Quantitative analysis method based on sodium content in polytetrahydrofuran

Abstract

The invention discloses a quantitative analysis method based on sodium content in polytetrahydrofuran, which comprises the following steps: determining a standard working curve which represents a linear relationship between the concentration of sodium ions and the emission spectrum intensity of the sodium ions, extracting the sodium ions in a polytetrahydrofuran sample by using an acid solution to obtain a to-be-detected solution, and determining the sodium content in the to-be-detected solution according to the to-be-detected solution. And detecting the emission spectrum intensity of sodium ions in the to-be-detected liquid, and calculating based on the emission spectrum intensity of the sodium ions in the to-be-detected liquid and the standard working curve to obtain the sodium content in the polytetrahydrofuran. According to the method, quantitative analysis of the sodium content in the polytetrahydrofuran is realized, the test period is short, the result accuracy is high, and the test process is environment-friendly.

Description

Technical Field

[0001] The present invention relates to the technical field of analysis and detection, and in particular to a quantitative analysis method based on the sodium content in polytetrahydrofuran. Background Art

[0002] Polytetrahydrofuran (PTHF) is a key raw material in spandex production, endowing it with high elasticity, excellent abrasion resistance, and hydrolysis resistance. Sodium ion content exceeding 1 ppm in PTHF can affect the uniformity and spinnability of spandex, reduce fiber strength, affect durability and stability during use, impact elastic recovery, affect color and transparency, impair chemical stability, and accelerate aging. Currently, conventional chemical analysis is unable to accurately measure trace amounts of sodium in PTHF. The sample is viscous and difficult to dissolve, the measurement cycle is long, and numerous chemical reagents are required, making accurate determination of sodium content in PTHF difficult. Summary of the Invention

[0003] In view of the above problems, the object of the present invention is to provide a quantitative analysis method for the sodium content in polytetrahydrofuran, which is simple, convenient, highly selective, accurate and sensitive, thereby overcoming the problems of the prior art in the sodium content in polytetrahydrofuran, such as long testing cycle, large number of chemical reagents used and low accuracy. The technical solution is as follows:

[0004] On the one hand, a quantitative analysis method based on sodium content in polytetrahydrofuran is provided, the method comprising the following steps:

[0005] Step 1) determining a standard working curve; the standard working curve characterizes the linear relationship between the concentration of sodium ions and the emission spectrum intensity of the sodium ions.

[0006] Step 2) using an acidic solution to extract sodium ions in the polytetrahydrofuran sample to obtain a test solution, and detecting the emission spectrum intensity of the sodium ions in the test solution.

[0007] Specifically, the acidic solution is an acidic aqueous solution. Polytetrahydrofuran is an organic polymer compound that is usually insoluble in an aqueous phase. Sodium ions have good solubility in an acidic solution. When the acidic solution contacts the polytetrahydrofuran, according to the principle of like dissolves like, the acidic aqueous phase provides an environment conducive to the dissolution and transfer of sodium ions, thereby promoting the extraction of sodium ions from the polytetrahydrofuran into the acidic solution. The amount of chemical reagents required is small, the extraction is sufficient, and the extraction process is environmentally friendly without releasing harmful substances. The sodium ions exist in the polytetrahydrofuran in the form of sodium phosphate. If sodium phosphate itself is soluble in water, it is alkaline. The acidic solution allows the sodium phosphate to dissolve in the acidic aqueous solution.

[0008] Step 3) Calculating based on the emission spectrum intensity of sodium ions in the test solution and the standard working curve to obtain the sodium content in the polytetrahydrofuran.

[0009] Specifically, the concentration of sodium ions in the test liquid can be calculated by substituting the emission spectrum intensity of sodium ions in the test liquid into the standard working curve. The total volume of the test liquid during extraction in step 2) can then be used to calculate the total amount of sodium ions in the test liquid, which is the sodium ion content in the polytetrahydrofuran sample. Furthermore, the sodium ion content per unit mass / unit volume of the polytetrahydrofuran sample can be obtained by dividing the total amount of sodium ions in the test liquid by the mass / volume of the polytetrahydrofuran sample based on the mass / volume of the polytetrahydrofuran sample. The specific calculation method can be set according to actual needs.

