A method for distinguishing glycine and sarcosine

Abstract

The application is a method for distinguishing glycine and sarcosine, characterized in that a "Na2SO3-Na2S2O3-KIO3-D-gluconic acid-delta-lactone" pH clock reaction system is used as a distinguishing solution, equal volumes of sample solutions of glycine and sarcosine to be distinguished at the same concentration are added into two groups of pH clock reaction systems respectively, and qualitative analysis of glycine and sarcosine is realized according to the different induction time of the sample to be distinguished to the pH clock reaction system. The qualitative analysis method for glycine and sarcosine has the characteristics of high accuracy, easy operation, convenience and the like.

Description

Technical Field

[0001] This invention relates to a method for differentiation, specifically, to establish a pH clock reaction system of "Na2SO3-Na2S2O3-KIO3-D-gluconic acid-δ-lactone", which differentiates the samples based on the different induction times of the pH clock system produced by the samples to be differentiated, and belongs to the field of analytical chemistry. Background Technology

[0002] Glycine (see structural formula (Ⅰ)) is a white to grayish-white crystalline powder and an important biomolecule that participates in various metabolic and signal transduction processes in living organisms. Glycine has a wide range of applications. In medicine, it is an important component of amino acid infusions and complete nutritional preparations, and is also used as an adjunct treatment for diseases such as hyperacidity and chronic enteritis, exhibiting various physiological activities such as liver protection and neuroprotection. In the food industry, glycine is used as a nutritional supplement, flavoring agent, and preservative in beverages, meat products, and baked goods to enhance flavor and extend shelf life. In agriculture, glycine is a key raw material for the synthesis of pesticides such as glyphosate and can also be used as a feed additive to promote animal growth. In the chemical and daily chemical industries, glycine is used to prepare electroplating additives, cosmetics, and hair dyes, playing a role in buffering, complexing, and stabilizing.

[0003] Sarcosine (see structural formula (II)), also known as N-methylglycine, is a white crystalline powder and a naturally occurring amino acid derivative found in the human body and food. In medicine, sarcosine is an important active amino acid component in the human body, used as an adjunct treatment for muscle damage, metabolic disorders, and cognitive decline, exhibiting various physiological activities such as anti-inflammatory repair, liver and brain protection, and improvement of muscle loss. In the food industry, sarcosine is used as a nutritional fortifier and preservative in functional beverages, sports foods, and snack foods. In agriculture, sarcosine can be used as a high-quality feed additive to promote muscle growth in livestock and aquatic animals, improve meat quality, reduce stress, and effectively promote healthy weight gain. In the chemical and daily chemical industries, sarcosine is used to prepare biosurfactants, skin care additives, and raw materials for washing and conditioning formulas, playing a role in oil control, soothing, antioxidant stabilization, moisturizing, and repairing functions.

[0004] Many natural foods, such as red meat, legumes, seafood, grains, and traditional Chinese medicine, contain both sarcosine and glycine. Both are important amino acids that participate in energy metabolism, substance synthesis, and physiological regulation. However, their structures differ; sarcosine is a derivative of glycine with an additional methyl group on its α-amino group. Therefore, their physicochemical properties, biological activities, target sites, and safe dosages also differ. Their metabolic pathways, pharmacological effects, mechanisms of action, and toxicological characteristics in vivo also differ significantly. Glycine focuses on nutritional supplementation, buffering, and basal metabolic regulation, while sarcosine focuses on muscle energy supply, anti-inflammatory repair, and metabolic regulation; their functional applications are irreplaceable. Therefore, accurately distinguishing between the two is crucial for the development of medical amino acid preparations, functional food formulations, precise detection of disease biomarkers, drug design, and precision manufacturing in industry and agriculture.

[0005] Currently, methods for detecting glycine and sarcosine include high-performance infrared spectroscopy, liquid chromatography, and proton nuclear magnetic resonance spectroscopy. However, most of these methods require large equipment and are expensive, making them unsuitable for on-site testing. Therefore, finding a detection and analysis method that is effective, easy to operate, and rapid is essential.

[0006]

[0007] Structural formula (I) Structure of glycine

[0008] Structure of sarcosine (II) Summary of the Invention

[0009] This invention aims to provide a novel and convenient method for distinguishing glycine and sarcosine. Specifically, it utilizes a pH clock reaction system of "Na2SO3-Na2S2O3-KIO3-D-gluconic acid-δ-lactone" as the distinguishing solution for qualitative detection of sample solutions. This method is based on the different sensitivity responses of this pH clock system to different amino acids. Specifically, the "Na2SO3-Na2S2O3-KIO3-D-gluconic acid-δ-lactone" pH clock reaction system is used as the distinguishing solution, and the pH change over time is recorded. When the pH clock reaction begins, equal volumes and concentrations of sample solutions containing glycine and sarcosine are added to the two pH clock systems. The qualitative distinction of the samples is achieved based on the different induction times of the pH clock system responses to the samples.

