Liquid chromatographic method for the determination of bisphenolic compounds in textiles and paper products

Abstract

This invention belongs to the field of detection technology, specifically relating to a liquid chromatography method for the detection of bisphenol compounds in textiles and paper products. The method of this invention uses textiles and paper products as test samples and includes the following steps: preparing a test sample solution; preparing standard solutions to form a gradient standard working solution; injecting the gradient standard working solution into a liquid chromatograph to determine the peak positions of 12 bisphenol compounds and constructing a standard curve equation; measuring the peak areas of the 12 bisphenol compounds in the test sample solution; substituting the obtained peak areas into the standard curve equation for calculation, and then performing appropriate conversions to finally obtain the content of the 12 bisphenol compounds in the test sample. The method of this invention has high detection sensitivity and good accuracy.

Description

Technical Field

[0001] This invention belongs to the field of detection technology, specifically relating to a liquid chromatography method for the detection of bisphenol compounds in textiles and paper products. Background Technology

[0002] Bisphenol compounds are a class of chemical substances containing two phenolic hydroxyl groups and having similar structures. They are one of the important chemical raw materials for synthesizing polymer materials. Among them, bisphenol A (BPA) is the most widely used both domestically and internationally. It is mainly used in the production of polymers such as polycarbonate (accounting for nearly 70% of global BPA production) and epoxy resin (accounting for nearly 30% of global BPA production). Due to the high performance, sustainability, and eco-efficiency of polycarbonate and epoxy resin, they are commonly used in the production of reusable water bottles and food storage containers, optical discs, eyeglasses, medical devices, building materials, container coatings, and high-performance paints and coatings. According to global market research, the global consumption of BPA is approximately 10 million tons.

[0003] Bisphenolic compounds are widely used as intermediates in polymers or polymer resins, such as polycarbonate plastics, epoxy resins and hardeners, inner coatings for packaging, and textile dyeing and finishing auxiliaries. They are also used in thermal paper, inks and coatings, adhesives, textiles and paper products, and paper or paperboard. Typical applications of bisphenolic compounds in textiles and paper products include color developers for thermochromic printing on color-changing textiles and paper products, color-fixing agents for textiles and paper products, leather tanning agents, dye intermediates, and flame retardants.

[0004] The European Union published (EU) 2016 / 2235 in its Official Journal, adding clause 66 of Annex XVII of the REACH Regulation concerning bisphenol A (BPA), formally including BPA in the REACH Regulation's restricted list. Effective January 2, 2020, thermal paper containing ≥0.02% BPA is prohibited from being placed on the market. The regulation will take effect 20 days after its publication in the Official Journal and applies to all member states. In early 2017, the EU officially published the sixteenth batch of the REACH Regulation's Substances of Very High Importance (SVHC) list, including four substances, including BPA. On April 6, 2022, ECHA and member states assessed 148 bisphenol-related substances and recommended restrictions on the use of more than 30 of them. OEKO-TEX ®The 2022 edition of the 100 Standard added bisphenol B with a limit of 1000 mg / kg, and listed bisphenol F, bisphenol S, and bisphenol AF as "monitored" substances in Annexes 4 and 6. Many bisphenol compounds are known endocrine disruptors with impacts on human health and the environment. Due to their widespread use, population restriction is considered the best approach to managing the risks of 34 bisphenol compounds.

[0005] Currently, three bisphenol compounds—bisphenol A, bisphenol B, and bisphenol F (2,2-bis(4′-hydroxyphenyl)-4-methylpentane)—have been identified as substances of very high concern (SVHCs). Given sufficient hazard information, further SVHC identification or a unified classification and labeling of bisphenol compounds is recommended. However, for many panel members, more data are needed before confirming potential endocrine disruption and reproductive toxicity.

[0006] It is well known that many bisphenol A (BPA) compounds are endocrine disruptors and toxic substances, affecting both human health and the environment. Due to their widespread use, they have potential hormonal or hypoxic effects. Long-term exposure to low levels of BPA can impact human health, being associated with obesity, cancer, diabetes, male reproductive dysfunction, and cardiovascular diseases. Since 2010, the Canadian government and the European Commission have issued regulations prohibiting the manufacture, import, and sale of polycarbonate baby bottles containing BPA. With the stringent regulations on BPA, bisphenol analogs have emerged as alternatives. The Canadian government has identified and is further managing the risks of 34 bisphenol compounds, including bisphenol F (BPF), bisphenol S (BPS), bisphenol B (BBB), bisphenol E (BPE), bisphenol AF (BPAF), and bisphenol Z (BPZ).

