Liquid phase detection method of modified isophorone diisocyanate

Abstract

The invention provides a liquid phase detection method of modified isophorone diisocyanate. The liquid phase detection method comprises the following steps: dissolving a to-be-detected substance with acetonitrile to obtain a to-be-detected solution; acetonitrile and an aqueous solution or methanol and an aqueous solution are used as mobile phases, a C18 chromatographic column is used for carrying out liquid chromatography detection on a to-be-detected solution, if the separation degree between a target peak of the modified isophorone diisocyanate and adjacent front and rear peaks is greater than a set threshold value, the to-be-detected substance contains the modified isophorone diisocyanate, and if the separation degree between the target peak and the adjacent front and rear peaks is greater than the set threshold value, the to-be-detected substance contains the modified isophorone diisocyanate. The qualitative and quantitative detection on the modified isophorone diisocyanate is realized.

Description

Technical Field

[0001] This application relates to the field of compound detection, and particularly to a liquid chromatography detection method for modified isophorone diisocyanate. Background Art

[0002] Modified isophorone diisocyanate, as a trimer of caprolactam-bonded isophorone diisocyanate, belongs to the non-yellowing and light-stable alicyclic polyisocyanate, and it shows extremely wide application prospects in the industrial production field, especially in the application of coatings.

[0003] In the polyurethane coating system, it plays a crucial role as a curing crosslinking agent. When introduced into the coating formulation, it first shows excellent performance in improving the curing speed, significantly accelerating the curing process and greatly improving production efficiency; its promotion effect on the performance of the final polymer cannot be underestimated. It can significantly improve the hydrolysis resistance, corrosion resistance and thermal stability of the final polymer. In coatings used in some humid environments, such as ship coatings, good hydrolysis resistance can prevent the coating from peeling and deteriorating due to long-term contact with water vapor; in the anti-corrosion coatings of chemical equipment, its excellent high corrosion resistance can effectively resist the erosion of various chemical substances and extend the service life of the equipment; for some coatings that need to be used in high-temperature environments, such as coatings for engine components, its excellent thermal stability can ensure that the coating still maintains good performance at high temperatures without deformation, failure and other problems.

[0004] In view of the key position of modified isophorone diisocyanate in coating applications, it is extremely necessary to detect it;

[0005] From the perspective of product quality, accurately detecting the content and purity of this substance in the coating can ensure the consistency and stability of the coating product performance. If the content is insufficient or the purity does not meet the standard, the coating may not be able to achieve the expected curing speed, nor can it endow the coating with the due hydrolysis resistance, corrosion resistance and thermal stability, resulting in uneven product quality.

[0006] From the aspect of use safety, modified isophorone diisocyanate itself has certain chemical activity and potential hazards. If it is not strictly detected during the production process, it may produce harmful gases or cause other safety problems during the use of the coating due to the mixing of impurities or accidental reactions, endangering the health and safety of construction workers and ultimate users.

[0007] In terms of environmental protection, detection is also essential. If the control of this substance is improper during the coating production process, it may be discharged into the environment along with wastewater and waste gas. Due to its certain chemical stability and difficulty in degradation in the environment, it may cause long-term pollution to ecological environments such as soil and water bodies. Through detection, its adverse effects on the environment can be effectively supervised and controlled. Summary of the Invention

[0008] The solution of this application provides a liquid-phase detection method for modified isophorone diisocyanate, realizing the liquid chromatography detection of modified isophorone diisocyanate.

[0009] To achieve the above objectives, the solution provides a liquid-phase detection method for modified isophorone diisocyanate, including the following steps:

[0010] Dissolve the test substance with acetonitrile to obtain a test solution;

[0011] Use acetonitrile and aqueous solution and methanol and aqueous solution as mobile phases respectively, and perform liquid chromatography detection on the test solution with a C18 chromatographic column. If the separation degrees between the two target peaks of modified isophorone diisocyanate and the adjacent front and rear peaks are both greater than the set threshold, then the test substance contains modified isophorone diisocyanate.

