Method for detecting and separating quaternary ammonium salt surfactant in total synthesis metal working fluid product

Abstract

The invention discloses a method for detecting and separating a quaternary ammonium salt surfactant in a fully-synthesized metal working fluid product. The method comprises the following steps: activating a weak cation column filler by using an activating solution, and meanwhile, ensuring that a solvent always exists in a chromatographic column before loading a sample; weighing a total synthesis product containing a quaternary ammonium salt surfactant, putting the total synthesis product into a beaker, and then diluting the total synthesis product by using a solvent of an activation column filler; the sample solution is loaded onto the activated column, and the sample is sucked through the column. The column is cleaned with an impurity cleaning solution so as to remove most of acids, alkalis and other impurities, and only quaternary ammonium salt is retained in the chromatographic column; continuously cleaning the chromatographic column by using a nonionic cleaning solution so as to remove the nonionic organic compound retained in the chromatographic column; under a full vacuum condition, drying the chromatographic column for a preset time length; and eluting the quaternary ammonium salt surfactant by using the eluent, and collecting the eluent.

Description

Technical Field

[0001] The invention relates to a method for detecting a metal surfactant, in particular to a method for detecting and separating a quaternary ammonium salt surfactant in a fully synthetic metalworking fluid product. Background Art

[0002] Quaternary ammonium salts are also called quaternary ammonium salts. They are compounds formed by replacing the four hydrogen atoms in the ammonium ion with hydrocarbon groups. + X - , the structural formula is:

[0003]

[0004] The four hydrocarbon groups R can be the same or different, and X is usually a halogen anion (F-, C1-, Br - , I-), or acid radical (HSO 4- , RCOO-, etc.), the properties of quaternary ammonium salts are similar to those of inorganic ammonium salts, they are easily soluble in water, and their aqueous solutions are conductive. In addition to the general properties of surfactants, quaternary ammonium salt surfactants also have some unique properties due to their special structure.

[0005] First, it has excellent bactericidal properties. The aqueous solution of quaternary ammonium surfactant has strong bactericidal ability, and its bactericidal performance depends on its permeability to cells and its ability to precipitate proteins. Therefore, it is widely used in the fields of sterilization, disinfection, mildew prevention, algae removal, etc. Typical bactericides include dodecyl dimethyl benzyl ammonium chloride, dodecyl dimethyl benzyl ammonium bromide, octadecyl dimethyl benzyl ammonium chloride and the new Gemini diquaternary ammonium salt.

[0006] Secondly, it has adsorption on solid surfaces. In nature, the surfaces of some solids such as fibers, metals and their oxides, plastics, silicates, and biological cell tissues are usually positively charged. Because the hydrophilic groups in the quaternary ammonium surfactant molecules are positively charged, the hydrophilic groups can form a tight monomolecular adsorption layer with them. Many application characteristics of quaternary ammonium surfactants are based on this adsorption layer, such as being added to fully synthetic metalworking fluid products as an anti-trash oil additive.

[0007] Quaternary ammonium salts are often added to fully synthetic metalworking fluid products as anti-trash oil additives and fungicides. However, such raw materials may be consumed, leaked or degraded during on-site use, thus affecting the use of the product on-site.

[0008] The common method for detecting quaternary ammonium salts in fully synthetic metalworking fluids is to use titration or ion chromatography to detect the halogen cluster or ion content in the product. However, due to the presence of various unknown external contaminations on site, the detection method of halogen cluster or ion content is not feasible. With the development of more modern separation technologies and analytical instruments, laboratories have also used advanced analytical instruments and separation methods to develop quantitative and qualitative analysis of quaternary ammonium surfactants in fully synthetic metalworking fluid products. Specific literature references are as follows: Research Progress on Pretreatment of Quaternary Ammonium Pesticide Residues Detection; Materials Guide, April 2014, Zhang Qingqing et al.; Determination of 7 Quaternary Ammonium Salts in Disinfectants by High Performance Liquid Chromatography; Analytical Instruments, Issue 4, 2021, Shanghai Quality Supervision and Inspection Technology Research Institute.

