Method for rapidly detecting pyridine
The color comparison method of the reaction between a metal ion standard solution and a pyridine water standard solution solves the problems of high cost and long cycle in the existing technology for pyridine residue detection, realizes rapid and simple pyridine residue detection, improves production efficiency and reduces costs.
Patent Information
- Application Number
- CN202510922698.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-04
- Publication Date
- 2025-09-09
AI Technical Summary
The existing methods for detecting pyridine residues are costly, complex to operate, and have a long detection cycle. This makes it difficult to quickly and easily detect pyridine residues in industrial production, leading to extended production cycles and increased costs.
The metal ion standard solution is reacted with the pyridine water standard solution, and the pyridine content is quickly detected by a color comparison method, which includes preparing a metal ion standard solution and a pyridine water standard solution, shaking the mixture, and comparing the mixture with a control solution to achieve rapid determination of the pyridine content.
It significantly improves the efficiency of pyridine detection and reduces the difficulty and cost of detection. It can provide instant feedback of test results on site, reduce the risk of rework operations, and improve production efficiency.
Smart Images
Figure CN120609815A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of pyridine analysis and detection, in particular to a method for rapid detection of pyridine. Background Art
[0002] Pyridine is a key raw material in the chemical and pharmaceutical industries, but its high toxicity requires strict control of residual levels. Existing detection methods, such as gas chromatography (GC) and liquid chromatography (LC), are expensive and complex to operate, with long detection cycles. Some colorimetric methods require the synthesis of specific colorants (such as tetrathiafulvalene compounds), which are cumbersome. Pyridine is often used as a reaction solvent in the production of citrus flavonoids or diosmin. However, due to the poor water solubility of the products, pyridine is often trapped by the citrus flavonoids or diosmin, making removal difficult. In actual industrial production, pyridine is often removed by repeated water washing. However, there is a lack of simple means to detect pyridine residues in the product. Consequently, the washed product must be tested by gas chromatography to determine if the pyridine residue meets the requirements. If it fails, repeated washing is required, further extending the entire process cycle. Therefore, the industry urgently needs a method that can quickly and conveniently detect pyridine residues to improve production efficiency. Summary of the Invention
[0003] In order to solve the above technical problems, an embodiment of the present invention provides a method for rapid detection of pyridine.
[0004] To achieve the above objectives, the embodiments of the present invention adopt the following technical solutions: The present invention provides a method for rapidly detecting pyridine, comprising the following steps: A. Prepare a standard solution of metal ions with a concentration of 0.1~1.0 mol / L; B. Prepare different concentrations of pyridine water standard solutions respectively and react with the metal ion standard solution in step A as control solutions; C. Mix the pyridine sample to be tested with the metal ion standard solution in step A and shake for 0.5-15 minutes to obtain a mixed reaction solution; D. Compare the mixed reaction solution obtained in step C with the control solution in step B to obtain the pyridine content in the pyridine sample to be tested.
[0005] In some embodiments, in step A, the metal ions in the metal ion standard solution include copper ions, cuprous ions, iron ions, ferrous ions, zinc ions, silver ions, or platinum ions.
[0006] In some embodiments, in step A, the metal ion standard solution is a copper sulfate solution or a ferrous sulfate solution.
[0007] In some embodiments, in step A, the concentration of the metal ion standard solution is 0.3 mol / L.
[0008] In some embodiments, in step B, the reaction temperature is 10-50° C., and the reaction time is 10 min-8 h.
[0009] In some embodiments, in step B, the concentration of the pyridine water standard solution is 50 ppm, 100 ppm, 200 ppm, 300 ppm, 500 ppm or 1000 ppm.
[0010] In some embodiments, in step B, the volume ratio of the pyridine water standard solution to the metal ion standard solution is 1:2.
[0011] In some embodiments, in step C, the volume ratio of the pyridine sample to be tested to the metal ion standard solution is 1:2.