[0012] In some embodiments, the test substance is a polymer solution, that is, a solution-type high molecular polymer, and the solvent is an aromatic solvent. The liquid-phase detection method for modified isophorone diisocyanate provided by this solution can be used to detect whether the polymer solution contains modified isophorone diisocyanate.

[0013] The liquid chromatography detection conditions for this modified isophorone diisocyanate are: column temperature 35°C, flow rate of the mobile phase 1 mL / min, detection wavelength 210 nm, and injection volume 5 μL.

[0014] Regarding the specification selection of the chromatographic column in the liquid chromatography detection conditions, it is a stainless steel column of 250 mm × 4.6 mm, and the column is filled with Inerstil ODS-3 C18, 5 μm packing material. It should be noted that due to the difference in the response values of the two target peaks of modified isophorone diisocyanate at a specific wavelength, in actual measurement, liquid chromatography detection needs to be performed on the first target peak and the second target peak of modified isophorone diisocyanate respectively. If the separation degrees between the first target peak and the second target peak of modified isophorone diisocyanate and their respective adjacent front and rear peaks are both greater than 1.5, then the test substance contains modified isophorone diisocyanate.

[0015] When detecting the first target peak of modified isophorone diisocyanate, when using acetonitrile to dissolve the analyte to obtain the analyte solution, acetonitrile and aqueous solution are selected as the mobile phase. In some embodiments, when the mobile phase is acetonitrile and aqueous solution, the volume ratio of acetonitrile to aqueous solution is 1.5 - 1.6:1. Preferably, the volume ratio of acetonitrile to aqueous solution is 61:39.

[0016] When detecting the first target peak of modified isophorone diisocyanate, the linearity of the analyte modified isophorone diisocyanate is good between 0.4409 - 26.4568 μg / mL.

[0017] When detecting the second target peak of modified isophorone diisocyanate, when using acetonitrile to dissolve the analyte to obtain the analyte solution, methanol and aqueous solution are selected as the mobile phase. In some embodiments, when the mobile phase is methanol and aqueous solution, the volume ratio of methanol to aqueous solution is 1.9 - 2:1. Preferably, the volume ratio of methanol to aqueous solution is 66:34.

[0018] When detecting the first target peak of modified isophorone diisocyanate, the linear range of the analyte modified isophorone diisocyanate has good linearity between 9.3266 - 233.1652 μg / mL.

[0019] After qualitatively detecting the first target peak and the second target peak of modified isophorone diisocyanate respectively, if further quantitative detection of modified isophorone diisocyanate is needed, the external standard quantitative method is adopted.

[0020] Further, the liquid phase detection method of modified isophorone diisocyanate provided by this solution includes the steps:

[0021] Obtain the first content of modified isophorone diisocyanate corresponding to the first target peak, obtain the second content of modified isophorone diisocyanate corresponding to the second target peak, and take the sum value of the first content and the second content as the content of modified isophorone diisocyanate.

[0022] Specifically, the quantitative detection method for the content of modified isophorone diisocyanate for each target peak is as follows:

[0023] Obtain linear calibration solutions of modified isophorone diisocyanate with different concentrations, use acetonitrile and aqueous solution or methanol and aqueous solution as the mobile phase, perform liquid chromatography detection on the analyte solution with a C18 chromatographic column, obtain the peak areas of the target peaks corresponding to the linear calibration solutions of modified isophorone diisocyanate with different concentrations, make a concentration - peak area linear correlation curve with the peak area as the ordinate and the concentration as the abscissa, and obtain the content of modified isophorone diisocyanate in the analyte based on the peak area of the analyte and the concentration - peak area linear correlation curve.

