A method for determining the content of a quaternary ammonium salt disinfectant

Abstract

The application provides a content determination method of quaternary ammonium salt disinfectant: 1 mL is taken and placed in a 100 mL volumetric flask, diluted to the scale with a mobile phase, 1 mL is taken and placed in a 10 mL volumetric flask, diluted to the scale with a mobile phase, and a test sample solution is obtained; benzalkonium chloride control samples are taken, dissolved and quantitatively diluted with a mobile phase to prepare C12 substituted homologues and C14 substituted homologues solutions, which are used as benzalkonium chloride control sample solutions; decamethylquinolinium chloride control samples are taken, dissolved and quantitatively diluted with a mobile phase to prepare a solution, which is used as a decamethylquinolinium chloride control sample solution; the benzalkonium chloride and decamethylquinolinium chloride control sample solutions are taken, and a chromatogram is recorded; the logarithmic values of the control sample solution concentrations and the logarithmic values of the corresponding peak areas are calculated to obtain a corresponding linear regression equation; the test sample solution is taken, and the content of benzalkonium chloride and decamethylquinolinium chloride in the test sample is calculated by the linear regression equation.

Description

Technical Field

[0001] This invention relates to a method for determining the content of a compound quaternary ammonium salt disinfectant, specifically a liquid chromatography method for simultaneously detecting the content of a single-chain quaternary ammonium salt, benzalkonium chloride, and a double-chain quaternary ammonium salt, decyl chloride. Background Technology

[0002] Quaternary ammonium salt disinfectants are currently the most widely used disinfectants, characterized by strong bactericidal ability, rapid action, and low irritation. Quaternary ammonium salt disinfectants mainly include single-chain and double-chain quaternary ammonium salt disinfectants. Taking benzalkonium chloride as an example, the single-chain quaternary ammonium salt disinfectant belongs to the broad-spectrum cationic surfactant class. Benzalkonium chloride has good chemical stability; its mechanism involves altering cell membrane permeability, causing the exudation of bacterial substances, thereby inhibiting bacterial metabolism and killing pathogenic microorganisms. This type of disinfectant is widely used for skin and environmental disinfection, mainly due to its low toxicity and irritation, good water solubility, and ease of use and storage. Among double-chain quaternary ammonium salt disinfectants, decanemethyl chloride, one of the more commonly used disinfectants, has the advantage of a broad bactericidal spectrum.

[0003] Benzalkonium chloride is a single-chain quaternary ammonium salt cationic surfactant and a non-oxidizing bactericide. It has good foaming properties, chemical stability and safety. It has a strong effect on Gram-positive bacteria, is chemically stable, is not easily affected by temperature changes, and is convenient to use and store. A 0.0025%~0.1% aqueous solution is non-corrosive to materials and non-irritating to the skin. Its mechanism of action is to change cell membrane permeability, thereby destroying cell structure and killing bacteria.

[0004] Decylamine chloride is a double-chain quaternary ammonium salt compound. Compared to benzalkonium chloride, it requires a lower dosage and shorter sterilization time, exhibiting stronger disinfection effects. However, its foaming properties and dirt-removing ability are weaker than those of benzalkonium chloride. Compound products of dedecylamine chloride and benzalkonium chloride retain the characteristics of their respective components, resulting in improved performance of compound disinfectants compared to single-component disinfectants. This improves sterilization efficiency, reduces toxicity, broadens the sterilization spectrum, and expands the product's applicability.

[0005] The molecular formula of benzalkonium chloride is C6H5CH2N(CH3)2CnH. 2n+1CL (n=8, 10, 12, 14, 16, 18) is a heterogeneous mixture composed of various even-numbered alkyl-benzyl chlorides. It has a boiling point of 100℃, a density of 0.98, a flash point of 41℃, and should be stored between 2 and 8℃. Benzalkonium chloride has high solubility in many solutions. The optimal pH range for use is 4.0–10.0. Benzalkonium chloride consists of three structurally similar quaternary ammonium salt compounds, characterized by a positively charged nitrogen atom bonded to three alkyl substituents and one benzyl substituent. The three homologues of benzalkonium chloride are: dodecyl dimethyl benzyl ammonium chloride, tetradecyl dimethyl benzyl ammonium chloride, and hexadecyl dimethyl benzyl ammonium chloride, where R is an alkyl group, starting from C8H. 17 To C 18 H 37 Its chemical structural formula is as follows:

[0006] Didecyl dimethyl ammonium chloride, also known as decylmethyl ammonium chloride, didecyl dimethyl ammonium chloride, etc., has the molecular formula C1 22 H 48 CLN is a cationic surfactant. It belongs to the double-chain quaternary ammonium salt class of compounds. At room temperature, it is a pale yellow transparent liquid, readily soluble in water and organic solvents, chemically stable, and irritating.

