Method for detecting free amine content in fatty amide propyl dimethyl betaine

Abstract

The present application relates to the field of chemical analysis, and particularly relates to a method for detecting free amine content in fatty amide propyl dimethyl betaine. The method comprises the following steps: using ethyl acetate to extract free amine in fatty amide propyl dimethyl betaine, the obtained oil phase is a to-be-tested solution, performing gas chromatography analysis on the to-be-tested solution, and measuring the free amine content in the to-be-tested solution. The method can quickly and accurately detect the free amine content in fatty amide propyl dimethyl betaine, significantly improves the detection efficiency and reliability, shortens the analysis time, meets the rapid detection demand in large-scale production, and can realize efficient detection on an industrial production line.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of chemical analysis, and in particular to a method for detecting the content of free amine in fatty amide propyl dimethyl betaine. BACKGROUND

[0002] Fatty amide propyl dimethyl betaine (PCDMA) is a zwitterionic surfactant with excellent surface activity, widely used in detergent, personal care products, industrial cleaning and agricultural adjuvants, etc. Its chemical structure contains both hydrophilic betaine group and hydrophobic fatty amide group, which makes it exhibit good surface activity, mildness and biodegradability in various environmental conditions. However, the problem of residual intermediate free amine in the production process of PCDMA not only affects the quality and performance of the product, but also may bring negative effects such as irritation and poor odor. Even with process optimization, trace amounts of free amine residues are still unavoidable. However, the relevant product standards require that the content of free amine be ≤0.5%. Therefore, how to accurately and quickly detect the content of free amine in the product has become a key link in production quality control.

[0003] Currently, the detection methods for free amine in PCDMA mainly include: (1) direct titration method to determine the content of active substance and free tertiary amine in PCDMA product (Daily Chemical Industry, 2011, No. 01, 68-72), the residual free amide content in PCDMA is low (≤0.5%), the direct titration difference subtraction method is simple to operate, but has low sensitivity and selectivity, is easily interfered by other alkaline impurities, has large detection error, and cannot accurately detect the content of free amide; (2) the method of potential titration for detecting free amide in standard Fatty Amide Propyl Dimethyl Betaine QB / T 4082-2010 5.3, which uses ether-n-butanol extraction, water bath evaporation and potential titration, but the detection method is complex, the detection time is long (about 4 hours), the selectivity is poor, the result error is large, and the safety of the experiment is low due to the use of ether solvent in the detection process.

[0004] Although the existing methods can meet the detection requirements to some extent, they generally have problems such as insufficient sensitivity, complex operation or poor selectivity, and are difficult to fully adapt to the requirements of rapid, simple and efficient detection in industrial production. Therefore, it is urgent to develop a free amide residual detection method with high sensitivity, high selectivity, simple operation and suitable for batch detection, in order to improve the quality control level of PCDMA, and meet the requirements of green chemistry and environmental protection. SUMMARY

[0005] The present application aims to at least partly solve one of the technical problems in the related art. To this end, the present application provides a method for detecting the free amine content in fatty amide propyl dimethyl betaine. The method can quickly and accurately detect the free amine content in fatty amide propyl dimethyl betaine, significantly improve the detection efficiency and reliability, shorten the analysis time, meet the rapid detection needs in large-scale production, and realize efficient detection on the industrial production line.

[0006] To this end, the present application provides a method for detecting the free amine content in fatty amide propyl dimethyl betaine, comprising the following steps:

[0007] The free amine in fatty amide propyl dimethyl betaine is extracted using ethyl acetate, and the obtained oil phase is the test solution.

[0008] In view of the problems of insufficient sensitivity, poor selectivity, and complex operation of the existing detection technology for residual free amide in PCDMA, the present application provides the above-mentioned detection method. Through pretreatment of fatty amide propyl dimethyl betaine, i.e. one-step extraction of free amine in the sample using ethyl acetate, the test sample is obtained by simple centrifugal separation, and then the test sample is analyzed by gas chromatography to measure the content of free amine in PCDMA. The pretreatment can be completed within 10 minutes, realizing efficient extraction of free amine in the sample, reducing the sample pretreatment steps, greatly reducing the operation complexity, and solving the technical bottleneck of rapid and direct detection of free amine in industrial production. The method combined with gas chromatography has the advantages of high selectivity and strong anti-interference, while reducing the safety risk in the experimental process, and has good chemical stability, environmental friendliness, and cost effectiveness. The recovery rate of the method is 90.0%-106%, the repeatability RSD is ≤4.04%, and the detection limit is 0.0008%.

[0009] According to an embodiment of the present application, the detection method further comprises:

[0010] The free amine is dissolved in ethyl acetate to prepare free amine standard solutions of different concentrations;

[0011] The free amine in fatty amide propyl dimethyl betaine is extracted using ethyl acetate, and the obtained oil phase is the test solution;

[0012] The free amine standard solutions of different concentrations are analyzed by gas chromatography, and a standard curve is obtained according to the test results;

[0013] The test solution is analyzed by gas chromatography, and the free amine content in fatty amide propyl dimethyl betaine is obtained according to the test results and the standard curve;

[0014] The gas chromatography analysis conditions are:

[0015] The chromatographic column is a medium-polarity capillary chromatographic column.