[0024] The calculation formula for the content of modified isophorone diisocyanate is as follows:

[0025]

[0026] Where X—the content of the target peak of modified isophorone diisocyanate, %;

[0027] A S —the average value of the peak area of the target peak of modified isophorone diisocyanate in the solution to be measured;

[0028] m s —the mass of the analyte weighed when preparing the solution to be measured, g;

[0029] V—the dilution volume of the solution to be measured, mL;

[0030] a—the intercept in the linear equation of the concentration-peak area linear correlation curve;

[0031] b—the slope in the linear equation of the concentration-peak area linear correlation curve;

[0032] k—the conversion coefficient between the analyte mass unit g and μg, k = 10 6 .

[0033] In addition, in order to further confirm the modified isophorone diisocyanate, the liquid phase detection method for the modified isophorone diisocyanate further includes the following steps:

[0034] Using acetonitrile and aqueous solution or methanol and aqueous solution as the mobile phase, performing liquid chromatography-mass spectrometry detection on the solution to be measured with a C18 chromatographic column. If the extracted ion chromatograms and mass spectra of the first target peak and the second target peak of the analyte and the standard modified isophorone diisocyanate are the same, it is determined that the analyte contains modified isophorone diisocyanate.

[0035] Further, when using acetonitrile and aqueous solution as the mobile phase, the mass spectrometry conditions are as follows: the volume ratio of acetonitrile to water is 80:20, maintained for 2 min; after 8 min, the volume ratio of acetonitrile to water is increased to 95:5 and maintained for 5 min; after 0.5 min, the volume ratio of acetonitrile to water is decreased to 80:20 and maintained for 2.5 min.

[0036] When using methanol and aqueous solution as the mobile phase, the mass spectrometry conditions are as follows: the volume ratio of methanol to water is 80:20, maintained for 2 min; after 8 min, the volume ratio of methanol to water is increased to 95:5 and maintained for 5 min; after 0.5 min, the volume ratio of methanol to water is decreased to 80:20 and maintained for 2.5 min.

[0037] Compared with the prior art, the present solution provides a liquid-phase detection method for detecting modified isophorone diisocyanate. This method uses acetonitrile to dissolve the analyte and uses acetonitrile and aqueous solution or methanol and aqueous solution as the mobile phase to detect the first target peak and the second target peak of modified isophorone diisocyanate respectively, realizing the detection of modified isophorone diisocyanate. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The drawings described herein are used to provide a further understanding of the present application and form a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation of the present application. In the drawings:

[0039] Figure 1 It is a typical chromatogram of the system blank (acetonitrile). Figure 2 It is a typical chromatogram of the formulation blank (aromatic solvent). Figure 3 It is a typical chromatogram of the linear calibration solution of modified isophorone diisocyanate. Figure 4 It is the linear correlation curve of modified isophorone diisocyanate corresponding to the first target peak. Figure 5 It is the chromatogram of the linear calibration solution. Figure 6 It is the chromatogram of the sample solution. Figure 7 It is the extracted ion chromatogram of the linear calibration solution of modified isophorone diisocyanate. Figure 8 It is the mass spectrum of the linear calibration solution of modified isophorone diisocyanate (the mass spectrum corresponding to a peak height of 100%), Figure 9 It is the extracted ion chromatogram of the sample solution. Figure 10 It is the mass spectrum of the sample solution (the mass spectrum corresponding to a peak height of 100%), Figures 11 to 13 Corresponding to the liquid chromatograms of three sample solutions. Figure 14 It is a typical chromatogram of the linear calibration solution of modified isophorone diisocyanate. Figure 15 It is the linear correlation curve of modified isophorone diisocyanate corresponding to the second target peak. Figure 16 It is the chromatogram of the linear calibration solution. Figure 17 It is the chromatogram of the sample solution. Figure 18 It is the extracted ion chromatogram of the linear calibration solution of modified isophorone diisocyanate. Figure 19 It is the mass spectrum of the linear calibration solution of modified isophorone diisocyanate (the mass spectrum corresponding to a peak height of 100%), Figure 20 It is the extracted ion chromatogram of the sample solution. Figure 21 It is the mass spectrum of the sample solution (the mass spectrum corresponding to a peak height of 100%). Figures 22 to 24 Corresponding to the liquid chromatograms of three sample solutions. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0040] Exemplary embodiments will be described in detail herein, and examples thereof are shown in the accompanying drawings. When the following description refers to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with one or more embodiments of this specification. On the contrary, they are merely examples of devices and methods consistent with some aspects of one or more embodiments of this specification as detailed in the appended claims.

