CN-121978235-A - AEC identification method prepared by oxidation method and carboxymethylation method

Abstract

The invention belongs to the technical field of chemical analysis and detection, and particularly relates to a method for distinguishing fatty alcohol-polyoxyethylene ether carboxylic acid prepared by an oxidation method from fatty alcohol-polyoxyethylene ether carboxylic acid prepared by a carboxymethylation method. The principle is that the impurities remained in fatty alcohol polyoxyethylene ether carboxylic acid products prepared by two methods are different, and the content of monochloroacetic acid and chloride ion impurities is measured by an ion chromatography method to identify. The method provided by the invention is simple and convenient to operate, high in accuracy and precision and good in repeatability, and provides reliable technical support for quality control and application and popularization of fatty alcohol-polyoxyethylene ether carboxylic acid products.

Inventors

• ZHANG JUN
• WANG JIANWEI
• TIAN XIN
• WANG TIANZHUANG
• LI GUOJIN

Assignees

• 中国日用化学研究院有限公司

Dates

Publication Date

20260505

Application Date

20260120

Claims (4)

1. 1. The AEC identification method prepared by an oxidation method and a carboxymethylation method is characterized by comprising the following steps: (1) Preparing a sample solution, namely accurately weighing a proper amount of AEC, adding ultrapure water, and performing ultrasonic treatment to prepare the sample solution with the concentration of 10-50 mg/mL; (2) Sample solution treatment, namely, the sample solution in the step (1) is subjected to activated and balanced treatment to obtain a C18 solid phase extraction column, effluent and leacheate are collected, then the effluent and the leacheate are uniformly mixed, and the mixture is filtered through a 0.22-micrometer organic microporous filter membrane, wherein the filtrate is used as the sample solution to be detected; (3) Establishing a standard curve, namely respectively taking monochloroacetic acid and sodium chloride, adding ultrapure water to prepare a reference stock solution, preparing a series of standard solutions with mass concentrations of monochloroacetic acid and chloride ions of 1-50 mu g/mL, measuring by an ion chromatograph, and drawing the standard curve; (4) Detecting a sample solution, namely detecting the sample solution to be detected obtained in the step (2) by adopting the same ion chromatographic parameter as that in the step (3), and quantitatively obtaining the content of monochloroacetic acid and chloride ions in the sample, thereby distinguishing fatty alcohol polyoxyethylene ether carboxylic acid products prepared by different processes; the parameters of the ion chromatograph are set as follows: an anion guard column SH-GP-2; an anion analysis column SH-AP-1; 4-6 mmol/L potassium hydroxide solution; The flow rate of the eluent is 0.6-0.8 mL/min; Isocratic elution; the temperature of the chromatographic column is 35-40 ℃; the temperature of the conductivity cell is 35-40 ℃; the voltage of the suppressor is 10-12V; Column pressure is 15-20 MPa; the sample injection amount is 25-50 mu L; The detection time is 20-30 min.
2. 2. The method for distinguishing AEC prepared by an oxidation method and a carboxymethylation method according to claim 1, wherein in the step (2), a sample solution is passed through the activated and equilibrated C18 solid-phase extraction column at a flow rate of 0.8-1.0 mL/min to obtain an effluent, and after the sample solution completely passes through the C18 solid-phase extraction column, the C18 solid-phase extraction column is rinsed with a methanol-water solution with a volume fraction of 50% to obtain a eluent.
3. 3. The method for distinguishing AEC according to claim 1, wherein the concentrations of the monochloroacetic acid series standard solutions in step (3) are 1. Mu.g/mL, 5. Mu.g/mL, 10. Mu.g/mL, 25. Mu.g/mL, and 50. Mu.g/mL, respectively, the concentrations of the sodium chloride series standard solutions are 1. Mu.g/mL, 5. Mu.g/mL, 10. Mu.g/mL, 25. Mu.g/mL, and 50. Mu.g/mL, respectively, and the monochloroacetic acid series standard solutions and the sodium chloride series standard solutions are prepared on-the-fly.
4. 4. The method for identifying AEC prepared by an oxidation method and a carboxymethylation method according to any one of claims 1 to 3, wherein the structural general formula of the AEC is RO (CH 2 CH 2 O) n CH 2 COOH; wherein R represents a linear or branched alkyl group of C 8 ~C 18 , and n ranges from 1 to 30.

