High-selectivity liquid chromatographic analysis method of cyanuric chloride

Abstract

The invention belongs to the technical field of analytical chemistry, and relates to a high-selectivity cyanuric chloride liquid chromatography analysis method, which comprises the following steps: carrying out derivatization reaction on a qualified cyanuric chloride sample to obtain a control derivative product; preparing a standard reference substance solution by using the reference derivative product, and analyzing by adopting high performance liquid chromatography to obtain a standard detection result for contrast; and carrying out high performance liquid chromatography analysis on the derivative product of the cyanuric chloride sample to be detected, and comparing with the standard detection result to obtain a quantitative detection result of the cyanuric chloride derivative product. The method can efficiently and sensitively detect the content of cyanuric chloride, and has the advantages of short operation time, good separation degree and strong anti-interference capability; quantitative determination can be rapidly and accurately completed by adopting a high performance liquid chromatograph with an ultraviolet detector, and the method has the advantages of loose requirements on experiments, simplicity in operation, low detection cost and easiness in implementation, and is suitable for analysis of cyanuric chloride and related products thereof.

Description

Technical Field

[0001] This invention belongs to the field of analytical chemistry technology and relates to a highly selective liquid chromatography method for the analysis of cyanuric chloride. Background Technology

[0002] Cyanuric chloride (C3N3Cl3), an important organic chemical intermediate, is prone to hydrolysis due to the active chlorine atoms in its molecular structure, leading to chemical instability. This instability not only affects the storage and use of the raw material but can also introduce impurities through subsequent synthesis processes, significantly impacting the purity and performance of triazine products.

[0003] The traditional method for detecting cyanuric chloride is the argentometric titration method (National Standard Method: GB / T 25814-2022). This method involves quantifying the chloride ions generated by the hydrolysis of cyanuric chloride under alkaline conditions using a silver nitrate standard titration solution. The free acid produced by the hydrolysis of cyanuric chloride is quantified using a sodium hydroxide standard titration solution and subtracted from the total amount of cyanuric chloride. This method has the following limitations in determining cyanuric chloride: (1) Low method specificity: Since this method is based on the total determination of chloride ions, other chlorine-containing compounds in the sample (such as inorganic chlorine or organic chlorine impurities) may interfere with the determination, leading to false positive results.

[0004] (2) Insufficient sensitivity and anti-interference ability: It relies on titration analysis, which has a large error in the low concentration range and is easily affected by coexisting ions (such as sulfides, bromides, etc.).

[0005] (3) Limited scope of application: It is only applicable to samples that can be completely hydrolyzed and quantitatively release chloride ions. If non-hydrolyzable chlorine (such as stably bound chlorine atoms) is present in cyanuric chloride, it will lead to deviations in the measurement results.

[0006] (4) The reactivity of chlorine at different positions cannot be distinguished: the hydrolysis reaction cannot provide information on the position of chlorine atoms in cyanuric chloride molecules (such as the difference in hydrolysis of chlorine on monomeric cyanuric chloride or triazine ring, and the production of cyanuric acid if cyanuric chloride is completely degraded), so it is difficult to assess its actual reaction characteristics.

[0007] Therefore, establishing efficient and accurate detection methods for cyanuric chloride is not only essential for the quality control of cyanuric chloride, but also of great significance for ensuring the quality control of downstream products of cyanuric chloride. Summary of the Invention

[0008] The main objective of this invention is to overcome the deficiencies in the prior art and provide a simple, rapid, highly selective, and highly sensitive liquid chromatography analysis method for cyanuric chloride.

[0009] To achieve the above objectives, the specific technical solution is as follows: This invention provides a highly selective liquid chromatography method for the quantitative detection of cyanuric chloride derivatives using high performance liquid chromatography, comprising the following steps: (1) The qualified cyanuric chloride sample was subjected to a derivatization reaction to obtain the control derivatized product; (2) A standard reference solution was prepared using the reference derivative, and the solution was analyzed by high performance liquid chromatography to obtain the standard detection results for reference. (3) The derivatives of the cyanuric chloride test sample were analyzed by high performance liquid chromatography and compared with the above standard test results to obtain the quantitative detection results of the cyanuric chloride derivatives.

