Method for rapidly determining content of 4, 4-dichlorodihydroxydiphenyl ether in laundry detergent

Abstract

The invention provides a method for rapidly determining the content of 4, 4-dichlorodihydroxydiphenyl ether in a laundry detergent, and belongs to the technical field of detergent component content detection. According to the method, the content of 4, 4-dichlorodihydroxydiphenyl ether in the laundry detergent is measured by adopting a high performance liquid chromatography. In the determination process, an acetonitrile-water-sodium chloride three-phase mixture is used for removing impurities, and a mixed solution of acetonitrile and toluene is used as an extracting agent for solid-phase elution; a flowing phase A is an acetic acid aqueous solution with the pH value of 3.5-4, and a flowing phase B is acetonitrile. According to the method, the high performance liquid chromatography is combined with the solid phase extraction technology, high-sensitivity and high-accuracy determination can be achieved, a standard curve is established, and the reliability and accuracy of a result are further guaranteed. The method disclosed by the invention is simple to operate, good in stability and repeatability, and capable of accurately and rapidly measuring the content of 4, 4-dichlorodihydroxydiphenyl ether.

Description

Technical Field

[0001] The present invention relates to the field of detecting the component content of washing powder, and particularly to a method for rapidly determining the content of 4,4-dichlorodihydroxydiphenyl ether in laundry detergent. Background Art

[0002] In a laundry detergent with components such as surfactant, anti-stain redeposition agent, fabric brightener, phosphorus-free water softener, fragrance, preservative, colorant and bacteriostatic agent, 4,4-dichlorodihydroxydiphenyl ether is widely used as a broad-spectrum antibacterial synergist that can effectively inhibit bacteria. The accurate determination of its content is of great significance for ensuring the quality of detergent products, avoiding environmental pollution and human health risks. In the prior art, the following problems mainly exist in the detection methods for the content of 4,4-dichlorodihydroxydiphenyl ether in laundry detergent:

[0003] Insufficient detection sensitivity: Traditional high-performance liquid chromatography (HPLC) methods mostly adopt direct injection or simple dilution. However, due to the interference of high-concentration impurities on 4,4-dichlorodihydroxydiphenyl ether in complex matrices, the requirements for high-precision determination cannot be met.

[0004] Insufficient analysis speed and stability: Due to insufficient pretreatment of impurities in the early stage, the chromatographic separation time is relatively long (>20 min), resulting in poor repeatability between batches.

[0005] In summary, the existing detection methods have significant defects in terms of sensitivity and operation convenience, and it is difficult to meet the requirements of the modern detergent industry for rapid, accurate and high-throughput detection of the content of 4,4-dichlorodihydroxydiphenyl ether. Therefore, there is an urgent need to develop a new detection method with both high sensitivity and rapidity to solve the above technical bottlenecks. Summary of the Invention

[0006] The object of the present invention is to propose a method for rapidly determining the content of 4,4-dichlorodihydroxydiphenyl ether in laundry detergent in view of the above problems existing in the prior art.

[0007] The object of the present invention can be achieved by the following technical solutions: A method for rapidly determining the content of 4,4-dichlorodihydroxydiphenyl ether in laundry detergent. The laundry detergent is a bactericidal and acaricidal laundry detergent, and its components include surfactants, anti-stain redeposition agents, fabric brighteners, phosphorus-free water softeners, fragrances, preservatives, colorants and bacteriostatic agents. The content of 4,4-dichlorodihydroxydiphenyl ether in the laundry detergent is determined by high performance liquid chromatography. The specific method includes the following steps: S1 Pretreatment: The laundry detergent sample is subjected to pretreatment operations to obtain a laundry detergent base liquid; the pretreatment operations include an impurity removal operation stage and a preliminary extraction operation stage; in the preliminary extraction operation stage, acetonitrile is selected as the solvent; the laundry detergent contains various components and some solid impurities. The purpose of pretreatment is to preliminarily remove these impurities while retaining the target substance as much as possible. Acetonitrile-water-sodium chloride is used as the impurity remover. In the acetonitrile-water-sodium chloride three-phase mixture, according to the volume-mass ratio, acetonitrile: water: sodium chloride is 20-22 mL: 5-5.5 mL: 2-2.2 g. The purpose of adding sodium chloride is to cause solid impurities to aggregate and precipitate through salting-out effect. A specific proportion of sodium chloride can promote the phase separation of the acetonitrile-water-salt system, forming a clear upper acetonitrile phase and a lower precipitate layer containing impurities, simplifying the separation. However, attention must be paid to the dosage, which should not only satisfy the induction of significant salting-out but also not have too high a concentration to interfere with subsequent operations and introduce new impurities.