[0010] The difference between this qualitative differentiation method and existing technologies lies in the fact that this invention uses a pH clock reaction system of "Na2SO3-Na2S2O3-KIO3-D-gluconic acid-δ-lactone" as the differentiation solution. The differentiation of samples is achieved based on the different induction times of the pH clock reaction system on the samples to be differentiated: if the induction time of the pH clock is slightly prolonged after adding the differentiation solution, the added sample contains glycine; if the induction time of the pH clock is significantly prolonged after adding the differentiation solution, the added sample contains sarcosine. The induction time is the time required from the start of the pH clock reaction system reaction to the pH reaching its lowest point. When the sample solution to be distinguished is detected in the distinguishing solution (pH clock system), the temperature of the pH clock system is controlled at any specific temperature within the range of 20-30 ℃.

[0011] The distinguishable concentration range of glycine and sarcosine in the distinguishing solution is 3 × 10⁻⁶. -4 mol / L - 1.7625×10 -3 mol / L.

[0012] The concentration range that the above-mentioned solutions can distinguish is the optimal concentration range determined experimentally. Within this concentration range, the effects of glycine and sarcosine on the distinguishing solution are significantly different, easy to observe and analyze, and easy to distinguish. Furthermore, the concentration ranges of each component in the distinguishing solution (pH clock system) are shown in Table 1, and the optimal concentrations of the distinguishing solution (pH clock system) obtained through multiple experiments are shown in Table 2. Table 1: Concentration of each component in the pH clock system

[0013] Table 2: Optimal concentrations of each component in the pH clock system

[0014] The specific experimental steps are as follows: 1. Prepare 40 mL of differentiating solution (pH clock system) according to the concentration range specified in Table 1, maintaining its temperature at a specific value between 20-30 ℃. Insert the prepared working electrode (pH composite 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). After setting the acquisition time and sampling rate in the chemical signal acquisition and analysis program on the computer, quickly click the start button to monitor the pH of the solution. The computer records the pH change curve of the clock system over time, i.e., the pH clock spectrum. When a substance needs to be detected, add the analyte immediately after the pH clock system reaction begins, and record the pH change over time in the same manner.

[0015] The basic parameters of a pH clock spectrum include: Induction time: The time required for the pH clock system reaction to begin and for the pH to reach its lowest point. Attached Figure Description

[0016] Figure 1 This is a graph showing the change in pH value of the distinguishing solution (pH clock system) over time when no sample to be distinguished was added in Example 1.

[0017] Figure 2 In Example 1, 3×10 -4 After adding mol / L glycine, a graph showing the change in pH value of the solution (pH clock system) over time was obtained.

[0018] Figure 3 In Example 1, 3×10 -4 After adding mol / L sarcosine, a graph showing the change in pH value of the solution (pH clock system) over time was obtained.

[0019] Figure 4 This is a graph showing the change in pH value of the distinguishing solution (pH clock system) over time when no sample to be distinguished was added, as shown in Example 2.

[0020] Figure 5 In Example 2, 9.75 × 10 -4 After adding mol / L glycine, a graph showing the change in pH value of the solution (pH clock system) over time was obtained.

[0021] Figure 6 In Example 2, 9.75 × 10 -4 After adding mol / L sarcosine, a graph showing the change in pH value of the solution (pH clock system) over time was obtained.

[0022] Figure 7This is a graph showing the change in pH value of the distinguishing solution (pH clock system) over time when no sample to be distinguished was added, as shown in Example 3.

[0023] Figure 8 In Example 3, 1.7625 × 10 -3 After adding mol / L glycine, a graph showing the change in pH value of the solution (pH clock system) over time was obtained.