[0016] The injection port temperature is 200-350 DEG C.

[0017] The detector temperature is 280-330 DEG C.

[0018] The chromatographic column is programmed to rise in temperature, the initial temperature is 150-250 DEG C, the temperature is kept for 0-5 min, the temperature is raised to 280-350 DEG C, and the temperature is kept for 1-30 min.

[0019] The injection volume is 0.1-2 mu L.

[0020] The column flow rate is 0.4-1.5 mL / min.

[0021] The carrier gas is nitrogen, hydrogen or helium. Thus, the detection time is greatly shortened, the cost of reagents, instruments and manpower is reduced, the contradiction between cost and efficiency that cannot be considered in the prior art is solved, and the demand for high-frequency batch detection in industrial production can be met.

[0022] According to the embodiment of the application, the free amine includes at least one of C8-C 18 fatty amide propyl dimethyl tertiary amine.

[0023] According to the embodiment of the application, the free amine includes at least one of octanamide propyl dimethyl tertiary amine, decanamide propyl dimethyl tertiary amine, lauramide propyl dimethyl tertiary amine, myristamide propyl dimethyl tertiary amine, palmitamide propyl dimethyl tertiary amine, and stearamide propyl dimethyl tertiary amine.

[0024] According to the embodiment of the application, the mass-volume ratio of the fatty amide propyl dimethyl betaine to ethyl acetate is (0.01-0.5) g:1 mL.

[0025] According to the embodiment of the application, the preparation method further includes: mixing the fatty amide propyl dimethyl betaine with a sodium chloride solution and a sodium hydroxide solution, mixing the obtained mixed solution with ethyl acetate, and performing extraction treatment.

[0026] According to the embodiment of the application, the stationary phase of the medium-polarity capillary chromatographic column is 5% phenyl-95% methyl polysiloxane.

[0027] According to the embodiment of the application, the chromatographic column includes at least one of DB-5HT 20m x 0.18mm x 0.18 mu m and DB-5 30m x 0.25mm x 0.25 mu m.

[0028] According to the embodiment of the application, in the chromatographic column temperature programming, the temperature rise rate is 5-25 DEG C / min.

[0029] According to embodiments of the present application, the split ratio of the gas chromatography analysis conditions is (5-20): 1.

[0030] Additional aspects and advantages of the present application will be in part apparent and in part pointed out below in the description of embodiments of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0031] The above and / or additional aspects and advantages of the present application will become apparent and be readily appreciated from the following description of embodiments of the present application, taken in conjunction with the accompanying drawings.

[0032] Figure 1 A gas chromatogram of Test Sample A in Example 1 of the present application is shown. DETAILED DESCRIPTION

[0033] Embodiments of the present application are described in detail below. The embodiments described below are examples for explaining the present application and should not be understood as limiting the present application.

[0034] It should be noted that the terms "first", "second" are used only for descriptive purposes and should not be construed as indicating or implying relative importance or an indicated number of the technical features indicated. Thus, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. Further, in the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise specified.

[0035] The endpoints of the ranges and any values described herein are not limited to the precise values stated. The ranges and values should be construed to be approximations that allow for significant variation. Within each range, other values are contemplated and should be considered as if specifically written out.

[0036] In order that the present application can be more readily understood, certain technical and scientific terms are specifically defined below. Unless specifically defined herein, all other technical and scientific terms used in this document concur in meaning with the general use of those terms by those skilled in the art to which the present application pertains.

[0037] In this document, the terms "comprises" or "comprising" are open-ended, that is, they mean including, but not limited to, the indicated features.

[0038] According to embodiments of the present application, the present application provides a method for detecting free amine content in fatty amido propyl dimethyl betaine, comprising the following steps:

[0039] The free amine in the fatty amide propyl dimethyl betaine is extracted by using ethyl acetate, and the obtained oil phase is a to-be-tested solution.

[0040] The sample pretreatment process is optimized, the free amide in the sample is extracted by using ethyl acetate in one step, and the to-be-tested sample is obtained by simple centrifugal separation, the pretreatment time can be completed within 10 minutes, and efficient extraction of the free amide in the sample is realized. 18 The trace detection of the fatty amide propyl dimethyl tertiary amine effectively monitors the product.

[0041] According to a specific embodiment of the application, the detection method further comprises:

[0042] The free amine is dissolved in ethyl acetate to prepare free amine standard solutions with different concentrations;

[0043] The free amine in the fatty amide propyl dimethyl betaine is extracted by using ethyl acetate, and the obtained oil phase is a to-be-tested solution;

[0044] The free amine standard solutions with different concentrations are subjected to gas chromatography analysis, and a standard curve is obtained according to the test results;

[0045] The to-be-tested solution is subjected to gas chromatography analysis, and the content of the free amine in the fatty amide propyl dimethyl betaine is obtained according to the test results and the standard curve;

[0046] The gas chromatography analysis conditions are as follows:

[0047] The chromatographic column is a medium-polarity capillary chromatographic column;

[0048] The injection port temperature is 200-350℃;

[0049] The detector temperature is 280-330℃;

[0050] The chromatographic column is programmed to have an initial temperature of 150-250℃, is kept for 0-5 minutes, is raised to 280-350℃, and is kept for 1-30 minutes;

[0051] The injection volume is 0.1-2μL;

[0052] The column flow rate is 0.4-1.5mL / min;

[0053] The carrier gas is nitrogen, hydrogen or helium.

