction column with the solution in the initial elution phase, reducing interference from plasticizers and antioxidants and effectively improving the sensitivity of subsequent chromatographic detection.

[0029] The test solution described in S111 is filtered through a filter membrane and then subjected to chromatographic detection. It can be understood that chromatographic detection achieves efficient separation based on the differences in the partition coefficients of different substances in the stationary and mobile phases, and, combined with a mass spectrometer detector, provides precise molecular structure information and quantitative data, thereby enabling simultaneous, rapid, and accurate qualitative and quantitative determination and quantification of multiple sensitizing substances such as hexamethylenediamine. The aforementioned method for determining sensitizing substances in polyurethane elastomer wearable products employs liquid nitrogen cryogenic pulverization technology for sample pretreatment. This process embrittles and pulverizes the sample at extremely low temperatures, avoiding material swelling and the release of heat-sensitive interfering substances caused by mechanical friction or solvent contact, thus ensuring the representativeness of the sample and the stability of the original components. The method leverages the excellent solubility of acetonitrile in target amine sensitizing substances and enhances solvent penetration and release through the cavitation effect of ultrasound, resulting in high and rapid extraction efficiency. This establishes an efficient and synergistic extraction and purification process, significantly improving the extraction efficiency and selectivity of target amine sensitizing substances. Purification is achieved using a mixed-type strong anion exchange reversed-phase solid-phase extraction column, which selectively adsorbs plasticizers and antioxidants while eluting sensitizing substances, reducing interference from plasticizers and antioxidants and effectively improving the sensitivity of subsequent chromatographic detection.

[0030] In one embodiment, the sample is sheared, the sheared sample is placed in a pulverizing container, and the sheared sample is cryogenically pulverized using liquid nitrogen to obtain pulverized powder, including the following steps: The sample is cut into small pieces to obtain a cut sample; The sheared sample is placed in a crushing container and immersed in liquid nitrogen for 1-3 minutes to allow the sheared sample to become fully brittle. The embrittled sheared sample was mechanically pulverized under conditions of continuous replenishment of liquid nitrogen to maintain low temperature, with a total pulverization time of 3-5 minutes. The pulverized powder is collected. In this embodiment, the sample is sheared into small pieces, increasing the contact area of ​​the cooling medium and shortening the time required for subsequent liquid nitrogen penetration and heat exchange. This lays the foundation for rapid and uniform deep freezing and improves the overall pretreatment efficiency. Immersing the sample in liquid nitrogen causes it to become fully and uniformly embrittled from the inside out. Its microstructure changes from a highly elastic or viscoelastic state at room temperature to a completely glassy state, and its mechanical properties change from tough to brittle, thus laying an ideal physical basis for subsequent mechanical impact pulverization. Continuous replenishment of liquid nitrogen during the pulverization process maintains a stable ultra-low temperature operating environment, effectively offsetting the heat inevitably generated by high-speed mechanical collisions and friction. This ensures that the temperature of the sample powder is always far below the decomposition threshold of its heat-sensitive components and the softening point of the material itself. By freezing and pulverizing the sample with liquid nitrogen, the thermal decomposition or volatile loss of the target sensitizing substances that may be caused by localized heating is avoided. The original chemical composition of the sample is preserved, and the migration and release of additives such as plasticizers and antioxidants from the matrix, which are aggravated by thermal effects in conventional pulverization, are suppressed. This greatly reduces non-target interfering substances introduced in the pretreatment stage.

[0031] In one embodiment, the frozen sample is pulverized to 100nm-200nm. In this embodiment, the frozen sample is a nanoparticle with a huge specific surface area. The small particle size and uniform distribution of the frozen sample significantly increase the solid-liquid contact specific surface area in the subsequent extraction step, allowing the extraction solvent to penetrate more quickly and completely. This comprehensively improves the extraction efficiency and repeatability of amine sensitizing substances, laying the sample foundation for subsequent ultra-high sensitivity detection methods, thereby accurately quantifying extremely low levels of amine sensitizing substances.

[0032] In one embodiment, the vortex mixing time is 2-5 minutes, and the vortex mixing speed is 2000-3000 r / min. In this embodiment, the vortex mixer generates strong shear and centrifugal forces, which can instantly break up any fine powder agglomerates that may exist after liquid nitrogen cryogenic pulverization. This forces all powder particles to be fully and uniformly dispersed in the acetonitrile solvent, forming a highly homogeneous suspension system. Within a suitable duration of 2-5 minutes, the solvent, under the action of the vortex, can forcibly and comprehensively wet the surface of each particle and even the tiny pores, completing the initial solid-liquid contact required for extraction.