[0007] Currently, there are many methods for quantifying quaternary ammonium salts in China. Traditional methods include titration and spectrophotometry. There are also some newer detection methods such as high-performance liquid chromatography (HPLC) and liquid chromatography-mass spectrometry (LC-MS).

[0008] Capillary electrophoresis is a liquid-phase separation technique that uses a flexible quartz capillary as the separation channel and a high-voltage direct current to drive sample migration. Capillary electrophoresis is characterized by high efficiency, speed, and the ability to handle small sample volumes. It has been used for the determination of benzalkonium chloride in eye drops. Capillary zone electrophoresis can efficiently separate large quantities of compounds, shortening analysis time. However, due to the limitations of capillary electrodialysis equipment, capillary electrophoresis technology is not yet widely used.

[0009] In spectrophotometry, replacing the blank reagent with a standard solution at a concentration slightly lower or higher than the sample concentration improves the precision and accuracy of the spectrophotometric method. This method uses relatively simple and low-complexity instruments and is widely used, but its accuracy is relatively low.

[0010] Chemical titration involves titrating an unknown analyte solution with a solution of known and accurate concentration (or adding the analyte solution to a standard solution) until the reaction is complete. The volume of the known concentration solution consumed is recorded, and the concentration of the unknown solution can be calculated based on the volume ratio and concentration ratio. Titration analysis is one of the earliest methods used in analytical chemistry. It does not require large instruments and is simple to operate, thus its application is widespread. However, this method also has limitations; it cannot perform qualitative analysis of substances.

[0011] Liquid chromatography-mass spectrometry (LC-MS) has several advantages, including wide applicability (different compounds have corresponding mass spectra), strong separation capabilities, and low detection limits. However, it also has some drawbacks: the equipment is expensive, resulting in higher costs; sample pretreatment is complex; and it requires highly skilled operators with maintenance experience and data processing and summarization abilities.

[0012] HPLC is currently the most commonly used detection method. Compared with other detection methods, this method has higher sensitivity and can be used in conjunction with ultraviolet detectors, diode array detectors, differential refractive index detectors, evaporative light scattering detectors, fluorescence detectors, etc.

[0013] The current methods for determining the content of quaternary ammonium salts are as follows: Determination of benzalkonium chloride content in the 2002 edition of "Disinfection Technical Specifications", benzalkonium chloride in the 2020 edition of Chinese Veterinary Pharmacopoeia (Part I), and compound glutaraldehyde solution in the 2012 edition of the Compilation of Veterinary Drug Quality Standards: potassium iodate titration method.

[0014] Disinfection Technical Specifications 2002 Edition: Sodium Tetraphenylborate Titration Method; Cosmetic Safety Technical Specifications 2015 Edition: Preservative Test Method: Benzalkonium Chloride.

[0015] Li Kaidong, Yang Fenfang, Lang Fengting, et al. Stability observation of a compound decylmethyl chloride disinfectant [J]. Chinese Journal of Disinfection, 2024, 41(02):99-102. : Decylmethyl chloride, liquid chromatography (evaporative light detector); benzalkonium chloride, liquid chromatography (ultraviolet detector).

[0016] Analytical methods for quaternary ammonium salts include chemical titration, ultraviolet spectrophotometry, capillary electrophoresis, high performance liquid chromatography, high performance liquid chromatography-mass spectrometry, and differential spectrophotometry.

[0017] Chemical titration and ultraviolet spectrophotometry can only measure the total amount and cannot achieve qualitative analysis of complex quaternary ammonium salts.