[0054] According to a specific embodiment of the present application, the type of free amine is not particularly limited, including but not limited to C8-C 18 fatty amide propyl dimethyl tertiary amine, specifically octanamide propyl dimethyl tertiary amine, decanamide propyl dimethyl tertiary amine, lauramide propyl dimethyl tertiary amine, myristamide propyl dimethyl tertiary amine, palmitamide propyl dimethyl tertiary amine, stearamide propyl dimethyl tertiary amine.

[0055] According to a specific embodiment of the present application, the mass-volume ratio of the fatty amide propyl dimethyl betaine to ethyl acetate is (0.01-0.5) g:1 mL, thereby achieving a better extraction effect.

[0056] According to a specific embodiment of the present application, the preparation method further comprises: mixing the fatty amide propyl dimethyl betaine with a sodium chloride solution and a sodium hydroxide solution, mixing the obtained mixed solution with ethyl acetate, and performing extraction treatment. Thereby, the extraction efficiency is improved. The sodium chloride is a strong electrolyte, which can significantly increase the ionic strength of the aqueous phase, thereby reducing the mutual solubility between the aqueous phase and the organic phase, reducing the emulsification ability, and further enhancing the separation effect of the two phases.

[0057] According to a specific embodiment of the present application, the stationary phase of the medium-polarity capillary column is 5% phenyl-95% methyl polysiloxane.

[0058] According to a specific embodiment of the present application, the chromatographic column comprises at least one of DB-5HT 20 m x 0.18 mm x 0.18 μm and DB-5 30 m x 0.25 mm x 0.25 μm.

[0059] According to a specific embodiment of the present application, in the temperature programming of the chromatographic column, the temperature rising speed is 5-25 ℃ / min.

[0060] According to a specific embodiment of the present application, in the gas chromatographic analysis, split injection can be used, and the split injection ratio can be (5-20):1, or splitless injection can also be selected, and the subsequent analysis effect is not affected.

[0061] The scheme of the present application will be explained below in conjunction with examples. Those skilled in the art will understand that the following examples are only used to illustrate the present application, and should not be regarded as limiting the scope of the present application. If the specific technology or condition is not specified in the examples, the technology or condition described in the literature in the art or according to the product instruction is used. If the reagent or instrument is not specified by the manufacturer, it is a conventional product that can be obtained by market purchase.

[0062] Example 1

[0063] The present example provides a rapid detection method for free amine in fatty amide propyl dimethyl betaine, comprising the following steps:

[0064] (1) Reagent Preparation:

[0065] Standard Stock Solution: Prepare an ethyl acetate solution containing octanamidopropyl dimethyl tertiary amine 357 mg / L, decanamidopropyl dimethyl tertiary amine 311.5 mg / L, lauranamidopropyl dimethyl tertiary amine 2491 mg / L, myristanamidopropyl dimethyl tertiary amine 844.5 mg / L, palmitanamidopropyl dimethyl tertiary amine 437 mg / L, stearanamidopropyl dimethyl tertiary amine 500 mg / L;

[0066] Standard Solution 1 : Prepare an ethyl acetate solution containing octanamidopropyl dimethyl tertiary amine 3.57 mg / L, decanamidopropyl dimethyl tertiary amine 3.115 mg / L, lauranamidopropyl dimethyl tertiary amine 24.91 mg / L, myristanamidopropyl dimethyl tertiary amine 8.445 mg / L, palmitanamidopropyl dimethyl tertiary amine 4.37 mg / L, stearanamidopropyl dimethyl tertiary amine 5.00 mg / L;

[0067] Standard Solution 2: Prepare an ethyl acetate solution containing octanamidopropyl dimethyl tertiary amine 7.14 mg / L, decanamidopropyl dimethyl tertiary amine 6.23 mg / L, lauranamidopropyl dimethyl tertiary amine 49.82 mg / L, myristanamidopropyl dimethyl tertiary amine 16.89 mg / L, palmitanamidopropyl dimethyl tertiary amine 8.74 mg / L, stearanamidopropyl dimethyl tertiary amine 10.00 mg / L;

[0068] Standard Solution 3: Prepare an ethyl acetate solution containing octanamidopropyl dimethyl tertiary amine 17.85 mg / L, decanamidopropyl dimethyl tertiary amine 15.58 mg / L, lauranamidopropyl dimethyl tertiary amine 124.55 mg / L, myristanamidopropyl dimethyl tertiary amine 42.23 mg / L, palmitanamidopropyl dimethyl tertiary amine 21.86 mg / L, stearanamidopropyl dimethyl tertiary amine 25.00 mg / L;