[0033] Furthermore, in one embodiment, before adding the pulverized powder to the acetonitrile solution and vortexing it to obtain the extraction mixture, the method further includes adding anhydrous sodium sulfate and mixing it with the pulverized powder. It is understood that the powder obtained by liquid nitrogen cryogenic pulverization may have trace amounts of ambient moisture adsorbed on its surface due to low-temperature condensation, or the material itself may contain a small amount of residual moisture. Sodium sulfate, as a highly efficient desiccant, is thoroughly mixed with the pulverized powder before the organic solvent is added, thereby actively and selectively adsorbing the coexisting water. This avoids the need to change the solvent and change machines again due to the presence of moisture, thus ensuring the selective extraction of polar amine-induced sensitizing substances by the acetonitrile solution.

[0034] In one embodiment, the ultrasonic extraction temperature is 38℃-44℃, and the ultrasonic extraction time is 50min-80min. In this embodiment, heating reduces the solvent viscosity and increases the diffusion coefficient of amine-induced sensitizing substances in the solvent, thereby enhancing the microjets' impact and disturbance efficiency generated by ultrasonic cavitation, allowing acetonitrile to more effectively penetrate the micropores and interfaces of the polyurethane matrix. The ultrasonic temperature of 38℃-44℃ is lower than the decomposition temperature of the heat-sensitive substances and the softening value of the polyurethane matrix, creating a mild extraction environment that improves the plastic while ensuring stability and extraction selectivity for amine-induced sensitizing substances. It is understood that, as a cross-linked network structure, polyurethane elastomers may contain target sensitizing substances in various forms such as physical encapsulation, hydrogen bonding, or weak chemical adsorption. The ultrasonic extraction time of 50min-80min ensures that the continuous cavitation effect generated by ultrasound has sufficient time to gradually and thoroughly destroy these interactions, allowing the target sensitizing substances to diffuse into the bulk solvent, thereby improving the extraction rate.

[0035] In one embodiment, the ultrasonic extractant is eluted and adsorbed in a hybrid strong anion exchange reversed-phase solid-phase extraction column to obtain a purified effluent, comprising the following steps: The hybrid strong anion exchange reversed-phase solid-phase extraction column was activated using acetonitrile; The ultrasonic extraction solution was transferred to an activated mixed-type strong anion exchange reversed-phase solid-phase extraction column, and the flow rate was controlled to allow the solution to flow down naturally. Acetonitrile is added to the hybrid strong anion exchange reversed-phase solid-phase extraction column for elution, and the purified effluent is collected. In this embodiment, the hybrid strong anion exchange reversed-phase solid-phase extraction column is activated using the same acetonitrile solvent as the elution solvent. This ensures a stable single solvent system during activation and sample loading elution, avoiding uncontrollable changes in amine sensitizing substances caused by sudden changes in solvent polarity, thus ensuring process reproducibility. The hybrid strong anion exchange reversed-phase solid-phase extraction column selectively adsorbs acidic interfering substances such as plasticizers and antioxidants, while neutral and highly hydrophobic impurities such as plasticizers are adsorbed by the packing material. Elution with acetonitrile washes away and collects the small amount of target amine sensitizing substances that remain in the pores and on the packing surface due to weak interactions, ensuring complete recovery of amine sensitizing substances and thus improving the sensitivity and accuracy of detection. Specifically, the hybrid strong anion exchange reversed-phase solid-phase extraction column is a ProElut PXA solid-phase extraction column.

[0036] Furthermore, in one embodiment, before transferring the ultrasonic extractant to the activated solid-phase extraction column, the following step is further included: Dilute ammonia is added dropwise to the ultrasonic extraction solution to adjust its pH to 9-10. In this embodiment, by adjusting the environment to neutral, the target amine sensitizing substances in the solution, such as hexamethylenediamine and 2-toluenediamine, are effectively deprotonated, thus converting them from their ionic form -NH4+. 3+ Converted into electroneutrally neutral molecules -NH 2 This avoids strong electrostatic interactions between the target amine sensitizing substances and the strong anion exchange groups in the extraction column packing, allowing the target amine sensitizing substances to flow through the solvent rapidly and quantitatively with acetonitrile during the rinsing process without hindrance; dilute ammonia is volatile and can be easily removed during the subsequent collection of the eluent, avoiding the influence of salt residue on the subsequent chromatographic detection cell.