Description

AEC identification method prepared by oxidation method and carboxymethylation method Technical Field The invention belongs to the technical field of chemical analysis, and particularly relates to an ion chromatographic analysis method for distinguishing fatty alcohol-polyoxyethylene ether carboxylic acid by an oxidation method from fatty alcohol-polyoxyethylene ether carboxylic acid by a carboxymethylation method. Background Fatty alcohol polyoxyethylene ether carboxylic Acid (AEC) is used as a green anionic surfactant with excellent performance, has the mildness of a nonionic surfactant and the high surface activity of an anionic surfactant, has the core advantages of good biodegradability, low toxicity, wide pH application range, strong hard water resistance and the like, and has been widely applied to the fields of daily cosmetics, medical auxiliary materials, electronic equipment cleaning and the like. At present, the process for industrially preparing AEC is mainly divided into an oxidation method and a carboxymethylation method, and the two methods have obvious differences in raw material selection, product residue characteristics, safety and application scene suitability. The carboxymethylation method takes monochloroacetic acid or sodium monochloroacetate as a carboxymethylation reagent, has the advantages of mature process, low production cost and easy mass production, but inevitably generates impurity residues in the reaction process, in particular to chlorine ions formed by dissociating incompletely converted monochloroacetic acid raw materials and sodium chloride serving as a reaction byproduct, wherein the monochloroacetic acid has extremely strong toxicity, irritation and corrosiveness, can cause acute injury of skin or mucous membrane when contacting a human body, has potential cancerogenic risks after long-term contact, shortens the service life of medical equipment and electronic equipment and reduces the operation stability and the use efficiency of the medical equipment and electronic equipment when the chlorine ions are too high in residual quantity, and therefore AEC prepared by the process has certain limitations. The oxidation method takes fatty alcohol polyoxyethylene ether as an initial raw material, and prepares AEC through noble metal catalytic oxidation reaction, chlorine-containing reagents are not needed in the preparation process, the obtained product does not contain monochloroacetic acid and chloride ion residues, the purity is obviously superior to that of products of a carboxymethylation method, and the requirements of daily cosmetics, medical auxiliary materials, electronic industry cleaning and other scenes with high safety requirements can be met. At present, the common detection method related to AEC adopts high performance liquid chromatography, gas chromatography and liquid chromatography-mass spectrometry to separate and identify the homologs (such as components with different carbon chain lengths) of fatty alcohol polyoxyethylene ether carboxylic acid, and the main components and impurities are quantified by comparing standard substances. For example, high performance liquid chromatography uses a C18 reverse phase column with a mobile phase that is eluted with a methanol-water gradient and detected by an evaporative light scattering detector. However, the existing detection method has the defects that AEC products prepared by two methods of an oxidation method and a carboxymethylation method cannot be distinguished, the problems of insufficient sensitivity, low response strength, poor separation effect, poor accuracy and precision, easiness in interference of fatty alcohol polyoxyethylene ether and polyethylene glycol derivatives in AEC and the like exist in detection of impurities in AEC, the applicability of AEC to different product types is obviously limited, and the experimental reagent consumption is more, so that the detection requirement of batch samples in an industrial production scene is difficult to meet. Disclosure of Invention The invention aims to overcome the defects in the prior art and provide an ion chromatographic analysis method for distinguishing an oxidation method AEC from a carboxymethylation method AEC. The method has the advantages of high accuracy, good precision, less reagent consumption and low cost. According to the ion chromatography analysis method for distinguishing the oxidative AEC from the carboxymethylation AEC, whether the AEC product is the oxidative AEC or the carboxymethylation AEC can be distinguished by detecting whether monochloroacetic acid and chloride ions are contained in the AEC sample. The method specifically comprises the following steps: the invention adopts the following technical scheme to realize the aim: the AEC identification method prepared by an oxidation method and a carboxymethylation method is characterized by comprising the following steps: (1) Preparing a sample solution, namely accurately weighing a p