Determination method for rapid screening of plastic part color masterbatch carcinogenic dye

Abstract

The invention provides a determination method for rapid screening of plastic part color masterbatch carcinogenic dyes, and the determination method for rapid screening of plastic part color masterbatch carcinogenic dyes comprises the following steps: crushing a plastic sample, adding the crushed plastic sample into dichloromethane, carrying out swelling and decoloration, and carrying out ultrasonic extraction to obtain a swelling mixed solution; adding methylbenzene into the swelled mixed solution to swell and decolor, and performing ultrasonic extraction and concentration to obtain a concentrated extract; adding the concentrated extract into a methanol precipitator, and separating to obtain a precipitate mixed solution; and eluting the precipitate mixed solution through an activated alumina small column, drying, and re-dissolving in methanol to obtain a to-be-detected solution, and analyzing by using a liquid chromatograph-mass spectrometer. Dye molecules are selectively released through step-by-step swelling of dichloromethane and toluene, so that the extraction effect of the color masterbatch dye in the plastic is improved; through combination of step-by-step solvent synergistic swelling extraction and multi-stage purification, drying of polymer dissolved impurities is avoided, and efficient and accurate extraction and determination of the plastic color masterbatch dye are realized.

Description

Technical Field

[0001] This disclosure relates to the technical field of plastic testing, and in particular to a method for rapid screening of carcinogenic dyes in plastic part color masterbatches. Background Technology

[0002] Plastic products that come into direct or prolonged contact with the human body, such as those used in smart wearable devices and medical device consumables, are experiencing rapid and continuous expansion. Azo dyes and disperse dyes in color masterbatches used in plastic products may cause contact dermatitis and chronic eczema upon prolonged contact with human skin. Furthermore, the decomposition products of azo dyes are classified as Group 1 carcinogens by the International Agency for Research on Cancer, posing a cancer risk. Color masterbatches containing cadmium and lead can penetrate the body through sweat, potentially causing neurotoxicity and liver and kidney damage. The health risks posed by sensitizing color masterbatches cannot be ignored; the sensitization hazards caused by colorant masterbatches are becoming increasingly prominent and are subject to strict regulation.

[0003] However, current methods for detecting color masterbatch dyes in complex composite plastics by directly extracting them with solvents have limited effectiveness in purifying the dyes. Due to the complex matrix of plastics, direct solvent extraction can co-dissolve large amounts of polymers and plasticizers, leading to severe background interference during subsequent instrumental analysis. Furthermore, solvents are less effective at extracting color masterbatch dyes from composite plastics and struggle to efficiently separate and accurately screen dyes with diverse properties.

[0004] For example, the analytical method for determining the residues of multiple additives in food contact plastic products disclosed in prior art CN201810139383.9 uses microwave-assisted extraction and concentration for sample pretreatment, prepares 48 standard solutions of phthalate esters, disperse dyes, and fluorescent whitening agents, plots a standard curve, and analyzes the samples using ultra-high performance liquid chromatography-high resolution mass spectrometry. This method uses microwave-assisted extraction, but when applied to composite plastic products such as smart wearable devices and medical device plastic consumables, direct solvent extraction co-dissolves a large amount of polymers, plasticizers, and other interfering substances, resulting in severe background interference during subsequent instrument analysis. Summary of the Invention

[0005] The purpose of this disclosure is to overcome the shortcomings of the prior art and provide a method for the rapid screening of carcinogenic dyes in plastic masterbatches that improves the extraction efficiency of masterbatches dyes in plastics and avoids interference from dissolved polymers.

[0006] The purpose of this disclosure is achieved through the following technical solution: A rapid screening method for carcinogenic dyes in masterbatches of plastic parts includes the following steps: The plastic sample is crushed to obtain plastic fragments; The plastic fragments were added to dichloromethane for the first swelling and decolorization, and then subjected to the first ultrasonic extraction treatment to obtain a swollen mixture. Toluene was added to the swollen mixture for a second swelling and decolorization, followed by a second ultrasonic extraction to obtain the swollen extract. The swollen extract is transferred to a rotary evaporator for concentration to obtain a concentrated extract. The concentrated extract is added to a methanol precipitant to precipitate the polymer, and the precipitate mixture is obtained after separation. The precipitate mixture was eluted and dried using an activated alumina column to obtain a dry mixture. The dried mixture was redissolved in methanol to obtain the test solution, which was then analyzed by liquid chromatography.

[0007] In one embodiment, the first ultrasonic extraction treatment takes 30-60 minutes and the ultrasonic frequency is 20-40 kHz.

[0008] In one embodiment, the second ultrasonic extraction process takes 40-60 minutes and the ultrasonic frequency is 20-40 kHz.

[0009] In one embodiment, when the swollen extract is transferred to a rotary evaporator for concentration, the evaporation is carried out under reduced pressure, and the water bath temperature of the rotary evaporator is controlled at 40°C-50°C.

[0010] In one embodiment, the mass ratio of methanol to water in the methanol precipitant is (100:0) to (93:7).

