A method for quantitatively detecting 2,3,6-trimethylphenol

Abstract

The present invention is a method for quantitatively detecting 2,3,6-trimethylphenol, which uses "NaClO2-C4H 13 A chlorite-ammonium-tetrathionate clock (CAT clock) reaction system using "NO (tetramethylammonium hydroxide)-Na2S4O6" as a substrate is used as a detection solution. The quantitative analysis of 2,3,6-trimethylphenol is achieved based on the different responses of the system to different concentrations of 2,3,6-trimethylphenol, namely, different induction times. The quantitative analysis method for 2,3,6-trimethylphenol involved in the present invention has the characteristics of high accuracy, easy operation, convenience and speed.

Description

Technical Field

[0001] The present invention relates to an analytical detection method, specifically to the establishment of "NaClO2- C4H 13 A chlorite-ammonium-tetrathionate clock system (hereinafter referred to as the CAT clock system) using "NO (tetramethylammonium hydroxide) - Na2S4O6" as a substrate is used to implement a quantitative analysis method for 2,3,6-trimethylphenol based on the different responses of the system to different concentrations of 2,3,6-trimethylphenol, namely, different induction times. This belongs to the field of analytical chemistry. Background Art

[0002] Trimethylphenol, also known as 2,3,6-trimethylphenol, has a structure shown in Formula (I). It is primarily used in the pharmaceutical industry to synthesize vitamin E cyclopentane (2,3,5-trimethyl-p-phenylhydroquinone). It is also used as a monomer for heat-resistant polyphenylene ether engineering plastics and a raw material for plastic alloys. Furthermore, it is an essential intermediate in the production of certain pesticides and disinfectants.

[0003] The determination of 2,3,6-trimethylphenol mainly adopts instrumental analysis method, such as high performance liquid chromatography (HPLC), gas chromatography, high performance liquid chromatography ultraviolet detection method (HPLC-UV), and also has the report of adopting determination methods such as iodine titration, photometry and fluorescence, chemiluminescence.Chromatography has the advantage of high sensitivity and good accuracy, but for samples with complex matrix, analytical sensitivity decreases.Therefore, it is very necessary to find a detection and analysis method with good detection effect and easy and fast operation.

[0004]

[0005] Structural formula (I) Structure of 2,3,6-trimethylphenol Summary of the Invention

[0006] The present invention aims to provide a new quantitative detection method for 2,3,6-trimethylphenol, namely, using "NaClO2-C4H 13 The NO-Na2S4O6" CAT clock system is a method for quantitatively detecting 2,3,6-trimethylphenol in a detection solution. This method is a standard curve (working curve) method developed based on the sensitive response of the CAT clock system to 2,3,6-trimethylphenol. Specifically, the "NaClO2- C4H 13A "NO-Na2S4O6" CAT clock reaction system was used as the detection solution, and a graph of pH changes over time was recorded. When the CAT clock reaction began, equal volumes of a series of 2,3,6-trimethylphenol sample solutions with different concentrations were added to the CAT clock system. Based on the different induction times generated by the system when the concentrations of the test solutions in the CAT clock system were different, quantitative detection of the 2,3,6-trimethylphenol samples was achieved.

[0007] A working curve was established based on the relationship between the concentration of 2,3,6-trimethylphenol in the CAT clock system and the induction time. The horizontal axis is the concentration of 2,3,6-trimethylphenol in the CAT clock system, and the vertical axis is the induction time t. When the concentration of 2,3,6-trimethylphenol in the system is 9.5×10 -8 mol / L -4.76×10 -7 When the induction time t is between 0.05 and 0.1 mol / L, there is a linear relationship between the induction time t and the concentration of 2,3,6-trimethylphenol, based on which the quantitative detection of 2,3,6-trimethylphenol in the sample can be achieved.

[0008] The difference between this quantitative detection method and the prior art is that the present invention uses "NaClO2- C4H 13 The NO-Na2S4O6"CAT clock system is used as the detection solution, and the system responds differently to different concentrations of 2,3,6-trimethylphenol, i.e., different induction times, thereby achieving quantitative analysis of 2,3,6-trimethylphenol.

[0009] The concentration range of 2,3,6-trimethylphenol in the test solution (CAT clock system) was 9.5×10 - 8 mol / L -4.76×10 -7 mol / L.