[0007] Currently, the production and application of bisphenol compounds are on the rise globally. Many bisphenol analogs exhibit endocrine-disrupting, cytotoxic, genotoxic, reproductive, and neurotoxic effects. Among them, BPAF, BPB, BPF, and BPS show estrogenic effects similar to or even higher than BPA, potentially impacting the human endocrine, reproductive, and nervous systems. German authorities are preparing a proposal to restrict the use of bisphenol A and other environmentally endocrine-disrupting bisphenols. Once it is clarified which bisphenols will be covered by the German proposal, ECHA and the European Commission will consider further regulatory actions on bisphenols.

[0008] Studies have shown that bisphenol A (BPA) compounds have certain embryotoxic and teratogenic effects, pose a carcinogenic risk, produce estrogen-like effects in organisms, and are also endocrine disruptors (environmental hormones), potentially leading to endocrine disorders and harming fetal and child health. Cancer and obesity caused by metabolic disorders are also believed to be related to BPA. BPA compounds inevitably pose a health hazard to humans during close contact between textiles and paper products and the skin, as well as through wastewater discharge from the textile industry. Industrial uses are expected to result in relatively low human exposure, while professional and consumer uses may lead to higher exposure. During daily use, textiles and paper products inevitably come into close contact with the skin, causing BPA compounds to accumulate in the body and thus causing harm. Therefore, researching detection methods for typical bisphenol compounds in imported and exported textiles and paper products is crucial for leveraging the risk warning and rapid response system for import and export commodities, focusing on consumer product quality and safety, strengthening precise prevention and control, strictly controlling product risks, promoting the expansion of import and export of high-quality consumer products, and simultaneously providing positive technical support for customs research on new technologies for impact assessment, trend prediction, and monitoring and early warning of technical trade measures, thus effectively safeguarding the rights and interests of Chinese consumers.

[0009] Therefore, research on detection technologies for various typical bisphenol compounds in textiles and paper products will provide a model for future research on other functional chemical substances in textiles and paper products, and will also provide technical support for the safety evaluation and supervision of imported and exported consumer goods. Furthermore, research on detection methods for bisphenol compounds in textiles and paper products is of significant practical importance for protecting human health and the ecological environment, overcoming technical trade barriers imposed by developed countries, promoting cleaner production, and improving the technological development level of enterprises.

[0010] Liu Fang et al., in SN / T 4424-2022 "Determination of Bisphenolic Compounds in Imported and Exported Textiles by High Performance Liquid Chromatography," used high performance liquid chromatography (HPLC) to simultaneously determine the content of seven bisphenolic compounds (bisphenol A, bisphenol S, bisphenol F, bisphenol AP, bisphenol AF, bisphenol B, and bisphenol Z) in textiles. The sample was extracted with 15 mL of methanol by ultrasonic extraction at room temperature for 30 min. The extract was separated on a C18 column using a methanol-water (65 / 35, v / v) mobile phase and a UV detection wavelength of 280 nm. These studies are limited to determining seven bisphenolic compounds in textiles, with a limit of detection of 15.0 mg / kg. The detection wavelength is also limited to a single wavelength, failing to comprehensively characterize the characteristic UV absorption wavelengths of multiple bisphenolic compounds. Therefore, this method cannot achieve the optimal detection limit with the highest sensitivity.

[0011] The invention CN111380984A, entitled "Method for Pretreatment of Vegetable Samples and Simultaneous Detection of Multiple Bisphenolic Compounds Therein," discloses and provides a vegetable pretreatment method, as well as a method for simultaneously detecting one or more bisphenolic compounds in vegetables, including bisphenol S (BPS), 4-cinnamylphenol (4-CP), bisphenol E (BPE), bisphenol B (BPB), bisphenol C (BPC), bisphenol Z (BPZ), bisphenol AP (BPAP), bisphenol AF (BPAF), bisphenol M (BPM), bisphenol BP (BPBP), tetrachlorobisphenol A (TCBPA), bisphenol PH (BPPH), tetrabromobisphenol A (TBBPA), bisphenol A (BPA), bisphenol P (BPP), and bisphenol F (BPF). The UPLC-ESI-MS / MS instrument used was a Waters ACQUITY UPLC tandem with a Waters Xevo TQD. The mass spectrometer used an ESI ion source, and multiple ion reaction monitoring (MRM) in a triple quadrupole was used as the mass analysis device for the tandem mass spectrometry. The chromatographic column was a Waters ACQUITY UPLC BEH C18 column, 2.1 × 100 mm, 1.7 μm. The mobile phase was methanol and water in a volume ratio of 80:20. The flow rate was 0.3 mL / min. The time was 3 min. The injection volume was 5 μL. The column temperature was 40 °C. The ion source temperature was 150 °C. The desolvation gas temperature was 450 °C. The limits of detection for the 16 compounds were 0.0026–6.2269 ng / g. -1 The lower limit of quantification is 0.0085-20.7564 ng / g. -1 The relative recoveries ranged from 52.5±1.6% (BPA) to 123.7±12.6% (BPM), 51.6±14.2% (BPF) to 124.1±12.3% (TBBPA), 49.3±6.9% (4-CP) to 157.3±16.5% (BPPH), 47.6±11.6% (BPZ) to 126.9±6.9% (BPB), 65.6±9.7% (TBBPA) to 124.1±15.8% (4-CP), and 42.5±6.9% (BPPH) to 126.8±18.4% (BPF). The relative recoveries ranged from 47.6±11.6% to 126.8±18.4% (BPF), indicating a large variation in recovery rates and coefficients of variation, exceeding the general limit analysis requirements.