[0011] In one embodiment, the precipitate mixture is eluted and dried by passing it through an activated alumina column to obtain a dried mixture, including the following steps: The precipitate mixture is concentrated and dissolved in dichloromethane to obtain a dissolved mixture. The dissolved mixture is passed through the alumina solid-phase extraction column; wherein, when the liquid level of the dissolved mixture drops to the surface of the packing material, it is eluted with dichloromethane and eluted with a strongly polar solvent to obtain an eluent; The eluent is dried by nitrogen blowing to obtain a dry mixture.

[0012] In one embodiment, after concentrating the precipitate mixture and dissolving it in dichloromethane to obtain a dissolved mixture, and before passing the dissolved mixture through the alumina solid-phase extraction column, the following step is further included: The alumina solid-phase extraction column was activated and pre-washed with dichloromethane.

[0013] In one embodiment, the rinsing rate of the alumina solid-phase extraction column for activation and pre-rinsing with dichloromethane is 1 drop / second to 3 drops / second.

[0014] In one embodiment, the dried mixture is redissolved in methanol and then subjected to liquid chromatography analysis, comprising the following steps: The dried mixture was reconstituted with methanol and then vortexed to obtain the reconstituted mixture. The reconstituted mixture is filtered through a filter membrane to obtain the test solution; The test solution was analyzed by liquid chromatography.

[0015] In one embodiment, preparing the standard solution includes the following steps: The color masterbatch standard material was diluted to volume with methanol solvent to obtain a primary standard stock solution; Different gradient volumes of the primary standard stock solution were diluted with methanol to obtain multiple sets of standard working solutions.

[0016] Compared with the prior art, this disclosure has at least the following advantages: The aforementioned method for rapid screening of carcinogenic dyes in plastic masterbatches utilizes dichloromethane and toluene to swell and permeate the plastic polymer network, thereby selectively releasing various dye molecules encapsulated in the plastic in stages. This overcomes the limitations of low extraction efficiency and narrow coverage of single solvents, improving the extraction effect of masterbatches in plastics. The synergistic assistance of ultrasound and heating significantly enhances mass transfer efficiency and shortens pretreatment time. Subsequent concentration, precipitation, and alumina column purification effectively remove co-extracted polymer matrix and impurities, increasing the concentration of the target analyte while reducing impurity interference. Combined with high-performance liquid chromatography and other precise analyses, rapid screening is achieved. Stepwise solvent-assisted swelling extraction and multi-stage purification avoid interference from polymer dissolution impurities, enabling efficient and accurate extraction and determination of carcinogenic dyes in the plastic matrix. This provides a reliable analytical method for the supervision and control of harmful dyes in plastic products. 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 A flowchart illustrating the steps of a rapid screening method for carcinogenic dyes in masterbatches of plastic parts, according to one embodiment; Figures 2 to 4 This is an ion extraction chromatogram of a chromatographic detection method according to one embodiment. 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] This disclosure relates to a method for rapid screening of carcinogenic dyes in plastic component color masterbatches, comprising the following steps: crushing a plastic sample to obtain plastic fragments; adding the plastic fragments to dichloromethane for a first swelling and decolorization, followed by a first ultrasonic extraction to obtain a swollen mixture; adding toluene to the swollen mixture for a second swelling and decolorization, followed by heating and a second ultrasonic extraction to obtain a swollen extract; transferring the swollen extract to a rotary evaporator for concentration to obtain a concentrated extract; adding the concentrated extract to a methanol precipitant to precipitate the polymer, obtaining a precipitate mixture; eluting and drying the precipitate mixture using an activated alumina column to obtain a dried mixture; redissolving the dried mixture in methanol to obtain a test solution, and performing liquid chromatography analysis on the test solution.

[0023] The aforementioned method for rapid screening of carcinogenic dyes in plastic masterbatches utilizes dichloromethane and toluene to swell and permeate the plastic polymer network, thereby selectively releasing various dye molecules encapsulated in the plastic in stages. This overcomes the limitations of low extraction efficiency and narrow coverage of single solvents, improving the extraction effect of masterbatches in plastics. The synergistic assistance of ultrasound and heating significantly enhances mass transfer efficiency and shortens pretreatment time. Subsequent concentration, precipitation, and alumina column purification effectively remove co-extracted polymer matrix and impurities, increasing the concentration of the target analyte while reducing impurity interference. Combined with high-performance liquid chromatography and other precise analyses, rapid screening is achieved. Stepwise solvent-assisted swelling extraction and multi-stage purification avoid interference from polymer dissolution impurities, enabling efficient and accurate extraction and determination of carcinogenic dyes in the plastic matrix. This provides a reliable analytical method for the supervision and control of harmful dyes in plastic products.

[0024] To better understand the technical solutions and beneficial effects of this disclosure, the following detailed description is provided in conjunction with specific embodiments: Please see Figure 1 As shown, this is a method for rapid screening of carcinogenic dyes in plastic masterbatches according to an embodiment of the present invention, comprising the following steps: S101 involves breaking the plastic sample to obtain plastic fragments. It is understood that physically disrupting the sample's macroscopic structure significantly increases its contact surface area with the subsequent solvent, thereby greatly improving swelling and extraction efficiency, laying the foundation for subsequent steps.