[0010] When 2,3,6-trimethylphenol was detected in the detection solution (CAT clock system), the temperature of the CAT clock system was controlled at 25±0.5°C.

[0011] Using the CAT clock system described above, the concentration range within which 2,3,6-trimethylphenol can be detected is the optimal concentration range determined experimentally. Within this concentration range, the induction time responds well to changes in 2,3,6-trimethylphenol concentration, with a large linear correlation coefficient. Furthermore, the concentration ranges of the components in the detection solution (CAT clock system) are shown in Table 1. The optimal concentrations of the detection solution (CAT clock system) obtained through multiple experiments are shown in Table 2:

[0012] Table 1: Concentrations of components in the CAT clock system

[0013] <![CDATA[NaClO2(mol / L)]]> <![CDATA[C4H 13 NO (Tetramethylammonium hydroxide) (mol / L) <![CDATA[Na2S4O6(mol / L)]]> 0.0107-0.0125 0.000294-0.000420 0.00124-0.00149

[0014] Table 2: Optimal concentrations of components in the CAT clock system

[0015] <![CDATA[NaClO2(mol / L)]]> <![CDATA[C4H 13 NO (Tetramethylammonium hydroxide) (mol / L) <![CDATA[Na2S4O6(mol / L)]]> 0.0116 0.000295 0.00149

[0016] The specific experimental steps are as follows:

[0017] 1. Prepare the test solution (CAT clock system) within the concentration range specified in Table 1. Maintain the temperature at 25 ± 0.5°C. Insert the prepared working electrode (pH combination electrode, Leici, E-331) into the solution. Connect the other end of the working electrode to a computer via a potential / temperature / pH integrated tester (Jiaxing Disheng Electronic Technology Co., Ltd., ZHFX-595). Open the chemical signal acquisition and analysis program on the computer, set the acquisition time and sampling rate, and quickly click Start to monitor the pH of the solution. The computer records the pH curve over time, which is the CAT clock spectrum. When testing a substance, add the substance immediately upon initiation of the CAT clock system reaction. Record the pH curve over time using the same CAT clock spectrum.

[0018] The basic parameters of the CAT clock spectrum include:

[0019] Induction time: the time required from the start of the CAT clock system reaction to pH stabilization.

[0020] pH jump range: the pH corresponding to the start of the pH jump in the system to the pH corresponding to the end of the pH jump.

[0021] 2. Establish a working curve for the relationship between the concentration of 2,3,6-trimethylphenol in the test solution and the pH induction time

[0022] A series of low-concentration 2,3,6-trimethylphenol solutions were prepared using ethanol as the solvent as sample solutions. At the start of the CAT clock system reaction, 4 μL of the sample solutions of different concentrations were added to 42 mL of the CAT clock system using a pipette, so that the concentration of 2,3,6-trimethylphenol in the system was 9.5×10 -8 mol / L -4.76×10 - 7 mol / L; the change in the CAT clock system response is the induction time, recorded as t; when the concentration of 2,3,6-trimethylphenol in the system is different, the induction time t of the CAT clock system is also different; the concentration of 2,3,6-trimethylphenol in the system is used as the horizontal axis and t is used as the vertical axis to draw a graph; when the concentration of 2,3,6-trimethylphenol in the system is between 9.5×10 -8 mol / L -4.76×10-7 When the concentration of 2,3,6-trimethylphenol was between 1.5 and 2.5 mol / L, the induction time t of the CAT clock system was in a linear relationship with the concentration of 2,3,6-trimethylphenol, and a working curve was obtained.

[0023] 3. Quantitative detection of 2,3,6-trimethylphenol

[0024] By adding a test sample of unknown concentration to the detection solution CAT clock system at the beginning of the CAT clock system reaction, the induction time (t) of the corresponding CAT clock system can be measured. Based on the corresponding relationship between t and concentration on the working curve, the concentration of 2,3,6-trimethylphenol in the detection system can be obtained, and then the concentration of 2,3,6-trimethylphenol in the test sample can be calculated. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a graph showing the change in pH value of the detection solution (CAT clock system) over time when no sample to be detected is added in Example 1.

[0026] Figure 2 In Example 1, 9.5×10 -8 1 mol / L 2,3,6-trimethylphenol, and the pH value of the detection solution (CAT clock system) changes with time.