[0018] Differential spectrophotometry requires derivatization before measurement, which is cumbersome and time-consuming.

[0019] Liquid chromatography-mass spectrometry (LC-MS) analysis is costly and is mostly used for residue analysis.

[0020] Liquid chromatography (LC) offers high resolution, sensitivity, rapid analysis, good repeatability, and high quantitative accuracy, and is now widely used for content detection. The 2015 "Cosmetic Safety Technical Specifications" and related literature use diode array detectors or ultraviolet detectors to determine benzalkonium chloride; in the stability observation of a compound decylmethyl chloride disinfectant, an evaporative light scattering detector was used to determine decylmethyl chloride.

[0021] When conducting production testing on a compound quaternary ammonium salt disinfectant, namely benzalkonium chloride and decanoic acid chloride, chemical titration cannot determine the content of both. Liquid chromatography can only detect benzalkonium chloride and decanoic acid chloride separately, resulting in a waste of personnel and equipment and delaying the product production cycle. Summary of the Invention

[0022] To address the above issues, a method was developed to simultaneously detect two quaternary ammonium salts, benzalkonium chloride and decyl chloride, using a single detector that meets the methodological requirements of high resolution and sensitivity, fast analysis speed, good repeatability, and high quantitative accuracy.

[0023] Its main technical solution is: a method for determining the content of quaternary ammonium salt disinfectants, comprising the following steps: Step 1: Preparation of the test solution: Accurately measure 1 mL and place it in a 100 mL volumetric flask. Add the mobile phase to dissolve and dilute to the mark, and shake well. Accurately measure 1 mL and place it in a 10 mL volumetric flask. Dilute to the mark with the mobile phase and shake well. This will give you a test solution containing approximately 0.094 mg of benzalkonium chloride C12-substituted homologue, 0.030 mg of benzalkonium chloride C14-substituted homologue, and 0.130 mg of decanoic acid per 1 mL. Step 2, Preparation of benzalkonium chloride reference solution: Take an appropriate amount of benzalkonium chloride reference standard, accurately weigh it, dissolve it in the mobile phase and quantitatively dilute it to prepare a solution containing approximately 0.047 mg, 0.094 mg, and 0.188 mg of C12 substituted homologues and approximately 0.015 mg, 0.030 mg, and 0.060 mg of C14 substituted homologues per 1 mL, which is used as the benzalkonium chloride reference solution; Step 3: Preparation of decyl chloride reference solution: Take an appropriate amount of decyl chloride reference standard, accurately weigh it, dissolve it in the mobile phase and quantitatively dilute it to prepare a solution containing approximately 0.065 mg, 0.130 mg and 0.260 mg per 1 mL, which is used as the decyl chloride reference solution; Step 4, Determination: Accurately measure 10 µL each of benzalkonium chloride and decyl chloride reference solutions and inject them into the liquid chromatograph. Record the chromatograms. Calculate the corresponding linear regression equation using the logarithm of the concentration of the reference solution and the logarithm of the corresponding peak area. The correlation coefficient (r) should not be less than 0.99. Accurately measure 10 µL of the test solution and determine it using the same method. Calculate the content of benzalkonium chloride and decyl chloride in the test solution using the linear regression equation. For benzalkonium chloride, calculate the content of C12 and C14 substituted homologues separately, and use the sum of C12 and C14 substituted homologues as the content of benzalkonium chloride. The liquid chromatography conditions were as follows: column: octadecylsilane-bonded silica gel (4.6 mm × 250 mm, 5 μm); Mobile phase: acetonitrile-trifluoroacetic acid, with acetonitrile volume fraction of 75%~85% and trifluoroacetic acid volume fraction of 0.1%~0.2%; Flow rate: 0.8~1.2 mL / min; Column temperature: 30~35℃; Detector: Evaporative light scattering detector; Drift tube temperature: 80~120℃; Gas flow rate: 2.0~3.0 mL / min; Gain factor: 1~2.

[0024] Preferably, the liquid chromatography conditions are as follows: acetonitrile volume fraction 80%, trifluoroacetic acid ratio 0.2%, flow rate 1.0 mL / min, column temperature 35℃, drift tube temperature 100℃, gas flow rate 3.0 mL / min, and gain factor 2.