[0069] Standard Solution 4: Prepare an ethyl acetate solution containing octanamidopropyl dimethyl tertiary amine 35.71 mg / L, decanamidopropyl dimethyl tertiary amine 31.16 mg / L, lauranamidopropyl dimethyl tertiary amine 249.10 mg / L, myristanamidopropyl dimethyl tertiary amine 84.47 mg / L, palmitanamidopropyl dimethyl tertiary amine 43.71 mg / L, stearanamidopropyl dimethyl tertiary amine 50.00 mg / L;

[0070] Standard solution 5: prepare an ethyl acetate solution containing octanamidopropyl dimethyl tertiary amine 71.41 mg / L, decanamidopropyl dimethyl tertiary amine 62.31 mg / L, lauranamidopropyl dimethyl tertiary amine 498.20 mg / L, myristanamidopropyl dimethyl tertiary amine 168.94 mg / L, palmitanamidopropyl dimethyl tertiary amine 87.42 mg / L, stearanamidopropyl dimethyl tertiary amine 100.00 mg / L;

[0071] Sodium chloride solution (5 mol / L NaCl): weigh 292 g of sodium chloride into a 2000 mL beaker, add 900 mL of water, stir to dissolve, and dilute to 1000 mL with water in a volumetric flask, and shake well;

[0072] Sodium hydroxide solution (400 g / L NaOH): weigh 400 g of sodium hydroxide into a 2000 mL beaker, add 900 mL of water, stir to dissolve, cool, and dilute to 1000 mL, and stir well.

[0073] (2) Preparation of the test solution:

[0074] Weigh 1.0 g of sample A (weigh to 0.0001 g) into a beaker, add 5 mL of sodium chloride solution, 1 mL of sodium hydroxide solution, add 5 mL of deionized water, transfer to a separatory funnel, and rinse the beaker with 10 mL of water, pour the rinse into the separatory funnel, and pour in 15 mL of ethyl acetate. Tighten the stopper and shake vigorously for at least 1 min (note to release pressure), allow to stand for a while to separate the layers, discard the lower aqueous phase, and pour the upper extract into a dry 25 mL volumetric flask (be careful not to let water droplets enter the volumetric flask), rinse the separatory funnel with a small amount of ethyl acetate, pour the rinse into the volumetric flask, dilute to the mark with ethyl acetate, and shake well for use.

[0075] (3) Gas chromatography test:

[0076] According to the following gas chromatography condition settings, equilibrate the chromatographic column, allow the gas chromatography system to obtain a stable baseline, inject for detection, record the chromatogram, and process the data with the chromatography workstation.

[0077] Chromatographic column: DB-5HT 20 m x 0.18 mm x 0.18 µm;

[0078] Injection port temperature: 300℃

[0079] Detector temperature: 330℃

[0080] Column oven program:

[0081]

[0082] Injection volume: 1.0 µL;

[0083] Split ratio: 5:1;

[0084] Column flow rate: 0.6 mL / min;

[0085] Carrier gas: N2;

[0086] Needle washing solvent: acetone.

[0087] The standard curve was obtained by gas chromatography analysis of the standard solution: octanamide propyl dimethyl tertiary amine y = 2.9384x-0.5874, decanamide propyl dimethyl tertiary amine y = 2.8995x-0.4024, lauramide propyl dimethyl tertiary amine y = 2.9908x-4.004, myristamide propyl dimethyl tertiary amine y = 2.9935x-2.1766, palmitamide propyl dimethyl tertiary amine y = 3.0042x-1.8535, stearamide propyl dimethyl tertiary amine y = 3.0176x-6.5869, and the linear relationship of each standard curve was >0.999.

[0088] Free amine residue calculation: the free amine residue in the sample was calculated by the standard curve and the detection results of the test solution. The gas chromatogram of sample A is shown in Figure 1 .

[0089] Repeatability verification: the test solution was detected by sampling 7 times respectively, and the standard deviation (SD) and relative standard deviation (RSD) were calculated.

[0090] Accuracy verification: the accuracy of the method was verified by the recovery rate index.

[0091] The repeatability data of the free amine residue in the same batch of fatty amide propyl dimethyl betaine were measured and shown in Table 1-2. Among them, C8-PKO is octanamide propyl dimethyl tertiary amine, C10-PKO is decanamide propyl dimethyl tertiary amine, C12-PKO is lauramide propyl dimethyl tertiary amine, C14-PKO is myristamide propyl dimethyl tertiary amine, C16-PKO is palmitamide propyl dimethyl tertiary amine, and C18-PKO is stearamide propyl dimethyl tertiary amine.

[0092] Table 1

[0093]

[0094] Table 2

[0095]

[0096] Example 2

[0097] The present embodiment provides a rapid detection method for free amine in fatty amide propyl dimethyl betaine, comprising the following steps:

[0098] (1) Reagent preparation:

[0099] Standard stock solution: Prepare an ethyl acetate solution containing octanamidopropyl dimethyl tertiary amine 357 mg / L, decanamidopropyl dimethyl tertiary amine 311.5 mg / L, lauranamidopropyl dimethyl tertiary amine 2491 mg / L, myristanamidopropyl dimethyl tertiary amine 844.5 mg / L, palmitanamidopropyl dimethyl tertiary amine 437 mg / L, stearanamidopropyl dimethyl tertiary amine 500 mg / L;