[0027] Figure 3 In Example 1, 1.9×10 -7 mol / L 2,3,6-trimethylphenol, and the pH value of the detection solution (CAT clock system) changes with time.

[0028] Figure 4 This is the working curve between pH induction time t and 2,3,6-trimethylphenol concentration in Example 1.

[0029] Figure 5 This is a graph showing the change in pH value of the test solution (CAT clock system) over time when no sample to be tested is added in Example 2.

[0030] Figure 6 In Example 2, 2.86×10 -7 mol / L 2,3,6-trimethylphenol, and the pH value of the detection solution (CAT clock system) changes with time.

[0031] Figure 7 In Example 2, 3.81×10 -7 mol / L 2,3,6-trimethylphenol, and the pH value of the detection solution (CAT clock system) changes with time.

[0032] Figure 8This is the working curve between pH induction time t and 2,3,6-trimethylphenol concentration in Example 2.

[0033] Figure 9 This is a graph showing the change in pH value of the detection solution (CAT clock system) over time when no sample to be detected is added in Example 3.

[0034] Figure 10 In Example 3, 3.81×10 -7 mol / L 2,3,6-trimethylphenol, and the pH value of the detection solution (CAT clock system) changes with time.

[0035] Figure 11 In Example 3, 4.76×10 -7 mol / L 2,3,6-trimethylphenol, and the pH value of the detection solution (CAT clock system) changes with time.

[0036] Figure 12 This is the working curve between pH induction time t and 2,3,6-trimethylphenol concentration in Example 3. Implementation Method Example 1

[0037] Application of "NaClO2- C4H 13 A CAT clock system with "NO - Na2S4O6" as the substrate is used as the detection solution to quantitatively analyze 2,3,6-trimethylphenol. Equal volumes of 2,3,6-trimethylphenol sample solutions of different concentrations are added to the CAT clock system, and a working curve (e.g., a linear relationship) is established between the 2,3,6-trimethylphenol concentration in the detection system and the induction time. This achieves the purpose of detecting 2,3,6-trimethylphenol in the CAT clock system, and then calculates the concentration of 2,3,6-trimethylphenol in the test sample.

[0038] (1) Prepare the test solution

[0039] First, distilled water was used to prepare 0.0195 mol / L NaClO2 solution, 0.00248 mol / L C4H 13 NO and 0.0052mol / L Na2S4O6 solution. To a 50mL beaker, add 24.0mL 0.0195mol / L NaClO2 solution, 6mL 0.00248mol / L C4H 13 NO solution, 12mL 0.0052mol / L Na2S4O6 solution, to ensure "NaClO2-C4H 13The concentrations of the components in the NO-Na2S4O6" CAT clock system are NaClO2 0.01114 mol / L, C4H 13 NO 0.000354mol / L, Na2S4O6 0.00149mol / L, the total volume was 42mL, and the temperature was controlled at 25℃.

[0040] At the same time, a series of 2,3,6-trimethylphenol sample solutions with different concentrations were prepared using ethanol as solvent.

[0041] (2) Obtaining CAT clock spectrum

[0042] The graph of the pH value of the prepared test solution changing with time is recorded by a computer equipped with a chemical signal acquisition and analysis program (without adding the test sample). Figure 1 As shown. The pH induction time was 1023.5s as a blank control. Two groups of test solutions with the same concentration of each component as the above test solution were prepared. For one group, at the beginning of the reaction, 4 μL of 1.00×10 -3 mol / L 2,3,6-trimethylphenol sample solution, so that the concentration of 2,3,6-trimethylphenol in the test solution is 9.5×10 -8 mol / L, the addition of 2,3,6-trimethylphenol shortened the induction time to 929s. Figure 2 As shown; for the other group, 4 μL of 2.00×10 -3 mol / L 2,3,6-trimethylphenol sample solution, so that the concentration of 2,3,6-trimethylphenol in the test solution is 1.9×10 -7 mol / L, the addition of 2,3,6-trimethylphenol makes the induction time become 798s. Figure 3 shown. Figure 2 、 Figure 3 It was confirmed that different concentrations of 2,3,6-trimethylphenol in the detection solution resulted in different induction times for the CAT clock system to appear. When the concentration of 2,3,6-trimethylphenol in the detection system was 9.5×10 -8 mol / L -4.76×10 -7 mol / L, the different induction times of the CAT clock system caused by different concentrations can be observed.