[0037] In one embodiment, the preparation of a standard working solution of hexamethylenediamine, hexamethylenetetramine, diethanolamine, N,N-dimethylacetamide, 2-toluenediamine, and N,N-dimethylacrylamide includes the following steps: The accurately weighed hexamethylenediamine, hexamethylenetetramine, diethanolamine, N,N-dimethylacetamide, 2-toluenediamine, and N,N-dimethylacrylamide standard substances were completely dissolved in isopropanol and then diluted to volume to prepare a primary standard stock solution. The primary standard stock solutions of hexamethylenediamine, hexamethylenetetramine, diethanolamine, N,N-dimethylacetamide, 2-toluenediamine, and N,N-dimethylacrylamide were diluted to volume with tetrahydrofuran, dimethyl sulfoxide, or dichloromethane to obtain standard working solutions. In this embodiment, isopropanol, as a moderately polar solvent with both hydrophilic and lipophilic properties, has good solubility for both polar and moderately polar amines and amides. Using isopropanol to prepare high-concentration primary stock solutions for all standards effectively overcomes the problem of poor solubility of some substances in water or instability in a single organic solvent, providing a reliable solution form for long-term storage. The use of strong soluble organic solvents such as tetrahydrofuran, dimethyl sulfoxide, or dichloromethane prevents the precipitation or adsorption of target substances during dilution, ensuring the accuracy of the working solution concentration. Furthermore, tetrahydrofuran, dimethyl sulfoxide, or dichloromethane have good miscibility with the acetonitrile extraction system and the chromatographic mobile phase system, thereby improving the accuracy of quantitative detection.

[0038] In one embodiment, before detecting the test solution, the ultrasonic extract is eluted and adsorbed by passing the ultrasonic extract through a solid-phase extraction column. After collecting the purified effluent, the method further includes the following steps: The purified effluent is dried by nitrogen blowing to obtain an effluent mixture; The effluent mixture was redissolved in acetic acid-acetonitrile solution to obtain the test solution. In this embodiment, the purified effluent volume was large, and the concentration of the target amine sensitizing substances was extremely low. The solvent was completely removed by gentle nitrogen blowing, causing all extracted and purified target amine sensitizing substances to concentrate and deposit at the bottom of the container, achieving high-fold enrichment of the target amine sensitizing substances and reducing the limit of quantitation and limit of detection of the method. Redissolution with acetic acid-acetonitrile solution, with acetic acid as the main component, is highly compatible with the initial mobile phase of reversed-phase liquid chromatography, thereby obtaining high resolution. Acetic acid can stably and efficiently promote the protonation of target amine sensitizing substances, and the slightly acidic environment can stabilize the target amine substances, preventing them from changing during the waiting period for sample injection, thereby improving the accuracy of detection.

[0039] In one embodiment, the pore size of the filter membrane is 0.20 μm-0.25 μm. In this embodiment, the filter membrane intercepts submicron particles that clog the column inlet or tubing and interfere with detection, thereby ensuring long-term stable operation of the instrument. This avoids problems such as a sharp increase in filtration resistance, slow speed, or even membrane rupture due to excessively high membrane pressure caused by excessively small pore size, ensuring the smoothness and reliability of the pretreatment operation.

[0040] In one embodiment, the chromatographic conditions for the chromatographic detection are as follows: Column: C18 (100 mm, 2.1 μm); Column oven: 40℃; Flow rate: 0.3 mL / min; Injection volume: 5 μL; Mobile phase A: 100% acetonitrile; Mobile phase B: 0.1% formic acid solution.

[0041] In this embodiment, acetonitrile is used as the organic phase, which has strong elution ability and low viscosity, resulting in lower post-column pressure and better peak shape. Formic acid is used as a volatile protonating agent, which can efficiently and stably promote the formation of ions of target compounds, thereby obtaining a high-intensity and stable mass spectrometry signal to adapt to the chromatographic detection of small-molecule polar and moderately polar sensitizing substances.

[0042] Compared with the prior art, this disclosure has at least the following advantages: The aforementioned method for determining sensitizing substances in polyurethane elastomer wearable products employs liquid nitrogen cryogenic pulverization technology for sample pretreatment. This process embrittles and pulverizes the sample at extremely low temperatures, avoiding material swelling and the release of heat-sensitive interfering substances caused by mechanical friction or solvent contact, thus ensuring the representativeness of the sample and the stability of the original components. The method leverages the excellent solubility of acetonitrile in target amine sensitizing substances and enhances solvent penetration and release through the cavitation effect of ultrasound, resulting in high and rapid extraction efficiency. This establishes an efficient and synergistic extraction and purification process, significantly improving the extraction efficiency and selectivity of target amine sensitizing substances. Purification is achieved using a mixed-type strong anion exchange reversed-phase solid-phase extraction column, which selectively adsorbs plasticizers and antioxidants while eluting sensitizing substances, reducing interference from plasticizers and antioxidants and effectively improving the sensitivity of subsequent chromatographic detection.

