CN112858275A - Method for rapidly detecting sodium glutamate in monosodium glutamate - Google Patents
Method for rapidly detecting sodium glutamate in monosodium glutamate Download PDFInfo
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- CN112858275A CN112858275A CN202110092812.3A CN202110092812A CN112858275A CN 112858275 A CN112858275 A CN 112858275A CN 202110092812 A CN202110092812 A CN 202110092812A CN 112858275 A CN112858275 A CN 112858275A
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Abstract
A method for rapidly detecting sodium glutamate in monosodium glutamate relates to the field of monosodium glutamate detection, weighing a colorimetric tube with 1.0g to 10mL of monosodium glutamate, adding water to dissolve the colorimetric tube, diluting to a scale of 10mL, covering and plugging the colorimetric tube, uniformly mixing, taking 2mL of the uniformly mixed solution, putting the solution into another colorimetric tube with 10mL, adding water to dissolve the solution, and diluting to a scale of 10mL to obtain a solution A; 2mL of the solution A is put into a 100mL triangular flask, 10mL of formaldehyde solution is added, 60mL of water is added, a phenolphthalein indicator is added, the mixture is shaken up to obtain monosodium glutamate purity determination solution B, 0.1mol/L NaOH solution is added into the triangular flask, a dropping bottle is adopted to titrate the monosodium glutamate purity determination solution B, and the color of the solution is changed from colorless to pink when the last drop of NaOH solution is dropped; 8 drops of 0.02g/L phenolphthalein indicator is added, so that the error is small, when the concentration of the formaldehyde solution is 37-40%, the color change is easier to observe in the titration result judgment, and the titration reaction precision is higher.
Description
Technical Field
The invention relates to the field of monosodium glutamate detection, and in particular relates to a method for quickly detecting sodium glutamate in monosodium glutamate.
Background
Gourmet powder, also known as "monosodium glutamate", is known as "sodium glutamate". The finished product is white columnar crystal or crystalline powder, and is one of the fresh-increasing seasonings widely used at home and abroad at present. The main components of the seasoning are glutamic acid and salt, and the seasoning is often used as a home seasoning in daily life to improve the delicate flavor of food. The monosodium glutamate can increase the delicate flavor of food, stimulate appetite of people, and is helpful for improving the digestibility of the food for human bodies. In addition, sodium glutamate, the main ingredient of monosodium glutamate, has the functions of treating chronic hepatitis, hepatic coma, neurasthenia, epilepsy, achlorhydria and other diseases. When the monosodium glutamate is excessively ingested, the inhibitory neurotransmitter can inhibit various nerve functions in a human body, so that a series of symptoms such as dizziness, headache, somnolence, muscle spasm and the like appear; people can also be scorched and have confusion; some people with more sensitive constitution may even feel aching bone and muscle weakness. In addition, excessive inhibitory neurotransmitters inhibit the secretion of thyroid stimulating hormone from the lower brain of the human body, which interferes with bone development, and the effect on children is particularly remarkable.
The existing methods for measuring monosodium glutamate mainly comprise an optical rotation method, a perchloric acid titration method, an acidimetric method and the like, and although the three methods are chemical methods, the three methods have large errors, low accuracy and long detection time.
In actual work, the optical rotation method is simple, convenient and quick to operate, stable in data, small in relative standard deviation and not preferred. However, if sucrose is added to the product, the measurement of the content of sodium glutamate by the optical rotation method is interfered and influenced. Since sucrose is optically active as sodium glutamate. As the content of the sucrose is increased, the absolute value of the optical rotation of the sucrose is increased according to a certain proportion. This makes it impossible to accurately determine the sodium glutamate content in monosodium glutamate by optical rotation.
The perchloric acid titration method can effectively eliminate the interference of substances such as cane sugar, starch and the like, and accurately measure the content of the sodium glutamate. However, it should be noted that perchloric acid and glacial acetic acid in a perchloric acid standard solution are volatile, and the concentration of perchloric acid and glacial acetic acid is greatly changed along with the time, so that the perchloric acid and glacial acetic acid are required to be calibrated again before each use, and the perchloric acid and glacial acetic acid standard solution is troublesome to use in actual work.
The acidimetric method has no reference electrode, and when the difference between the standard solution and the measured object is too large during detection, the result has certain drift, and then the cleaning cost is a little (when the measured liquid and the measured liquid are mixed), so that the acidimetric method is not suitable for the technical field of rapid detection.