[0043] (3) Quantitative detection

[0044] A working curve was established based on the relationship between the concentration of 2,3,6-trimethylphenol in the detection system and the induction time, such as Figure 4As shown in the figure, the horizontal axis is the concentration of 2,3,6-trimethylphenol in the CAT clock system, and the vertical axis is the induction time t. When the concentration of 2,3,6-trimethylphenol in the detection system is 9.5×10 -8 mol / L -4.76×10 -7 mol / L, the induction time has a linear relationship with the concentration of 2,3,6-trimethylphenol, and the linear equation is t = -1.0×10 9 c+1029.9, R 2 =0.9958. Based on this, the quantitative detection of 2,3,6-trimethylphenol in the sample can be achieved. Example 2

[0045] (1) Prepare the test solution

[0046] First, distilled water was used to prepare 0.0195 mol / L NaClO2 solution, 0.00248 mol / L C4H 13 NO and 0.0052mol / L Na2S4O6 solution. To a 50mL beaker, add 26.0mL 0.0195mol / LNaClO2 solution, 5mL 0.00248mol / L C4H 13 NO solution, 11mL 0.0052mol / L Na2S4O6 solution, to ensure "NaClO2-C4H 13 The concentrations of the components in the NO-Na2S4O6" CAT clock system are NaClO2 0.01207 mol / L, C4H 13 NO 0.000295mol / L, Na2S4O6 0.00136mol / L, the total volume was 42mL, and the temperature was controlled at 25℃.

[0047] At the same time, a series of 2,3,6-trimethylphenol sample solutions with different concentrations were prepared using ethanol as solvent.

[0048] (2) Obtaining CAT clock spectrum

[0049] The graph of the pH value of the prepared test solution changing with time is recorded by a computer equipped with a chemical signal acquisition and analysis program (without adding the test sample). Figure 5 As shown. The pH induction time was 1027.5s as a blank control. Two other test solutions with the same concentration of each component as the above test solution were prepared. For one of the two groups, 4 μL of 3.0×10 -3mol / L 2,3,6-trimethylphenol sample solution, so that the concentration of 2,3,6-trimethylphenol in the test solution is 2.86×10 -7 mol / L, the addition of hydroquinone shortened the induction time to 670.5s. Figure 6 As shown; for the other group, 4 μL of 4.0×10 - 3 mol / L 2,3,6-trimethylphenol sample solution, so that the concentration of 2,3,6-trimethylphenol in the test solution is 3.81×10 -7 mol / L, the addition of 2,3,6-trimethylphenol makes the induction time become 571.5s. Figure 7 shown. Figure 6 、 Figure 7 It was confirmed that different concentrations of 2,3,6-trimethylphenol in the detection solution resulted in different induction times for the CAT clock system to appear. When the concentration of 2,3,6-trimethylphenol in the detection system was 9.5×10 -8 mol / L -4.76×10 -7 mol / L, the different induction times of the CAT clock system caused by different concentrations can be observed.

[0050] (3) Quantitative detection

[0051] A working curve was established based on the relationship between the concentration of 2,3,6-trimethylphenol in the detection system and the induction time, such as Figure 8 As shown in the figure, the horizontal axis is the concentration of 2,3,6-trimethylphenol in the CAT clock system, and the vertical axis is the induction time t. When the concentration of 2,3,6-trimethylphenol in the detection system is 9.5×10 -8 mol / L -4.76×10 -7 mol / L, the induction time has a linear relationship with the concentration of 2,3,6-trimethylphenol, and the linear equation is t = -1.0×10 9 +1030.4, R 2 =0.9954. Based on this, the quantitative detection of 2,3,6-trimethylphenol in the sample can be achieved. Example 3

[0052] (1) Prepare the test solution

[0053] First, distilled water was used to prepare 0.0195 mol / L NaClO2 solution, 0.00248 mol / L C4H 13NO and 0.0052mol / L Na2S4O6 solution. To a 50mL beaker, add 25.0mL 0.0195mol / LNaClO2 solution, 7mL 0.00248mol / L C4H 13 NO solution, 10mL 0.0052mol / L Na2S4O6 solution, to ensure "NaClO2-C4H 13 The concentrations of the components in the NO-Na2S4O6" CAT clock system are NaClO2 0.01116 mol / L, C4H 13 NO 0.000413mol / L, Na2S4O6 0.00124mol / L, the total volume was 42mL, and the temperature was controlled at 25℃.