[0041] Example 1 Liquid Chromatography Detection of the First Target Peak of Modified Isophorone Diisocyanate

[0042] 1.1 Reagents: Acetonitrile: Chromatographic grade; Standard sample of modified isophorone diisocyanate: Purity 76.82%.

[0043] 1.2 Instruments: XE205DU Analytical Balance; Thermo Scientific Vanquish Liquid Chromatograph with DAD detector;

[0044] Chromatographic column: 250 mm × 4.6 mm (i.d.) stainless steel column filled with Inerstil ODS-3 C18, 5 μm packing material.

[0045] 1.3 Preparation of Linear Calibration Solution of Modified Isophorone Diisocyanate

[0046] Weigh 0.06 g (accurate to 0.0001 g) of the modified isophorone diisocyanate standard and place it in a 50 mL volumetric flask. Then add 45 mL of acetonitrile, ultrasonically oscillate for 5 min, cool to room temperature, dilute to the mark with acetonitrile, and shake well to obtain the standard mother liquor of modified isophorone diisocyanate. Accurately pipette 0.050 mL, 0.10 mL, 0.50 mL, 1.00 mL, 2.00 mL, and 3.00 mL of the standard mother liquor of modified isophorone diisocyanate into 6 100 mL volumetric flasks respectively, make up the volume with acetonitrile, and shake well to prepare 6 linear calibration solutions of modified isophorone diisocyanate with different concentrations.

[0047] 1.4 Preparation of Sample Solution

[0048] Weigh 0.2 g (accurate to 0.0001 g) of three samples to be tested and place them in 50 mL volumetric flasks. Add 45 mL of acetonitrile, ultrasonically oscillate for 10 min, cool to room temperature, dilute to the mark with acetonitrile, filter with a 0.45 μm filter membrane, and reserve. Prepare two sample solutions in parallel for each batch: SMP 1-1, SMP 1-2, SMP 2-1, SMP 2-2, SMP 3-1, SMP 3-2, where the samples to be tested are polyisocyanate products polymerized from modified isophorone diisocyanate.

[0049] 1.5 Liquid Chromatography Detection:

[0050] After the chromatographic system is stable, under the operating conditions of column temperature: 35°C, mobile phase: ψ(acetonitrile + water) = 61 + 39, mobile phase flow rate: 1.0 mL / min, detection wavelength: 210 nm, injection volume: 5.0 μL, after the verification of linearity, precision, and accuracy is completed, inject the sample solution for analysis. Average the peak areas of the first target peaks of modified isophorone diisocyanate obtained from two parallel injections of each sample solution. The content of modified isophorone diisocyanate in the sample to be tested is calculated according to the following formula:

[0051]

[0052] Where X—the content of the target peak of modified isophorone diisocyanate, %;

[0053] A S —the average value of the peak areas of the target peaks of modified isophorone diisocyanate in the solution to be tested;

[0054] m s —the mass of the analyte weighed when preparing the solution to be tested, g;

[0055] V—the dilution volume of the solution to be tested, mL;

[0056] a—the intercept in the linear equation of the concentration-peak area linear correlation curve;

[0057] b—the slope in the linear equation of the concentration-peak area linear correlation curve;

[0058] k—the conversion coefficient between the analyte mass unit g and μg, k = 10 6 .