[0010] In an exemplary embodiment, step 1) includes the following steps:

[0011] Detect the emission spectrum intensity of sodium ions in sodium ion standard working solutions with different concentrations;

[0012] A standard working curve is determined according to the emission spectrum intensity of sodium ions in the sodium ion standard working solutions of different concentrations and the concentration values ​​of sodium ions in the sodium ion standard working solutions of different concentrations.

[0013] In an exemplary embodiment, the range of the standard working curve is 0.2 to 2 ppm.

[0014] In an exemplary embodiment, the acidic aqueous solution is a 1 wt % hydrochloric acid aqueous solution.

[0015] In an exemplary embodiment, the anion in the sodium ion standard working solution is a chloride ion.

[0016] In an exemplary embodiment, step 2) includes the following steps:

[0017] A 1 wt % hydrochloric acid aqueous solution and the polytetrahydrofuran sample are placed in a mixing container and mixed under heating conditions to obtain a mixture. The mixture is transferred to a liquid separator while hot, shaken, allowed to stand, and separated into layers. The obtained aqueous phase solution is used as the test solution.

[0018] In an exemplary embodiment, the mixing container is a closed container.

[0019] In an exemplary embodiment, the heating condition is 65°C.

[0020] The present invention discloses a quantitative analysis method for sodium content in polytetrahydrofuran (PTHF). The method comprises determining a standard working curve, wherein the standard working curve characterizes the linear relationship between sodium ion concentration and the emission spectrum intensity of the sodium ions. An acidic solution is used to extract sodium ions from a polytetrahydrofuran sample to obtain a test solution. The emission spectrum intensity of the sodium ions in the test solution is detected. The sodium content in the polytetrahydrofuran is calculated based on the emission spectrum intensity of the sodium ions in the test solution and the standard working curve. The present invention achieves quantitative analysis of the sodium content in the polytetrahydrofuran. The method has a short testing cycle, high result accuracy, and an environmentally friendly testing process. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] To more clearly illustrate the technical solution of the present invention, the following briefly introduces the drawings required for use in the embodiments or descriptions of the prior art. Obviously, the drawings described below are only some embodiments of the present invention, and those skilled in the art can derive other drawings based on these drawings without inventive effort.

[0022] Figure 1 The present invention provides a quantitative analysis method for sodium content in polytetrahydrofuran.

[0023] Figure 2 This is an emission spectrum intensity diagram of sodium ions provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0024] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0025] This application example provides a quantitative analysis method based on the sodium content in polytetrahydrofuran. For specific steps, please refer to Figure 1 , Figure 1 The present invention is a flow chart of a quantitative analysis method based on the sodium content in polytetrahydrofuran, wherein the method comprises the following steps:

[0026] Step 1) determining a standard working curve; the standard working curve characterizes the linear relationship between the concentration of sodium ions and the emission spectrum intensity of the sodium ions.

[0027] Specifically, the sodium ion solution used to determine the standard working curve can be selected according to actual needs, such as sodium chloride solution. The sodium chloride solution can be a standard concentration solution purchased directly or prepared by oneself.

[0028] Step 2) using an acidic solution to extract sodium ions in the polytetrahydrofuran sample to obtain a test solution, and detecting the emission spectrum intensity of the sodium ions in the test solution.

[0029] Specifically, the acidic solution is an acidic aqueous solution. Polytetrahydrofuran is an organic polymer compound that is generally insoluble in aqueous phases. Sodium ions are highly soluble in acidic solutions. When the acidic solution comes into contact with polytetrahydrofuran, the acidic aqueous phase provides an environment conducive to the dissolution and transfer of sodium ions, according to the principle of like dissolves like. This facilitates the extraction of sodium ions from the polytetrahydrofuran into the acidic solution. This requires minimal amounts of chemical reagents, resulting in sufficient extraction and an environmentally friendly extraction process without the release of harmful substances. Sodium in polytetrahydrofuran exists primarily as sodium ions and sodium phosphate. Given that aqueous sodium phosphate solutions are alkaline, the sodium in the sodium phosphate is more susceptible to dissociation in acidic solutions.