[0024] Figure 9 In Example 3, 1.7625 × 10 -3 After adding mol / L sarcosine, a graph showing the change in pH value of the solution (pH clock system) over time was obtained. Detailed Implementation Example 1

[0025] This embodiment verifies the feasibility of the method for distinguishing glycine and sarcosine according to the following steps: (1) Preparation of differentiating solutions First, prepare 0.188 mol / L Na2SO3 solution, 0.0153 mol / L Na2S2O3 solution, 0.152 mol / L KIO3 solution and 0.1 mol / L D-gluconic acid-δ-lactone solution using distilled water. Add 12.9 mL of 0.188 mol / L Na₂SO₃ solution, 5.1 mL of 0.0153 mol / L Na₂S₂O₃ solution, 6.1 mL of 0.152 mol / L KIO₃ solution, and 15.9 mL of 0.1 mol / L D-gluconic acid-δ-lactone solution sequentially to a 50 mL beaker to ensure that the concentrations of each component in the “Na₂SO₃-Na₂S₂O₃-KIO₃-D-gluconic acid-δ-lactone” pH clock system are: Na₂SO₃ 0.06063 mol / L, Na₂S₂O₃ 0.00195075 mol / L, KIO₃ 0.02318 mol / L, and D-gluconic acid-δ-lactone. The concentration was 0.03975 mol / L, the total volume was 40 mL, and the temperature was controlled at 24 ℃.

[0026] Simultaneously, using distilled water as a solvent, prepare 0.3... A sample solution containing glycine and sarcosine at a concentration of mol / L to be distinguished.

[0027] (2) Obtain pH clock spectrum The pH value of the prepared differentiating solution (pH clock system) over time was plotted by a computer equipped with a chemical signal acquisition and analysis program (without the sample to be tested added). For example... Figure 1As shown, the pH induction time was 625 s as a blank control. Two additional groups of differentiating solutions were prepared with the same concentrations of each component as the aforementioned differentiating solutions. For one group, at the start of the reaction, 40 μL of 0.3 mol / L glycine sample solution was added to a 40 mL pH clock system, resulting in a glycine concentration of 3 × 10⁻⁶ in the differentiating solution. -4 The addition of glycine at a concentration of mol / L prolonged the induction time to 639 s. Figure 2 As shown; for the other group, at the start of the reaction, 40 μL of 0.3 mol / L sarcosine sample solution was added to a 40 mL pH clock system, so that the concentration of sarcosine in the distinguishing solution was 3 × 10⁻⁶. -4 The addition of mol / L creatine prolonged the induction time to 651 s. Figure 3 As shown.

[0028] (3) Distinguish Because glycine and sarcosine have different structures, their effects on the induction time of the pH clock system also differ. (Comparison) Figure 1 , Figure 2 , Figure 3 It can be seen that the addition of glycine slightly prolongs the induction time of the pH clock compared to the time without the sample being tested; the addition of sarcosine significantly prolongs the induction time of the pH clock compared to the time without the sample being tested. These experiments demonstrate that glycine and sarcosine can be distinguished by comparing the changes in the induction time of the pH clock system.

[0029] Take two pre-prepared 0.3 mol / L solutions of the samples to be distinguished (one is a glycine solution, and the other is a sarcosine solution, but the two have not yet been distinguished), label one as Sample 1 and the other as Sample 2; prepare two sets of distinguishing solutions with the same concentration of each component as above, and add 40 μL of 0.3 mol / L Sample 1 and Sample 2 to each solution, so that their concentrations in the distinguishing solutions are 3 × 10⁻⁶. -4 mol / L.

[0030] Analysis and comparison show that the addition of sample 1 slightly prolongs the induction time of the pH clock system (induction time and...). Figure 2 Corresponding to, and Figure 3 (Not corresponding), while the addition of sample 2 significantly prolonged the induction time of the pH clock system (induction time and Figure 3 Corresponding to, and Figure 2 (Not corresponding). Therefore, Sample 1 is a glycine solution and Sample 2 is a sarcosine solution, thus achieving the distinction between glycine and sarcosine. Example 2

[0031] This embodiment verifies the feasibility of the method for distinguishing glycine and sarcosine according to the present invention through the following steps: (1) Preparation of differentiating solutions First, prepare 0.188 mol / L Na2SO3 solution, 0.0153 mol / L Na2S2O3 solution, 0.152 mol / L KIO3 solution and 0.1 mol / L D-gluconic acid-δ-lactone solution using distilled water. Add 13 mL of 0.188 mol / L Na₂SO₃ solution, 5 mL of 0.0153 mol / L Na₂S₂O₃ solution, 6 mL of 0.152 mol / L KIO₃ solution, and 16 mL of 0.1 mol / L D-gluconic acid-δ-lactone solution sequentially to a 50 mL beaker to ensure that the concentrations of each component in the “Na₂SO₃-Na₂S₂O₃-KIO₃-D-gluconic acid-δ-lactone” pH clock system are: Na₂SO₃ 0.0611 mol / L, Na₂S₂O₃ 0.0019125 mol / L, KIO₃ 0.0228 mol / L, and D-gluconic acid-δ-lactone. The concentration was 0.04 mol / L, the total volume was 40 mL, and the temperature was controlled at 24 ℃.