[0009] However, the detection methods in the prior art cannot detect the types of quaternary ammonium surfactants and the contents of various quaternary ammonium surfactants in the fully synthetic metalworking fluid products. At the same time, it is also impossible to accurately separate the quaternary ammonium surfactants in the fully synthetic metalworking fluid products. Summary of the invention

[0010] In order to solve the above technical problems and enable the present invention to accurately separate the quaternary ammonium salt surfactant in the fully synthetic metalworking fluid product, a method for separating the quaternary ammonium salt surfactant in the fully synthetic metalworking fluid product is provided, wherein the method comprises:

[0011] Step S1001, using an activation solution to activate the weak cation column filler, and at the same time, before loading the sample, ensuring that there is always solvent in the chromatographic column;

[0012] Step S1002, weighing a fully synthesized product containing a quaternary ammonium salt surfactant into a beaker, and then diluting it with a solvent of a chromatographic column filler to form a sample solution;

[0013] Step S1003, loading the sample solution onto the activated chromatographic column, and aspirating the sample through the chromatographic column;

[0014] Step S1004, cleaning the chromatographic column with an impurity cleaning solution to remove acid, alkali and some other impurities, and retain the quaternary ammonium salt in the chromatographic column;

[0015] Step S1005, continue to clean the chromatographic column with a non-ionic cleaning solution to remove the non-ionic organic compounds retained in the chromatographic column;

[0016] Step S1006, drying the chromatographic column for a predetermined time under vacuum conditions;

[0017] Step S1007, eluting the quaternary ammonium salt surfactant with a de-eluting solution, and collecting the eluent to obtain the separated quaternary ammonium salt surfactant.

[0018] According to an embodiment of the present invention, the method for separating quaternary ammonium salt surfactants in the fully synthetic metalworking fluid product satisfies at least one of the following conditions:

[0019] In step S1001, 2 g / 12 mL weak cation column packing is activated using 1 column volume of methanol and 2 column volumes of 75 / 25 water / methanol, pH 11;

[0020] In step S1002, the ratio between the total synthesis product and the solvent of the chromatographic column filler is: (1:8) to (1.5:8);

[0021] In step S1003, the sample is drawn into the chromatographic column at a flow rate of about 1-2 ml / min;

[0022] In step S1004, the chromatographic column is washed with 2 column volumes of 75 / 25 water / methanol, pH 11;

[0023] In step S1005, the chromatographic column is continuously cleaned with one column volume of 100% methanol;

[0024] In step S1006, 2 column volumes of 70 / 30 (200 mM ammonium acetate containing 10% acetic acid / methanol, pH adjusted to <3 with acetic acid, are used to elute the quaternary ammonium surfactant.

[0025] According to an embodiment of the present invention, the chromatographic column is a WCX column.

[0026] According to one embodiment of the present invention, the sample solution is loaded into the activated chromatographic column in a drip-flow manner.

[0027] According to another aspect of the present invention, the present invention provides a method for detecting quaternary ammonium salt surfactants in a fully synthetic metalworking fluid product, comprising any of the steps described above, and

[0028] Step S1008, quantitatively transferring the eluent into a volumetric flask filled with deionized water;

[0029] Step S1009, analyzing the eluate quantitatively transferred to the volumetric flask by HPLC, determining the type of the unknown quaternary ammonium salt surfactant by retention time, and determining the content of the unknown quaternary ammonium salt surfactant by using an external standard method. DETAILED DESCRIPTION

[0030] The following description is used to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are only examples, and those skilled in the art can think of other obvious variations. The basic principles of the present invention defined in the following description can be applied to other embodiments, variations, improvements, equivalents, and other technical solutions that do not deviate from the spirit and scope of the present invention.

[0031] According to a preferred embodiment of the present invention, a method for detecting quaternary ammonium salt surfactant in a fully synthetic metalworking fluid product comprises:

[0032] Step S1, using 1 column volume of methanol and 2 column volumes of 75 / 25 (water / methanol, pH 11) to activate 2 g / 12 mL weak cation (WCX) column packing, while ensuring that there is always solvent in the chromatographic column before loading the sample;

[0033] Step S2, weighing about 1.0-1.5 g of the fully synthesized product containing the quaternary ammonium salt surfactant into a beaker, and then diluting it with 8 mL of a chromatographic column filler solvent;

[0034] Step S3, loading the sample solution onto the activated column and aspirating the sample through the column. The sample is aspirated into the chromatographic column at a flow rate of about 1-2 ml / min, and the best flow rate is a trickle flow;

[0035] Step S4, washing the column with 2 column volumes of 75 / 25 (water / methanol, pH 11) to remove most of the acid, base and some other impurities, and only the quaternary ammonium salt is retained in the chromatographic column;

[0036] Step S5, then continue to wash the chromatographic column with one column volume of 100% methanol to remove the non-ionic organic compounds retained in the chromatographic column;

[0037] Step S6, drying the chromatographic column under full vacuum conditions for 2 minutes;

[0038] Step S7, elute the quaternary ammonium surfactant with 2 column volumes of 70 / 30 (200 mM ammonium acetate containing 10% acetic acid / methanol, adjusted to pH <3 with acetic acid), and collect the eluate in a clean 50 mL beaker;

[0039] Step S8, quantitatively transferring the eluate into a 25 mL volumetric flask filled with deionized water;

[0040] Step S9, analyzing the eluate quantitatively transferred to a 25 mL volumetric flask filled with deionized water by HPLC, determining the type of the unknown quaternary ammonium salt surfactant by retention time, and determining the content of the unknown quaternary ammonium salt surfactant by an external standard method.