[0012] Compared with the existing technology, the present invention has the following advantages: Currently, pyridine detection is usually carried out by gas chromatography (GC), which takes a long time, is costly, requires high equipment requirements, and is complex to operate; and in most cases, the product needs to be dried before being tested by GC. If it fails, rework and further processing of the pyridine are required, which prolongs the production cycle and increases production costs; however, the method of the present invention can significantly improve detection efficiency, reduce detection difficulty and cost, and can perform on-site detection, provide immediate feedback on test results, and reduce the risk of rework. BRIEF DESCRIPTION OF THE DRAWINGS
[0013] Figure 1 Color comparison chart of 50ppm, 100ppm, 200ppm and 300ppm copper sulfate control solution and Example 1-3; Figure 2 GC diagram of the refined citrus flavonoids in Example 1; Figure 3 GC diagram of the refined citrus flavonoids in Example 2; Figure 4 GC diagram of the refined citrus flavonoids in Example 3; Figure 5 Color comparison chart of 100ppm, 200ppm, 300ppm and 500ppm ferrous sulfate control solution and Example 4-5; Figure 6 GC diagram of the refined citrus flavonoids in Example 4; Figure 7 GC diagram of the refined citrus flavonoids in Example 5; Figure 8 This is the GC chart of the refined citrus flavonoids in Example 6. DETAILED DESCRIPTION
[0014] The following will be combined with the accompanying drawings to clearly and completely describe the technical solutions in some embodiments of the present disclosure. Obviously, the embodiments described are only some embodiments of the present disclosure, not all embodiments. Based on the embodiments provided by the present disclosure, all other embodiments obtained by ordinary technicians in this field are within the scope of protection of the present disclosure.
[0015] Preparation of citrus flavonoids mother liquor In a 100L reactor, 45L of pyridine, 5kg of hesperidin, 1.56kg of sodium carbonate, and 1.98kg of elemental iodine were added. The temperature was raised to 75°C and the reaction was carried out for 7h. After the reaction was completed, the pyridine was removed by concentration. After concentration, 50kg of purified water was added and stirred at room temperature. The mixture was centrifuged to obtain a wet product of citrus flavonoids. The wet product was added to a 100L reactor and dissolved with a sodium hydroxide aqueous solution (2.4% mass fraction). The temperature was raised to 35°C, the pH was adjusted to 4-6 with hydrochloric acid, crystallized, and centrifuged to obtain a crude citrus flavonoids product and a crude mother liquor (the crude mother liquor was set aside: the pyridine sample to be tested). The crude citrus flavonoids product was added to a 100L reactor and dissolved with a sodium hydroxide aqueous solution (2.4% mass fraction). The temperature was raised to 35°C, the pH was adjusted to 4-6 with hydrochloric acid, crystallized, and centrifuged to obtain a refined citrus flavonoids product and a refined mother liquor (the refined mother liquor was set aside: the pyridine sample to be tested). The refined citrus flavonoids product is dried to obtain the finished citrus flavonoids product.
[0016] Preparation of diosmin stock solution To a 10L reactor, add 4.5L of pyridine, 0.5kg of hesperidin, 0.156kg of sodium carbonate, and 0.198kg of elemental iodine. Heat to 115°C and react for 3 hours. After the reaction is complete, concentrate to remove pyridine. After concentration, add 5kg of purified water, stir at room temperature, and centrifuge to obtain a wet product of diosmin. The wet product is added to a 10L reactor and dissolved with a 2.4% mass fraction sodium hydroxide aqueous solution. Heat to 35°C, adjust the pH to 7-9 with phosphoric acid, crystallize, and centrifuge to obtain a crude diosmin product and a crude mother liquor (the crude mother liquor is set aside: it is the pyridine sample to be tested). The crude diosmin is added to a 10L reactor and dissolved with a 2.4% mass fraction sodium hydroxide aqueous solution. Heat to 35°C, adjust the pH to 7-9 with hydrochloric acid, crystallize, and centrifuge to obtain a refined diosmin product and a refined mother liquor (the refined mother liquor is set aside: it is the pyridine sample to be tested). The refined diosmin product is dried to obtain the finished diosmin product.