[0012] The invention CN111337600A, entitled "A Method for Soil Pretreatment and Detection of Multiple Bisphenolic Compounds in Soil," is similar to the aforementioned patent. It utilizes an ultra-high performance liquid chromatography-mass spectrometry (UPLC-MS / MS) analysis platform to construct a method for quantitative analysis and detection of 16 bisphenolic compounds (BPs) in soil, including bisphenol S (BPS), 4-cinnamylphenol (4-CP), bisphenol E (BPE), bisphenol B (BPB), bisphenol C (BPC), bisphenol Z (BPZ), bisphenol AP (BPAP), bisphenol AF (BPAF), bisphenol M (BPM), bisphenol BP (BPBP), tetrachlorobisphenol A (TCBPA), bisphenol PH (BPPH), tetrabromobisphenol A (TBBPA), bisphenol A (BPA), bisphenol P (BPP), and bisphenol F (BPF). The UPLC-MS / MS instrument used was a Waters ACQUITY UPLC in tandem with a Waters Xevo TQD. The mass spectrometer used an ESI ion source, and multiple ion reaction monitoring (MRM) in a triple quadrupole was used as the mass analysis device for the tandem mass spectrometer. The column was a Waters ACQUITY UPLC BEH C18 column, 2.1 × 100 mm, 1.7 μm. The mobile phase was water and methanol, with a volume ratio of 20:80. The flow rate was 0.3 mL / min. The time was 3 min. The injection volume was 5 μL. The column temperature was 40 °C. The ion source temperature was 150 °C. The desolvation gas temperature was 450 °C. Summary of the Invention

[0013] The technical problem to be solved by the present invention is to provide a qualitative, quantitative, and highly sensitive liquid chromatography method suitable for the detection of bisphenol compounds in textiles and paper products.

[0014] To address the aforementioned technical problems, this invention provides a liquid chromatography method for the detection of bisphenol compounds in textiles and paper products, using textiles and paper products as samples, and includes the following steps:

[0015] 1) Preparation of the sample solution to be tested:

[0016] After the sample to be tested is cut into small pieces, an extractant is added and ultrasonic extraction is performed. The resulting extract is cooled to room temperature and then filtered through a 0.20–0.45 µm filter head to obtain the sample solution to be tested.

[0017] The purpose is to provide qualitative and quantitative analysis for high performance liquid chromatography (HPLC), that is, to determine the results using HPLC.

[0018] 2) Preparation of standard solutions:

[0019] Twelve bisphenol compounds were dissolved in a solvent at the same concentration to form a mixed standard working solution (i.e., the concentrations of the 12 bisphenol compounds in the mixed standard working solution were consistent).

[0020] The mixed standard working solutions are serially diluted to form a gradient standard working solution;

[0021] 3) Inject the gradient standard working solutions into the liquid chromatograph and use a diode array detector (DAD) to determine the elution positions of the 12 bisphenol compounds. Record the corresponding peak areas and construct a standard curve equation with concentration as the x-axis and peak area as the y-axis.

[0022] 4) Take the sample solution obtained in step 1) and directly determine the peak area of ​​the 12 bisphenol compounds in the sample solution according to the method described in step 3);

[0023] Alternatively, the sample solution obtained in step 1) can be diluted with an extractant to obtain a diluted sample solution. The peak areas of the 12 bisphenol compounds in the diluted sample solution can be determined according to the method described in step 3).

[0024] Substitute the obtained peak area into the standard curve equation obtained in step 3) for calculation, and then perform the corresponding conversion to finally obtain the content of 12 bisphenol compounds in the sample to be tested.

[0025] As an improvement to the liquid chromatography detection method of the present invention applicable to textiles and paper products, the 12 bisphenol compounds are: bisphenol A (BPA), bisphenol B (BPB), bisphenol C (BPC), bisphenol E (BPE), bisphenol S (BPS), bisphenol F (BPF), bisphenol M (BPM), bisphenol P (BPP), bisphenol AP (BPAP), bisphenol AF (BPAF), bisphenol Z (BPZ), and tetrabromobisphenol A (TBBPA).