[0032] Simultaneously, using distilled water as a solvent, prepare 0.3... A sample solution containing glycine and sarcosine at a concentration of mol / L to be distinguished.

[0033] (2) Obtain pH clock spectrum The pH value of the prepared differentiating solution (pH clock system) over time was plotted by a computer equipped with a chemical signal acquisition and analysis program (without the sample to be tested added). For example... Figure 4 As shown, the pH induction time was 623 s as a blank control. Two additional groups of differentiating solutions were prepared with the same concentrations of each component as the aforementioned differentiating solutions. For one group, at the start of the reaction, 130 μL of 0.3 ppm pH solution was added to a 40 mL pH clock system. A glycine sample solution of mol / L resulted in a glycine concentration of 9.75 × 10⁻⁶ mol / L in the differentiating solution. -4 The addition of glycine at a concentration of mol / L prolonged the induction time to 650 s. Figure 5 As shown; for the other group, at the start of the reaction, 130 μL of 0.3 mol / L sarcosine sample solution was added to a 40 mL pH clock system, so that the concentration of sarcosine in the distinguishing solution was 9.75 × 10⁻⁶. -4 The addition of creatine at a concentration of mol / L prolonged the induction time to 661 s. Figure 6 As shown.

[0034] (3) Distinguish Because glycine and sarcosine have different structures, their effects on the induction time of the pH clock system also differ. (Comparison) Figure 4 , Figure 5 , Figure 6 It can be seen that the addition of glycine slightly prolongs the induction time of the pH clock compared to the time without the sample being tested; the addition of sarcosine significantly prolongs the induction time of the pH clock compared to the time without the sample being tested. These experiments demonstrate that glycine and sarcosine can be distinguished by comparing the changes in the induction time of the pH clock system.

[0035] Take two pre-prepared 0.3 mol / L solutions of the samples to be differentiated (one is a glycine solution, and the other is a sarcosine solution, but the two have not yet been distinguished), label one as Sample 1 and the other as Sample 2; prepare two sets of differentiating solutions with the same concentrations of each component as described above, and add 130 μL of 0.3 mol / L Sample 1 and Sample 2 to each solution, so that their concentrations in the differentiating solutions are 9.75 × 10⁻⁶. -4 mol / L.

[0036] Analysis and comparison show that the addition of sample 1 slightly prolongs the induction time of the pH clock system (induction time and...). Figure 5 Corresponding to, and Figure 6 (Not corresponding), while the addition of sample 2 significantly prolonged the induction time of the pH clock system (induction time and Figure 6 Corresponding to, and Figure 5 (Not corresponding). Therefore, Sample 1 is a glycine solution and Sample 2 is a sarcosine solution, thus achieving the distinction between glycine and sarcosine. Example 3

[0037] This embodiment verifies the feasibility of the method for distinguishing glycine and sarcosine according to the present invention through the following steps: (1) Preparation of differentiating solutions First, prepare 0.188 mol / L Na2SO3 solution, 0.0153 mol / L Na2S2O3 solution, 0.152 mol / L KIO3 solution and 0.1 mol / L D-gluconic acid-δ-lactone solution using distilled water. Add 13.1 mL of 0.188 mol / L Na₂SO₃ solution, 5.2 mL of 0.0153 mol / L Na₂S₂O₃ solution, 5.9 mL of 0.152 mol / L KIO₃ solution, and 15.8 mL of 0.1 mol / L D-gluconic acid-δ-lactone solution sequentially to a 50 mL beaker to ensure that the concentrations of each component in the “Na₂SO₃-Na₂S₂O₃-KIO₃-D-gluconic acid-δ-lactone” pH clock system are: Na₂SO₃ 0.06157 mol / L, Na₂S₂O₃ 0.001989 mol / L, KIO₃ 0.02242 mol / L, and D-gluconic acid-δ-lactone. The concentration was 0.0395 mol / L, the total volume was 40 mL, and the temperature was controlled at 24 ℃.

[0038] Simultaneously, using distilled water as a solvent, prepare 0.3... Sample solutions of glycine and sarcosine to be distinguished at mol / L.