[0059] 1.6 Precision Verification:

[0060] Inject the system blank (acetonitrile) and solvent blank (aromatic solvent) 2 times repeatedly, and inject the linear calibration solution of modified isophorone diisocyanate with a concentration of 8.8189 μg / mL 7 times repeatedly. Calculate the average values, standard deviations, and relative standard deviations (%RSD) of the retention times and peak areas respectively. The results are shown in Table 1 below. It can be seen that the %RSDs of the retention times and peak areas are within the acceptable range, proving that the system repeatability meets the requirements. The typical chromatogram of the system blank (acetonitrile) is shown in Figure 1 , and the typical chromatogram of the preparation blank (aromatic solvent) is shown in Figure 2 , and the typical chromatogram of the linear calibration solution of modified isophorone diisocyanate is shown in Figure 3 .

[0061] Table 1 System Repeatability of the Modified Isophorone Diisocyanate Linear Calibration Solution 1.6 Method Repeatability:

[0062]

[0063] The first target peak of the modified isophorone diisocyanate was detected in the analyte. Take a batch of analytes and perform parallel determinations 6 times. Inject the same sample solution 2 times repeatedly, and calculate the average value, standard deviation, and relative standard deviation (%RSD) of the mass fraction. The results are shown in Table 2 - Table 3. The %RSD of the measured mass fraction is within the acceptable range, proving that the method repeatability meets the requirements.

[0064] Table 2 Method Repeatability

[0065]

[0066] Table 3 Evaluation of Precision Test Results

[0067]

[0068]

[0069] 1.7 Detection Limit and Quantification Limit:

[0070] After the instrument system is stable, inject the modified isophorone diisocyanate linear calibration solution 7 times repeatedly, calculate the detection limit (LOD) and calculate the quantification limit (LOQ). The results are shown in Table 4:

[0071] Table 4 Detection Limit and Quantification Limit

[0072]

[0073] 1.8 Linear Range:

[0074] Inject each modified isophorone diisocyanate linear calibration solution twice in parallel. The detection results are shown in Table 5. Draw a linear correlation curve with the concentration as the abscissa and the peak area as the ordinate as Figure 4 shown. The results show that: The concentration of the modified isophorone diisocyanate has good linearity between 0.4409 - 26.4568 μg / mL. The linear equation is y = 0.14426x - 0.01403, and the linear correlation coefficient r = 0.99987, which is greater than 0.99, proving that the linearity meets the requirements. The concentration of the mother liquor of the modified isophorone diisocyanate peak 1

[0075] Table 5 Linear Measurement Results

[0076]

[0077]

[0078] 1.9 Accuracy:

[0079] The first target peak containing modified isophorone diisocyanate is detected in the analyte, and the accuracy is confirmed by sample spiking recovery. Specimen stock solution S1: Standard stock solution S2: Add the specimen and the standard at ratios of 1:0.8, 1:1, and 1:1.2. The preparation of the accuracy solution of modified isophorone diisocyanate is shown in Table VI, where SB is the blank sample solution. The accuracy determination results are shown in Tables VII - VIII:

[0080] Table VI Preparation of the accuracy solution of modified isophorone diisocyanate

[0081]

[0082] Table VII Accuracy test results

[0083]

[0084]

[0085] Table VIII Evaluation of accuracy test results

[0086] Average recovery rate, % Acceptable standard, % Conclusion 105.3 80～110 Meet the requirements

[0087] 1.10 Specificity:

[0088] Inject the linear calibration solution of modified isophorone diisocyanate and the specimen solution for analysis separately. The resolution can be obtained from the chromatogram report generated by the chromatographic workstation. The resolution of the linear calibration solution and the specimen solution is shown in Table IX. The chromatogram is shown in Figures 5 to 6 .

[0089] Table IX Analytical method validation - Resolution

[0090]

[0091] n.a. = not applicable, that is, there is no adjacent peak near the target peak.

[0092] Mass spectrometry analysis:

[0093] The extracted ion chromatogram (EIC) and mass spectrum of the linear calibration solution of modified isophorone diisocyanate are shown in Figures 7 to 8 , and the extracted ion chromatogram (EIC) and mass spectrum of the specimen solution are shown in Figures 9 to 10 , and the results show that the retention time of the chromatographic peak of modified isophorone diisocyanate peak 1 in the standard solution and the sample solution is the same, and the obtained mass spectra Figure 1 are consistent, meeting the specificity requirements.