[0010] This invention improves the detection efficiency of cyanuric chloride by employing pre-column derivatization. It generates a stable derivative with stronger ultraviolet absorption through derivatization reaction, and compares the results with the standard detection results of the control derivative to demonstrate the effectiveness of the detection and analysis method. This allows for efficient and sensitive detection of cyanuric chloride content, avoiding false positives that may occur with traditional methods. Furthermore, this method has the advantages of high selectivity, short running time, good separation, and strong anti-interference ability.

[0011] Furthermore, the derivative is obtained by a derivatization reaction between a derivatizing reagent and a cyanuric chloride sample under acid-binding conditions. The derivatizing reagent is selected from one of p-methylthiophenol, o-toluenethiophenol, 4-phenylphenol, 3-methylthiophenol, 4-methylthiophenol, p-methoxyphenol, 4-chloro-2-methylphenol, and 2-methoxythiophenol, with p-methylthiophenol being preferred.

[0012] This invention utilizes a selected derivatization reagent, whose thiol group (-SH) can undergo a selective nucleophilic substitution reaction with the active chlorine site of cyanuric chloride to generate a stable derivative with stronger ultraviolet absorption, while the hydroxyl group generated by hydrolysis cannot react with the thiol group.

[0013] The cyanuric chloride derivatives obtained by this invention can effectively overcome the detection bias caused by the poor stability of the raw materials themselves, and can enhance the chromatographic retention behavior and detection sensitivity of the target analytes. It achieves baseline separation and accurate quantification of cyanuric chloride and its potential degradation products, providing reliable data support for the quality control of cyanuric chloride and its related products.

[0014] If the derivatizing reagent is p-methylthiophenol, the reaction is as follows: The above-mentioned compound I is the derivative 2,4-dihydroxy-6-(p-toluenethio)-1,3,5-triazine, compound II is the derivative 2-hydroxy-4,6-bis(p-toluenethio)-1,3,5-triazine, compound III is the derivative 2,4,6-tris(p-toluenethio)-1,3,5-triazine, and compound IV is cyanuric acid.

[0015] Furthermore, the derivatization reaction process of the derivative product is as follows: the cyanuric chloride sample is dissolved in a solvent, the derivatization reagent and the acid-binding agent are added, and the reaction is carried out at 0~10℃ for 1.5-3h, and then the temperature is raised to 30~40℃ for 1.5-3h.

[0016] Furthermore, the molar ratio of the derivatizing reagent to the cyanuric chloride sample is (1~3):1; the molar ratio of the acid-binding agent to the cyanuric chloride sample is (1~3):1.

[0017] Furthermore, the acid-binding agent is selected from one or more of sodium bicarbonate and potassium bicarbonate; sodium bicarbonate is preferred.

[0018] Furthermore, the solvent for dissolving the cyanuric chloride sample is one or more of acetone, tetrahydrofuran, dichloromethane, dichloroethane, and chloroform; acetone is preferred.

[0019] Further, the derivatizing reagent is selected from p-toluenethiophenol, and the reference derivatized products include 2,4-dihydroxy-6-(p-toluenethio)-1,3,5-triazine, 2-hydroxy-4,6-bis(p-toluenethio)-1,3,5-triazine, and 2,4,6-tris(p-toluenethio)-1,3,5-triazine; the standard reference solution is obtained by diluting the reference derivatized products with acetonitrile to a final volume, with a concentration of 0.1~1000 μg / mL.

[0020] Furthermore, the step of quantitatively detecting cyanuric chloride derivatives using high performance liquid chromatography also includes: preparing a reference solution using reference substances, wherein the reference substances include cyanuric acid, cyanuric chloride and p-methylthiophenol; the reference solution is obtained by diluting the reference substances with acetonitrile to a final volume, and the concentration is 0.1~1000 μg / mL.

[0021] Furthermore, the detection conditions for the liquid chromatography analysis are as follows: Chromatographic column: Octadecylsilane-bonded silica gel column; the column length is 250 mm, the inner diameter is 4.6 mm, and the particle size is 5 µm; Mobile phase: Mobile phase A is a 0.1% aqueous solution of formic acid or water, and mobile phase B is acetonitrile; Preferred mobile phases: Mobile phase A is a 0.1% aqueous solution of formic acid, and mobile phase B is acetonitrile.