[0100] Standard solution 1 : Prepare an ethyl acetate solution containing octanamidopropyl dimethyl tertiary amine 3.57 mg / L, decanamidopropyl dimethyl tertiary amine 3.115 mg / L, lauranamidopropyl dimethyl tertiary amine 24.91 mg / L, myristanamidopropyl dimethyl tertiary amine 8.445 mg / L, palmitanamidopropyl dimethyl tertiary amine 4.37 mg / L, stearanamidopropyl dimethyl tertiary amine 5.00 mg / L;

[0101] Standard solution 2: Prepare an ethyl acetate solution containing octanamidopropyl dimethyl tertiary amine 7.14 mg / L, decanamidopropyl dimethyl tertiary amine 6.23 mg / L, lauranamidopropyl dimethyl tertiary amine 49.82 mg / L, myristanamidopropyl dimethyl tertiary amine 16.89 mg / L, palmitanamidopropyl dimethyl tertiary amine 8.74 mg / L, stearanamidopropyl dimethyl tertiary amine 10.00 mg / L;

[0102] Standard solution 3: Prepare an ethyl acetate solution containing octanamidopropyl dimethyl tertiary amine 17.85 mg / L, decanamidopropyl dimethyl tertiary amine 15.58 mg / L, lauranamidopropyl dimethyl tertiary amine 124.55 mg / L, myristanamidopropyl dimethyl tertiary amine 42.23 mg / L, palmitanamidopropyl dimethyl tertiary amine 21.86 mg / L, stearanamidopropyl dimethyl tertiary amine 25.00 mg / L;

[0103] Standard solution 4: Prepare an ethyl acetate solution containing octanamidopropyl dimethyl tertiary amine 35.71 mg / L, decanamidopropyl dimethyl tertiary amine 31.16 mg / L, lauranamidopropyl dimethyl tertiary amine 249.10 mg / L, myristanamidopropyl dimethyl tertiary amine 84.47 mg / L, palmitanamidopropyl dimethyl tertiary amine 43.71 mg / L, stearanamidopropyl dimethyl tertiary amine 50.00 mg / L;

[0104] Standard solution 5: prepare an ethyl acetate solution containing octanamidopropyl dimethyl tertiary amine 71.41 mg / L, decanamidopropyl dimethyl tertiary amine 62.31 mg / L, lauranamidopropyl dimethyl tertiary amine 498.20 mg / L, myristanamidopropyl dimethyl tertiary amine 168.94 mg / L, palmitanamidopropyl dimethyl tertiary amine 87.42 mg / L, stearanamidopropyl dimethyl tertiary amine 100.00 mg / L;

[0105] Sodium chloride solution (5 mol / L NaCl): weigh 292 g of sodium chloride into a 2000 mL beaker, add 900 mL of water, stir to dissolve, and dilute to 1000 mL with water in a volumetric flask, and shake well;

[0106] Sodium hydroxide solution (400 g / L NaOH): weigh 400 g of sodium hydroxide into a 2000 mL beaker, add 900 mL of water, stir to dissolve, cool, and dilute to 1000 mL, and stir well.

[0107] (2) Preparation of the test solution:

[0108] Weigh 1.0 g of sample B (weigh to 0.0001 g) into a beaker, add 5 mL of sodium chloride solution, 1 mL of sodium hydroxide solution, add 5 mL of deionized water, transfer to a separatory funnel, and rinse the beaker with 10 mL of water, pour the rinse into the separatory funnel, and pour in 15 mL of ethyl acetate. Tighten the stopper and shake vigorously for at least 1 min (note to release pressure), allow to stand for a while to separate the layers, discard the lower aqueous phase, and pour the upper extract into a dry 25 mL volumetric flask (be careful not to let water droplets enter the volumetric flask), rinse the separatory funnel with a small amount of ethyl acetate, pour the rinse into the volumetric flask, dilute to the mark with ethyl acetate, and shake well for use.

[0109] (3) Gas chromatography test:

[0110] According to the following gas chromatography condition settings, equilibrate the chromatographic column, allow the gas chromatography system to obtain a stable baseline, inject for detection, record the chromatogram, and process the data with the chromatographic workstation.

[0111] Chromatographic column: DB-5HT 20 m x 0.18 mm x 0.18 µm;

[0112] Injection port temperature: 300℃

[0113] Detector temperature: 330℃

[0114] Column oven program:

[0115]

[0116] Injection volume: 1.0 µL;

[0117] Split ratio: 5:1;

[0118] Column flow rate: 0.6 mL / min;

[0119] Carrier gas: N2;

[0120] Needle washing solvent: acetone.

[0121] Obtain the standard curve by gas chromatography analysis of the standard solution.

[0122] Calculate the free amine residue in the sample by the standard curve and the detection results of the test solution.

[0123] Repeatability verification: sample detection of the test solution for 7 times respectively, calculate the standard deviation (SD) and relative standard deviation (RSD).

[0124] Accuracy verification: use the recovery rate index to test the accuracy of the method.

[0125] The repeatability data of free amine residue in the same batch of fatty amide propyl dimethyl betaine is shown in Table 3-4.