[0008] S2 Solid-phase extraction: After activating the solid-phase extraction column with an extractant, the laundry detergent base liquid is eluted with the extractant to obtain an initial extract. After the initial extract is successively concentrated, fixed in volume and filtered, a sample solution is obtained; the extractant is a mixed solution of acetonitrile and toluene, and according to the volume ratio, acetonitrile: toluene is 3-4: 1. In the elution operation, the volume ratio of the extractant to the laundry base liquid is 2: 0.5-1.

[0009] Polarity Matching and Solubility Optimization: Characteristics of the Target Compound: Role of Acetonitrile: As a solvent, acetonitrile can fully dissolve the target compound; Role of Toluene in Adjustment: Toluene is a non-polar solvent. By reducing the overall solvent polarity, it can selectively retain the target compound, reduce the co-extraction of highly polar impurities, and improve the resolution. Synergistic Effect of the Mixed Solvent: With an appropriate ratio of acetonitrile to toluene, by volume, acetonitrile:toluene is 3 - 4:1, an ideal partition coefficient can be established, enabling the efficient retention of the target compound in the solid phase while allowing some impurities to dissolve in the liquid phase and be discarded. Compatibility with Subsequent Analysis: Connection with the HPLC Mobile Phase: The mobile phase B of high-performance liquid chromatography (HPLC) is acetonitrile. Using an extraction agent with acetonitrile as the main component can simplify the sample pretreatment process. After the extracted sample is concentrated and volume-fixed, the residual acetonitrile can be directly incorporated into the HPLC system without additional purification, reducing human error and operational complexity. Control of Trace Residual Toluene: Through concentration and subsequent dilution for volume fixation, the content of toluene can be reduced below the detection limit, avoiding interference with chromatographic analysis (such as tailing peaks or baseline noise). Considerations for Process Stability: Volatility and Operational Safety: Toluene has a relatively low boiling point and is prone to volatilization during the concentration process after extraction, reducing the risk of solvent residue and avoiding the decomposition of the target compound at high temperatures.

[0010] In summary, the mixed solution of acetonitrile and toluene as an extraction agent can effectively separate the complex components in the laundry detergent and efficiently enrich the target substance through polarity complementarity; as a non-polar solvent, toluene can separate the target substance from the interfering substances and release the target substance into the acetonitrile phase.

[0011] Through steps S1 and S2, the target substance in the laundry detergent can be extracted and well separated from the brightening agent, phosphorus-free water softener, anti-stain redeposition agent, and preservative in the laundry detergent.

[0012] S3 Establish the Standard Curve: Perform high-performance liquid chromatography measurements on several standard solutions of 4,4-dichlorodihydroxydiphenyl ether with different concentrations respectively. According to the measurement results, with the peak area as the ordinate and the concentration as the abscissa, make a linear equation of the peak area versus the concentration to obtain the standard curve of the content of 4,4-dichlorodihydroxydiphenyl ether;

[0013] The reasons for using the external standard method are as follows: 1. The laundry detergent itself contains multiple components, which will interfere with the separation and detection of HPLC. If the internal standard method is used, it is necessary to find a substance that does not exist in the sample and has similar properties to the analyte as the internal standard, which is relatively difficult in practical applications. The external standard method removes interfering substances as much as possible through pretreatment steps (such as preliminary extraction and solid-phase extraction), enabling the analyte in the sample to be accurately determined and reducing the dependence on the internal standard. 2. Matrix effect residue: Although pretreatment and solid-phase extraction cannot completely eliminate the matrix, after treatment, the residual interference has been reduced to an acceptable level. In addition, multi-point calibration of the standard curve helps to correct minor deviations. 3. The external standard method uses the same experimental conditions in sample analysis and standard sample analysis, and calculates the content by comparing the peak area of the analyte in the sample with the corresponding value of the standard sample with a known concentration. The key to this method is to ensure that the conditions in the analysis process of the sample and the standard sample are exactly the same, such as the mobile phase, column temperature, detector settings, etc. The operation is relatively simple and the detection time is fast.