[0022] Furthermore, the elution method of the chromatographic column is gradient elution, and the elution program of the gradient elution is as follows: the volume ratio of mobile phase A to mobile phase B is (10%~30%)~(70~90%), and the elution time of the mobile phase is 0~40 min; the preferred elution program is shown in the table below:

[0023] Furthermore, the flow rate in the chromatographic analysis is 1 mL / min, the column temperature is 25℃, and the injection volume is 5 µm; the ultraviolet wavelength for ultraviolet detection is 190 nm to 240 nm.

[0024] Compared with the prior art, the present invention has the following significant advantages: The method for detecting cyanuric chloride of the present invention is a highly selective liquid chromatography analysis method for cyanuric chloride, which can efficiently and sensitively detect the content of cyanuric chloride, avoid the false positive phenomenon that may occur in traditional methods, and also has the advantages of short running time, good separation and strong anti-interference ability.

[0025] This invention utilizes a high-performance liquid chromatograph equipped with an ultraviolet detector to quickly and accurately complete quantitative determination. It has relatively relaxed experimental requirements, is simple to operate, has low detection costs, and is easy to implement. It is suitable for the analysis of cyanuric chloride and related products. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0027] Figure 1 This is the 1H NMR spectrum of 2,4-dihydroxy-6-(p-toluenethio)-1,3,5-triazine of the present invention; Figure 2 This is the 1H NMR spectrum of 2-hydroxy-4,6-bis(p-toluenethio)-1,3,5-triazine of the present invention; Figure 3 This is the 1H NMR spectrum of 2,4,6-tris(p-toluenethio)-1,3,5-triazine of this invention; Figure 4 This is a chromatogram showing the peak positioning of the cyanuric chloride derivative of this invention; Figure 5 These are chromatograms of cyanuric chloride derivatives from freshly opened bags and after being stored for 3 days, according to the present invention. Figure 6 This is a chromatogram of the cyanuric chloride derivative of the present invention after being opened and left for 7 days. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0029] Unless otherwise specified in the embodiments of the present invention, the techniques or conditions described in the literature in this field or the product instructions shall be followed; if the manufacturers of the reagents or instruments used are not specified, they are all conventional products that can be purchased through legitimate channels.

[0030] The instruments and experimental materials used in the following examples are as follows: instrument: Agilent 1200 / Ultimate 3000 high performance liquid chromatograph (UV detector); Experimental materials: Cyanide chloride comes from Huanggang Meifeng Chemical Technology Co., Ltd. (production material); p-Methylthiophenol is from Shanghai Aladdin Biochemical Technology Co., Ltd.; Sodium bicarbonate is from Tianjin Kemeo Chemical Reagent Co., Ltd. The acetone was sourced from Sinopharm Chemical Reagent Co., Ltd. Acetonitrile was sourced from Wuhan Futon Holdings Co., Ltd., and the reagent water was purified water.

[0031] Example 1 Preparation of standard reference standards for derivatives I, II, and III: Synthesis of the monosubstituted derivative 2,4-dihydroxy-6-(p-toluenethio)-1,3,5-triazine: In a 150 mL three-necked flask, 1.8 g (9.8 mmol) of qualified cyanuric chloride and 80 mL of anhydrous acetone were added, and the mixture was stirred in an ice bath (0–5 °C) until completely dissolved. Then, 1.22 g (9.8 mmol) of a acetone solution of p-methylthiophenol (10 mL) was slowly added dropwise, maintaining low temperature and stirring for 5 min to ensure homogeneous mixing. 0.83 g (9.8 mmol) of sodium bicarbonate was dissolved in 25 mL of purified water and added dropwise to the reaction system, controlling the adding rate to avoid violent exothermic reactions. The reaction mixture was stirred continuously in an ice bath for 5 h, during which the reaction progress was monitored by TLC until the starting material spot gradually disappeared and the product spot became clearly visible. After the reaction was complete, insoluble salts were removed by vacuum filtration. The filtrate was concentrated by rotary evaporation and poured into 100 mL of ice water to precipitate a white solid. The product was collected by vacuum filtration and washed with cold acetone to remove unreacted impurities, yielding the white target product. NMR data were as follows: 1 H NMR (300MHz, CDCl3): δ7.39 (d, J = 8.1 Hz, 2H), 7.23 (d, J = 10.1 Hz, 2H), 2.38 (s, 3H), LC-MS: [M+H] + =236.0, the 1H NMR spectrum is shown below. Figure 1 .