[0030] Step 3) Calculate based on the emission spectrum intensity of sodium ions in the test solution and the standard working curve to obtain the sodium content in the polytetrahydrofuran.

[0031] Specifically, the concentration of sodium ions in the test liquid can be obtained by substituting the emission spectrum intensity of sodium ions in the test liquid into the standard working curve for calculation. Then, based on the total volume of the test liquid used in the extraction in step 2), the total amount of sodium ions in the test liquid can be calculated as the sodium ion content in the polytetrahydrofuran sample. Furthermore, based on the mass / volume of the polytetrahydrofuran sample, the total amount of sodium ions in the test liquid can be divided by the mass / volume of the polytetrahydrofuran sample to obtain the sodium ion content in the polytetrahydrofuran sample per unit mass / unit volume. The specific calculation method can be set according to actual needs.

[0032] In the embodiment of the present application, step 1) includes the following steps:

[0033] Detect the emission spectrum intensity of sodium ions in sodium ion standard working solutions with different concentrations;

[0034] Specifically, Figure 2 This is a graph of the emission spectrum intensity of sodium ions provided by an embodiment of the present invention. It should be noted that Figure 2 There are dotted lines and solid lines in the figure, where the dotted line represents background noise (matrix interference noise in the sample) and the solid line represents the measured intensity of the sodium ion element in the sample at 589.592 nm.

[0035] A standard working curve is determined according to the emission spectrum intensity of sodium ions in the sodium ion standard working solutions of different concentrations and the concentration values ​​of sodium ions in the sodium ion standard working solutions of different concentrations.

[0036] Specifically, the emission spectrum intensity of sodium ions in standard working solutions of sodium ions with different concentrations can be directly fitted using corresponding fitting software. For example, Origin (data analysis and mapping software) can be used to draw a working curve to obtain a linear relationship between the concentration value of sodium ions and the emission spectrum intensity of sodium ions.

[0037] In the embodiment of the present application, the range of the standard working curve is: 0.2~2ppm.

[0038] Specifically, the range of 0.2 to 2 ppm is selected because the control index of sodium in the polytetrahydrofuran sample is less than 1 ppm. Even when the operating conditions are abnormal, the sodium content can be controlled below 2 ppm in most cases. In the embodiment of the present application, the acidic solution is a 1 wt % hydrochloric acid aqueous solution.

[0039] Specifically, considering that the delamination effect is poor during the extraction process using neutral pure water, when preparing the acidic solution, hydrochloric acid, sulfuric acid, or nitric acid can be selected. In specific implementations, the selection is based on actual needs. For example, a 1 wt% hydrochloric acid aqueous solution prepared by mixing hydrochloric acid and water is used as the acidic solution in the embodiment of the present application.

[0040] In the embodiment of the present application, the anion in the sodium ion standard working solution is chloride ion.

[0041] Specifically, the embodiment of the present application does not specifically limit the type of anions in the sodium ion standard working solution. Preferably, when hydrochloric acid and water are mixed to prepare a 1wt% hydrochloric acid aqueous solution as the acidic solution in the embodiment of the present application, in order to avoid the introduction of more anion species and causing an impact on the test, the sodium ion standard working solution is a sodium chloride solution.

[0042] In the embodiment of the present application, step 2) includes the following steps:

[0043] A 1 wt% hydrochloric acid aqueous solution and a polytetrahydrofuran sample were placed in a mixing container and mixed under heating conditions to obtain a mixture. The mixture was transferred to a liquid separator while hot, shaken, allowed to stand, and separated into layers. The obtained aqueous phase solution was used as the test solution.