[0017] Preparation of standard solution Prepare pyridine water standard solutions: concentrations are 50ppm, 100ppm, 200ppm, 300ppm, 500ppm, and 1000ppm respectively.
[0018] Preparation of copper sulfate standard solution Add 5.0 g of copper sulfate and 100 mL of purified water to a 250 mL conical flask to prepare a copper sulfate standard solution.
[0019] Preparation of control solution Take 5 mL of pyridine water standard solution and 10 mL of copper sulfate standard solution, mix and stir for 10 minutes to prepare a control solution.
[0020] Status of copper sulfate control solution 50ppm is blue, transparent and clear; 100ppm is light blue, transparent and clear; 200ppm is blue with a little solid suspended; 300ppm is blue with a lot of blue solid suspended; 500ppm and 1000ppm are blue with turbidity and a little blue solid (such as Figure 1 Shown are 50 ppm, 100 ppm, 200 ppm and 300 ppm copper sulfate control solutions compared to Examples 1-4 below).
[0021] Example 1
[0022] Take 5mL of the above-mentioned refined mother liquor of citrus flavonoids and add it to a 25mL colorimetric tube. Then add 10mL of the above-mentioned copper sulfate standard solution. After stirring for 10 minutes, the system becomes blue, transparent and clear. Compared with the copper sulfate control solution, the pyridine content is between 50-100ppm. The refined mother liquor is sent for gas chromatography detection, and the result shows that the residual pyridine content is 67ppm; the dried citrus flavonoids refined product is sent for gas chromatography detection, and the result shows that the residual pyridine content is 63ppm (GC test results are as follows Figure 2 ).
[0023] Example 2
[0024] Take 5 mL of the crude mother liquor of the above-mentioned citrus flavonoids and add it to a 25 mL colorimetric tube. Then add 10 mL of the above-mentioned copper sulfate standard solution and stir thoroughly for 10 minutes. A small amount of solid is suspended in the system and the solution is light blue. Compared with the copper sulfate control solution, the pyridine content is between 100-200 ppm. The crude mother liquor is sent to gas chromatography for detection, and the result shows that the residual pyridine content is 132 ppm; the dried crude citrus flavonoids is sent to gas chromatography for detection, and the result shows that the residual pyridine content is 128 ppm (GC test results are as follows Figure 3 ).
[0025] Example 3
[0026] Take 5 mL of the crude mother liquor of diosmin and add it to a 25 mL colorimetric tube. Then add 10 mL of the copper sulfate standard solution and stir thoroughly for 10 minutes. The system has solid suspension and the solution is blue. Compared with the copper sulfate control solution, the pyridine content is between 200-300 ppm. The crude mother liquor is sent to gas chromatography for detection, and the result shows 251 ppm. The dried refined diosmin is sent to gas chromatography for detection, and the result shows that the residual pyridine content is 233 ppm (GC test results are as follows Figure 4 ).
[0027] Preparation of ferrous sulfate standard solution Add 8.34 g of ferrous sulfate heptahydrate into a 250 mL conical flask, and then add 95.44 mL of purified water to prepare a ferrous sulfate standard solution. After nitrogen substitution, seal and store the flask to prepare a ferrous sulfate standard solution.
[0028] Preparation of control solution Separately take 5 mL of the above-mentioned pyridine water standard solution and 10 mL of the ferrous sulfate standard solution and mix them thoroughly to react to prepare a reference solution (light yellow). After nitrogen substitution, seal and store the reference solution to prepare a reference solution.