[0026] As a further improvement to the liquid chromatography method of the present invention for the detection of bisphenol compounds in textiles and paper products: the liquid chromatography conditions in step 3) are as follows:

[0027] Flow rate: 0.2–2.0 mL / min; column temperature: 20–45 °C; injection volume: 1–20 µL;

[0028] Mobile phase A: methanol; Mobile phase B: water; Gradient elution program: 0 min, 40% A; 0–6 min, 40% A–65% A; 6–10 min, 65% A–72% A; 10–18 min, 72% A–75% A; 18–21 min, 75% A; 21–23 min, 75% A–40% A; Flow rate: 1.0 mL / min.

[0029] As a further improvement to the liquid chromatography method of the present invention for the detection of bisphenol compounds in textiles and paper products: the liquid chromatography column is: Zorbax Extend-C 18 5 μm, 4.6 mm (id) × 15 cm column or equivalent;

[0030] Detection wavelengths: 258 nm, 278 nm, 286 nm; the detection wavelength for bisphenol S is 258 nm; the detection wavelength for tetrabromobisphenol A is 286 nm; the detection wavelength for the remaining 10 bisphenol compounds (bisphenol A, bisphenol B, bisphenol C (BPC), bisphenol E, bisphenol F, bisphenol M, bisphenol P, bisphenol AP, bisphenol AF, bisphenol Z) is 278 nm.

[0031] As a further improvement of the liquid chromatography detection method of the present invention applicable to textiles and paper products: the solvent in step 2) is methanol or acetonitrile; the extractant in step 1) is methanol.

[0032] As a further improvement to the liquid chromatography detection method of the present invention applicable to textiles and paper products, step 1) is as follows:

[0033] 1.1) Cut the sample to be tested into small pieces of 5mm × 5mm as the test sample;

[0034] 1.2) At a material-to-liquid ratio of 1g / 10~50mL, the sample and extractant are placed together in the extractor. After sealing the extractor, ultrasonic extraction is performed at room temperature for 10~60 min.

[0035] Generally, weigh 1g of the mixed sample, accurate to 0.01g, place it in a glass extractor with a screw cap, and add 10-50 mL of methanol or equivalent solvent to immerse all the sample in the liquid.

[0036] As a further improvement of the liquid chromatography detection method of the present invention applicable to bisphenol compounds in textiles and paper products: step 2) is: setting up gradient standard working solutions with concentrations of bisphenol compounds of 1 μg / mL, 3 μg / mL, 5 μg / mL, 7 μg / mL and 10 μg / mL.

[0037] Table 1. Chemical Information of 12 Bisphenol Compounds

[0038]

[0039]

[0040]

[0041] When preparing standard solutions, the 12 bisphenol compound standard substances in Table 1 can be dissolved in methanol or acetonitrile to prepare standard stock solutions with a concentration of 100~1000μg / mL; the standard stock solutions of the 12 bisphenol compounds in Table 1 can be dissolved in methanol or acetonitrile to prepare mixed standard working solutions with a concentration of 0.1~100μg / mL.

[0042] In step 3) of this invention, the "liquid chromatography conditions" setting employs full-wavelength scanning. First, the characteristic UV absorption wavelengths of 12 bisphenol compounds are determined. To obtain the optimal detection sensitivity for simultaneously determining these 12 bisphenol compounds, a three-channel, three-wavelength acquisition method is used for qualitative and quantitative analysis: detection wavelengths of 258 nm, 278 nm, and 286 nm. However, some similar studies limit detection wavelengths to a single wavelength, failing to comprehensively characterize the characteristic UV absorption wavelengths of multiple bisphenol compounds.

[0043] Bisphenolic compounds are typically used in textiles and paper products as color developers for thermochromic printing on color-changing textiles and paper products, as fixing agents for textiles and paper products, as tanning agents for leather, as dye intermediates, and as flame retardants. If bisphenolic compounds are detected in thermochromic textiles and paper products, their content is generally high, making HPLC more suitable and providing more accurate results. This invention targets textile and paper samples, employing ultrasonic extraction with methanol or acetonitrile. The samples are then purified by filtration using a 0.20–0.45 µm organic phase filter, eliminating the need for cumbersome SPE purification. Finally, high-performance liquid chromatography (HPLC) is used for determination. This method offers advantages such as the use of inexpensive and widely available instruments, simple operation, and rapid efficiency.

[0044] Compared with the prior art, the present invention has the following significant advantages:

[0045] (1) This method utilizes high performance liquid chromatography (HPLC) gradient elution conditions to effectively separate 12 bisphenol compounds within 25 min. The chromatographic peaks are completely separated, with symmetrical and sharp peak shapes, and the responses are all optimal, further improving the detection sensitivity and accuracy of the detection method. The method is highly sensitive, simple to operate, accurate and reliable. The ultra-high performance liquid chromatography method described in this invention is suitable for the confirmation and quantitative determination of 12 bisphenol compounds in textiles and paper products.