[0039] (2) Obtain pH clock spectrum The pH value of the prepared differentiating solution (pH clock system) over time was plotted by a computer equipped with a chemical signal acquisition and analysis program (without the sample to be tested added). For example... Figure 7 As shown, the pH induction time was 627 s as a blank control. Two additional groups of differentiating solutions were prepared with the same concentrations of each component as the aforementioned differentiating solutions. For one group, at the start of the reaction, 235 μL of 0.3 mol / L glycine sample solution was added to 40 mL of the pH clock system, resulting in a glycine concentration of 1.7625 × 10⁻⁶ in the differentiating solution. -3 The addition of glycine at a concentration of mol / L prolonged the induction time to 666 s. Figure 8 As shown; for the other group, at the start of the reaction, 235 μL of 0.3 mol / L sarcosine sample solution was added to a 40 mL pH clock system, so that the concentration of sarcosine in the distinguishing solution was 1.7625 × 10⁻⁶. -3 The addition of creatine at a concentration of mol / L prolonged the induction time to 683 s. Figure 9 As shown.

[0040] (3) Distinguish Because glycine and sarcosine have different structures, their effects on the induction time of the pH clock system also differ. (Comparison) Figure 7 , Figure 8 , Figure 9 It can be seen that the addition of glycine slightly prolongs the induction time of the pH clock compared to the time without the sample being tested; the addition of sarcosine significantly prolongs the induction time of the pH clock compared to the time without the sample being tested. These experiments demonstrate that glycine and sarcosine can be distinguished by comparing the changes in the induction time of the pH clock system.

[0041] Take two pre-prepared 0.3 mol / L solutions of the samples to be differentiated (one is a glycine solution, and the other is a sarcosine solution, but the two have not yet been distinguished), label one as Sample 1 and the other as Sample 2; prepare two sets of differentiating solutions with the same concentrations of each component as described above, and add 235 μL of 0.3 mol / L Sample 1 and Sample 2 to each solution, so that their concentrations in the differentiating solutions are 1.7625 × 10⁻⁶. -3 mol / L.

[0042] Analysis and comparison show that the addition of sample 1 slightly prolongs the induction time of the pH clock system (induction time and...). Figure 8 Corresponding to, and Figure 9 (Not corresponding), while the addition of sample 2 significantly prolonged the induction time of the pH clock system (induction time and...). Figure 9 Corresponding to, and Figure 8 (Not corresponding). Therefore, Sample 1 is a glycine solution and Sample 2 is a sarcosine solution, thus achieving the distinction between glycine and sarcosine.

[0043] As can be seen from the above examples, the concentration is 3×10 -4 mol / L - 1.7625×10 -3 Glycine and sarcosine in the mol / L range can be distinguished using the method of this invention.

Claims

1. A method for distinguishing between glycine and sarcosine, characterized in that: A sample solution for distinguishing glycine and sarcosine was prepared using distilled water as a solvent. The pH clock reaction system of "Na2SO3-Na2S2O3-KIO3-D-gluconic acid-δ-lactone" was used as the distinguishing solution, and the pH value of the clock system was recorded over time. The pH clock system temperature is controlled at any specific temperature within the range of 20-30℃. When the pH clock reaction begins, equal volumes of glycine and sarcosine solutions of the samples to be distinguished are added to two sets of pH clock reaction systems of the same concentration. The samples to be distinguished are differentiated based on the different induction times of the pH clock reaction system caused by the samples to be distinguished: if the induction time of the pH clock is slightly prolonged after adding the solution to be distinguished, the added sample to be distinguished is a sample containing glycine; if the induction time of the pH clock is significantly prolonged after adding the solution to be distinguished, the added sample to be distinguished is a sample containing sarcosine. The induction time is the time required from the start of the pH clock reaction system to the pH reaching its lowest point. The molar concentration ranges of each component in the distinguishing solution are: Na₂SO₃ 0.06-0.07 mol / L, Na₂S₂O₃ 0.0015-0.0025 mol / L, KIO₃ 0.02-0.03 mol / L, and D-gluconic acid-δ-lactone 0.035-0.045 mol / L; the distinguishable concentration range of the sample solution in the distinguishing solution is 3 × 10⁻⁶ mol / L. -4 mol / L - 1.7625×10 -3 mol / L.

2. The method according to claim 1, characterized in that: The molar concentrations of the components in the solution were: Na₂SO₃ 0.0611 mol / L, Na₂S₂O₃ 0.0019125 mol / L, KIO₃ 0.0228 mol / L, and D-gluconic acid-δ-lactone 0.04 mol / L.

3. The method according to claim 1, characterized in that: The clock system temperature is controlled at 24 ℃.

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