[0094] 1.1 Content determination:

[0095] The determination results of the modified isophorone diisocyanate peaks in the samples are shown in Table X respectively. The relevant liquid chromatograms are shown in Figures 11 to 13 , where the sample solution SMP1-1 corresponds to Figure 11 , the sample solution SMP2-1 corresponds to Figure 12 , the sample solution SMP3-1 corresponds to Figure 13 .

[0096] Table X Determination results of the modified isophorone diisocyanate peaks in the samples

[0097]

[0098] Note: LOD of the modified isophorone diisocyanate peak 1 = 0.0032%.

[0099] Example 2

[0100] 1.1 Reagents: Acetonitrile: Chromatographically pure; Methanol, chromatographically pure, Standard sample of modified isophorone diisocyanate: Purity 20.17%.

[0101] 1.2 Instruments: The same as those in Example 1;

[0102] 1.3 Preparation of the linear calibration solution of modified isophorone diisocyanate:

[0103] Weigh 0.06 g (accurate to 0.0001 g) of the modified isophorone diisocyanate standard sample and place it in a 50 mL volumetric flask. Then add 45 mL of acetonitrile, ultrasonically oscillate for 5 min, cool to room temperature, dilute to the mark with acetonitrile, and shake well to obtain the standard mother liquor of modified isophorone diisocyanate. Accurately pipette 2.00 mL, 4.00 mL, 8.00 mL, 10.00 mL, and 25.00 mL of the standard mother liquor of modified isophorone diisocyanate into 5 100 mL volumetric flasks respectively, make up the volume with acetonitrile, and shake well. Together with the above standard mother liquor of modified isophorone diisocyanate, prepare 6 linear calibration solutions of modified isophorone diisocyanate with different concentrations.

[0104] 1.4 Preparation of the sample solution:

[0105] Weigh 0.2 g (accurate to 0.0001 g) of three samples to be measured and place them in a 50 mL volumetric flask. Add 45 mL of acetonitrile, ultrasonically oscillate for 10 min, cool to room temperature, dilute to the mark with acetonitrile, filter with a 0.45 μm filter membrane, and set aside. Prepare two sample solutions in parallel for each batch: SMP 1-1, SMP 1-2, SMP 2-1, SMP 2-2, SMP 3-1, SMP 3-2, where the sample to be measured is a polyisocyanate product polymerized from modified isophorone diisocyanate.

[0106] 1.5 Liquid chromatography detection:

[0107] After the chromatographic system is stable, under the operating conditions of column temperature: 35 °C, mobile phase: ψ(methanol + water) = 66 + 34, mobile phase flow rate: 1.0 mL / min, detection wavelength: 210 nm, injection volume: 5.0 μL, after the linearity, precision, and accuracy verifications are completed, inject the sample solution for analysis, and detect the peak area of the second target peak of modified isophorone diisocyanate obtained from two parallel injections of each sample solution.

[0108] 1.6 Precision verification:

[0109] Inject the system blank (acetonitrile) and solvent blank (aromatic solvent) repeatedly for 2 times, and inject the linear calibration solution of modified isophorone diisocyanate with a concentration of 37.3064 μg / mL repeatedly for 7 times. Calculate the average value, standard deviation, and relative standard deviation (%RSD) of the retention time and peak area respectively. The results are shown in Table XI below. It can be seen that the %RSD of the retention time and peak area are both within the acceptable range, proving that the system repeatability meets the requirements. The typical chromatogram of the modified isophorone diisocyanate linear calibration solution is shown in Figure 14 .

[0110] Table XI System repeatability of the linear calibration solution of modified isophorone diisocyanate

[0111]

[0112] 1.6 Method repeatability:

[0113] The second target peak of modified isophorone diisocyanate is detected in the analyte. Take a batch of analytes and measure them in parallel for 6 times, and inject the same sample solution repeatedly for 2 needles. Calculate the average value, standard deviation, and relative standard deviation (%RSD) of the mass fraction. The results are shown in Tables XII - XIII. The %RSD of the measured mass fraction is within the acceptable range, proving that the method repeatability meets the requirements.