[0025] The beneficial effects of this invention are as follows: This invention provides a liquid chromatography method that requires only one liquid chromatography unit and one operator to simultaneously detect the content of single-chain quaternary ammonium salt benzalkonium chloride and double-chain quaternary ammonium salt decyl chloride. Attached Figure Description

[0026] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 The Vt graph shows the product of this invention at 35°C, acetonitrile-0.2% trifluoroacetic acid (80:20), and a flow rate of 1.0 mL / min. Figure 2a This is a graph showing the recovery rate of benzalkonium chloride in this invention; Figure 2b This is a graph showing the recovery rate of decyl chloride in this invention; Figure 3a This is a repeatability diagram of benzalkonium chloride in this invention; Figure 3bThis is a repeatability diagram of decyl chloride of the present invention; Figure 4a This is the linear Vt plot of benzalkonium chloride in this invention; Figure 4b This is the linear regression curve of benzalkonium chloride C12 in this invention; Figure 4c This is the linear regression curve of benzalkonium chloride C14 in this invention; Figure 5a This is the linear Vt plot of decyl chloride of the present invention; Figure 5b This is the linear regression curve of decyl chloride in this invention; Figure 6a The Vt plot is for a robust flow rate of 0.8 mL / min. Figure 6b The Vt plot is for a robust flow rate of 1.2 mL / min. Figure 7a This is the Vt graph for the durability of this invention at a column temperature of 30°C; Figure 7b This is the Vt graph for the durability of this invention at a column temperature of 33°C; Figure 8a The Vt plot is for the durable acetonitrile-0.2% trifluoroacetic acid (75:25) of this invention; Figure 8b The Vt plot is for the durable acetonitrile-0.2% trifluoroacetic acid (85:15) of this invention; Figure 8c The Vt plot is for the durable acetonitrile-0.1% trifluoroacetic acid (80:20) of this invention; Figure 9 The Vt chromatogram of the Thermo HypersilGOLD C18 durable chromatographic column of this invention; Figure 10a The Vt diagram for the system adaptability of benzalkonium chloride 6 to low concentrations in this invention; Figure 10b This is a Vt plot showing the concentration of benzalkonium chloride 6 in the control of the system adaptability of the present invention; Figure 10c The Vt diagram for the system adaptability of benzalkonium chloride 6 to high concentrations in this invention; Figure 11a The system adaptability of the present invention is shown in the Vt diagram for low concentration of decyl chloride 6-peptide; Figure 11b The Vt plot is shown for the concentration of decanoic acid 6-peptide in the control of the system adaptability of this invention. Figure 11c The system adaptability of the present invention is shown in the Vt diagram for high concentrations of decyl chloride 6-peptide; Figure 12aThe Vt graph for the solution stability of benzalkonium chloride at low concentration (0-12h) is shown in the figure for this invention. Figure 12b This is a Vt graph showing the concentration of benzalkonium chloride in the 0-12h control for the solution stability of this invention. Figure 12c The Vt graph for the solution stability of benzalkonium chloride (0-12h) in this invention is a high-concentration control. Figure 13a The Vt graph for the solution stability of decanoic acid ammonium chloride at a low concentration (0-12h) is shown in the figure. Figure 13b This is a Vt graph showing the concentration of decanoic acid chloride in the 0-12h control for the solution stability of this invention; Figure 13c The Vt graph for the solution stability of decanoic acid ammonium chloride at 0-12h is a high concentration compared to the previous method. Figure 14 The Vt graph shows the stability of the solution of the present invention over 0-12 hours. Detailed Implementation

[0027] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings.

[0028] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0029] 1. Preparation of the test solution: Preparation of the test solution: Accurately measure 1 mL and place it in a 100 mL volumetric flask. Add the mobile phase to dissolve and dilute to the mark, and shake well. Accurately measure 1 mL and place it in a 10 mL volumetric flask. Dilute to the mark with the mobile phase and shake well to obtain a test solution containing approximately 0.094 mg of benzalkonium chloride C12-substituted homologue, 0.030 mg of benzalkonium chloride C14-substituted homologue, and 0.130 mg of decanoic acid per 1 mL.