[0046] (2) The determination method disclosed in this invention has good linearity in the range of 1.0 to 10.0 µg / mL, with a linear correlation coefficient of 0.99 or higher. The limit of detection (LOD) of the method is 0.1 to 0.7 mg / kg, and the limit of detection (LOQ) of the method is 0.3 to 2.3 mg / kg. Attached Figure Description

[0047] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0048] Figure 1 These are liquid chromatograms of 12 bisphenol compounds.

[0049] Figure 1 The top image shows the high-performance liquid chromatography (HPLC) chromatograms of 12 bisphenol compounds detected at a wavelength of 258 nm, with bisphenol S showing the best response at this wavelength. The middle image shows the HPLC chromatograms of 12 bisphenol compounds detected at a wavelength of 278 nm, with the following compounds showing the best response at this wavelength: bisphenol A, bisphenol B, bisphenol C (BPC), bisphenol E, bisphenol F, bisphenol M, bisphenol P, bisphenol AP, bisphenol AF, and bisphenol Z. The bottom image shows the HPLC chromatograms of 12 bisphenol compounds detected at a wavelength of 286 nm, with tetrabromobisphenol A showing the best response at this wavelength.

[0050] Figures 2-13 These are the ultraviolet spectra of 12 bisphenol compounds.

[0051] Figure 2 This is the ultraviolet spectrum of bisphenol A; Figure 3 The image shows the UV spectrum of bisphenol AF. Figure 4 The image shows the UV spectrum of bisphenol AP. Figure 5 This is the ultraviolet spectrum of bisphenol B; Figure 6 This is the ultraviolet spectrum of bisphenol C; Figure 7 The image shows the ultraviolet spectrum of bisphenol E. Figure 8 The image shows the ultraviolet spectrum of bisphenol F. Figure 9 The image shows the UV spectrum of bisphenol M. Figure 10 The image shows the ultraviolet spectrum of bisphenol P. Figure 11 The image shows the ultraviolet spectrum of bisphenol S. Figure 12 The image shows the ultraviolet spectrum of bisphenol Z. Figure 13 This is the ultraviolet spectrum of tetrabromobisphenol A. Detailed Implementation

[0052] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto:

[0053] 1. Reagents and Materials

[0054] Unless otherwise stated, all reagents used in the analysis were HPLC grade, and all water used was Grade I water.

[0055] 1.1 Methanol.

[0056] 1.2 Acetonitrile.

[0057] 1.3 Bisphenol compound standard substances: Bisphenol A (BPA) (purity ≥99.70%), Bisphenol B (BPB) (purity ≥99.80%), Bisphenol C (BPC) (purity ≥98.80%), Bisphenol E (BPE) (purity ≥99.90%), Bisphenol S (BPS) (purity ≥99.90%), Bisphenol F (BPF) (purity ≥99.90%), Bisphenol M (BPM) (purity ≥99.90%), Bisphenol P (BPP) (purity ≥99.90%), Bisphenol AP (BPAP) (purity ≥99.90%), Bisphenol AF (BPAF) (purity ≥99.90%), Bisphenol Z (BPZ) (purity ≥99.70%), Tetrabromobisphenol A (TBBPA) (purity ≥99.00%), etc.

[0058] 1.4 Standard stock solutions: Prepare standard stock solutions of 12 bisphenol compounds with a concentration of 1000 μg / mL using methanol or other suitable solvents (e.g., acetonitrile); then take appropriate amounts of the above standard stock solutions and prepare mixed standard stock solutions with a concentration of 100 μg / mL using the corresponding methanol or other suitable solvents (e.g., acetonitrile) (the 12 bisphenol compounds in the mixed standard stock solutions have the same concentration).

[0059] 1.5 Standard working solutions: Prepare gradient standard working solutions (mixed standard working solutions) with appropriate methanol or other suitable solvents (e.g., acetonitrile) to obtain concentrations of 1 μg / mL, 3 μg / mL, 5 μg / mL, 7 μg / mL and 10 μg / mL.

[0060] Note: Both the standard stock solution and the gradient standard working solution should be stored at 4 ℃ protected from light, and their shelf lives are 12 months and 6 months, respectively.

[0061] 2. Instruments and Equipment

[0062] 2.1 High-performance liquid chromatograph (HPLC): with diode array detector (DAD).

[0063] 2.2 Ultrasonic generator: operating frequency is 40 kHz.

[0064] 2.3 Analytical balance: sensitivity of 0.0001 g and 0.01 g.

[0065] 2.4 Extractor: 50 mL glass tube with screw cap.

[0066] 2.5 Rotary vacuum evaporator.

[0067] 2.6 Organic phase filter membrane: 0.45 µm.