[0114] Table XII Method repeatability

[0115]

[0116]

[0117] Evaluation of Precision Test Results, Table XIII

[0118]

[0119] 1.7 Detection Limit and Quantitation Limit:

[0120] After the instrument system is stable, the modified isophorone diisocyanate linear calibration solution is injected repeatedly 7 times, and the detection limit (LOD) is calculated and the quantitation limit (LOQ) is calculated. The results are shown in Table IV:

[0121] Table IV Detection Limit and Quantitation Limit

[0122]

[0123] 1.8 Linear Range:

[0124] The modified isophorone diisocyanate linear calibration solutions are injected in parallel twice, and the test results are shown in Table XV. A linear correlation curve is plotted with the concentration as the abscissa and the peak area as the ordinate as Figure 15 shown. The results show that: the concentration of the peak 2 of the modified isophorone diisocyanate has good linearity between 9.3266 - 233.1652 μg / mL. The linear equation is y = 0.128x + 0.124, and the linear correlation coefficient r = 0.997, which is greater than 0.99, proving that the linearity meets the requirements. The concentration of the mother liquor of the peak 2 of the modified isophorone diisocyanate

[0125] Table XV Linear Measurement Results

[0126]

[0127] 1.9 Accuracy:

[0128] The second target peak containing the modified isophorone diisocyanate is detected in the analyte, and the accuracy is confirmed by sample spiking recovery. Sample stock solution S1: Standard stock solution S2: The sample and the standard are added in the ratios of 1:0.8, 1:1, and 1:1.2. The preparation of the accuracy solution of the modified isophorone diisocyanate is shown in Table XVI, where SB is the blank sample solution. The accuracy determination results are shown in Tables XVII - XVIII:

[0129] Table XVI Preparation of the Accuracy Solution of the Modified Isophorone Diisocyanate

[0130]

[0131]

[0132] Table XVIII Evaluation of Accuracy Test Results

[0133] Average recovery rate, % Acceptable standard, % Conclusion 103.6 80～110 Meet the requirements

[0134] 1.10 Specificity:

[0135] Inject the modified isophorone diisocyanate linear calibration solution and the sample solution separately for analysis. The resolution can be obtained from the chromatogram report generated by the chromatographic workstation. The resolution of the linear calibration solution and the sample solution is shown in Table XIX, and the chromatogram is shown in Figures 16 to 17 .

[0136] Table XIX Analytical Method Validation - Resolution

[0137]

[0138] n.a. = not applicable, that is, there is no adjacent peak near the target peak.

[0139]

[0140] Table XVII Accuracy Test Results

[0141] Mass Spectrometry Analysis:

[0142] The extracted ion chromatogram (EIC) and mass spectrum of the modified isophorone diisocyanate linear calibration solution are shown in Figures 18 to 19 , and the extracted ion chromatogram (EIC) and mass spectrum of the sample solution are shown in Figures 20 to 21 , and the results show that the chromatographic peak retention times of the modified isophorone diisocyanate peak 1 in the standard solution and the sample solution are the same, and all the obtained mass spectra Figure 1 are consistent, meeting the specificity requirements.

[0143] 1.11 Content Determination:

[0144] The determination results of the modified isophorone diisocyanate peak in the sample are shown in Table XX respectively, and the relevant liquid chromatograms are shown in Figures 22 to 24 , where the sample solution SMP1-1 corresponds to Figure 22 , the sample solution SMP2-1 corresponds to Figure 23 , and the sample solution SMP3-1 corresponds to Figure 24 .

[0145] Table XX Determination Results of the Modified Isophorone Diisocyanate Peak in the Sample

[0146]

[0147] Note: The peak of LOD-modified isophorone diisocyanate is 0.0031%.