[0032] Synthesis of the disubstituted derivative 2-hydroxy-4,6-bis(p-toluenethio)-1,3,5-triazine: In a 150 mL three-necked flask, 1.8 g (9.8 mmol) of qualified cyanuric chloride and 80 mL of anhydrous acetone were added, and the mixture was stirred in an ice bath (0–5 °C) until completely dissolved. Then, 2.44 g (19.6 mmol) of p-methylthiophenol was added in portions, and the mixture was stirred at low temperature for 5 min to ensure homogeneous mixing. 1.66 g (19.6 mmol) of sodium bicarbonate was dissolved in 25 mL of purified water and added dropwise to the reaction system. The reaction mixture was stirred continuously in an ice bath for 2 h, then the temperature was raised to 30–40 °C, and the reaction was continued with stirring for 2 h until the starting material was completely converted (TLC confirmed). After the reaction, the reaction solution was filtered to remove inorganic salts, and the filtrate was concentrated under reduced pressure. The crude product was precipitated by adding 100 mL of ice water, filtered under vacuum, and washed with cold acetone to obtain the white target product. NMR data were as follows: 1 H NMR(300MHz, DMSO-d6): δ7.37 (t, J =7.6 Hz, 4H), 7.22 (t, J =7.5 Hz, 4H), 2.37(d, J =6.9 Hz, 6H), LC-MS: [M+H] + =342.1, the 1H NMR spectrum is shown below. Figure 2 .

[0033] Synthesis of the trisubstituted derivative 2,4,6-tris(p-tolylthio)-1,3,5-triazine: A qualified cyanuric chloride sample (1.8 g, 9.8 mmol) was placed in a 150 mL three-necked flask, and 80 mL of anhydrous acetone was added. The mixture was cooled to 0–5 °C in an ice bath and stirred until completely dissolved. Then, p-methylthiophenol (3.7 g, 29.4 mmol) was added in portions, and the mixture was stirred continuously for 5 minutes to ensure homogeneity. Sodium bicarbonate (2.5 g, 29.8 mmol) was dissolved in 27 mL of purified water and slowly added dropwise to the reaction system. The reaction was continued in an ice bath for 1 hour, then the ice bath was removed, and the temperature was raised to 30–40 °C and the reaction was continued for 4 hours. The reaction progress was monitored by TLC during the reaction. After the reaction was complete, insoluble impurities were removed by filtration. The filtrate was concentrated by rotary evaporation, and 100 mL of ice water was added to precipitate a white solid. The product was collected by vacuum filtration and washed with cold acetone to obtain the white target product. NMR data were as follows: 1 H NMR (300MHz, DMSO-d6): δ7.30 (d, J = 8.1 Hz, 6H), 7.15 (d, J =7.9Hz, 6H), 2.35 (s, 9H), LC-MS: [M+H] + =448.1, the 1H NMR spectrum is shown below. Figure 3 .

[0034] Example 2 Development and Methodological Investigation of Method for Determination of Cyanide Chloride Purity (1) Solution preparation Accurately weigh 25 mg each of 2,4-dihydroxy-6-(p-toluenethio)-1,3,5-triazine, 2-hydroxy-4,6-bis(p-toluenethio)-1,3,5-triazine, 2,4,6-tris(p-toluenethio)-1,3,5-triazine, cyanuric acid, cyanuric chloride, and p-methylthiophenol into 50 mL volumetric flasks. Dissolve in acetonitrile and dilute to the mark, shake well, and perform high-performance liquid chromatography (HPLC) analysis.

[0035] (2) Analysis steps Turn on the liquid chromatography system, wait for the baseline to stabilize, then inject the sample, injecting one blank and one sample solution, and record the chromatogram.

[0036] Depend on Figure 4 As can be seen from the chromatogram, each component presents a corresponding chromatographic peak, which can be effectively separated, and the peak shape is good.

[0037] (3) Regression equation and linear relationship Standard solutions of different concentrations were prepared using samples 2,4-dihydroxy-6-(p-toluenethio)-1,3,5-triazine, 2-hydroxy-4,6-bis(p-toluenethio)-1,3,5-triazine, and 2,4,6-tris(p-toluenethio)-1,3,5-triazine.