[0068] 3. Blank polyester samples and white paper samples refer to samples that have been tested in advance to ensure that they do not contain the 12 bisphenol compounds described in this invention.

[0069] Example 1: A liquid chromatography method for the detection of 12 bisphenol compounds in textiles and paper products, using textiles and paper products as samples, includes the following steps:

[0070] 1) Preparation of the sample solution to be tested:

[0071] (1) Take the sample to be tested, cut it into small pieces of about 5mm×5mm, and mix them well;

[0072] (2) Weigh 1.0 g of the above-mentioned shredded sample, accurate to 0.01 g, place it in a glass extractor with a screw cap, add 15 mL of methanol, so that all the sample is submerged in the liquid, seal the extractor, and extract it by ultrasonic extraction in an ultrasonic generator for 30 min.

[0073] That is, the ratio of the sample to the extractant is 1g / 15mL;

[0074] (3) After cooling to room temperature, filter the sample solution with a 0.45 µm filter head, and then place the filtered sample solution in a sample injection bottle and seal it for qualitative and quantitative analysis by high performance liquid chromatography.

[0075] 2) Preparation of standard solutions

[0076] (1) Prepare standard stock solutions with a concentration of approximately 1000 μg / mL by using methanol or other suitable solvents for 12 bisphenol compound standard substances;

[0077] (2) Take an appropriate amount of the above standard stock solutions and prepare a mixed standard stock solution with a concentration of 100 μg / mL using methanol or other suitable solvent;

[0078] (3) Prepare gradient standard working solutions with concentrations of 1 μg / mL, 3 μg / mL, 5 μg / mL, 7 μg / mL and 10 μg / mL using methanol or other suitable solvents;

[0079] 3) Inject the gradient standard solutions into the high-performance liquid chromatograph (HPLC) and determine the peak positions of the 12 bisphenol compounds using a diode array detector (DAD). Record the corresponding peak areas and construct a standard curve equation with concentration on the x-axis and peak area on the y-axis. Details are as follows:

[0080] a) Column: Zorbax Extend-C 18 5 μm, 4.6 mm (id) × 15 cm column or equivalent;

[0081] b) Flow rate: 1.0 mL / min;

[0082] c) Detector: Diode array detector (DAD);

[0083] d) Detection wavelengths: 258 nm, 278 nm, 286 nm;

[0084] e) Column temperature: 40 ℃;

[0085] f) Injection volume: 10 µL;

[0086] g) Mobile phase A: water; Mobile phase B: methanol;

[0087] h) The gradient elution procedure is shown in Table 2.

[0088] Table 2. Gradient elution program for high performance liquid chromatography

[0089] 0 1.0 60 40 6 1.0 35 65 10 1.0 28 72 18 1.0 25 75 21 1.0 25 75 23 1.0 60 40

[0090] Note: The detection wavelength for bisphenol S is 258 nm; the detection wavelength for tetrabromobisphenol A is 286 nm. The detection wavelength for the remaining 10 bisphenol compounds (bisphenol A, bisphenol B, bisphenol C (BPC), bisphenol E, bisphenol F, bisphenol M, bisphenol P, bisphenol AP, bisphenol AF, and bisphenol Z) is 278 nm.

[0091] The equations for the obtained standard curves are shown in Table 3.

[0092] 4) Take the filtered sample obtained in step 1) and determine the 12 bisphenol compounds in the test sample solution according to the method in step 3) (i.e., replace 10µL of gradient standard solution with 10µL of filtered sample, and the rest are the same). Use the established standard curve (linear equation) to obtain the content of 12 bisphenol compounds in the sample solution; then, according to the sample dilution factor (i.e., the conversion relationship between 1g of sample and filtered sample), obtain the content of 12 bisphenol compounds in the test sample.

[0093] 5) Qualitative Analysis

[0094] (Corresponding to step 4) Under the same test conditions, the analyte in the sample and the standard substance detected at the same time have the same retention time, with a retention time tolerance of ± 0.1 min. Furthermore, the UV spectrum of the sample is compared with the UV spectrum of the standard solution, and the UV spectra are consistent. Therefore, it is determined that the corresponding analyte is present in the sample.

[0095] 6) Quantitative analysis

[0096] Corresponding to step 4), this method uses the external standard method for quantification. Based on the content of the analyte in the sample solution, a standard working solution with a similar concentration is selected. The standard working solution and the sample solution are injected in equal volumes for determination. The response values ​​of the 12 bisphenol compounds in the standard working solution and the sample solution to be tested should all be within the linear range of the instrument.

[0097] Note 1: If the detection response value of the sample solution exceeds the linear range of the instrument, it can be appropriately diluted before measurement.

[0098] Note 2: Under the above chromatographic conditions, the high-performance liquid chromatograms and corresponding ultraviolet spectra of the 12 bisphenol compounds are shown below. Figure 1 and Figures 2 to 13 .