Disclosure of Invention
In order to solve the problems in the prior art, the invention provides a method for rapidly detecting sodium glutamate in monosodium glutamate.
The technical scheme is as follows: a method for rapidly detecting sodium glutamate in monosodium glutamate comprises the following steps: (1) accurately weighing 1.0g to 10mL of monosodium glutamate in a colorimetric tube, adding water to dissolve the monosodium glutamate, diluting to 10mL of scales, covering and uniformly mixing, taking 2mL of the uniformly mixed solution, putting the uniformly mixed solution into another 10mL colorimetric tube, adding water to dissolve the uniformly mixed solution, and diluting to 10mL of scales to obtain a solution A.
(2) And 2mL of the solution A is taken and placed into a 100mL triangular flask, 10mL of formaldehyde solution is added, 60mL of water is added, a phenolphthalein indicator is added, the mixture is shaken up to obtain monosodium glutamate purity determination solution B, 0.1mol/L NaOH solution is added into the triangular flask, a dropping bottle is adopted to titrate the monosodium glutamate purity determination solution B, the color change of the solution is observed while the titration is carried out, when the last one drop of NaOH solution is dropped, the color of the solution is changed from colorless to pink, and the solution does not change color within half a minute after standing.
(3) Under the condition of constant sampling quantity, the content of each drop of the measuring solution is calculated according to the equivalent 3.0 percent of sodium glutamate, and a reagent blank test is carried out at the same time.
Preferably, distilled water or purified water is adopted as water in the step (1).
Preferably, the concentration of the formaldehyde solution in step (2) is 37-40%.
Preferably, 8 drops of phenolphthalein indicator are added in step (2).
Preferably, the concentration of the phenolphthalein indicator in the step (2) is 0.02 g/L.
Preferably, step (3) blank test: 60mL of water and 10mL of 37-40% formaldehyde solution are mixed with 8 drops of 0.02g/L phenolphthalein indicator, and the mixture is titrated to pink color with 0.1mol/L NaOH solution, and the number of drops of consumed measuring solution is counted.
The invention has the beneficial effects that:
(1) the phenolphthalein indicator is adopted, the phenolphthalein indicator does not change color when meeting acidic substances and does not change color when meeting neutral substances, but the phenolphthalein indicator changes into red when meeting alkaline substances, and compared with other indicators, the phenolphthalein indicator is simpler and quicker in color without gradual change in the middle;
(2) according to the invention, 8 drops of 0.02g/L phenolphthalein indicator is added, so that the error is small, when the concentration of the formaldehyde solution is 37-40%, the color change is easier to observe in the titration result judgment, and the titration reaction precision is higher;
(3) the method can quickly and accurately complete the test, and has the advantages of simple and convenient operation, quickness, stable data, small relative standard deviation, short time and the like.
Detailed Description
In order to better understand the invention, the following description of the implementation of the example further illustrate the content of the invention, but the content of the invention is not limited to the following embodiments.
Embodiment one, the method for rapidly detecting monosodium glutamate in monosodium glutamate, the step is:
(1) accurately weighing 1.0g to 10mL of monosodium glutamate in a colorimetric tube, adding water to dissolve the monosodium glutamate, diluting to 10mL of scales, covering and uniformly mixing, taking 2mL of the uniformly mixed solution, putting the uniformly mixed solution into another 10mL colorimetric tube, adding distilled water or purified water to dissolve the uniformly mixed solution, and diluting to 10mL of scales to obtain a solution A;
(2) and 2mL of the solution A is taken and put into a 100mL Erlenmeyer flask, 10mL of formaldehyde solution with the concentration of 37-40% is added, 60mL of water is added, 8 drops of phenolphthalein indicator with the concentration of 0.02g/L are added, the mixture is shaken uniformly to obtain monosodium glutamate purity determination solution B, 0.1mol/L of NaOH solution is added into the Erlenmeyer flask, the monosodium glutamate purity determination solution B is titrated by using a dropper, the color change of the solution is observed while the titration is carried out, when the last drop of NaOH solution is dripped, the color of the solution is changed from colorless to pink, and the solution does not change color after standing for half a minute.
Under the condition of unchanged sampling amount, calculating the content of each drop of the measuring solution according to the equivalent of 3.0 percent of the sodium glutamate, simultaneously carrying out a reagent blank test, mixing 60mL of water and 10mL of 37-40 percent formaldehyde solution with 8 drops of 0.02g/L phenolphthalein indicator in the blank test, titrating the mixture by using 0.1mol/L NaOH solution until the mixture is pink as same as the sample, and recording the number of drops of the consumed measuring solution.