[0025] S103, the plastic fragments are added to dichloromethane for the first swelling and decolorization, followed by ultrasonic extraction to obtain a swollen mixture. Dichloromethane is a moderately polar halogenated hydrocarbon solvent with good permeability and strong swelling capacity, effectively disrupting the surface structure of the plastic fragments and penetrating into their amorphous regions. This initially relaxes the intermolecular forces between polymer chains, creating release channels for dyes and additives in the plastic. Ultrasonic treatment utilizes the strong mechanical vibrations generated by cavitation to accelerate the diffusion and exchange of solvent into the plastic, effectively promoting the mass transfer of target compounds from the swollen regions to the liquid phase, thereby achieving efficient decolorization and preliminary extraction, laying the foundation for subsequent deeper swelling and extraction.

[0026] S105, toluene is added to the swollen mixture for a second swelling and decolorization. After heating and ultrasonic extraction, a swollen extract is obtained. It is understood that toluene, as a weakly polar aromatic hydrocarbon solvent, has a stronger penetration and swelling capacity into the initially relaxed polymer network. Its molecular structure is more similar to the chain segments of many plastics, which can further weaken the interactions between polymer chains, thereby deeply releasing the lower polarity additives and dye molecules encapsulated in the crystalline regions or deep matrix of the plastic. Heating further reduces the energy barrier of polymer chain movement, significantly improving the swelling efficiency; simultaneously, ultrasonic treatment utilizes its cavitation effect to intensify solvent exchange and target mass transfer, ensuring complete extraction. The good solubility of toluene also helps to transfer colorants and co-extracts with a wide range of polarities that were not fully released during the first swelling into the liquid phase, achieving more thorough decolorization and enrichment.

[0027] S107, the swollen extract is transferred to a rotary evaporator for concentration to obtain a concentrated extract. It is understood that by removing most of the extraction solvent under mild heating and reduced pressure conditions through rotary evaporation, the solution volume can be significantly reduced, thereby concentrating the target analyte dispersed in a large amount of solvent and increasing its unit concentration to meet the sensitivity requirements of subsequent purification and detection. Simultaneously, this process also helps to volatilize and remove some low-boiling-point interfering solvents or impurities.

[0028] S109, the concentrated extract is added to a methanol precipitant to precipitate the polymer, and the precipitate mixture is obtained after separation. It is understood that when a concentrated extract containing soluble polymers is injected into a large amount of methanol, the polymer's solubility changes abruptly, causing it to precipitate rapidly. This effectively removes high molecular weight polymers that are co-dissolved during the extraction process.

[0029] S111 involves eluting and drying the precipitate mixture using an activated alumina column to obtain a dry mixture. Activated alumina is an adsorbent with a polar surface. When the precipitate mixture containing the target dye and small molecule impurities passes through the column, the alumina, through its surface active sites, selectively and strongly adsorbs residual pigments and highly polar interfering substances or acidic / basic impurities in the solution. The target carcinogenic dye is selectively eluted by the elution solvent, achieving separation of the target analyte from the impurities. Subsequent drying removes the elution solvent, yielding a dry analyte that facilitates accurate volume reconstitution.

[0030] S113, the dried mixture is redissolved in methanol to obtain the test solution, which is then subjected to liquid chromatography analysis. It is understood that methanol has good solubility, low UV background absorption, and excellent compatibility with reversed-phase liquid chromatography mobile phase systems; through separation by the chromatographic column and detection by a mass spectrometer, accurate qualitative identification and precise quantification of various carcinogenic dyes can be achieved, thereby enabling rapid screening for carcinogenic dyes in masterbatches.

[0031] The aforementioned method for rapid screening of carcinogenic dyes in plastic masterbatches utilizes dichloromethane and toluene to swell and permeate the plastic polymer network, thereby selectively releasing various dye molecules encapsulated in the plastic in stages. This overcomes the limitations of low extraction efficiency and narrow coverage of single solvents, improving the extraction effect of masterbatches in plastics. The synergistic assistance of ultrasound and heating significantly enhances mass transfer efficiency and shortens pretreatment time. Subsequent concentration, precipitation, and alumina column purification effectively remove co-extracted polymer matrix and impurities, increasing the concentration of the target analyte while reducing impurity interference. Combined with high-performance liquid chromatography and other precise analyses, rapid screening is achieved. Stepwise solvent-assisted swelling extraction and multi-stage purification avoid interference from polymer dissolution impurities, enabling efficient and accurate extraction and determination of carcinogenic dyes in the plastic matrix. This provides a reliable analytical method for the supervision and control of harmful dyes in plastic products.

[0032] In one embodiment, the first ultrasonic extraction process takes 30-60 minutes at a frequency of 20-40 kHz. In this embodiment, an extraction time of 30-60 minutes allows dichloromethane to effectively penetrate most of the plastic fragments and release the dye, meeting the reliability requirements of screening. If the extraction time is too short, the solvent cannot fully penetrate the plastic fragments, resulting in incomplete swelling and incomplete release of the target dye. If the extraction time is too long, the solvent temperature may rise excessively, leading to the loss of low-boiling-point components or unnecessary energy and time consumption. When the ultrasonic frequency is 20-40 kHz, the ultrasound can generate a sufficient number of cavitation bubbles in the solvent. The resulting strong shock waves and microjets can disrupt the boundary layer on the plastic surface, thereby accelerating solvent diffusion and the desorption and mass transfer of dye molecules, while avoiding excessively strong thermal effects or weakened cavitation due to excessively high frequencies.