[0126] Table 3

[0127]

[0128] Table 4

[0129]

[0130] Example 3

[0131] The present embodiment provides a rapid detection method of free amine in fatty amide propyl dimethyl betaine, comprising the following steps:

[0132] (1) Reagent preparation:

[0133] Standard stock solution: prepare an ethyl acetate solution containing octanamide propyl dimethyl tertiary amine 357 mg / L, decanamide propyl dimethyl tertiary amine 311.5 mg / L, lauramide propyl dimethyl tertiary amine 2491 mg / L, myristamide propyl dimethyl tertiary amine 844.5 mg / L, palmitamide propyl dimethyl tertiary amine 437 mg / L, and stearamide propyl dimethyl tertiary amine 500 mg / L;

[0134] Standard solution 1: prepare an ethyl acetate solution containing octanamide propyl dimethyl tertiary amine 3.57 mg / L, decanamide propyl dimethyl tertiary amine 3.115 mg / L, lauramide propyl dimethyl tertiary amine 24.91 mg / L, myristamide propyl dimethyl tertiary amine 8.445 mg / L, palmitamide propyl dimethyl tertiary amine 4.37 mg / L, and stearamide propyl dimethyl tertiary amine 5.00 mg / L;

[0135] Standard solution 2: prepare an ethyl acetate solution containing octanamidopropyl dimethyl tertiary amine 7.14 mg / L, decanamidopropyl dimethyl tertiary amine 6.23 mg / L, lauranamidopropyl dimethyl tertiary amine 49.82 mg / L, myristanamidopropyl dimethyl tertiary amine 16.89 mg / L, palmitanamidopropyl dimethyl tertiary amine 8.74 mg / L, stearanamidopropyl dimethyl tertiary amine 10.00 mg / L;

[0136] Standard solution 3: prepare an ethyl acetate solution containing octanamidopropyl dimethyl tertiary amine 17.85 mg / L, decanamidopropyl dimethyl tertiary amine 15.58 mg / L, lauranamidopropyl dimethyl tertiary amine 124.55 mg / L, myristanamidopropyl dimethyl tertiary amine 42.23 mg / L, palmitanamidopropyl dimethyl tertiary amine 21.86 mg / L, stearanamidopropyl dimethyl tertiary amine 25.00 mg / L;

[0137] Standard solution 4: prepare an ethyl acetate solution containing octanamidopropyl dimethyl tertiary amine 35.71 mg / L, decanamidopropyl dimethyl tertiary amine 31.16 mg / L, lauranamidopropyl dimethyl tertiary amine 249.10 mg / L, myristanamidopropyl dimethyl tertiary amine 84.47 mg / L, palmitanamidopropyl dimethyl tertiary amine 43.71 mg / L, stearanamidopropyl dimethyl tertiary amine 50.00 mg / L;

[0138] Standard solution 5: prepare an ethyl acetate solution containing octanamidopropyl dimethyl tertiary amine 71.41 mg / L, decanamidopropyl dimethyl tertiary amine 62.31 mg / L, lauranamidopropyl dimethyl tertiary amine 498.20 mg / L, myristanamidopropyl dimethyl tertiary amine 168.94 mg / L, palmitanamidopropyl dimethyl tertiary amine 87.42 mg / L, stearanamidopropyl dimethyl tertiary amine 100.00 mg / L;

[0139] Sodium chloride solution (5 mol / L NaCl): weigh 292 g of sodium chloride into a 2000 mL beaker, add 900 mL of water, stir to dissolve, and dilute to 1000 mL with water, and shake well;

[0140] Sodium hydroxide solution (400 g / L NaOH): weigh 400 g of sodium hydroxide into a 2000 mL beaker, add 900 mL of water, stir to dissolve, cool, and dilute to 1000 mL, and stir well.

[0141] (2) Preparation of the test solution:

[0142] Take sample C 1.0 g (weigh to 0.0001 g) in a beaker, add 5 mL of sodium chloride solution, 1 mL of sodium hydroxide solution, add 5 mL of deionized water, transfer to a separatory funnel, and rinse the beaker with 10 mL of water, and pour the rinse into the separatory funnel, and remove 15 mL of ethyl acetate. Plug the stopper and shake vigorously for at least 1 min (note to relieve pressure), allow to stand until the layers are completely separated, and discard the lower aqueous phase, and pour the upper extract into a dry 25 mL volumetric flask (be careful to prevent water droplets from entering the flask), and rinse the separatory funnel with a small amount of ethyl acetate, and pour the rinse into the volumetric flask, and dilute to the mark with ethyl acetate, and shake well for use.

[0143] (3) Gas chromatography test:

[0144] According to the following gas chromatography condition setting, equilibrate the chromatographic column, and after the gas chromatography system obtains a stable baseline, inject and detect, record the chromatogram, and process the data by the chromatographic workstation.

[0145] Chromatographic column: DB-5 30 m x 0.25 mm x 0.25 µm;

[0146] Injection port temperature: 300℃

[0147] Detector temperature: 330℃

[0148] Column oven program:

[0149]

[0150] Injection volume: 1.0 µL;

[0151] Split ratio: 5:1;

[0152] Column flow rate: 0.6 mL / min;

[0153] Carrier gas: N2;

[0154] Needle washing solvent: acetone.