[0014] Determination of sample solution S4: Perform high-performance liquid chromatography determination on the sample solution, and use the standard curve to quantitatively analyze the determination results to obtain the content of 4,4-dichlorodihydroxydiphenyl ether in the laundry detergent sample.

[0015] Preferably, in step S1, centrifugation technology is used in both the impurity removal operation stage and the preliminary extraction operation stage.

[0016] Preferably, in step S2, the solid-phase extraction column is a C18 column.

[0017] Preferably, in step S2, the concentration operation is carried out using a rotary evaporator for concentration.

[0018] Preferably, in step S2, the filtration operation is carried out using a 0.45 μm organic phase microfiltration membrane. Effectively remove impurities and particles: Pore size selectivity: The 0.45 μm micropores can retain most suspended solid impurities, while allowing the target compound (4,4-dichlorodihydroxydiphenyl ether) and small molecule solvents (acetonitrile) to pass through smoothly. This ensures the purity of the sample solution and avoids problems such as column clogging or tailing peaks in subsequent HPLC analysis due to large particles. Compatibility and chemical stability: The filter membrane material is selected to be suitable for the organic phase and has excellent chemical inertness, resistant to strong polar organic solvents such as acetonitrile and toluene, and is not prone to dissolution, swelling or chemical reactions, thus avoiding the loss or contamination of the target compound. Anti-adsorption performance: Compared with the aqueous phase filter membrane, the organic phase filter membrane has stronger surface hydrophobicity, reducing the possibility of adsorption of the target compound on the filter membrane and ensuring high recovery. Optimize chromatographic analysis performance: Protect the chromatographic system: The filtered sample solution can be directly injected into the HPLC system, avoiding physical damage (such as clogging) or chemical degradation (such as oxidation) of the expensive chromatographic column by impurities, and extending the service life of the instrument. Improve peak shape quality: The presence of impurities may lead to peak broadening, splitting or baseline noise. Through precise filtration, the symmetry and resolution of the target peak can be significantly improved, meeting the sensitivity and precision requirements of quantitative analysis.

[0019] Preferably, in high performance liquid chromatography, the detector is a VWD detector, and the detection wavelength is 278 nm; the chromatographic column is a C18 column.

[0020] Preferably, in the high performance liquid chromatography determination operation, the column temperature of the chromatographic column is set at 30 °C.

[0021] Preferably, in the high performance liquid chromatography determination operation, the injection volume is 5 - 6 μL, and the flow rate is set at 1 - 1.1 mL / min.

[0022] Beneficial effects: Compared with the prior art, the present invention has the following beneficial effects:

[0023] Improve detection accuracy: By combining high performance liquid chromatography (HPLC) with solid phase extraction technology, this method can achieve high sensitivity and high accuracy determination, ensuring the accurate detection of trace components of 4,4-dichlorodihydroxydiphenyl ether in laundry detergent. The establishment of the standard curve further guarantees the reliability and accuracy of the results.

[0024] High sensitivity, strong selectivity and good separation effect: Under the optimized conditions of high performance liquid chromatography, the method of the present invention can provide high sensitivity and high selectivity detection, significantly improving the separation effect of the analysis, and can accurately identify and determine trace components of 4,4-dichlorodihydroxydiphenyl ether in laundry detergent. By selecting appropriate mobile phase ratios and chromatographic columns, matrix interference can be avoided, ensuring accurate quantitative analysis of the target substance.

[0025] Simplification of the pretreatment step: During the pretreatment process, an acetonitrile-water-sodium chloride mixture is used as the impurity removal agent, and centrifugation technology is combined to remove impurities, improving the purity of the laundry detergent sample and making subsequent determinations more accurate. This pretreatment method of impurity removal and preliminary extraction makes sample preparation more efficient.