[0030] 2. Preparation of the control solution: Take an appropriate amount of benzalkonium chloride reference standard, accurately weigh it, dissolve it in the mobile phase and quantitatively dilute it to prepare a solution containing approximately 0.047 mg, 0.094 mg, and 0.188 mg of C12 substituted homologues and approximately 0.015 mg, 0.030 mg, and 0.060 mg of C14 substituted homologues per 1 mL, as benzalkonium chloride reference standard solutions (1), (2), and (3).

[0031] Take an appropriate amount of decanoic acid chloride reference standard, accurately weigh it, dissolve it in the mobile phase and quantitatively dilute it to prepare a solution containing approximately 0.065 mg, 0.130 mg and 0.260 mg per 1 mL, as decanoic acid chloride reference standard solutions (1), (2) and (3).

[0032] 3. Determination method: Accurately measure 10 µL each of the above-mentioned benzalkonium chloride and decyl chloride reference solutions, inject them into the liquid chromatograph, record the chromatograms, and calculate the corresponding linear regression equations using the logarithm of the concentration of the reference solution and the logarithm of the corresponding peak area. The correlation coefficient (r) should not be less than 0.99.

[0033] Accurately measure 10 µL of the test solution and determine it using the same method. Calculate the contents of benzalkonium chloride and decyl chloride in the test sample using a linear regression equation. For benzalkonium chloride, calculate the contents of C12 and C14 substituted homologues, and use the sum of C12 and C14 substituted homologues as the content of benzalkonium chloride.

[0034] 4. Liquid chromatography conditions: Chromatographic column: Octadecylsilane-bonded silica gel as packing material (4.6 mm × 250 mm, 5 μm); Mobile phase: acetonitrile-trifluoroacetic acid, with acetonitrile volume fraction of 75%~85% and trifluoroacetic acid volume fraction of 0.1%~0.2%; Flow rate: 0.8~1.2 mL / min; Column temperature: 30~35℃; Detector: Evaporative light scattering detector; Drift tube temperature: 80~120℃; Gas flow rate: 2.0~3.0 mL / min; Gain factor: 1~2.

[0035] The preferred conditions for liquid chromatography are as follows: acetonitrile volume fraction of 80%, trifluoroacetic acid ratio of 0.2%, flow rate of 1.0 mL / min, column temperature of 35℃, drift tube temperature of 100℃, gas flow rate of 3.0 mL / min, and gain factor of 2.

[0036] The technical problem to be solved is to provide a method for determining the content of compound quaternary ammonium salt disinfectants. This method provides a basis for simultaneously detecting the content of single-chain quaternary ammonium salt benzalkonium chloride and double-chain quaternary ammonium salt decyl chloride, filling a technical gap in this field.

[0037] The steps are as follows: Solution preparation: Preparation of the test solution: Accurately measure 1 mL and place it in a 100 mL volumetric flask. Add the mobile phase to dissolve and dilute to the mark, and shake well. Accurately measure 1 mL and place it in a 10 mL volumetric flask. Dilute to the mark with the mobile phase and shake well to obtain a test solution containing approximately 0.094 mg of benzalkonium chloride C12-substituted homologue, 0.030 mg of benzalkonium chloride C14-substituted homologue, and 0.130 mg of decanoic acid per 1 mL.

[0038] Preparation of the control solution: Take an appropriate amount of benzalkonium chloride reference standard, accurately weigh it, dissolve it in the mobile phase and quantitatively dilute it to prepare a solution containing approximately 0.047 mg, 0.094 mg, and 0.188 mg of C12 substituted homologues and approximately 0.015 mg, 0.030 mg, and 0.060 mg of C14 substituted homologues per 1 mL, as benzalkonium chloride reference standard solutions (1), (2), and (3).

[0039] Take an appropriate amount of decanoic acid chloride reference standard, accurately weigh it, dissolve it in the mobile phase and quantitatively dilute it to prepare a solution containing approximately 0.065 mg, 0.130 mg and 0.260 mg per 1 mL, as decanoic acid chloride reference standard solutions (1), (2) and (3).

[0040] Determination method: Accurately measure 10 µL each of the above-mentioned benzalkonium chloride and decyl chloride reference solutions, inject them into the liquid chromatograph, record the chromatograms, and calculate the corresponding linear regression equations using the logarithm of the concentration of the reference solution and the logarithm of the corresponding peak area. The correlation coefficient (r) should not be less than 0.99.

