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    Home > Chemicals Industry > Chemical Technology > Content determination method included in the general rules of "Chinese Pharmacopoeia" (1)

    Content determination method included in the general rules of "Chinese Pharmacopoeia" (1)

    • Last Update: 2022-06-29
    • Source: Internet
    • Author: User
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    The general methods of content determination included in the four general rules of the 2015 edition of the Chinese Pharmacopoeia mainly include ultraviolet spectrophotometry, high performance liquid chromatography, gas chromatography, thin layer chromatography, nitrogen determination, volatile oil determination, and tannin determination.


    The following mainly introduces the content determination methods included in the General Rules of the Chinese Pharmacopoeia


    1.


    (1) Brief description

    1.


    Measuring method (General 2204) for a predetermined volatile oil 2.


    (2) Instruments and utensils

    1.



    2.


    3.


    (3) Reagents and reagents

    1.


    2.


    (4) Operation method

    1.


    2.


    (5) Calculation


    In the formula, V is the amount of volatile oil; W is the weight of the test product


    2.


    (1) Brief description

    From 1985 to 2000 edition of the Chinese Pharmacopoeia, the tannin content determination method has been used in the skin powder method.
    Although it has a wide range of applications, it has a large amount of sample consumption, a long measurement time, and no selectivity.
    The test results are high, and the amount of skin powder Great shortcomings
    .
    In recent years, it is difficult to guarantee the supply and quality of skin powder reagents, which greatly restricts the application of skin powder method
    .
    The 2005 edition of "Chinese Pharmacopoeia" was revised to phosphomolybdic acid-casein ultraviolet-visible spectrophotometry
    .
    The 2015 edition of the "Chinese Pharmacopoeia" four-part tannin content determination method (General Rule 2202) still uses this determination method
    .

    (2) Instruments and utensils

    1.
    Ultraviolet-visible spectrophotometer
    .

    2.
    Measuring flasks and pipettes
    .

    (3) Test drug and test solution

    1.
    Gallic acid reference substance
    .

    2.
    Phosphoric acid , hydrochloric acid (analytical grade)
    .

    3.
    Casein (biochemical reagent)

    4.
    Phosphomolybdotungstic acid test solution: Take 100g of sodium tungstate and 50g of sodium molybdate, add 700ml of water to dissolve, add 100ml of hydrochloric acid, 50ml of phosphoric acid , heat and reflux for 10 hours, let cool, then add 150g of lithium sulfate , 50ml of water and 0.
    2 of bromine.
    ml, boil to remove residual bromine (about 15 minutes), let cool, dilute to 100ml with water, filter, and get it
    .
    This product must not be green (if it turns green after being placed, add 0.
    2ml of bromine and boil to remove the excess bromine, that's it)
    .

    5.
    Sodium carbonate test solution: Take 12.
    5g of sodium carbonate or 10.
    5g of anhydrous sodium carbonate , add water to dissolve it into 100ml, and get it
    .

    (4) Operation method

    This measurement should be operated in the dark
    .

    1.
    Preparation of reference substance solution.
    Weigh 50mg of gallic acid reference substance accurately, put it in a 100ml brown volumetric flask, add water to dissolve and dilute to the mark, accurately measure 5ml, place it in a 50ml brown volumetric flask, dilute to the mark with water, shake well, Immediately
    .

    2.
    Preparation of the standard curve Precisely measure 0.
    5ml, 1ml, 2ml, 3ml, 4ml, 5ml of the reference solution and put them into 25ml brown measuring flasks.
    Add 1ml of phosphomolybdotungstic acid test solution, and then add 11.
    5ml, 11ml of water respectively.
    , 10ml, 9ml, 8ml, 7ml, dilute to the mark with sodium carbonate test solution, shake well, 30 minutes later, use the corresponding reagent as a blank, according to the 2015 edition of the "Chinese Pharmacopoeia" four parts UV-spectrophotometry (General Rule 0401), Measure the absorbance at a wavelength of 760nm, and draw a standard curve with absorbance as the ordinate and concentration as the abscissa
    .

    3.
    The preparation of the test solution should be sampled according to the amount specified under each category, accurately weighed, placed in a 250ml brown measuring flask, add 150ml of water, and place overnight, ultrasonicate for 10 minutes, let cool, dilute to the mark with water, and shake well , Let stand (to precipitate the solids), filter, discard 50ml of the initial filtrate, accurately measure 20ml of the subsequent filtrate, place it in a 100ml brown measuring flask, dilute to the mark with water, shake well, and get it
    .

    4.
    Measurement method

    (1) Total phenols: accurately measure 2ml of the test solution, put it in a 25ml brown measuring bottle, follow the method under the standard curve preparation item, add 10ml of water starting from "adding 1ml of phosphomolybdic tungstic acid test solution", and measure the absorbance according to law Value, read the equivalent amount of gallic acid (mg) in the test solution from the standard curve, calculate it, and get it
    .

    (2) Non-adsorbed polyphenols: accurately measure 25ml of the test solution, add it to a 100ml conical flask with a stopper already containing 0.
    6g of casein, tightly stop it , and keep it in a 30℃ water bath for 1 hour.
    Shake, take out, let cool, shake well, filter, discard the initial filtrate, accurately measure 2ml of the subsequent filtrate, and place it in a 25ml brown measuring flask.
    Follow the method under the standard curve preparation item and start from "Add Phosphomolybdic Tungstic Acid Test Starting from 1ml”, add 10ml of water, determine the absorption value according to the law, read the amount of gallic acid (mg) in the test solution from the standard curve, calculate it, and get it
    .

    (5) Records and calculations

    1.
    Record the weighing volume of the reference substance and the test substance, the dilution of the test substance solution, the volume of the measurement during the measurement process, etc.
    ; the volume of the reference substance solution and the corresponding absorbance value in the preparation of the standard curve, and calculate the regression equation
    .

    2.
    Calculate the total phenols and the non-adsorbed polyphenols according to the standard curve method, and the difference between the two is the tannin content
    .
    That is: tannin content = total phenols-non-adsorbed polyphenols
    .

    (6) Matters needing attention

    1.
    The medicinal material samples should generally be crushed through a No.
    3 sieve
    .

    2.
    The chromogenic solution reacted completely after 30 minutes and was stable within 3 hours
    .
    Therefore, it is stipulated that the colorimetric measurement should be performed after 30 minutes after color development
    .

    Related Links: Determination Methods and General Procedures of Chinese Medicines (2)

     

     

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