[0044] Specifically, upon cooling, the polytetrahydrofuran and aqueous solution will separate into separate layers, and at temperatures below 40°C, the polytetrahydrofuran will slowly solidify into a white, waxy solid. Therefore, the mixture should be transferred to a liquid separator while still hot, shaken, allowed to stand, and separated into separate layers. The resulting aqueous solution is used as the test solution. The present embodiments do not impose specific limitations on the model, material, or size of the mixing container.

[0045] In the embodiment of the present application, the mixing container is a closed container.

[0046] Specifically, when a fixed amount of acidic solution is used for one-time extraction, a closed solution is used for mixing in order to avoid concentration error caused by volume loss.

[0047] In the embodiment of the present application, the heating condition is 65°C.

[0048] Specifically, the embodiment of the present application does not make specific requirements on the temperature of the heating conditions. Suitable temperature conditions can be selected for heating at 40 to 80°C. When the temperature is lower than 40°C, the polytetrahydrofuran sample will gradually solidify into a white waxy solid. For example, the preferred heating condition is 65°C. In the absence of interference from other chemical substances, the chemical structure of polytetrahydrofuran is relatively stable and no obvious chemical reactions will occur rapidly. Its molecular chains will not spontaneously undergo drastic changes such as breakage or polymerization at this temperature. Moreover, 65°C is also a relatively safe temperature for the operator, which ensures the full extraction of sodium ions and avoids the slow oxidation reaction of polytetrahydrofuran at higher temperatures for a long time, which may lead to molecular chain degradation.

[0049] The technical solution of this application is described below with reference to specific embodiments.

[0050] Example 1

[0051] A method for detecting sodium content in polytetrahydrofuran comprises the following steps:

[0052] (1) Prepare sodium standard working solution with sodium standard stock solution. The preparation process is to accurately pipette 2.00 mL of 1 mg / mL sodium standard stock solution into a 100 mL volumetric flask, dilute to volume with high-purity water, and shake well. The concentration of this sodium standard working solution is 0.02 mg / mL, i.e., 20 ppm (it should be noted that 1 mL of sodium standard working solution prepared in this Example 1 is used in subsequent calculations as 1 g). Prepare sodium series standard solutions with sodium standard working solution. The preparation process is to accurately pipette 1.00 mL, 2.00 mL, 5.00 mL, and 10.00 mL of 20 ppm sodium standard working solution into a group of 100 mL volumetric flasks, dilute to volume with high-purity water, and shake well. The concentrations of this sodium series standard solution are 0.2 ppm, 0.4 ppm, 1 ppm, and 2 ppm, respectively.

[0053] (2) Determine the emission spectrum intensity of sodium in the sodium series standard solution and draw a standard curve. The process of drawing the standard curve is as follows: the concentration of the sodium series standard solution is used as the horizontal axis, and the emission spectrum intensity corresponding to the concentration of the sodium series standard solution measured by inductively coupled plasma atomic emission spectrometry is used as the vertical axis to draw the standard curve.

[0054] (3) Sample pretreatment: Prepare a 500ml beaker and add 100g of polytetrahydrofuran sample and 100g of 1wt% hydrochloric acid solution respectively. Place a watch glass on the beaker and pour a small amount of water on the watch glass. Stir the mixture vigorously at 250 rpm at 65°C using an electromagnetic stirring rod for 60 minutes. Pour the hot mixture into a 250ml separatory funnel and shake for 2 minutes to separate the mixture into two phases. Let it stand for 30 minutes. Filter carefully with 5A filter paper to obtain the bottom aqueous phase solution as the test solution.