[0041] Accurately measure 10 µL of the test solution and determine it using the same method. Calculate the contents of benzalkonium chloride and decyl chloride in the test sample using a linear regression equation. For benzalkonium chloride, calculate the contents of C12 and C14 substituted homologues, and use the sum of C12 and C14 substituted homologues as the content of benzalkonium chloride.

[0042] Liquid chromatography conditions: Column: Octadecylsilane-bonded silica gel (4.6 mm × 250 mm, 5 μm), WelchWelchrom @C18 was used; Mobile phase: acetonitrile-trifluoroacetic acid, with acetonitrile volume fraction of 75%~85% and trifluoroacetic acid volume fraction of 0.1%~0.2%; Flow rate: 0.8~1.2 mL / min; Column temperature: 30~35℃; Detector: Evaporative light scattering detector; Drift tube temperature: 80~120℃; Gas flow rate: 2.0~3.0 mL / min; Gain factor: 1~2.

[0043] Preferably, the volume fraction of acetonitrile is 80%, the proportion of trifluoroacetic acid is 0.2%, the flow rate is 1.0 mL / min, the column temperature is 35℃, the drift tube temperature is 100℃, the gas flow rate is 3.0 mL / min, and the gain factor is 2.

[0044] (1) Accuracy Prepare a test solution containing 0.0388 mg / mL of benzalkonium chloride C12-substituted homologue, and add 0.0283 mg / mL, 0.0353 mg / mL, and 0.0424 mg / mL of benzalkonium chloride control C12-substituted homologue, respectively. Prepare a test solution containing 0.0124 mg / mL of benzalkonium chloride C14-substituted homologue, and add 0.0090 mg / mL, 0.0113 mg / mL, and 0.0136 mg / mL of benzalkonium chloride control C14-substituted homologue, respectively. Prepare a solution containing 0.0745 mg / mL of decanoic acid chloride as a test sample, and add 0.0479 mg / mL, 0.0653 mg / mL, and 0.0828 mg / mL of decanoic acid chloride control, respectively.

[0045] Perform the determination according to the above method and calculate the recovery rate of each component.

[0046] Recovery rate test results

[0047] The experimental results show that the recovery rates of each component are between 85% and 110%, and the relative standard deviations of the recovery rates are all less than 2.0%, indicating that the method has high accuracy.

[0048] (2) Repeatability Prepare the corresponding test solution and control solution according to the method, and measure 6 samples for evaluation.

[0049] Repeatability test results

[0050] The experimental results showed that the determination results of the six parallel test samples were basically consistent. The relative standard deviations of the peak areas of the test sample solution and the control solution were all less than 3.0%, and the relative standard deviations of the test sample content were less than 2.0%. The experimental results indicate that the method has good repeatability.

[0051] (3) Linearity and Range To accurately determine the amount of each component, a linearity study was conducted on each component, that is, to examine the relationship between the peak area and concentration of each component within a certain range. Specifically, the stock solution of the reference standard was precisely diluted to prepare 6 reference standard solutions of different concentrations. The concentration of the reference standard solution in the method was taken as 100%, and the determination was carried out according to the above method. Chromatograms were recorded, and a linear regression curve was plotted with the logarithm of the concentration of each reference standard solution as the abscissa and the logarithm of the peak area as the ordinate.

[0052] Linearity and range test results of each component

[0053] (4) Durability This method examines the extent to which minute changes in chromatographic conditions do not affect the measurement results, and can be used to provide a basis for routine inspections. It primarily focuses on testing chromatographic conditions such as flow rate, column temperature, mobile phase ratio, and different brands of the same type of chromatographic column.

[0054] Flow rate: The flow rates were investigated at 0.8 mL / min, 1.0 mL / min, and 1.2 mL / min.

[0055] Column temperature: The column temperatures were tested at 30℃, 33℃, and 35℃ respectively.

[0056] Mobile phase ratios: Acetonitrile-2% trifluoroacetic acid (85:15), acetonitrile-2% trifluoroacetic acid (80:20), acetonitrile-2% trifluoroacetic acid (75:25), and acetonitrile-1% trifluoroacetic acid (80:20) were investigated respectively.