[0033] In one embodiment, the second ultrasonic extraction process takes 40-60 minutes and the ultrasonic frequency is 20-40 kHz. The ultrasonic duration of 40-60 minutes, combined with the addition of [unspecified ingredient], ensures the complete release of highly encapsulated dye molecules from the plastic. The stable cavitation effect generates a strong microjets and impacts, further disrupting the inter-polymer chain forces and enhancing solvent exchange, thereby achieving efficient and complete extraction of dyes from complex plastic matrices in a relatively short time.

[0034] Furthermore, in one embodiment, during the second ultrasonic foil extraction, the heating temperature of the swollen mixture is controlled at 55°C-65°C. The second ultrasonic extraction is performed in a pressure-resistant, sealed container within a fume hood. In this embodiment, the heating temperature is set to 55°C-65°C. The thermal effect significantly reduces the energy barrier of polymer molecular chains, allowing toluene to deeply penetrate and swell the initially relaxed plastic, effectively releasing the target dye encapsulated in the crystalline region or deep network. This avoids the risk of excessive solvent evaporation or decomposition of heat-sensitive target substances due to excessively high temperatures. The system contains dichloromethane residue from the first extraction; its vapor pressure increases under heating conditions. The pressure-resistant, sealed container safely withstands the pressure, and the fume hood can forcefully expel the vapor when the container is transferred or opened, ensuring the safety of the experimental process.

[0035] In one embodiment, when the swollen extract is transferred to a rotary evaporator for concentration, the evaporation is carried out under reduced pressure, and the water bath temperature of the rotary evaporator is controlled at 40°C-50°C. In this embodiment, under moderate reduced pressure of -0.08MPa to -0.05MPa, the boiling points of the main solvents in the extraction system, dichloromethane and toluene, are significantly reduced; the water bath temperature of 40°C-50°C ensures that the low-boiling-point dichloromethane continues to volatilize efficiently in the later stages of evaporation, while providing driving force for the higher-boiling-point toluene under reduced pressure. This achieves simultaneous evaporation of the mixed solvents, avoiding decomposition, isomerization, or other degradation reactions of some heat-sensitive target substances due to overheating, and ensuring the integrity of the analytical target.

[0036] Furthermore, in one embodiment, toluene is added to the swollen mixture for a second swelling and decolorization. After heating and ultrasonic extraction to obtain the swollen extract, before transferring the swollen extract to a rotary evaporator for concentration to obtain the concentrated extract, the following steps are also included: The swollen extract was frozen to -20°C to -15°C for 1-2 hours. Immediately after freezing, the swollen extract was rapidly filtered through a pre-cooled filter membrane. In this embodiment, after deep swelling and extraction, the swollen extract may contain a large number of plastic polymer molecules dissolved by toluene or highly swollen. High molecular weight polymers become viscous during subsequent rotary evaporation concentration, potentially clogging pipes, causing foaming, and significantly interfering with subsequent precipitation and solid-phase extraction purification efficiency. Freezing the extract at -20°C to -15°C for 1-2 hours drastically reduces the solubility of toluene in the polymer, causing dissolved or highly dispersed polymer segments to aggregate and precipitate, forming microgels or precipitates. Using a pre-cooled filter membrane for rapid filtration can effectively retain these solid or semi-solid polymer impurities at low temperatures, while target carcinogenic dyes and other small molecule analytes remain dissolved in frozen toluene and pass smoothly through the filter membrane. This removes matrix interferences, protects the rotary evaporator, avoids operational difficulties during the concentration process, reduces the burden on subsequent methanol precipitation and alumina column purification, and improves the overall purification effect, reproducibility, and detection sensitivity of the method.

[0037] In one embodiment, the mass ratio of methanol to water in the methanol precipitant is (100:0) to (93:7). In this embodiment, methanol is the main component of the precipitant, and its strong polarity causes a sharp drop in the solubility of non-polar or weakly polar polymers, resulting in rapid precipitation. By adding water, while ensuring polymer precipitation efficiency, a trace amount of polarity adjustment is introduced. The addition of a small amount of water can further increase the overall polarity of the mixed solvent, theoretically promoting more thorough polymer precipitation. At the same time, for some target dyes with relatively high polarity, the micro-aqueous environment helps them maintain a stable dissolved state during the precipitation process, reducing losses caused by co-precipitation or encapsulation. The water content of the methanol precipitant is less than 7%, avoiding excessively high polarity of the precipitant that would cause dissolved dyes to precipitate.