[0043] The following are some specific examples. When %, it refers to a percentage by weight. It should be noted that the following examples do not exhaustively list all possible scenarios, and unless otherwise specified, the materials used in the following examples are commercially available.

[0044] Example 1 Prepare standard working solutions of hexamethylenediamine, hexamethylenetetramine, diethanolamine, N,N-dimethylacetamide, 2-toluenediamine, and N,N-dimethylacrylamide. Select a polyurethane watchband from a smart bracelet and cut it into 5mm x 5mm pieces. Place the cut samples in a pre-prepared clean cryogenic pulverizer bottle and immerse them in liquid nitrogen for 1 minute to allow for complete embrittlement. After embrittlement, mechanically pulverize the samples for 5 minutes while continuously replenishing liquid nitrogen to maintain the low temperature, and collect the pulverized powder. Weigh 1.0g of the pulverized powder and 1.0g of anhydrous sodium sulfate into a 20mL sample bottle, add 5mL of acetonitrile solution, and vortex mix at a speed not less than 2000 rpm for 2 minutes. Place the container in an ultrasonic extractor at 40℃ for 60 minutes, adding dilute ammonia to the ultrasonic extract to adjust the pH to 9. Activate the Pro Elut PXA solid-phase extraction column with 5mL of acetonitrile, and transfer the ultrasonic extract to the Pro Elut PXA solid-phase extraction column. Impurities were adsorbed using a PXA solid-phase extraction column. After collecting the eluent, it was eluted with 1 mL of acetonitrile. The eluent and eluent were combined and dried under nitrogen at 45 °C. Finally, it was redissolved with 1 mL of 0.1% acetic acid-acetonitrile solution and filtered through a 0.22 μm filter membrane to obtain the test solution. The test solution was then subjected to chromatographic detection.

[0045] Example 2 Prepare standard working solutions of hexamethylenediamine, hexamethylenetetramine, diethanolamine, N,N-dimethylacetamide, 2-toluenediamine, and N,N-dimethylacrylamide. Select earphone covers and cut them into 5mm x 5mm pieces. Place the cut samples in a pre-prepared clean cryogenic pulverizer bottle and immerse them in liquid nitrogen for 1 minute to allow for complete embrittlement. After embrittlement, mechanically pulverize the cut samples for 5 minutes while continuously replenishing liquid nitrogen to maintain the low temperature, and collect the pulverized powder. Weigh 1.0g of the pulverized powder and 1.0g of anhydrous sodium sulfate into a 20mL sample bottle, add 5mL of acetonitrile solution, and vortex mix at a speed not less than 2000r / min for 2 minutes. Place the container in an ultrasonic extractor at 40℃ for 60 minutes, and add dilute ammonia to the ultrasonic extract to adjust the pH to 9. Activate the ProElut PXA solid-phase extraction column with 5mL of acetonitrile, and transfer the ultrasonic extract to the ProElut PXA solid-phase extraction column. Impurities were adsorbed using a PXA solid-phase extraction column. After collecting the eluent, it was eluted with 1 mL of acetonitrile. The eluent and eluent were combined and dried under nitrogen at 45 °C. Finally, it was redissolved with 1 mL of 0.1% acetic acid-acetonitrile solution and filtered through a 0.22 μm filter membrane to obtain the test solution. The test solution was then subjected to chromatographic detection.