[0055] (4) 1wt% hydrochloric acid was used as a blank solution, and the sodium content of the test solution was measured using inductively coupled plasma emission spectroscopy. The sample content was calculated by back-calculating the sample content using the calibration solution and the calibration blank. The test solution was detected using an inductively coupled plasma spectrometer. Specifically, the inductively coupled plasma spectrometer was started, the instrument was preheated for 3h, and the instrument parameters were set as follows: RF power 1200W, cooling gas flow 15L / min, auxiliary gas flow 1.5L / min, and carrier gas flow 0.90L / min. After the instrument was stable, the sample was analyzed. Before the measurement, high-purity argon was purged for 5 minutes. The wavelength was preset to 589.592nm, and the standard solution was introduced into the inductively coupled plasma spectrometer. The working curve was fitted (the method was directly established on the instrument to automatically fit the working curve, and the researcher did not need to fit the working curve through the fitting software). The spectral line intensity of the sodium element was measured from the working curve, and the sodium content was calculated. The precision experiment and accuracy experiment were carried out using this method. The results showed that this method fully met the analysis of the sodium content of the polytetrahydrofuran sample. As can be seen from the above technical solutions of the embodiments of the present invention, the present invention discloses a quantitative analysis method based on the sodium content in polytetrahydrofuran. The method determines a standard working curve, wherein the standard working curve characterizes the linear relationship between the concentration of sodium ions and the emission spectrum intensity of the sodium ions. An acidic solution is used to extract the sodium ions in the polytetrahydrofuran sample to obtain a test liquid, and the emission spectrum intensity of the sodium ions in the test liquid is detected. Then, the sodium content in the polytetrahydrofuran is calculated based on the emission spectrum intensity of the sodium ions in the test liquid and the standard working curve. The present invention realizes quantitative analysis of the sodium content in polytetrahydrofuran, with a short test cycle, high result accuracy, and an environmentally friendly test process.

[0056] The above description fully discloses the specific embodiments of the present invention. It should be noted that any modifications made by those skilled in the art to the specific embodiments of the present invention do not depart from the scope of the claims. Accordingly, the scope of the claims of the present invention is not limited solely to the foregoing specific embodiments.

Claims

1. A quantitative analysis method based on sodium content in polytetrahydrofuran, characterized in that, The method comprises the following steps: Step 1) determining a standard working curve; the standard working curve characterizes the linear relationship between the concentration of sodium ions and the emission spectrum intensity of the sodium ions; Step 2) extracting sodium ions in the polytetrahydrofuran sample using an acidic solution to obtain a test solution, and detecting the emission spectrum intensity of the sodium ions in the test solution; Step 3) Calculating based on the emission spectrum intensity of sodium ions in the test solution and the standard working curve to obtain the sodium content in the polytetrahydrofuran.

2. The quantitative analysis method based on sodium content in polytetrahydrofuran according to claim 1, wherein Step 1) includes the following steps: Detect the emission spectrum intensity of sodium ions in sodium ion standard working solutions with different concentrations; A standard working curve is determined according to the emission spectrum intensity of sodium ions in the sodium ion standard working solutions of different concentrations and the concentration values ​​of sodium ions in the sodium ion standard working solutions of different concentrations.

3. The quantitative analysis method based on sodium content in polytetrahydrofuran according to any one of claims 1 or 2, characterized in that, The range of the standard working curve is: 0.2~2ppm.

4. The quantitative analysis method based on sodium content in polytetrahydrofuran according to claim 1, wherein The acidic solution is a 1 wt% hydrochloric acid aqueous solution.

5. The quantitative analysis method based on sodium content in polytetrahydrofuran according to any one of claims 2 and 4, characterized in that, The anions in the sodium ion standard working solution are chloride ions.

6. The quantitative analysis method based on sodium content in polytetrahydrofuran according to claim 5, wherein Step 2) includes the following steps: The 1 wt % hydrochloric acid aqueous solution and the polytetrahydrofuran sample are placed in a mixing container and mixed under heating conditions to obtain a mixture. The mixture is transferred to a liquid separation device while hot, shaken, allowed to stand, and separated into layers. The obtained aqueous phase solution is used as the test solution.

7. The quantitative analysis method based on sodium content in polytetrahydrofuran according to claim 6, wherein The mixing container is a closed container.

8. The quantitative analysis method based on sodium content in polytetrahydrofuran according to claim 6, wherein: The heating condition is 65°C.

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