[0038] Furthermore, in one embodiment, before adding the concentrated extract to the methanol precipitant, the methanol precipitant is cooled to maintain a low temperature of 0°C-5°C. In this embodiment, the low temperature of 0°C-5°C significantly reduces the solubility of methanol. When the concentrated extract is injected into the cold methanol, the combined effect of temperature difference and solvent polarity causes a sharp drop in the movement of polymer molecular chains, resulting in faster and more complete precipitation and the formation of a denser precipitate. This is beneficial for subsequent solid-liquid separation and reduces the encapsulation and adsorption of the target analyte. The low temperature also suppresses side reactions, degradation, or additional dissolution losses that may occur due to localized exothermic mixing or overall temperature increases. Low-temperature precipitation reduces solvent evaporation during mixing and keeps the system stable, avoiding differences in precipitation behavior caused by temperature fluctuations.

[0039] Furthermore, in one embodiment, after adding the concentrated extract to a methanol precipitant to precipitate the polymer and obtaining a precipitate mixture after separation, the following steps are included: An acidified methanol aqueous solution is added to the precipitate mixture to induce secondary precipitation. The precipitate mixture after secondary precipitation is centrifuged. In this embodiment, the volume ratio of the precipitate mixture without secondary precipitation to the acidified methanol aqueous solution is 1:1. The acidified methanol aqueous solution is prepared by mixing methanol and an aqueous solution containing 0.1% formic acid at a mass ratio of 95:5 to 80:20. The aqueous phase ratio of the methanol aqueous solution further enhances the overall polarity of the mixed solvent, which can force the relatively polar polymer residues that may not have fully precipitated in the first precipitation due to their high solubility to undergo secondary precipitation, thereby more thoroughly removing the high molecular weight matrix. Secondly, the acidic environment can protonate and neutralize any trace alkaline additives or degradation products that may be present in the extract, converting them into ionic form and changing their solubility, making them easier to precipitate and remove. For some target carcinogenic dyes that may be unstable under alkaline or neutral conditions, the acidic environment can play a stabilizing role, preventing them from decomposing during subsequent processing or storage. Through secondary precipitation and centrifugation, the purity of the test solution is ensured, effectively reducing the matrix complexity in the final test solution, thereby improving the detection accuracy of liquid chromatography-mass spectrometry analysis.

[0040] In one embodiment, the precipitate mixture is eluted and dried by passing it through an activated alumina column to obtain a dried mixture, including the following steps: The precipitate mixture is concentrated and dissolved by adding dichloromethane to obtain a dissolved mixture; The dissolved mixture is added to the alumina solid-phase extraction column. When the liquid level drops to the surface of the packing material, it is rinsed with an appropriate amount of dichloromethane and eluted with a strong polar solvent to obtain the eluent. The eluent is dried by nitrogen blowing to obtain a dry mixture. In this embodiment, the supernatant containing the target analyte is concentrated and then redissolved in dichloromethane, transferring the target analyte to a solvent environment suitable for alumina column adsorption and elution. Eluting with moderately polar dichloromethane selectively washes away non-polar to weakly polar impurities adsorbed on the column, while retaining polar and moderately polar target carcinogenic dyes at the active adsorption sites on the alumina. Elution with a strongly polar solvent quantitatively desorbs and collects the target dye molecules from the alumina column. Through elution, elution, and drying, fine separation and concentration are achieved, including removal of interfering substances and recovery of the target analyte.

[0041] In one embodiment, the highly polar solvent is methanol. In this embodiment, methanol is a highly polar protic solvent whose hydroxyl groups can compete with the active sites on the surface of alumina filler by forming strong hydrogen bonds, thereby efficiently displacing and eluting the adsorbed target dye molecules. Methanol is the most commonly used mobile phase component in reversed-phase liquid chromatography-mass spectrometry analysis. As the final eluent, methanol ensures that the solvent system of the obtained dried product is highly compatible with the mobile phase used in instrument analysis after reconstitution.

[0042] In one embodiment, after concentrating the precipitate mixture and dissolving it in dichloromethane to obtain a dissolved mixture, and before passing the dissolved mixture through the alumina solid-phase extraction column, the following step is further included: The alumina solid-phase extraction column was activated and pre-washed with dichloromethane. In this embodiment, dichloromethane effectively penetrates and completely wets the entire porous structure of the alumina packing material, removing any air that may remain inside the column. The rinsing activation creates a stable, moderately polar solvent environment dominated by dichloromethane. The rinsing activation can pre-remove trace impurities that may have been introduced into the packing material during production, storage, or loading, and balance the acid-base surface characteristics of the packing material, preventing these factors from interfering with the adsorption of the target analyte or contaminating the sample.

[0043] In one embodiment, the rinsing rate of the alumina solid-phase extraction column for activation pre-elution with dichloromethane is 1 drop / second to 3 drops / second. In this embodiment, each drop of dichloromethane is approximately 0.02 ml to 0.03 mL. Controlling the rinsing solution to pass through the column at a rate of 1 drop / second to 3 drops / second ensures sufficient and uniform contact time between the solvent and the packing material. If the flow rate is too high, the solvent will quickly pass through the column bed due to gravity, potentially resulting in incomplete wetting of the packing material and uneven activation. If the flow rate is too slow, although sufficient contact is achieved, the pretreatment time will be unnecessarily prolonged, reducing overall efficiency.