[0155] By gas chromatography analysis of the standard solution, a standard curve is obtained.

[0156] Free amine residue calculation: the free amine residue in the sample is calculated by the standard curve and the detection results of the test solution.

[0157] Repeatability verification: the test solution is sampled and detected for 7 times respectively, and the standard deviation (SD) and relative standard deviation (RSD) are calculated.

[0158] Accuracy verification: the recovery rate index is used to verify the accuracy of the method.

[0159] The repeatability data of the free amine residue in the same batch of fatty amido propyl dimethyl betaine is shown in Tables 5-6.

[0160] Table 5

[0161]

[0162] Table 6

[0163]

[0164] Example 4

[0165] The embodiment provides a rapid detection method of free amine in fatty amido propyl dimethyl betaine, which is only different from the embodiment 1 in that the sample A is replaced by sample D, the carrier gas is hydrogen, and the repeatability data of the free amine residue in the same batch of fatty amido propyl dimethyl betaine is shown in Tables 7-8.

[0166] Table 7

[0167]

[0168] Table 8

[0169]

[0170] Example 5

[0171] The embodiment provides a rapid detection method of free amine in fatty amido propyl dimethyl betaine, which is only different from the embodiment 1 in that the sample A is replaced by sample E, the carrier gas is helium, and the repeatability data of the free amine residue in the same batch of fatty amido propyl dimethyl betaine is shown in Tables 9-10.

[0172] Table 9

[0173]

[0174] Table 10

[0175]

[0176] Example 6

[0177] The embodiment provides a rapid detection method of free amine in fatty amido propyl dimethyl betaine, which is only different from the embodiment 1 in that the sample A is replaced by sample F, the column flow is 0.4 mL / min, and the repeatability data of the free amine residue in the same batch of fatty amido propyl dimethyl betaine is shown in Tables 11-12.

[0178] Table 11

[0179]

[0180] Table 12

[0181]

[0182] Example 7

[0183] This example provides a rapid detection method for free amine in fatty amide propyl dimethyl betaine, which is only different from Example 1 in that sample A is replaced by sample G, and the column flow rate is 1.2 mL / min. The repeatability data of free amine residue in the same batch of fatty amide propyl dimethyl betaine are shown in Tables 13-14.

[0184] Table 13

[0185]

[0186] Table 14

[0187]

[0188] Example 8

[0189] This example provides a rapid detection method for free amine in fatty amide propyl dimethyl betaine, which is only different from Example 1 in that sample A is replaced by sample H, and the column flow rate is 1.5 mL / min. The repeatability data of free amine residue in the same batch of fatty amide propyl dimethyl betaine are shown in Tables 15-16.

[0190] Table 15

[0191]

[0192] Table 16

[0193]

[0194] Example 9

[0195] This example provides a rapid detection method for free amine in fatty amide propyl dimethyl betaine, which is only different from Example 1 in that sample A is replaced by sample I, and the column oven program is:

[0196]

[0197] The repeatability data of free amine residue in the same batch of fatty amide propyl dimethyl betaine are shown in Tables 17-18.

[0198] Table 17

[0199]

[0200] Table 18

[0201]

[0202] Example 10

[0203] The present example provides a method for rapid detection of free amine in fatty amido propyl dimethyl betaine, which is only different from Example 1 in that sample A is replaced by sample J, and the column oven program is as follows:

[0204]

[0205] The repeatability data of free amine residue in the same batch of fatty amido propyl dimethyl betaine are shown in Tables 19-20.

[0206] Table 19

[0207]

[0208] Table 20

[0209]

[0210] Example 11

[0211] According to the standard curve y = 2.9384x - 0.5874 corresponding to the octanamide propyl dimethyl tertiary amine detected in Example 1, the detection limit is determined by using the noise method, and the concentration corresponding to the detection limit of three times the noise is 0.0008%.

[0212] Comparative Example 1

[0213] The difference between this comparative example and Example 1 is that:

[0214] Step (2): Preparation of the test solution:

[0215] 1.0 g of sample A (weighed to 0.0001 g) was taken in a beaker, 5 mL of sodium chloride solution, 1 mL of sodium hydroxide solution was added, stirred and dissolved, and diluted with water to 25 mL in a volumetric flask. Since the main components in the sample include fatty amido propyl dimethyl betaine, residual free amine, free fatty acid, chloroacetic acid and its by-products, the composition is complex, chromatographic separation is difficult, and the addition of sodium chloride and sodium hydroxide in the test solution also has certain influence on chromatographic test, so the content of free amine in fatty amido propyl dimethyl betaine cannot be determined.