[0038] The relationship between the peak area and concentration of 2,4-dihydroxy-6-(p-toluenethio)-1,3,5-triazine, 2-hydroxy-4,6-bis(p-toluenethio)-1,3,5-triazine, and 2,4,6-tris(p-toluenethio)-1,3,5-triazine was analyzed by linear regression.

[0039] The linear range of 2,4-dihydroxy-6-(p-toluenethio)-1,3,5-triazine was calculated to be 0.72–25.1 µg / mL, with a regression equation of y = 281.76x - 0.1372 and a correlation coefficient of 0.9988; the linear range of 2-hydroxy-4,6-bis(p-toluenethio)-1,3,5-triazine was calculated to be 0.11–25.5 µg / mL, with a regression equation of y = 381.79x - 0.0227 and a correlation coefficient of 0.9985; and the linear range of 2,4,6-tris(p-toluenethio)-1,3,5-triazine was calculated to be 0.26–25.6 µg / mL, with a regression equation of y = 492.20x - 0.0429 and a correlation coefficient of 0.9992; where x represents concentration and y represents peak area.

[0040] (4) Method detection limit The limits of detection (LODs) for 2,4-dihydroxy-6-(p-toluenethio)-1,3,5-triazine, 2-hydroxy-4,6-bis(p-toluenethio)-1,3,5-triazine, and 2,4,6-tris(p-toluenethio)-1,3,5-triazine were 0.24 µg / mL, 0.04 µg / mL, and 0.08 µg / mL, respectively, and were determined by a signal-to-noise ratio (S / N) ≥ 3 (S / N is the ratio of the peak signal value detectable by the sample to the peak signal value of the noise signal).

[0041] (5) Average recovery test The recovery results of 2,4-dihydroxy-6-(p-toluenethio)-1,3,5-triazine, 2-hydroxy-4,6-bis(p-toluenethio)-1,3,5-triazine and 2,4,6-tris(p-toluenethio)-1,3,5-triazine are shown in Tables 1-3.

[0042] Table 1. Recovery results of 2,4-dihydroxy-6-(p-toluenethio)-1,3,5-triazine

[0043] Table 2. Recovery results of 2-hydroxy-4,6-bis(p-toluenethio)-1,3,5-triazine

[0044] Table 3. Recovery results of 2,4,6-tris(p-toluenethio)-1,3,5-triazine

[0045] (6) Precision test The precision test results of 2,4-dihydroxy-6-(p-toluenethio)-1,3,5-triazine, 2-hydroxy-4,6-bis(p-toluenethio)-1,3,5-triazine and 2,4,6-tris(p-toluenethio)-1,3,5-triazine are shown in Tables 1-3.

[0046] Table 4. Precision test results of 2,4-dihydroxy-6-(p-toluenethio)-1,3,5-triazine

[0047] Table 5. Precision test results of 2-hydroxy-4,6-bis(p-toluenethio)-1,3,5-triazine

[0048] Table 6. Precision Test Results of 2,4,6-Tris(p-Toluenethio)-1,3,5-Triazine

[0049] Conclusion: The peak area RSD of the product in six consecutive repeatable solutions was ≤2%, indicating that the method has good precision, thus demonstrating the effectiveness of the detection and analysis method.

[0050] Example 3 Purity testing of newly opened cyanuric chloride samples: (a) Pre-column derivatization: 1.8 g of cyanuric chloride sample was dissolved in 80 mL of acetone, and then 3.7 g of p-toluylthiophenol (3 equivalents) and sodium bicarbonate solution (2.5 g of sodium bicarbonate dissolved in 27 mL of purified water) were added. The reaction was carried out at 0-5 °C for 2 h, and then the temperature was increased to 30-40 °C for 2 h. The derivatized reaction solution was diluted with the mobile phase to a concentration of 100 μg / mL to obtain the test solution.