[0054] At the same time, a series of 2,3,6-trimethylphenol sample solutions with different concentrations were prepared using ethanol as solvent.

[0055] (2) Obtaining CAT clock spectrum

[0056] The graph of the pH value of the prepared test solution changing with time is recorded by a computer equipped with a chemical signal acquisition and analysis program (without adding the test sample). Figure 9 As shown. The pH induction time was 1022s as a blank control. Two groups of test solutions with the same concentration of each component as the above test solution were prepared. For one group, at the beginning of the reaction, 4 μL of 4×10 -3 mol / L 2,3,6-trimethylphenol sample solution, so that the concentration of 2,3,6-trimethylphenol in the test solution is 3.81×10 -7 mol / L, the addition of 2,3,6-trimethylphenol shortened the induction time to 570s. Figure 10 As shown; for the other group, 4 μL of 5×10 -3 mol / L 2,3,6-trimethylphenol sample solution, so that the concentration of 2,3,6-trimethylphenol in the test solution is 4.76×10 -7 mol / L, the addition of 2,3,6-trimethylphenol makes the induction time become 471s. Figure 11 shown. Figure 10 、 Figure 11 It was confirmed that different concentrations of 2,3,6-trimethylphenol in the detection solution resulted in different induction times for the CAT clock system to appear. When the concentration of 2,3,6-trimethylphenol in the detection system was 9.5×10 -8 mol / L -4.76×10 -7mol / L, the different induction times of the CAT clock system caused by different concentrations can be observed.

[0057] (3) Quantitative detection

[0058] A working curve was established based on the relationship between the concentration of 2,3,6-trimethylphenol in the detection system and the induction time, such as Figure 12 As shown in the figure, the horizontal axis is the concentration of 2,3,6-trimethylphenol in the CAT clock system, and the vertical axis is the induction time t. When the concentration of 2,3,6-trimethylphenol in the detection system is 9.5×10 -8 mol / L -4.76×10 -7 mol / L, the induction time has a linear relationship with the concentration of 2,3,6-trimethylphenol, and the linear equation is t = -1.0×10 9 c+1030.57, R 2 =0.99539. Based on this, the quantitative detection of 2,3,6-trimethylphenol in the sample can be achieved.

Claims

1. A quantitative detection method for 2,3,6-trimethylphenol, characterized in that: Prepare a solution of 2,3,6-trimethylphenol, a sample to be tested, using ethanol as solvent; Application of "NaClO2-C4H 13 NO-Na2S4O6" CAT clock reaction system was used as the detection solution, in which C4H 13 NO represents tetramethylammonium hydroxide, and a graph of pH changes over time is recorded. The temperature of the CAT clock system is controlled within the range of 25±0.5°C. When the CAT clock reaction begins, equal volumes of a series of sample solutions of varying concentrations are added to the CAT clock system. Quantitative detection of the sample is achieved based on the different induction times generated by the system at varying concentrations of the sample solution in the CAT clock system. The induction time is the time required from the start of the CAT clock reaction to pH stabilization. A working curve was established based on the relationship between the concentration of the test solution in the CAT clock system and the induction time. The horizontal axis was the concentration of the test solution 2,3,6-trimethylphenol in the CAT clock system, and the vertical axis was the induction time t. When the concentration of 2,3,6-trimethylphenol in the system was 9.5×10 -8 mol / L-4.76×10 -7 When the induction time t is between 0.1% and 0.1% mol / L, there is a linear relationship between the induction time t and the concentration of 2,3,6-trimethylphenol, thereby realizing the quantitative detection of 2,3,6-trimethylphenol in the sample; The molar concentration range of each component in the test solution is: NaClO2 0.0107-0.0125mol / L, C4H 13 NO0.000294-0.000420mol / L, Na2S4O6 0.00124-0.00149mol / L.

2. The quantitative detection method according to claim 1, wherein: The molar concentrations of the components in the test solution are NaClO2 0.0116mol / L, C4H 13 NO 0.000295mol / L, Na2S4O6 0.00149mol / L.

3. The quantitative detection method according to claim 1, wherein: The temperature of the CAT clock system was controlled at 25°C when detecting 2,3,6-trimethylphenol solution.

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