[0099] 7) Detection limit

[0100] The lowest detection limit (LOD) was determined using a signal-to-noise ratio of 3 (S / N=3), and the lowest quantitation limit (LOQ) was determined using a signal-to-noise ratio of 10 (S / N=10). The limits of determination for this method in liquid chromatography for the detection of 12 bisphenol compounds in textiles and paper products are shown in Table 3.

[0101] The high-performance liquid chromatography method disclosed in this invention shows good linearity for 12 bisphenol compounds in the concentration range of 1–10 μg / mL, as shown in Table 3.

[0102] Table 3. Linear equations and linear correlation coefficients for the determination of 12 bisphenol compounds by high performance liquid chromatography.

[0103] Bisphenol S Bis(4-hydroxyphenyl)sulfone 3.865 Y = 46.50x - 19.88 0.99980 0.1 0.3 Bisphenol F Bisphenol F 6.857 Y = 8.90x - 3.80 0.99985 0.2 0.7 Bisphenol E Bisphenol E 7.889 Y = 8.30x - 3.40 0.99983 0.2 0.7 Bisphenol A Bisphenol A 8.840 Y = 8.10x - 2.69 0.99976 0.2 0.7 Bisphenol B 2,2-Bis(4-hydroxyphenyl)butane 10.360 Y = 7.56x - 3.24 0.99980 0.3 0.9 Bisphenol AF Hexafluorobisphenol A 10.218 Y = 3.43x - 1.36 0.99990 0.6 2.0 Bisphenol AP Bisphenol AP 11.451 Y = 6.50x - 2.36 0.99981 0.3 0.9 Bisphenol C Bisphenol C 11.675 Y = 8.39x - 3.05 0.99986 0.3 0.9 Bisphenol Z Bisphenol Z 12.609 Y = 6.53x - 2.87 0.99992 0.4 1.3 Bisphenol M Bisphenol M 19.299 Y = 5.59x - 2.51 0.99997 0.7 2.3 Bisphenol P Bisphenol P 20.030 Y = 6.38x - 3.33 0.99993 0.6 2.0 Tetrabromobisphenol A Tetrabromobisphenol A 20.991 Y = 6.10x - 3.11 0.99990 0.4 1.3

[0104] Comparative Example 1: The detection wavelength in Example 1 was changed to only 278 nm;

[0105] Therefore, the linear equation obtained for bisphenol S is Y = 24.82x - 6.22: the linear correlation coefficient (r) is 0.99913, the LOD is 0.13 mg / kg, and the LOQ is 0.42 mg / kg;

[0106] The linear equation obtained for tetrabromobisphenol A is Y = 4.23x - 7.27: the linear correlation coefficient (r) is 0.99924, the LOD is 0.86 mg / kg, and the LOQ is 2.87 mg / kg.

[0107] Experiment 1: Sample Addition Recovery and Precision Experiment

[0108] A standard mixed solution of 12 bisphenol compounds was added to blank polyester samples and blank white paper samples at concentrations of 3 mg / kg, 5 mg / kg and 10 mg / kg, respectively. Six replicates were set for each concentration. The recovery rates of bisphenol compounds in polyester samples were determined according to the above pretreatment and analytical methods. The results are shown in Tables 4 and 5.

[0109] Table 4. Recovery rates and relative standard deviations of bisphenol compounds at different concentrations added to blank polyester samples (n=6)

[0110]

[0111] Table 5. Recovery rates and relative standard deviations of bisphenol compounds at different concentrations added to blank white paper samples (n=6)

[0112]

[0113] The polyester sample (added 10 mg / kg) described in Experiment 1 was tested according to the method described in Comparative Example 1. The results were as follows: the average recovery rate of bisphenol S was 88.7%, and the relative standard deviation was 9.2%; the average recovery rate of tetrabromobisphenol A was 90.4%, and the relative standard deviation was 8.7%. Comparing these results with the average recovery rate (%) and RSD (%) corresponding to 10 mg / kg in Table 4, it can be seen that the present invention has a technical advantage in terms of higher recovery rate and detection precision compared to the method described in Comparative Example 1.

[0114] Experiment 2, Detection of positive samples

[0115] Four commercially available textiles with thermosensitive color-changing patterns and four samples of thermosensitive printed white paper were extracted and diluted to a fixed volume according to the above procedures. Each sample was tested in parallel six times, and the results were determined by high performance liquid chromatography. The results are shown in Tables 6 and 7.

[0116] Table 6. Results of Tests on Positive Heat-Sensitive Textile Samples

[0117]

[0118] ND: Indicates not detected.