[0026] High efficiency of solid-phase extraction: Using a C18 solid-phase extraction column can effectively separate 4,4-dichlorodihydroxy diphenyl ether from other impurities or matrices in the laundry detergent, ensuring the accuracy of the determination. Moreover, a mixed solution of acetonitrile and toluene is used as the extraction agent, improving the extraction efficiency and further enhancing the separation and recovery rate of the sample.

[0027] Optimization of the concentration and filtration steps: The concentration operation is carried out using a rotary evaporator, enabling the sample to be concentrated at low temperature, avoiding thermal degradation of components and ensuring the recovery rate of the target substance. The filtration operation is carried out using a 0.45μm organic phase microporous filter membrane to effectively remove particulate impurities and ensure the accuracy of the determination results.

[0028] Fast analysis speed: The total detection time of this method is about 10 minutes, with a relatively fast analysis speed, which can improve the experimental throughput and meet the requirements of a high-efficiency laboratory.

[0029] Optimization conditions for high-performance liquid chromatography: During the determination process of high-performance liquid chromatography in the present invention, by setting appropriate chromatographic conditions such as temperature, injection volume, flow rate, detector wavelength, etc., the separation effect can be further optimized, and the separation efficiency and detection sensitivity can be improved. In particular, by adjusting the ratio of the mobile phase and the acidic conditions, the separation effect of 4,4-dichlorodihydroxy diphenyl ether is more ideal, reducing possible matrix interference.

[0030] In summary, the present invention has the advantages of high efficiency, precision, sensitivity, strong selectivity, fast analysis speed, etc., and can provide a reliable analysis tool for the quality control of 4,4-dichlorodihydroxy diphenyl ether in laundry detergent, being suitable for wide application in production and quality inspection. Description of the drawings

[0031] Figure 1 It is the chromatogram of the laundry detergent sample.

[0032] Figure 2 It is the chromatogram of 4,4-dichlorodihydroxy diphenyl ether obtained under the condition that mobile phase A is ultrapure water and mobile phase B is acetonitrile with a volume ratio of 2:8.

[0033] Figure 3 It is the chromatogram of 4,4-dichlorodihydroxy diphenyl ether obtained under the condition that mobile phase A is an acetic acid aqueous solution with pH = 4 and mobile phase B is methanol with a volume ratio of 2:8.

[0034] Figure 4The chromatogram of 4,4-dichlorodihydroxydiphenyl ether obtained when mobile phase A is an aqueous acetic acid solution with a pH of 6 and mobile phase B is acetonitrile under the condition of a volume ratio of 2:8;

[0035] Figure 5 The chromatogram of 4,4-dichlorodihydroxydiphenyl ether obtained when mobile phase A is an aqueous acetic acid solution with a pH of 5 and mobile phase B is acetonitrile under the condition of a volume ratio of 2:8.

[0036] Figure 6 The chromatogram of 4,4-dichlorodihydroxydiphenyl ether obtained when mobile phase A is an aqueous acetic acid solution with a pH of 4.5 and mobile phase B is acetonitrile under the condition of a volume ratio of 2:8.

[0037] Figure 7 The chromatogram of 4,4-dichlorodihydroxydiphenyl ether obtained when mobile phase A is an aqueous acetic acid solution with a pH of 3.5 and mobile phase B is acetonitrile under the condition of a volume ratio of 2:8. Detailed implementation mode

[0038] The following are specific embodiments of the present invention and in combination with the attached drawings, the technical solutions of the present invention are further described, but the present invention is not limited to these embodiments.

[0039] In the antibacterial and acaricidal laundry detergent containing surfactant, anti-stain redeposition agent, fabric brightener, phosphorus-free water softener, essence, preservative, colorant and bacteriostatic agent, 4,4-dichlorodihydroxydiphenyl ether is widely used, especially in the antibacterial and acaricidal laundry detergents of Ariel and Tide. In the examples, Ariel antibacterial and acaricidal laundry detergent is selected as the sample to determine 4,4-dichlorodihydroxydiphenyl ether.