[0044] In one embodiment, the dried mixture is redissolved in methanol and then subjected to liquid chromatography analysis, comprising the following steps: The dried mixture was reconstituted with methanol and then vortexed to obtain the reconstituted mixture. The reconstituted mixture is filtered through a filter membrane to obtain the test solution; The test solution was analyzed by liquid chromatography. In this embodiment, the target carcinogenic dye has good solubility and, as the main component of the mobile phase in reversed-phase liquid chromatography, it ensures high compatibility between the sample solvent and the mobile phase, thereby guaranteeing sharp chromatographic peaks and stable retention times. By vortexing, the trace target substance dried on the tube wall or bottom is ensured to be fully and rapidly dissolved and evenly dispersed by methanol to obtain a homogeneous reconstituted mixture. The reconstituted mixture is then passed through a filter membrane, which is 0.22 μm or 0.45 μm thick, to retain any extremely fine particulate matter, insoluble impurities, or potential crystal nuclei that may be present in the solution, thereby obtaining a clear and transparent test solution.

[0045] In one embodiment, preparing the standard solution includes the following steps: The color masterbatch standard material was diluted to volume with methanol solvent to obtain a primary standard stock solution; Different gradient volumes of the primary standard stock solution were diluted with methanol to obtain multiple sets of standard working solutions of varying concentrations. In this embodiment, high-purity standards were accurately weighed and diluted to volume using methanol, a solvent highly compatible with the analytical terminal, to prepare a high-concentration, high-accuracy primary standard stock solution. Subsequently, using precision pipettes and volumetric flasks, a stepwise dilution method was employed to dilute the stock solution with methanol into a series of standard working solutions with gradient concentrations. By constructing the instrument's calibration curve, precise quantitative analysis of the target dye in actual plastic samples was subsequently performed, ensuring the accuracy and traceability of the detection results. Specifically, the masterbatch standard substances include one of Basic Red 9, Basic Violet 14, Disperse Blue 1, Disperse Orange 11, Disperse Yellow 3, Solvent Yellow 1, Solvent Yellow 2, and Solvent Yellow 3. All masterbatch standard substances are known or listed in regulations (such as the EU REACH regulation) as high-risk colorants that may be carcinogenic, mutagenic, or reproductively toxic, covering multiple chemical categories such as azo dyes, triphenylmethanes, and anthraquinones.

[0046] Compared with the prior art, this disclosure has at least the following advantages: The aforementioned method for rapid screening of carcinogenic dyes in plastic masterbatches utilizes dichloromethane and toluene to swell and permeate the plastic polymer network, thereby selectively releasing various dye molecules encapsulated in the plastic in stages. This overcomes the limitations of low extraction efficiency and narrow coverage of single solvents, improving the extraction effect of masterbatches in plastics. The synergistic assistance of ultrasound and heating significantly enhances mass transfer efficiency and shortens pretreatment time. Subsequent concentration, precipitation, and alumina column purification effectively remove co-extracted polymer matrix and impurities, increasing the concentration of the target analyte while reducing impurity interference. Combined with high-performance liquid chromatography and other precise analyses, rapid screening is achieved. Stepwise solvent-assisted swelling extraction and multi-stage purification avoid interference from polymer dissolution impurities, enabling efficient and accurate extraction and determination of carcinogenic dyes in the plastic matrix. This provides a reliable analytical method for the supervision and control of harmful dyes in plastic products.

[0047] 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.

[0048] Example 1 Obtain a plastic sample of a mobile phone casing and crush it into 5mm × 5mm plastic fragments using a pulverizer. Weigh 0.5g of the fragments and place them in a glass bottle. Add 20ml of dichloromethane solvent and place the bottle in an ultrasonic cleaner at room temperature. Perform ultrasonic extraction at 35kHz for 30 minutes until the sample dissolves, swells, or decolorizes, obtaining a swollen mixture. To ensure sealing, tighten the bottle cap or seal it with tape during ultrasonic extraction. Add 10mL of toluene directly to the swollen mixture and transfer the entire mixture to a pressure-resistant, sealed ultrasonic extraction vessel. Place the vessel in a 55℃ water bath and perform ultrasonic extraction in a fume hood at 35kHz for 40 minutes. After cooling, obtain the swollen extract. Transfer the swollen extract to a rotary evaporator and concentrate it to approximately 10mL to obtain a concentrated extract. Slowly add the concentrated extract to a methanol precipitant solution and let it stand for 10 minutes to precipitate the polymer. After centrifugation, transfer the supernatant to separate the precipitate mixture. Concentrate the precipitate mixture under nitrogen blowing to approximately 0.5mL. Activation pre-elution was performed on the activated alumina column using 5 mL of dichloromethane at a flow rate of 1 drop / second. The concentrated precipitate mixture was dissolved in 1 mL of dichloromethane and loaded entirely onto the activated alumina column. When the liquid level dropped to the alumina surface, it was eluted with 5 mL of dichloromethane, and the color bands were observed to separate. Elution was then performed with 10 mL of methanol, and the eluent was collected. The eluent was concentrated to near dryness by nitrogen blowing, and then reconstituted with 1 mL of methanol solution. After filtration, the test solution was obtained and analyzed by liquid chromatography-mass spectrometry (LC-MS).