[0119] Note: Since the positive sample has a high detection content, it needs to be diluted by a large factor. That is, the filtered sample obtained in step 1) (3) is diluted, and then the filtered sample diluted solution is used for step 4) detection to obtain the content of 12 bisphenol compounds in the filtered sample diluted solution. Then, according to the conversion relationship between 1g of sample and the filtered sample diluted solution, the content of 12 bisphenol compounds in the sample to be tested is obtained.

[0120] Table 7. Results of positive thermal white paper sample testing

[0121]

[0122] Verification test: The samples 1# to 8# described in Experiment 2 above were detected by high performance liquid chromatography. The results were as follows: Bisphenol A was detected in samples 1# to 8#. The results were basically consistent with those in Tables 6 and 7 above.

[0123] Finally, it should be noted that the above examples are merely some specific embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments and many variations are possible. All variations that can be directly derived or conceived by those skilled in the art from the disclosure of the present invention should be considered within the scope of protection of the present invention.

Claims

1. A liquid chromatography method for the detection of bisphenol compounds in thermochromic textiles and paper products, using textiles and paper products as samples, characterized in that... Includes the following steps: 1) Preparation of the sample solution to be tested: After the sample to be tested is cut into small pieces, an extractant is added and ultrasonic extraction is performed. The resulting extract is cooled to room temperature and then filtered through a 0.20–0.45 µm filter head to obtain the sample solution to be tested. 2) Preparation of standard solutions: Twelve bisphenol compounds were dissolved in solvents at the same concentration to form mixed standard working solutions; The mixed standard working solutions are serially diluted to form a gradient standard working solution; The 12 bisphenol compounds are: bisphenol A (BPA), bisphenol B (BPB), bisphenol C (BPC), bisphenol E (BPE), bisphenol S (BPS), bisphenol F (BPF), bisphenol M (BPM), bisphenol P (BPP), bisphenol AP (BPAP), bisphenol AF (BPAF), bisphenol Z (BPZ), and tetrabromobisphenol A (TBBPA). 3) Inject the gradient standard working solutions into the liquid chromatograph and use a diode array detector to determine the peak positions of the 12 bisphenol compounds. Record the corresponding peak areas and construct a standard curve equation with concentration as the x-axis and peak area as the y-axis. The liquid chromatography conditions are as follows: Flow rate: 0.2–2.0 mL / min; column temperature: 20–45 °C; injection volume: 1–20 µL; Mobile phase A: methanol; Mobile phase B: water; Gradient elution program: 0 min, 40% A; 0–6 min, 40% A–65% A; 6–10 min, 65% A–72% A; 10–18 min, 72% A–75% A; 18–21 min, 75% A; 21–23 min, 75% A–40% A; Flow rate: 1.0 mL / min; The liquid chromatography column was: Zorbax Extend-C 18 5 μm, 4.6 mm (id) × 15 cm chromatographic column; Detection wavelengths: 258 nm, 278 nm, 286 nm; the detection wavelength for bisphenol S is 258 nm; the detection wavelength for tetrabromobisphenol A is 286 nm; the detection wavelength for the remaining 10 bisphenol compounds: bisphenol A, bisphenol B, bisphenol C, bisphenol E, bisphenol F, bisphenol M, bisphenol P, bisphenol AP, bisphenol AF, and bisphenol Z is 278 nm. 4) Take the sample solution obtained in step 1) and directly determine the peak area of ​​12 bisphenol compounds in the sample solution according to the liquid chromatography conditions in step 3). Alternatively, the sample solution obtained in step 1) can be diluted with an extractant to obtain a diluted sample solution. The peak areas of the 12 bisphenol compounds in the diluted sample solution can be determined according to the liquid chromatography conditions in step 3). Substitute the obtained peak area into the standard curve equation obtained in step 3) for calculation, and then perform the corresponding conversion to finally obtain the content of 12 bisphenol compounds in the sample to be tested.

2. The liquid chromatography detection method for 12 bisphenol compounds in thermochromic textiles and paper products according to claim 1, characterized in that: The solvent in step 2) is methanol or acetonitrile; the extractant in step 1) is methanol.

3. The liquid chromatography detection method for 12 bisphenol compounds in thermochromic textiles and paper products according to claim 2, characterized in that: Step 1) is as follows: 1.1) Cut the sample to be tested into small pieces of 5mm × 5mm as the test sample; 1.2) At a material-to-liquid ratio of 1g / 10~50mL, the sample and extractant are placed together in the extractor. After sealing the extractor, ultrasonic extraction is performed at room temperature for 10~60 min.

4. The liquid chromatography detection method for 12 bisphenol compounds in thermochromic textiles and paper products according to claim 3, characterized in that: Step 2) involves setting up gradient standard working solutions with concentrations of bisphenol compounds of 1 μg / mL, 3 μg / mL, 5 μg / mL, 7 μg / mL, and 10 μg / mL.

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