And (4) calculating a result: the actual sample consumed 35 drops of the measurement solution, the reagent blank consumed 3 drops of the measurement solution, and the actual sample consumed 32 drops of the measurement solution, and the content of sodium glutamate in the sample was 32 × 3.0% =96% g.
Example two, the procedure was the same except that "8 drops of phenolphthalein indicator with a concentration of 0.02g/L was added" in example one, and "4 drops of phenolphthalein indicator with a concentration of 0.02g/L was added".
And (4) calculating a result: 19 drops of the measuring solution are consumed by the actual sample, 2 drops of the measuring solution are consumed by the reagent blank, 17 drops of the measuring solution are consumed by the sample, and the content of the sodium glutamate in the sample is 17 multiplied by 3.0% =51% g.
Example three, the procedure was the same as in example one except that "8 drops of phenolphthalein indicator with a concentration of 0.02g/L was added" was changed to "2 drops of phenolphthalein indicator with a concentration of 0.02 g/L".
And (4) calculating a result: the actual sample consumed 10 drops of the measurement solution, the reagent blank consumed 2 drops of the measurement solution, and the actual sample consumed 8 drops of the measurement solution, and the content of sodium glutamate in the sample was 8 × 3.0% =24% g.
The monosodium glutamate sold in the market can be divided into 99%, 98%, 95%, 90% and 80% according to the content of sodium glutamate, according to the first to third embodiments, the same sample is tested, data obtained in the second embodiment and the third embodiment are not in accordance with practical situations, and the error is too large compared with that of the first embodiment, so that multiple experiments prove that the error of the data obtained by adding 8 drops of 0.02g/L phenolphthalein indicator is minimum and is most representative.
Example four, the "37-40% formaldehyde solution" in example one was diluted 2-fold, and the other steps were the same. This example changed the color of the solution from colorless to pale pink when the last drop of NaOH solution was dropped, and did not change color within half a minute of standing.
Example five the "37-40% formaldehyde solution" in example one was diluted 2.5 times, and the other steps were the same. This example changed the color of the solution from colorless to light red when the last drop of NaOH solution was dropped, and did not change color within half a minute of standing.
Example six, in example one, the "37-40% formaldehyde solution" was diluted 4-fold, and the other steps were the same. This example changed the color of the solution from colorless to reddish when the last drop of NaOH solution was dropped, and did not change color within half a minute of standing.
Comparing the first embodiment with the fourth embodiment with the fifth embodiment with the sixth embodiment, it can be seen that, when formaldehyde solutions with different concentrations are added to the same sample and the concentration of the formaldehyde solution is 37-40%, the color change is easier to observe in the titration result judgment and the titration reaction precision is higher through multiple verification tests.
In the seventh embodiment, the procedure of "adding 8 drops of 0.02g/L phenolphthalein indicator" in the first embodiment is changed to "adding 8 drops of 0.02g/L thymol blue indicator", and the blank test is carried out by mixing 60mL of water and 10mL of 37-40% formaldehyde solution, adding 8 drops of 0.02g/L thymol blue indicator, titrating the mixture with 0.1mol/L NaOH solution until the sample becomes blue, counting the number of drops of the consumed measuring solution, and the other steps are the same as those in the first embodiment.
And titrating the monosodium glutamate purity determination solution B by using 0.1mol/L NaOH solution, observing that the color of the monosodium glutamate purity determination solution B is changed from yellow to green, and the color is changed from green to blue just when the last drop is dripped, wherein the color is not faded within half a minute.
Example eight, the "adding 8 drops of phenolphthalein indicator with a concentration of 0.02 g/L" in example one was changed to "adding 8 drops of litmus indicator with a concentration of 0.02 g/L". The blank test was carried out by mixing 60mL of water and 10mL of 37-40% formaldehyde solution with 8 drops of 0.02g/L litmus indicator, titrating the mixture with 0.1mol/L NaOH solution until the sample becomes blue, counting the number of consumed measurement solution drops, and the other steps were the same as in example one.
And titrating the monosodium glutamate purity determination solution B by using 0.1mol/L NaOH solution, observing that the solution color of the monosodium glutamate purity determination solution B is changed from red to purple, and the solution color is changed from purple to blue just when the last drop is dripped, wherein the solution color does not fade within half a minute.