[0046] Comparative Example 1 Prepare standard working solutions of hexamethylenediamine, hexamethylenetetramine, diethanolamine, N,N-dimethylacetamide, 2-toluenediamine, and N,N-dimethylacrylamide; select a polyurethane watchband from a smart bracelet of the same origin as in Example 1; cut it into small fragments of approximately 1cm × 1cm. Accurately weigh 1.0g of this sample fragment and fill it into a 10mL stainless steel extraction tube; load the filled extraction tube into a supercritical fluid extraction apparatus. Prepare two different extracts from the material sample: one using 5.0 mL / min carbon dioxide with 0.10 mL / min isopropanol as a co-solvent, and the second using 4.0 mL / min carbon dioxide with 1.0 mL / min isopropanol as a co-solvent. All extraction operations were performed at 50°C and 300 bar back pressure; the extraction program was: 30 min dynamic, 20 min static, 10 min dynamic, repeated twice. Isopropanol was used as a compensating solvent at a flow rate of 0.25 mL / min. After extraction, the extract with a high proportion of isopropanol was collected, and the solvent was evaporated until the extract was essentially dry. It was then reconstituted with isopropanol, with 10 mL added to PVC and 9 mL each to HDPE, LDPE, and EVA. For the extract with a low proportion of isopropanol, the volume was directly adjusted to the appropriate level after collection. Before analysis, the extract solution was filtered through a 0.45µm glass syringe needle filter, and the extract solution was then subjected to chromatographic analysis.

[0047] It should be noted that the preparation of standard working solutions includes the following steps: Accurately weigh 10 mg of each of the following standards: hexamethylenediamine, hexamethylenetetramine, diethanolamine, N,N-dimethylacetamide, 2-toluenediamine, and N,N-dimethylacrylamide into a 100 mL amber volumetric flask, dissolve them completely in isopropanol, and then dilute to the mark to prepare a primary standard stock solution; accurately transfer 0 μL, 10 μL, 20 mL, 40 μL, 100 μL, 200 μL, 300 μL, and 500 μL of the primary standard stock solution with a concentration of 100 mg / L into a 10 mL volumetric flask, and dilute to the mark with tetrahydrofuran, dimethyl sulfoxide, or dichloromethane to obtain standard working solutions with concentrations of 0 mg / L, 0.1 mg / L, 0.2 mg / L, 0.4 mg / L, 1.0 mg / L, 2.0 mg / L, 3.0 mg / L, and 5.0 mg / L, respectively.

[0048] During chromatographic analysis, considering the differences in properties of the six specific compounds, the mobile phase polarity was adjusted to separate compounds with different retention properties, using the gradient elution procedure shown in the table below: Table 1 Gradient rinsing program Mass spectrometry conditions: Heated electrospray source HESI, positive / negative ion scanning; ion source temperature: 350℃; ion transfer line temperature: 350℃; capillary voltage: 3500V; collision gas: helium; sheath gas pressure: 25 bar; auxiliary gas pressure: 8 bar; desolvation gas flow rate: 25 mL / min; cone gas flow rate: 8 mL / min; multiple reaction detection (MRM) mode. Table 2. Determination results of various compounds using multiple reaction detection (MRP) scanning mode of liquid chromatography-tandem mass spectrometry. Table 3 Test results of the examples and comparative examples It should be noted that, Figures 2 to 7 The ion extraction chromatograms for hexamethylenediamine, hexamethylenetetramine, diethanolamine, N,N-dimethylacetamide, 2-toluenediamine, and N,N-dimethylacrylamide are shown in sequence.

[0049] From Table 3 above and Figures 2-7It can be seen that, compared with the comparative example, the spiked recoveries of each substance in the comparative example are significantly lower than those in Examples 1 and 2. The spiked recoveries of hexamethylenediamine, hexamethylenetetramine, diethanolamine, N,N-dimethylacetamide, 2-toluenediamine, and N,N-dimethylacrylamide in Examples 1 and 2 are consistently above 81%, indicating that the extraction completeness is better after purification by liquid nitrogen cryogenic pulverization, ultrasonication, and Pro Elut PXA solid-phase extraction column in the method for determining sensitizing substances in polyurethane elastomer wearable products. The precision deviation of the methods in Examples 1 and 2 is smaller than that in Comparative Example 1, indicating better reproducibility of the method for determining sensitizing substances in polyurethane elastomer wearable products. The detection limits of Examples 1 and 2 are lower than those in the comparative example, indicating higher detection sensitivity. The chromatogram of Example 1 is stable and the peak shape is clean, indicating good anti-interference and high chromatographic detection sensitivity.

[0050] The embodiments described above are merely illustrative of several implementations of this disclosure, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the disclosed patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this disclosure, and these all fall within the protection scope of this disclosure. Therefore, the protection scope of this patent should be determined by the appended claims.