[0040] A method for quickly determining the content of 4,4-dichlorodihydroxydiphenyl ether in the sample of Ariel antibacterial and acaricidal laundry detergent. The specific determination method includes the following steps: S1 Pretreatment: First, pretreat the laundry detergent sample, preliminarily extract the laundry detergent to remove solid impurities therein, etc. The pretreatment method includes the following steps: Take 200 mL of the laundry detergent sample and place it in 10 50 mL centrifuge tubes (i.e., 20 mL of laundry detergent in each centrifuge tube), then add 5 mL of water, 2 g of sodium chloride and 20 mL of acetonitrile to each centrifuge tube, centrifuge at 4000 r / min for 10 min, and transfer the upper clear liquid to another centrifuge tube; Then add 20 mL of acetonitrile to each centrifuge tube respectively, and then carry out centrifugation operation. After completion, combine the extraction liquids; Obtain the laundry detergent base liquid;

[0041] S2 Solid-phase extraction: The extraction agent includes acetonitrile and toluene, and the volume ratio of acetonitrile to toluene is 4:1. Using acetonitrile and toluene as the extraction agent can achieve the full extraction of the target analyte, providing a basis for accurately detecting its content. The extraction is solid-phase extraction. The solid-phase extraction includes the following steps: Load 1 cm high anhydrous sodium sulfate (which plays a drying role) at the upper end of the solid-phase extraction cartridge (C18 column, specification: 500 mg, 3 mL). First, pre-rinse the solid-phase extraction cartridge with the extraction agent and discard the eluate. Then pass the laundry base liquid through the column and perform elution with the extraction agent. In the elution operation, the volume ratio of the extraction agent to the laundry base liquid is 2:1. Control the flow rate at 0.5 mL / min. After the elution is completed, concentrate the obtained eluate with a rotary evaporator, dissolve the residue with acetonitrile, and pass it through a 0.45 μm organic phase microporous filter membrane to obtain the sample solution.

[0042] S3 Establish a standard curve: First, provide a series of concentrations of 4,4-dichlorodihydroxy diphenyl ether standard solutions, and the concentration range of the 4,4-dichlorodihydroxy diphenyl ether standard solutions is 10 - 100 mg / L. Weigh 10 mg of the standard 4,4-dichlorodihydroxy diphenyl ether, accurate to 0.1 mg. Dissolve it with an appropriate amount of acetonitrile and transfer it to a 10 mL volumetric flask and make up to the mark. Shake well. The obtained solution is the 4,4-dichlorodihydroxy diphenyl ether standard stock solution. Accurately pipette 1 mL, 2 mL, 4 mL, 6 mL, and 10 mL of the 4,4-dichlorodihydroxy diphenyl ether standard stock solution into 5 100 mL volumetric flasks respectively, and make up to the mark with acetonitrile to obtain a series of concentrations of 4,4-dichlorodihydroxy diphenyl ether standard solutions. Perform high-performance liquid chromatography analysis on the series of concentrations of 4,4-dichlorodihydroxy diphenyl ether standard solutions respectively. Take the peak area as the ordinate and the concentration as the abscissa, and make a linear equation of the peak area against the concentration to obtain the standard curve of the content of 4,4-dichlorodihydroxy diphenyl ether. The standard curve and correlation coefficient of the content of 4,4-dichlorodihydroxy diphenyl ether are y = 165.34x - 1.698, R 2 = 0.9987 (y is the peak area; x is the mass concentration, mg / L).

[0043] S4 Sample solution analysis: Perform high-performance liquid chromatography determination on the sample solution, and the determination results are as Figure 1 shown; Use the standard curve to perform quantitative analysis on the determination results to obtain the content of 4,4-dichlorodihydroxy diphenyl ether in the laundry detergent sample;

[0044] Take the average value of the contents obtained from two parallel determinations as the final test result. The measured content of 4,4-dichlorodihydroxy diphenyl ether in the laundry detergent sample is 39.28 mg / L.