[0216] Comparative Example 2

[0217] This comparative example uses the standard method for detecting free amine in fatty amido propyl dimethyl betaine in "Fatty Amido Propyl Dimethyl Betaine" QB / T 4082-2010 5.3, which is as follows:

[0218] Take sample J 10g-15g (accurately to 0.001g) in a beaker, add 10 mL water, 15 mL sodium chloride solution and 2 drops of phenolphthalein indicator, shake well, then neutralize with sodium hydroxide solution until the solution is pink, then add 1 mL of sodium hydroxide solution in excess. Place the beaker in a water bath and heat to 35-40°C, stir well to make it fully react, then transfer to a separatory funnel, and rinse the beaker with 20 mL of water, 30 mL of rinsing liquid into the separatory funnel. Plug in the plug and shake vigorously for at least 1 min, after fully standing and separating, the lower water phase is put into another separatory funnel, and 30 mL of ether-n-butanol mixed solution (volume ratio 2:1) is added, and the extraction is repeated twice, the upper liquid of three times extraction is collected and put into the same separatory funnel, after standing for 30 min, the lower water phase is discarded, and the upper extraction liquid is poured into a dry volumetric flask (note to prevent water droplets from entering the volumetric flask), at the same time, a small amount of ether is used to rinse the separatory funnel, and the rinsing liquid is added to the volumetric flask, and the volume is set to the scale with ether, shake well for standby. Take 20.0 mL of the above extraction liquid with a pipette into a 250 mL beaker, heat to drive off the solvent on a water bath, and blow dry with nitrogen or compressed air. Add 5 mL of anhydrous ethanol to the residue, heat and blow dry again. Add 100 mL of ethanol aqueous solution to the beaker and stir on an electromagnetic stirrer, then titrate with hydrochloric acid standard titration solution (hydrochloric acid concentration is 0.05 mol / L) to draw the titration curve. The maximum jump point of the potential value between pH 6-7 is the titration end point. Record the volume of hydrochloric acid standard titration solution consumed. At the same time, a blank test is carried out, and the volume of hydrochloric acid standard titration solution consumed is recorded.

[0219] This method can only detect the total free amine content in fatty amide propyl dimethyl betaine, and cannot distinguish the specific free amine type. The repeatability data of free amine residue in the same batch of fatty amide propyl dimethyl betaine is shown in Tables 21-22.

[0220] Table 21

[0221]

[0222] Table 22

[0223]

[0224] In the description of the specification, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are contained in at least one embodiment or example of the present application. In the specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any suitable manner in any one or more embodiments or examples. In addition, the person skilled in the art can combine and combine the different embodiments or examples described in the specification and the features of the different embodiments or examples without contradiction.

[0225] Although the embodiments of the present application have been shown and described above, it is understood that the above-described embodiments are exemplary and are not to be construed as limiting the present application, and those skilled in the art can make changes, modifications, replacements and variations to the above-described embodiments within the scope of the present application.

Claims

1. A method for the detection of free amine content in fatty acyl amido propyl dimethyl betaine, characterized by, The method comprises the following steps: extracting free amine in fatty amide propyl dimethyl betaine using ethyl acetate, and obtaining an oil phase as a to-be-tested solution; performing gas chromatography analysis on the to-be-tested solution, and measuring the content of free amine in the to-be-tested solution; dissolving the free amine in ethyl acetate to prepare free amine standard solutions with different concentrations; extracting free amine in fatty amide propyl dimethyl betaine using ethyl acetate, and obtaining an oil phase as a to-be-tested solution; performing gas chromatography analysis on the free amine standard solutions with different concentrations, and obtaining a standard curve according to the test results; performing gas chromatography analysis on the to-be-tested solution, and obtaining the content of free amine in fatty amide propyl dimethyl betaine according to the test results and the standard curve; The gas chromatography analysis conditions are as follows: The chromatographic column is a medium-polarity capillary chromatographic column; The injection port temperature is 200-350 DEG C; The detector temperature is 280-330 DEG C; The chromatographic column is programmed to have an initial temperature of 150-250 DEG C, a holding time of 0-5 min, a temperature rise to 280-350 DEG C, and a holding time of 1-30 min; The injection volume is 0.1-2 mu L; The column flow rate is 0.4-1.5 mL / min; The carrier gas is nitrogen, hydrogen or helium; The mass-volume ratio of the fatty amide propyl dimethyl betaine to ethyl acetate is (0.01-0.5) g:1 mL; In the chromatographic column programming, the temperature rise rate is 5-25 DEG C / min; 2. The detection method according to claim 1, characterized in that, The free amine includes at least one of C8-C 18 at least one of a fatty amide propyl dimethyl tertiary amine.

3. The method of claim 1, wherein, In the gas chromatography analysis conditions, the injection split ratio is (5-20):

1.

4. The method of claim 1, wherein, The free amine includes at least one of octanamide propyl dimethyl tertiary amine, decanamide propyl dimethyl tertiary amine, lauramide propyl dimethyl tertiary amine, myristamide propyl dimethyl tertiary amine, palmitamide propyl dimethyl tertiary amine and stearic amide propyl dimethyl tertiary amine.

5. The method of claim 1, wherein The detection method further comprises mixing the fatty amide propyl dimethyl betaine with a sodium chloride solution and a sodium hydroxide solution, mixing the obtained mixed solution with ethyl acetate, and performing extraction treatment.

6. The detection method according to claim 1, characterized in that, The stationary phase of the medium-polarity capillary chromatographic column is 5% phenyl-95% methyl polysiloxane. The chromatographic column includes at least one of DB-5HT 20m*0.18mm*0.18mu m and DB-5 30m*0.25mm*0.25mu m.

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