[0049] Example 2 Obtain a plastic sample of the surgical membrane plastic layer and crush it into 5mm × 5mm plastic fragments using a pulverizer. Weigh 0.5g of the fragments and place them in a glass bottle. Add 20ml of dichloromethane solvent and place the bottle in an ultrasonic cleaner at room temperature. Perform ultrasonic extraction at 35kHz for 30 minutes until the sample dissolves, swells, or decolorizes, obtaining a swollen mixture. To ensure sealing, tighten the bottle cap or seal it with tape during ultrasonic extraction. Add 10mL of toluene directly to the swollen mixture and transfer the entire mixture to a pressure-resistant, sealed ultrasonic extraction vessel. Place the vessel in a 55℃ water bath and perform ultrasonic extraction in a fume hood at 35kHz for 40 minutes. After cooling, obtain the swollen extract. Transfer the swollen extract to a rotary evaporator and concentrate it to approximately 10mL to obtain a concentrated extract. Slowly add the concentrated extract to a methanol precipitant solution and let it stand for 10 minutes to precipitate the polymer. After centrifugation, remove the supernatant and separate the precipitate mixture. Concentrate the precipitate mixture under nitrogen blowing to approximately 0.5mL. Activation pre-elution was performed on the activated alumina column using 5 mL of dichloromethane at a flow rate of 1 drop / second. The concentrated precipitate mixture was dissolved in 1 mL of dichloromethane and loaded entirely onto the activated alumina column. When the liquid level dropped to the alumina surface, it was eluted with 5 mL of dichloromethane, and the color bands were observed to separate. Elution was then performed with 10 mL of methanol, and the eluent was collected. The eluent was concentrated to near dryness by nitrogen blowing, and then reconstituted with 1 mL of methanol solution. After filtration, the test solution was obtained and analyzed by liquid chromatography-mass spectrometry (LC-MS).

[0050] Comparative Example 3 Obtain a mobile phone casing plastic sample from the same source as in Example 1, and pulverize it into 5mm × 5mm plastic fragments using a pulverizer. Weigh 0.5g of the plastic fragments and place them in a microwave extraction vessel, then add 30mL of dichloromethane. Seal the extraction vessel and place it in a microwave extraction apparatus. Heat to 120°C within 5 minutes and maintain this temperature for 10 minutes. After completion, allow the vessel to cool to room temperature; transfer the entire mixture in the extraction vessel to a centrifuge tube, centrifuge at 5000 rpm for 5 minutes, carefully aspirate the supernatant using a pipette, and filter it through a 0.22 μm organic phase needle filter. Collect the filtrate in a sample vial. Analyze the filtered filtrate directly using liquid chromatography-mass spectrometry (LC-MS).

[0051] It should be noted that, Figures 2 to 4 , Figures 2 to 4 The chromatograms of Basic Red 9, Basic Violet 14, Disperse Blue 1, Disperse Orange 11, Disperse Yellow 3, Solvent Yellow 1, Solvent Yellow 2, and Solvent Yellow 3 are those of Example 1.

[0052] Preparation of standard solutions: Accurately weigh 0.01 g of the standard substance into a 50 mL volumetric flask, dissolve it in methanol and dilute to the mark to prepare a single-component standard stock solution with an effective concentration of 200 mg / L. Transfer an appropriate amount of the standard stock solution into a volumetric flask, dilute to the mark with methanol, and prepare a primary standard stock solution with a single-component concentration of 5 mg / L. Transfer appropriate amounts of each of the prepared primary standard stock solutions of Basic Red 9, Basic Violet 14, Solvent Yellow 2, Solvent Yellow 3, Solvent Yellow 1, Disperse Blue 1, Disperse Yellow 3, and Disperse Orange 11 into the same volumetric flask, dilute to the mark with methanol, and prepare a standard mixed working concentrate. Accurately pipette a certain amount of the standard mixed working solution and dilute it stepwise with methanol to prepare a series of standard working solutions. The standard working solutions of Basic Red 9, Basic Violet 14, Solvent Yellow 2, and Solvent Yellow 3 were prepared with concentrations of 0.01 mg / L, 0.025 mg / L, 0.05 mg / L, 0.1 mg / L, and 0.2 mg / L, respectively. The standard working solutions of Solvent Yellow 1, Disperse Blue 1, Disperse Yellow 3, and Disperse Orange 11 were prepared with concentrations of 0.05 mg / L, 0.1 mg / L, 0.2 mg / L, 0.5 mg / L, and 1.0 mg / L, respectively.

[0053] Chromatographic conditions: Hypersil GOLDTMVANQUISH column (100*2.1*1.9); column oven temperature 40℃; mobile phase: B: 0.1% formic acid water; C: acetonitrile.

[0054] Table 1 Chromatographic gradient elution program table Mass spectrometry conditions: Transmission tube temperature: 350℃, ion source temperature: 350℃, voltage: 3500V, ion source type: ESI, select ion monitoring (SIM) mode.