[0051] (b) Sample injection and detection: The chromatographic conditions were as follows: An Agilent C18 column was used, with a length of 250 mm, an inner diameter of 4.6 mm, and a particle size of 5 µm; mobile phase A was 0.1% formic acid aqueous solution; mobile phase B was acetonitrile; the flow rate was 1 mL / min, the column temperature was 25℃, and the injection volume was 5 µl; the UV detection wavelength was 240 nm. Gradient elution was used, and the specific elution program is shown in Table 7. Table 7 Gradient elution program

[0052] Inject the sample solution into the chromatograph to obtain the following results: Figure 5 The chromatogram shown, calculated using the area normalization method, indicates that the purity of cyanuric chloride (converted to 2,4,6-tris(p-toluenethio)-1,3,5-triazine) is 99.08%, 2,4-dihydroxy-6-(p-toluenethio)-1,3,5-triazine is 0.24%, 2-hydroxy-4,6-bis(p-toluenethio)-1,3,5-triazine is 0.25%, and cyanuric acid is 0.04%.

[0053] Example 4 Purity test of cyanuric chloride sample in Example 1 after aliquoting and storage for 3 days: (a) Pre-column derivatization: 1.8 g of cyanuric chloride sample was dissolved in 80 mL of acetone, and then 3.7 g of p-toluene and sodium bicarbonate solution (2.5 g of sodium bicarbonate dissolved in 27 mL of purified water) were added. The reaction was carried out at 0-5 °C for 2 h, and then the temperature was raised to 30-40 °C for 2 h. The derivatized reaction solution was diluted with the mobile phase to a concentration of 100 μg / mL to obtain the test solution.

[0054] (b) Sample injection and detection: The chromatographic conditions were as follows: An Agilent C18 column, 250 mm long, 4.6 mm inner diameter, and 5 µm particle size; mobile phase A was 0.1% formic acid aqueous solution; mobile phase B was acetonitrile; flow rate was 1 mL / min; column temperature was 25 °C; injection volume was 5 µl; and UV detection wavelength was 240 nm. The gradient elution program was as described in Example 2. The sample solution was injected into the chromatograph to obtain the following... Figure 5 The chromatogram shown indicates that, based on the area normalization method, the purity of cyanuric chloride is 98.50%, 2,4-dihydroxy-6-(p-toluenethio)-1,3,5-triazine is 0.59%, 2-hydroxy-4,6-bis(p-toluenethio)-1,3,5-triazine is 0.38%, and cyanuric acid is 0.08%.

[0055] Example 5 Purity test of cyanuric chloride sample in Example 1 after aliquoting and storage for 7 days: The test was performed according to the method and steps in Example 3, and the results were as follows: Figure 6The chromatogram shown, calculated using the area normalization method, indicates that the purity of cyanuric chloride (converted to 2,4,6-tris(p-toluenethio)-1,3,5-triazine) is 95.41%, 2,4-dihydroxy-6-(p-toluenethio)-1,3,5-triazine is 0.02%, 2-hydroxy-4,6-bis(p-toluenethio)-1,3,5-triazine is 3.08%, and cyanuric acid is 1.00%.

[0056] The purity tests of the cyanuric chloride samples from Examples 2-4 after different storage days are detailed in the table below: Table 8 Purity test of cyanuric chloride samples after different storage days

[0057] Conclusion: The quality standard for cyanuric chloride is a purity of 99.0% or higher; it becomes substandard if left for more than 3 days.

[0058] Comparative Example 1 Weigh 0.2 g of the same batch of cyanuric chloride as in Example 2 into a clean, dry conical flask. Immediately add 15 ml of potassium hydroxide solution, attach a condenser, and heat under reflux for 10 min. After cooling, transfer the solution to a 250 mL beaker. Wash the condenser and conical flask several times with 50 ml of water to make the total volume of the sample solution approximately 75 mL. Add a small piece of Congo red test paper and neutralize with concentrated nitric acid until the paper turns from red to blue. Add another 2 ml of concentrated nitric acid and cool to room temperature. Add 5 ml of starch indicator solution while stirring. Insert the silver and calomel electrodes, adjust the instrument, and perform potentiometric titration with silver nitrate standard titration solution. Correct the blank titration using the same method.

[0059] Parallel test results were 99.91% and 99.80%. However, the content measured according to Example 2 of this invention was 99.08%, with the remainder being various impurities. This indicates that the content measured by the method described in GB / T 25814-2022 is inflated.