Claims

1. A method for determining sensitizing substances in polyurethane elastomer wearable products, characterized in that, Includes the following steps: Prepare standard working solutions of hexamethylenediamine, hexamethylenetetramine, diethanolamine, N,N-dimethylacetamide, 2-toluenediamine, and N,N-dimethylacrylamide; The sample is sheared, and the sheared sample is placed in a crushing container. The sheared sample is then crushed by liquid nitrogen cryogenic crushing to obtain pulverized powder. The pulverized powder is added to an acetonitrile solution and vortexed to obtain an extraction mixture; The extraction mixture is placed in an ultrasonic device for ultrasonic extraction to obtain an ultrasonic extract. The ultrasonic extract was eluted and adsorbed through a mixed strong anion exchange reversed-phase solid-phase extraction column, and the purified effluent was collected to obtain the test solution. The test solution is filtered through a filter membrane and then subjected to chromatographic detection.

2. The method for determining sensitizing substances in polyurethane elastomer wearable products according to claim 1, characterized in that, The sample is sheared, and the sheared sample is placed in a pulverizing container. The sheared sample is then cryogenically pulverized using liquid nitrogen to obtain pulverized powder, including the following steps: The sample is cut into small pieces to obtain a cut sample; The sheared sample is placed in a crushing container and immersed in liquid nitrogen for 1-3 minutes to allow the sheared sample to become fully brittle. The embrittled sheared sample was mechanically pulverized under conditions of continuous replenishment of liquid nitrogen to maintain low temperature, with a total pulverization time of 3-5 minutes. Collect the pulverized powder.

3. The method for determining sensitizing substances in polyurethane elastomer wearable products according to claim 2, characterized in that, The frozen sample was pulverized to 100nm-200nm.

4. The method for determining sensitizing substances in polyurethane elastomer wearable products according to claim 1, characterized in that, The vortex mixing time is 2 min to 5 min, and the vortex mixing speed is 2000 r / min to 3000 r / min.

5. The method for determining sensitizing substances in polyurethane elastomer wearable products according to claim 1, characterized in that, The ultrasonic extraction temperature is 38℃-44℃, and the ultrasonic extraction time is 50min-80min.

6. The method for determining sensitizing substances in polyurethane elastomer wearable products according to claim 1, characterized in that, The ultrasonic extraction solution is eluted and adsorbed in a mixed-type strong anion exchange reversed-phase solid-phase extraction column to obtain a purified effluent, including the following steps: The mixed-type strong anion exchange reversed-phase solid-phase extraction column was activated using acetonitrile; The ultrasonic extraction solution was transferred to an activated mixed-type strong anion exchange reversed-phase solid-phase extraction column, and the flow rate was controlled to allow the solution to flow down naturally. Acetonitrile was added to the mixed-type strong anion exchange reversed-phase solid-phase extraction column for elution, and the purified effluent was collected.

7. The method for determining sensitizing substances in polyurethane elastomer wearable products according to claim 1, characterized in that, The preparation of standard working solutions of hexamethylenediamine, hexamethylenetetramine, diethanolamine, N,N-dimethylacetamide, 2-toluenediamine, and N,N-dimethylacrylamide includes the following steps: The accurately weighed hexamethylenediamine, hexamethylenetetramine, diethanolamine, N,N-dimethylacetamide, 2-toluenediamine, and N,N-dimethylacrylamide standard substances were completely dissolved in isopropanol and then diluted to volume to prepare a primary standard stock solution. The primary standard stock solutions of hexamethylenediamine, hexamethylenetetramine, diethanolamine, N,N-dimethylacetamide, 2-toluenediamine, and N,N-dimethylacrylamide were diluted to volume with tetrahydrofuran, dimethyl sulfoxide, or dichloromethane to obtain standard working solutions.

8. The method for determining sensitizing substances in polyurethane elastomer wearable products according to claim 1, characterized in that, Before testing the test solution, the ultrasonic extract is eluted and adsorbed by passing the ultrasonic extract through a solid-phase extraction column. After collecting the purified effluent, the following steps are also included: The purified effluent is dried by nitrogen blowing to obtain an effluent mixture; The effluent mixture was redissolved in an acetic acid-acetonitrile solution to obtain the test solution.

9. The method for determining sensitizing substances in polyurethane elastomer wearable products according to claim 8, characterized in that, The pore size of the filter membrane is 0.20μm-0.25μm.

10. The method for determining sensitizing substances in polyurethane elastomer wearable products according to claim 1, characterized in that, The chromatographic conditions for the chromatographic detection are as follows: Column: C18 (100 mm, 2.1 μm); Column oven: 40℃; Flow rate: 0.3 mL / min; Injection volume: 5 μL; Mobile phase A: 100% acetonitrile; Mobile phase B: 0.1% formic acid solution.

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