[0041] Example 1

[0042] Weigh 1.3307 g of the fully synthetic product containing cetylpyridinium chloride. The product formula is as follows:

[0043] Element weight% water 65.8 Alkylamine 20.0 fatty acid 10.0 Emulsifier 3.0 Cetylpyridinium chloride 2.5

[0044] According to steps S001 to S008, each phase of liquid is collected and dried. The following is the recovery rate of each phase:

[0045] Elution solvent Recovery rate % Water / methanol (75, 25), pH 11 2.9 100% Methanol 4 70 / 30 (200 mM ammonium acetate containing 10% acetic acid) / methanol, pH < 3 85

[0046] The 70 / 30 (200 mM ammonium acetate containing 10% acetic acid) / methanol phase was made up to volume with deionized water and then quantified by HPLC-ELSD, wherein the calibration curve of cetylpyridinium chloride was: Log Area = 1.3229*Log Conc + 0.5313.

[0047] The final results of the external standard method are as follows:

[0048] Sample weight 1330.7mg Constant volume 25mL Cetylpyridinium chloride (test value) 2.35％ Cetylpyridinium chloride (theoretical value) 2.50％ Cetylpyridinium chloride (recovery rate) 94％

[0049] Therefore, the quaternary ammonium salt surfactant in the fully synthetic metalworking fluid product can be efficiently recovered by the method of the present invention.

[0050] It should be understood by those skilled in the art that the embodiments of the present invention shown in the above description are only examples and do not limit the present invention. The advantages of the present invention have been fully and effectively achieved. The functional and structural principles of the present invention have been demonstrated and explained in the embodiments, and the embodiments of the present invention may be deformed or modified in any way without departing from the principles.

Claims

1. A method for separating quaternary ammonium salt surfactants from fully synthetic metalworking fluid products, characterized in that: The method comprises: Step S1001, using an activation solution to activate the weak cation column filler, and at the same time, before loading the sample, ensuring that there is always solvent in the chromatographic column; Step S1002, weighing a fully synthesized product containing a quaternary ammonium salt surfactant into a beaker, and then diluting it with a solvent of a chromatographic column filler to form a sample solution; Step S1003, loading the sample solution onto the activated chromatographic column, and aspirating the sample through the chromatographic column; Step S1004, cleaning the chromatographic column with an impurity cleaning solution to remove acid, alkali and some other impurities, and retain the quaternary ammonium salt in the chromatographic column; Step S1005, continue to clean the chromatographic column with a non-ionic cleaning solution to remove the non-ionic organic compounds retained in the chromatographic column; Step S1006, drying the chromatographic column for a predetermined time under vacuum conditions; Step S1007, eluting the quaternary ammonium salt surfactant with a de-eluting solution, and collecting the eluent to obtain the separated quaternary ammonium salt surfactant.

2. The method for separating quaternary ammonium salt surfactants from the fully synthetic metalworking fluid product according to claim 1, characterized in that: At least one of the following conditions must be met: In step S1001, 2 g / 12 mL weak cation column packing is activated using 1 column volume of methanol and 2 column volumes of 75 / 25 water / methanol, pH 11; In step S1002, the ratio between the total synthesis product and the solvent of the chromatographic column filler is: (1:8) to (1.5:8); In step S1003, the sample is drawn into the chromatographic column at a flow rate of about 1-2 ml / min; In step S1004, the chromatographic column is washed with 2 column volumes of 75 / 25 water / methanol, pH 11; In step S1005, the chromatographic column is continuously cleaned with one column volume of 100% methanol; In step S1006, 2 column volumes of 70 / 30 (200 mM ammonium acetate containing 10% acetic acid / methanol, pH adjusted to <3 with acetic acid, are used to elute the quaternary ammonium surfactant.

3. The method for separating quaternary ammonium salt surfactants from the fully synthetic metalworking fluid product according to claim 1, characterized in that: The chromatographic column adopts a WCX column.

4. The method for separating quaternary ammonium salt surfactants from a fully synthetic metalworking fluid product according to claim 1, characterized in that: The sample solution was loaded into the activated column in a drip-flow manner.

5. A method for detecting quaternary ammonium salt surfactants in fully synthetic metalworking fluid products, characterized in that: It comprises the steps as claimed in any one of claims 1 to 4, and Step S1008, quantitatively transferring the eluent into a volumetric flask filled with deionized water; Step S1009, analyzing the eluate quantitatively transferred to the volumetric flask by HPLC, determining the type of the unknown quaternary ammonium salt surfactant by retention time, and determining the content of the unknown quaternary ammonium salt surfactant by using an external standard method.

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