[0055] Table 2 Mass Spectrometry Analysis Parameters Table 3. Comparison of test data between the examples and the comparative examples. Table 3 shows that, compared to Examples 1 and 2, Comparative Example 1 exhibits significantly higher spiked recoveries, extremely large relative standard deviations (RSDs), and significantly higher method limits of detection (MDLs). This indicates that the direct extraction method is completely unsuitable for accurate quantification and trace screening due to the lack of effective purification steps. This demonstrates that the present invention, through stepwise swelling, purification processes, and multi-stage purification including methanol precipitation and alumina column purification, effectively removes interference from the complex plastic matrix, ensuring the accuracy, precision, and sensitivity of the detection results. It achieves efficient and accurate extraction and determination of carcinogenic dyes in the plastic matrix, providing a reliable analytical method for the supervision and control of harmful dyes in plastic products.

[0056] Compared to Example 2, the plastic layer of the medical surgical membrane typically contains more processing aids, stabilizers, and other co-additives in its material formulation compared to a mobile phone case. These are more likely to be co-extracted during the swelling extraction process, leading to a more complex matrix in subsequent precipitation and purification steps, resulting in a slight matrix effect and slight fluctuations in the recovery rate. However, the recovery rates of Example 2 are all greater than 79.8%, RSDs are all less than 8.2, and MDLs are all less than those of Comparative Example 1. This indicates that the rapid screening method for carcinogenic dyes in plastic masterbatches achieves efficient and accurate extraction and determination of carcinogenic dyes in the plastic matrix.

[0057] 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 rapid screening of carcinogenic dyes in masterbatches of plastic parts, characterized in that, Includes the following steps: The plastic sample is crushed to obtain plastic fragments; The plastic fragments were added to dichloromethane for the first swelling and decolorization, and then subjected to the first ultrasonic extraction treatment to obtain a swollen mixture. Toluene was added to the swollen mixture for a second swelling and decolorization, followed by a second ultrasonic extraction to obtain the swollen extract. The swollen extract is transferred to a rotary evaporator for concentration to obtain a concentrated extract. The concentrated extract is added to a methanol precipitant to precipitate the polymer, and the precipitate mixture is obtained after separation. The precipitate mixture was eluted and dried using an activated alumina column to obtain a dry mixture. The dried mixture was redissolved in methanol to obtain the test solution, which was then analyzed by liquid chromatography.

2. The method for rapid screening of carcinogenic dyes in masterbatches of plastic parts according to claim 1, characterized in that, The first ultrasonic extraction treatment lasted for 30-60 minutes, and the ultrasonic frequency was 20kHz-40kHz.

3. The method for rapid screening of carcinogenic dyes in masterbatches of plastic parts according to claim 1, characterized in that, The second ultrasonic extraction process takes 40-60 minutes and the ultrasonic frequency is 20-40 kHz.

4. The method for rapid screening of carcinogenic dyes in masterbatches of plastic parts according to claim 1, characterized in that, When the swollen extract is transferred to a rotary evaporator for concentration, the evaporation is carried out under reduced pressure, and the water bath temperature of the rotary evaporator is controlled at 40℃-50℃.

5. The method for rapid screening of carcinogenic dyes in masterbatches of plastic parts according to claim 1, characterized in that, The mass ratio of methanol to water in the methanol precipitant is (100:0) to (93:7).

6. The method for rapid screening of carcinogenic dyes in masterbatches of plastic parts according to claim 1, characterized in that, The precipitate mixture is eluted and dried using an activated alumina column to obtain a dried mixture, including the following steps: The precipitate mixture is concentrated and dissolved in dichloromethane to obtain a dissolved mixture. The dissolved mixture is passed through the alumina solid-phase extraction column; wherein, when the liquid level of the dissolved mixture drops to the surface of the packing material, it is eluted with dichloromethane and eluted with a strongly polar solvent to obtain an eluent; The eluent is dried by nitrogen blowing to obtain a dry mixture.

7. The method for rapid screening of carcinogenic dyes in masterbatches of plastic parts according to claim 6, characterized in that, After concentrating the precipitate mixture and dissolving it in dichloromethane to obtain a dissolved mixture, and before passing the dissolved mixture through the alumina solid-phase extraction column, the following steps are also included: The alumina solid-phase extraction column was activated and pre-washed with dichloromethane.

8. The method for rapid screening of carcinogenic dyes in masterbatches of plastic parts according to claim 7, characterized in that, The rinsing rate for activating and pre-rinsing the alumina solid-phase extraction column with dichloromethane is 1 drop / second to 3 drops / second.

9. The method for rapid screening of carcinogenic dyes in masterbatches of plastic parts according to claim 1, characterized in that, The dried mixture was redissolved in methanol and then analyzed by liquid chromatography, including the following steps: The dried mixture was reconstituted with methanol and then vortexed to obtain the reconstituted mixture. The reconstituted mixture is filtered through a filter membrane to obtain the test solution; The test solution was analyzed by liquid chromatography.

10. The method for rapid screening of carcinogenic dyes in masterbatches of plastic parts according to claim 1, characterized in that, The preparation of a standard solution includes the following steps: The color masterbatch standard material was diluted to volume with methanol solvent to obtain a primary standard stock solution; Different gradient volumes of the primary standard stock solution were diluted with methanol to obtain multiple sets of standard working solutions.

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