[0057] Chromatographic columns: Different brands of the same type of chromatographic columns (4.6mm×250mm, 5μm) were tested.

[0058]

[0059] The experimental results show that minor changes in chromatographic conditions have no significant impact on the detection results, indicating that the method has good robustness.

[0060] (5) System applicability Inject the reference solution six times consecutively, record the peak areas of benzalkonium chloride C12 and C14 substituted homologues and decyl chloride, and calculate the RSD of the peak areas.

[0061] System suitability test results

[0062] The injection results show that after six consecutive injections, the RSD values ​​of the peak areas of each component all meet the requirements, indicating that the system has good applicability.

[0063] (6) Solution stability Inject the test solution and reference solution separately according to the above method and record the chromatograms. Starting from the preparation of the test solution, determine the stability of the solution at 0, 4, 8, and 12 hours each day.

[0064] Solution stability

[0065] The test results showed that both the test sample and the control sample were stable within 12 hours (RSD values ​​were both less than 2%). The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the inventive concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this application.

Claims

1. A method for determining the content of quaternary ammonium salt disinfectants, characterized in that, Includes the following steps: Step 1: Preparation of the test solution: Accurately measure 1 mL and place it in a 100 mL volumetric flask. Add the mobile phase to dissolve and dilute to the mark, and shake well. Accurately measure 1 mL and place it in a 10 mL volumetric flask. Dilute to the mark with the mobile phase and shake well. This will give you a test solution containing approximately 0.094 mg of benzalkonium chloride C12-substituted homologue, 0.030 mg of benzalkonium chloride C14-substituted homologue, and 0.130 mg of decanoic acid per 1 mL. Step 2, Preparation of benzalkonium chloride reference solution: Take an appropriate amount of benzalkonium chloride reference standard, accurately weigh it, dissolve it in the mobile phase and quantitatively dilute it to prepare a solution containing approximately 0.047 mg, 0.094 mg, and 0.188 mg of C12 substituted homologues and approximately 0.015 mg, 0.030 mg, and 0.060 mg of C14 substituted homologues per 1 mL, which is used as the benzalkonium chloride reference solution; Step 3: Preparation of decyl chloride reference solution: Take an appropriate amount of decyl chloride reference standard, accurately weigh it, dissolve it in the mobile phase and quantitatively dilute it to prepare a solution containing approximately 0.065 mg, 0.130 mg and 0.260 mg per 1 mL, which is used as the decyl chloride reference solution; Step 4, Determination: Accurately measure 10 µL each of benzalkonium chloride and decyl chloride reference solutions and inject them into the liquid chromatograph. Record the chromatograms. Calculate the corresponding linear regression equation using the logarithm of the concentration of the reference solution and the logarithm of the corresponding peak area. The correlation coefficient (r) should not be less than 0.

99. Accurately measure 10 µL of the test solution and determine it using the same method. Calculate the content of benzalkonium chloride and decyl chloride in the test solution using the linear regression equation. For benzalkonium chloride, calculate the content of C12 and C14 substituted homologues separately, and use the sum of C12 and C14 substituted homologues as the content of benzalkonium chloride. The liquid chromatography conditions were as follows: column: octadecylsilane-bonded silica gel (4.6 mm × 250 mm, 5 μm); Mobile phase: acetonitrile-trifluoroacetic acid, with acetonitrile volume fraction of 75%~85% and trifluoroacetic acid volume fraction of 0.1%~0.2%; Flow rate: 0.8~1.2 mL / min; Column temperature: 30~35℃; Detector: Evaporative light scattering detector; Drift tube temperature: 80~120℃; Gas flow rate: 2.0~3.0 mL / min; Gain factor: 1~2.

2. The method for determining the content of a quaternary ammonium salt disinfectant according to claim 1, characterized in that: The liquid chromatography conditions are as follows: acetonitrile volume fraction 80%, trifluoroacetic acid ratio 0.2%, flow rate 1.0 mL / min, column temperature 35℃, drift tube temperature 100℃, gas flow rate 3.0 mL / min, and gain factor 2.

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