[0045] The equipment and parameters used are as follows: When performing high performance liquid chromatography analysis, the chromatographic column used is a C18 column with a specification of 4.6×250 mm and a packing particle size of 5 μm; the column temperature is 30 °C. The flow rate is 1 mL / min; the injection volume is 5 μL; the detector is a VWD detector; the detection wavelength is 278 nm;

[0046] Anhydrous sodium sulfate: Burn sodium sulfate at 650 °C for 4 h and place it in a desiccator for later use;

[0047] Analytical balance with a sensitivity of 0.1 mg; centrifuge; Agilent 1260.

[0048] Method reliability verification: 1. The standard addition method was used to determine the sample recovery rate of 4,4-dichlorodihydroxydiphenyl ether. The average value of 6 determinations was used as the original value of the sample. Different masses of standard samples were added and the experiments were carried out according to the above method to calculate the recovery rate. The results are shown in Table 1. It can be seen from Table 1 that the analysis error is small, the loss during the operation process is small, and the method is accurate and reliable. The sample recovery rate of 4,4-dichlorodihydroxydiphenyl ether:

[0049]

[0050] Table 1

[0051] 2. Precision: The method repeatability experiment was carried out. Under repeatability conditions, the average value and coefficient of variation of 4,4-dichlorodihydroxydiphenyl ether were determined. Each sample was measured in parallel 6 times a day for 6 days of repetition, and each sample had a total of 36 repeatability data. The results are shown in Table 2. It can be seen from Table 2 that the repeatability coefficient of variation is between 1.76 - 2.81%, and the precision is good.

[0052]

[0053] Table 2

[0054] Extractor verification: To ensure complete extraction of the laundry detergent, it is very necessary to select a suitable extractant.

[0055] The effects of using different extractants on the detection results are different. The specific measurement results are shown in Table 3:

[0056]

[0057] Table 3

[0058] From the above data, it is known that choosing an acetonitrile-toluene mixed solution as the extractant, with the volume ratio of acetonitrile:toluene being 3 - 4:1, has an ideal effect.

[0059] Verification of the dosage of the extractant: The laundry detergent sample was eluted with a toluene-acetonitrile mixed solution (the volume ratio of acetonitrile to toluene was 4:1) at different extraction volumes, and the volume of the extractant was added step by step. After extraction with different volumes of the extractant, the sample was injected for detection. The detection results are shown in Table 4;

[0060]

[0061]

[0062] Table 4

[0063] According to the above parameter analysis, in the elution operation, the volume ratio of the extractant to the laundry base liquid of 2:0.5-1 has an ideal effect.

[0064] Verification of the effectiveness of the selected mobile phase type: 1. Ultra-pure water was used as mobile phase A, and acetonitrile was used as mobile phase B; the measurement results are as Figure 2 shown. 2. An acetic acid aqueous solution with a pH of 4 was used as mobile phase A, and methanol was used as mobile phase B; the measurement results are as Figure 3 shown. The results show that the peak appearance effect is very poor when mobile phase A (ultra-pure water) does not add acetic acid. When acetic acid is added to adjust the pH to 4 and mobile phase B is changed to methanol, tailing occurs. Only when mobile phase A is adjusted to acetic acid and mobile phase B is acetonitrile, the peak appearance effect is the best, without tailing and shoulder peak phenomena. Therefore, acetic acid is selected as mobile phase A and acetonitrile is used as mobile phase B.

[0065] Verification of the pH value of the selected mobile phase A: The pH of mobile phase A was 6, 5, 4.5, and 3.5 respectively; the measurement results are as Figure 4 , 5 , 6, and 7 shown respectively. Under the conditions of pH 5 and 6, the peak appearance effect of 4,4-dichlorodihydroxydiphenyl ether is very poor. Under the condition of pH 4.5, the peak appearance effect is greatly improved, but the peak shape is still tilted backward. Under the condition of pH 3.5, the peak appearance effect of 4,4-dichlorodihydroxydiphenyl ether is very good. Therefore, in the claims, the pH value of mobile phase A is determined to be 3.5-4.

[0066] The specific embodiments described herein are merely illustrative of the spirit of the present invention. Those skilled in the art of the present invention can make various modifications or supplements to the described specific embodiments or use similar methods for substitution, but will not deviate from the spirit of the present invention or exceed the defined scope.