The phenolphthalein indicator does not change color when meeting acidic substances and does not change color when meeting neutral substances, but changes color when meeting alkaline substances, and the middle non-gradient color is simple and quick compared with litmus and thymol blue.
In conclusion, the phenolphthalein indicator is adopted, the phenolphthalein indicator does not change color when meeting acidic substances and does not change color when meeting neutral substances, but the phenolphthalein indicator changes into red when meeting alkaline substances, and compared with other indicators, the phenolphthalein indicator is simpler and quicker in color without gradual change in the middle; 8 drops of 0.02g/L phenolphthalein indicator is added, so that the error is small, when the concentration of the formaldehyde solution is 37-40%, the color change is easier to observe in the titration result judgment, and the titration reaction precision is higher; the method can quickly and accurately complete the test, and has the advantages of simple and convenient operation, quickness, stable data, small relative standard deviation, short time and the like.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be able to cover the technical scope of the present invention by equivalent replacement or change according to the technical solution and the inventive concept of the present invention within the technical scope of the present invention.
Claims (6)
1. A method for rapidly detecting sodium glutamate in monosodium glutamate is characterized by comprising the following steps:
(1) accurately weighing 1.0g to 10mL of monosodium glutamate in a colorimetric tube, adding water to dissolve the monosodium glutamate, diluting to 10mL of scales, covering and uniformly mixing, taking 2mL of the uniformly mixed solution, putting the uniformly mixed solution into another 10mL colorimetric tube, adding water to dissolve the uniformly mixed solution, and diluting to 10mL of scales to obtain a solution A;
(2) taking 2mL of the solution A, putting the solution A into a 100mL triangular flask, adding 10mL of formaldehyde solution, adding 60mL of water, adding a phenolphthalein indicator, shaking uniformly to obtain monosodium glutamate purity determination solution B, adding 0.1mol/L NaOH solution into the triangular flask, titrating the monosodium glutamate purity determination solution B by using a dropping bottle, observing the color change of the solution while titrating, and changing the color of the solution from colorless to pink when the last drop of NaOH solution is dropped, wherein the solution does not change the color after standing for half a minute;
(3) under the condition of constant sampling quantity, the content of each drop of the measuring solution is calculated according to the equivalent 3.0 percent of sodium glutamate, and a reagent blank test is carried out at the same time.
2. The method for rapidly detecting sodium glutamate in monosodium glutamate according to claim 1, wherein distilled water or purified water is adopted as water in step (1).
3. The method for rapidly detecting sodium glutamate in monosodium glutamate according to claim 1, wherein the concentration of the formaldehyde solution in the step (2) is 37-40%.
4. The method for rapidly detecting sodium glutamate in monosodium glutamate according to claim 1, wherein 8 drops of phenolphthalein indicator is added in step (2).
5. The method for rapidly detecting sodium glutamate in monosodium glutamate according to claim 1, wherein the concentration of phenolphthalein indicator in step (2) is 0.02 g/L.
6. The method for rapidly detecting sodium glutamate in monosodium glutamate according to claim 1, wherein the blank test in step (3): 60mL of water and 10mL of 37-40% formaldehyde solution are mixed with 8 drops of 0.02g/L phenolphthalein indicator, and the mixture is titrated to pink color with 0.1mol/L NaOH solution, and the number of drops of consumed measuring solution is counted.
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Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104198479A (en) * | 2014-08-16 | 2014-12-10 | 中山鼎晟生物科技有限公司 | Rapid detection kit for sodium glutamate in gourmet powder |
| CN106770910A (en) * | 2016-11-25 | 2017-05-31 | 防城港市质量技术监督局 | A kind of assay method of organic acid content |
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2021
- 2021-01-25 CN CN202110092812.3A patent/CN112858275A/en active Pending
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104198479A (en) * | 2014-08-16 | 2014-12-10 | 中山鼎晟生物科技有限公司 | Rapid detection kit for sodium glutamate in gourmet powder |
| CN106770910A (en) * | 2016-11-25 | 2017-05-31 | 防城港市质量技术监督局 | A kind of assay method of organic acid content |
Non-Patent Citations (4)
| Title |
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| 张君: "味精中谷氨酸钠含量三种试验方法的比较", 《新农业》 * |
| 李秀凉 等: "《生物化学》", 31 August 2018, 黑龙江大学出版社 * |
| 王晓英 等: "《食品分析技术》", 31 January 2010, 华中科技大学出版社 * |
| 钟宏星 等: "鸡精调味料中谷氨酸钠测定的不确定度分析", 《食品安全质量检测学报》 * |
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