[0148] Those skilled in the art should understand that the technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as within the scope described in this specification.

[0149] The above embodiments only represent several implementation manners of the present application. The description is relatively specific and detailed, but it should not be understood as a limitation to the scope of the present application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several deformations and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the appended claims.

Claims

1. A liquid-phase detection method for modified isophorone diisocyanate, characterized in that, It includes the following steps: Dissolve the analyte in acetonitrile to obtain a test solution; Use acetonitrile and aqueous solution and methanol and aqueous solution as mobile phases respectively, and perform liquid chromatography detection on the test solution with a C18 chromatographic column. If the resolution between the two target peaks of modified isophorone diisocyanate and the adjacent front and rear peaks is greater than the set threshold, the analyte contains modified isophorone diisocyanate.

2. The liquid-phase detection method of the modified isophorone diisocyanate according to claim 1, characterized in that The liquid chromatography detection conditions are: column temperature 35°C, flow rate of the mobile phase 1 mL / min, detection wavelength 210 nm, injection volume 5 μL.

3. The liquid phase detection method of the modified isophorone diisocyanate according to claim 1, characterized in that, The specification of the chromatographic column is selected as a 250 mm×4.6 mm stainless steel column filled with Inerstil ODS-3 C18, 5 μm packing material.

4. The liquid-phase detection method of the modified isophorone diisocyanate according to claim 1, wherein If the resolution between the first target peak and the second target peak of modified isophorone diisocyanate and their respective adjacent front and rear peaks is greater than 1.5, the analyte contains modified isophorone diisocyanate.

5. The liquid-phase detection method of the modified isophorone diisocyanate according to claim 1, characterized in that, When detecting the first target peak of modified isophorone diisocyanate, when using acetonitrile to dissolve the analyte to obtain a test solution, select acetonitrile and aqueous solution as the mobile phase, and the volume ratio of acetonitrile to aqueous solution is 1.5 - 1.6:

1.

6. The liquid-phase detection method of the modified isophorone diisocyanate according to claim 1, characterized in that, When detecting the second target peak of modified isophorone diisocyanate, when using acetonitrile to dissolve the analyte to obtain a test solution, select methanol and aqueous solution as the mobile phase, and the volume ratio of methanol to aqueous solution is 1.9 - 2:

1.

7. The liquid phase detection method of the modified isophorone diisocyanate according to claim 1, characterized in that, Obtain the first content of modified isophorone diisocyanate corresponding to the first target peak, obtain the second content of modified isophorone diisocyanate corresponding to the second target peak, and take the sum value of the first content and the second content as the content of modified isophorone diisocyanate.

8. The liquid phase detection method of the modified isophorone diisocyanate according to claim 1, wherein Use acetonitrile and aqueous solution or methanol and aqueous solution as the mobile phase, and perform liquid chromatography - mass spectrometry detection on the test solution with a C18 chromatographic column. If the extracted ion chromatograms and mass spectra of the first target peak and the second target peak of the analyte and the standard modified isophorone diisocyanate are the same, it is determined that the analyte contains modified isophorone diisocyanate.

9. The liquid-phase detection method of the modified isophorone diisocyanate according to claim 8, characterized in that, When using acetonitrile and aqueous solution as the mobile phase, the mass spectrometry conditions are: the volume ratio of acetonitrile to water is 80:20, maintained for 2 min; after 8 min, the volume ratio of acetonitrile to water is increased to 95:5 and maintained for 5 min; after 0.5 min, the volume ratio of acetonitrile to water is decreased to 80:20 and maintained for 2.5 min.

10. The liquid phase detection method of the modified isophorone diisocyanate according to claim 8, characterized in that, When using methanol and aqueous solution as the mobile phase, the mass spectrometry conditions are: the volume ratio of methanol to water is 80:20, maintained for 2 min; after 8 min, the volume ratio of methanol to water is increased to 95:5 and maintained for 5 min; after 0.5 min, the volume ratio of methanol to water is decreased to 80:20 and maintained for 2.5 min.

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