[0029] Status of ferrous sulfate control solution 50ppm light yellow, transparent and clear; 100ppm light yellow, transparent and clear; 200ppm yellow, slightly turbid with a few solids; 300ppm light yellow, turbid with a lot of yellow solids; 500ppm brownish yellow, turbid with a lot of solids; 1000ppm green, turbid with a lot of green solids (Comparison chart of ferrous sulfate and implementation case as shown in the figure) Figure 5 ).
[0030] Example 4
[0031] Take 5 mL of the above-mentioned refined mother liquor of citrus flavonoids and add it to a 25 mL colorimetric tube. Then add 10 mL of the above-mentioned ferrous sulfate standard solution. After stirring for 10 minutes, the system is light yellow and slightly turbid with a small amount of solid. Compared with the ferrous sulfate control solution, the pyridine content is between 100-200 ppm. The refined mother liquor is sent for gas chromatography, and the results show that the residual pyridine content is 159 ppm; the dried citrus flavonoids refined product is sent for gas chromatography detection, and the results show that the residual pyridine content is 137 ppm (GC test results are as follows Figure 6 ).
[0032] Example 5
[0033] Take 5mL of the crude citrus flavonoids mother liquor and add it to a 25mL colorimetric tube. Then add 10mL of the ferrous sulfate standard solution and stir thoroughly. The system is light yellow and turbid with a large amount of yellow solid. Compared with the ferrous sulfate control solution, the pyridine content is between 300-500ppm. The crude citrus flavonoids mother liquor is sent for gas chromatography, and the result shows that the residual pyridine content is 332ppm. The dried crude citrus flavonoids is sent for gas chromatography, and the result shows that the residual pyridine content is 335ppm (GC test results are as follows Figure 7 ).
[0034] Example 6
[0035] Take 5 mL of the above-mentioned refined mother liquor of diosmin and add it to a 25 mL colorimetric tube. Then add 10 mL of the above-mentioned ferrous sulfate standard solution. After stirring for 10 minutes, the system is light yellow and slightly turbid with a small amount of solid. Compared with the ferrous sulfate control solution, the pyridine content is between 100-200 ppm. The refined mother liquor is sent for gas chromatography, and the results show that the residual pyridine content is 148 ppm; the dried refined product is sent for gas chromatography, and the results show that the residual pyridine content is 121 ppm (GC test results are as follows Figure 8 ).
[0036] In the description of this specification, specific features, structures, materials or characteristics may be combined in an appropriate manner in any one or more embodiments or examples.
[0037] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.
Claims
1. A method for rapid detection of pyridine, characterized in that, The following steps are involved: A. Prepare a standard solution of metal ions with a concentration of 0.1~1.0 mol / L; B. Prepare different concentrations of pyridine water standard solutions respectively and react with the metal ion standard solution in step A as control solutions; C. Mix the pyridine sample to be tested with the metal ion standard solution in step A and shake for 0.5-15 minutes to obtain a mixed reaction solution; D. Compare the mixed reaction solution obtained in step C with the control solution in step B to obtain the pyridine content in the pyridine sample to be tested.
2. The method according to claim 1, characterized in that In step A, the metal ions in the metal ion standard solution include copper ions, cuprous ions, iron ions, ferrous ions, zinc ions, silver ions or platinum ions.
3. The method according to claim 1, characterized in that In step A, the metal ion standard solution is a copper sulfate solution or a ferrous sulfate solution.
4. The method according to claim 1, wherein In step A, the concentration of the metal ion standard solution is 0.3 mol / L.
5. The method according to claim 1, wherein In step B, the reaction temperature is 10-50° C., and the reaction time is 10 min-8 h.
6. The method according to claim 1, characterized in that In step B, the concentration of the pyridine water standard solution is 50 ppm, 100 ppm, 200 ppm, 300 ppm, 500 ppm or 1000 ppm.
7. The method according to claim 1, characterized in that In step B, the volume ratio of the pyridine water standard solution to the metal ion standard solution is 1:
2.
8. The method according to claim 1, characterized in that In step C, the volume ratio of the pyridine sample to be tested to the metal ion standard solution is 1:2.