[0060] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A highly selective liquid chromatography method for the analysis of cyanuric chloride, characterized in that, The quantitative detection of cyanuric chloride derivatives was performed using high-performance liquid chromatography, including the following steps: (1) The qualified cyanuric chloride sample was subjected to a derivatization reaction to obtain the control derivatized product; (2) A standard reference solution was prepared using the reference derivative, and the solution was analyzed by high performance liquid chromatography to obtain the standard detection results for reference. (3) The derivatives of the cyanuric chloride test sample were analyzed by high performance liquid chromatography and compared with the above standard test results to obtain the quantitative detection results of the cyanuric chloride derivatives.

2. The highly selective liquid chromatography method for cyanuric chloride analysis according to claim 1, characterized in that, The derivative is obtained by derivatization reaction of a derivatizing reagent with a cyanuric chloride sample under acid-binding conditions. The derivatizing reagent is selected from one of p-methylthiophenol, o-toluenethiophenol, 4-phenylphenol, 3-methylthiophenol, 4-methylthiophenol, p-methoxyphenol, 4-chloro-2-methylphenol, and 2-methoxythiophenol.

3. The highly selective liquid chromatography method for cyanuric chloride analysis according to claim 2, characterized in that, The derivatization reaction process of the derivative product is as follows: the cyanuric chloride sample is dissolved in a solvent, the derivatization reagent and the acid-binding agent are added, and the reaction is carried out at 0~10℃ for 1.5-3h, and then the temperature is raised to 30~40℃ for 1.5-3h.

4. The highly selective liquid chromatography method for the analysis of cyanuric chloride according to claim 2 or 3, characterized in that, The molar ratio of the derivatizing reagent to the cyanuric chloride sample is (1~3):1; the molar ratio of the acid-binding agent to the cyanuric chloride sample is (1~3):

1.

5. The highly selective liquid chromatography method for the analysis of cyanuric chloride according to claim 2 or 3, characterized in that, The acid-binding agent is selected from one or more of sodium bicarbonate and potassium bicarbonate; And / or, the solvent for dissolving the cyanuric chloride sample is one or more of acetone, tetrahydrofuran, dichloromethane, dichloroethane, and chloroform; preferably acetone.

6. The highly selective liquid chromatography method for the analysis of cyanuric chloride according to any one of claims 2 or 3, characterized in that, The derivatizing reagent is selected from p-toluenethiophenol, and the reference derivatized products include 2,4-dihydroxy-6-(p-toluenethio)-1,3,5-triazine, 2-hydroxy-4,6-bis(p-toluenethio)-1,3,5-triazine, and 2,4,6-tris(p-toluenethio)-1,3,5-triazine; the standard reference solution is obtained by diluting the reference derivatized products with acetonitrile to a final volume, with a concentration of 0.1~1000 μg / mL.

7. The highly selective liquid chromatography method for the analysis of cyanuric chloride according to claim 1, characterized in that, The steps for quantitative detection of cyanuric chloride derivatives using high performance liquid chromatography further include: preparing a reference solution using reference substances, wherein the reference substances include cyanuric acid, cyanuric chloride and p-methylthiophenol; the reference solution is obtained by diluting the reference substances with acetonitrile to a final volume, and the concentration is 0.1~1000 μg / mL.

8. The highly selective liquid chromatography method for the analysis of cyanuric chloride according to any one of claims 1-3, characterized in that, The chromatographic conditions for the liquid chromatography analysis are as follows: Chromatographic column: Octadecylsilane-bonded silica gel column; the column length is 250 mm, the inner diameter is 4.6 mm, and the particle size is 5 µm; Mobile phase: Mobile phase A is a 0.1% aqueous solution of formic acid or water, and mobile phase B is acetonitrile; Preferred mobile phases: Mobile phase A is a 0.1% aqueous solution of formic acid, and mobile phase B is acetonitrile.

9. The highly selective liquid chromatography method for the analysis of cyanuric chloride according to claim 8, characterized in that, The elution method of the chromatographic column is gradient elution, and the elution program of the gradient elution is as follows: the volume ratio of mobile phase A to mobile phase B is (10%~30%)~(70~90%), and the elution time of the mobile phase is 0~40 min.

10. The highly selective liquid chromatography method for the analysis of cyanuric chloride according to claim 8, characterized in that, The flow rate for the chromatographic analysis was 1 mL / min, the column temperature was 25℃, and the injection volume was 5 µm; the UV wavelength for UV detection was 190 nm to 240 nm.

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