Claims

1. A method for rapidly determining the content of 4,4-dichlorodihydroxydiphenyl ether in laundry detergent, characterized in that, The content of 4,4-dichlorodihydroxydiphenyl ether in laundry detergent is determined by high performance liquid chromatography. The specific method includes the following steps: S1 Pretreatment: The laundry detergent sample is pretreated to obtain a laundry detergent base liquid; the pretreatment includes an impurity removal operation stage and a preliminary extraction operation stage; S2 Solid phase extraction: After activating the solid phase extraction column with an extractant, the laundry detergent base liquid is eluted with the extractant to obtain an initial extract. After the initial extract is successively concentrated, volume-fixed, and filtered, a sample solution is obtained; S3 Establishing a standard curve: High performance liquid chromatography determination operations are respectively carried out on several 4,4-dichlorodihydroxydiphenyl ether standard solutions with different concentrations. According to the determination results, with the peak area as the ordinate and the concentration as the abscissa, a linear equation is made for the peak area versus the concentration to obtain a standard curve for the content of 4,4-dichlorodihydroxydiphenyl ether; S4 Sample solution determination: High performance liquid chromatography determination operation is carried out on the sample solution, and quantitative analysis is carried out on the determination results using the standard curve to obtain the content of 4,4-dichlorodihydroxydiphenyl ether in the laundry detergent sample.

2. The method for rapidly determining the content of 4,4-dichlorodihydroxydiphenyl ether in laundry detergent according to claim 1, wherein In step S1, in the impurity removal operation stage, a mixture of acetonitrile-water-sodium chloride is used as the impurity remover. According to the volume-mass ratio, acetonitrile: water: sodium chloride is 20-22 mL: 5-5.5 mL: 2-2.2 g; in the preliminary extraction operation stage, acetonitrile is selected as the solvent; in both the impurity removal operation stage and the preliminary extraction operation stage, centrifugation technology is used.

3. The method for rapidly determining the content of 4,4'-dichlorodihydroxydiphenyl ether in laundry detergent according to claim 1, characterized in that, In step S2, the solid phase extraction column is a C18 column.

4. The method for rapidly determining the content of 4,4-dichlorodihydroxydiphenyl ether in laundry detergent according to claim 1, characterized in that, In step S2, the extractant is a mixed solution of acetonitrile and toluene. According to the volume ratio, acetonitrile: toluene is 3-4:

1. In the elution operation, the volume ratio of the extractant to the laundry base liquid is 2: 0.5-1.

5. The method for rapidly determining the content of 4,4-dichlorodihydroxydiphenyl ether in laundry detergent as described in claim 1, in step S2, the concentration operation is carried out using a rotary evaporator for concentration.

6. The method for rapidly determining the content of 4,4-dichlorodihydroxydiphenyl ether in laundry detergent as described in claim 1, in step S2, the filtration operation is carried out using a 0.45 μm organic phase microporous filter membrane for filtration.

7. The method for rapidly determining the content of 4,4-dichlorodihydroxydiphenyl ether in laundry detergent as described in claim 1, in high performance liquid chromatography, the detector is a VWD detector, and the detection wavelength is 278 nm; the chromatographic column is a C18 column.

8. The method for rapidly determining the content of 4,4-dichlorodihydroxydiphenyl ether in laundry detergent as described in claim 1, in the high performance liquid chromatography determination operation, the column temperature of the chromatographic column is set at 30 °C.

9. The method for rapidly determining the content of 4,4-dichlorodihydroxydiphenyl ether in laundry detergent as described in claim 1, in the high performance liquid chromatography determination operation, the injection volume is 5-6 μL, and the flow rate is set at 1-1.1 mL / min.

10. The method for rapidly determining the content of 4,4-dichlorodihydroxydiphenyl ether in laundry detergent according to claim 1, wherein, In the high performance liquid chromatography determination operation, the mobile phase composition is as follows: Mobile phase A is an acetic acid aqueous solution with a pH value of 3.5-4; mobile phase B is acetonitrile; the volume ratio of mobile phase A to mobile phase B is 1.5-2.5: 7.5-8.5.

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