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    Home > Chemicals Industry > Chemical Technology > Inspection Method for the Minimum Loading Quantity of Chinese Medicine Preparations (General Rules 0942) (2)

    Inspection Method for the Minimum Loading Quantity of Chinese Medicine Preparations (General Rules 0942) (2)

    • Last Update: 2022-06-24
    • Source: Internet
    • Author: User
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    (2) Distillation method

    1.
    Brief description

    (1) The distillation method uses the method of measuring the relative density after distillation to determine the ethanol content (%) (v/v) in various preparations at 20°C
    .
    According to the nature of the preparation, there are three methods

    .

    (2) The distillation method is to dilute the sample according to regulations, distill, collect the distillate to a certain volume, adjust the temperature of the distillate to 20℃, measure the relative density, check the ethanol content from the ethanol relative density table, and then calculate the sample The amount of ethanol in it
    .
    Before the determination of this method, the test product needs to be pretreated by different methods.
    The operation is cumbersome, and the accuracy and reproducibility are not as good as gas chromatography

    .

    2.
    Method of operation

    (1) The first method: This method is used to determine the ethanol content in most liquid extracts, tinctures and glycerin preparations
    .
    According to the different ethanol content in the preparation, it can be divided into two situations: ① Those with ethanol content less than 30%: take the test product, shake it, adjust the temperature to 20°C, accurately measure 25ml, and place 150~200ml In the distillation flask, add about 25ml of water, add some glass beads or zeolite and other substances, connect the condenser, heat with an electric heating jacket, and slowly distill (the speed is based on the distillate drop by drop), and the distillate is introduced into the 25ml measuring flask When the distillate reaches about 23ml, stop the distillation

    .
    Adjust the temperature of the distillate to 20°C, add 20°C water to the mark, and shake well

    .
    At 20℃, the relative density is measured according to the method under the relative density measurement method (2015 version of "Chinese Pharmacopoeia" General Rules 0601)

    .
    Find out the ethanol content (%) (v/v) in the ethanol relative density table, that is, the ethanol content (%) (v/v) in the test product; ②For those with more than 30% ethanol: take the Shake the sample, adjust the temperature to 20°C, accurately measure 25ml, place it in a 150-200ml distillation flask, add about 50ml of water, add a few glass beads, and distill as described above

    .
    The distillate is introduced into a 50ml measuring flask.
    When the distillate reaches about 48ml, the distillation is stopped

    .
    Adjust the temperature of the distillate to 20°C, add 20°C water to the mark, and shake well

    .
    The relative density was determined according to the above method at 20°C

    .
    Multiply the content of ethanol (%) (v/v) by 2 to get it

    .

    (2) The second method: This method is used to determine the amount of ethanol in preparations containing volatile substances such as volatile oil, chloroform , diethyl ether , camphor, etc.
    , in tinctures and syrups
    .
    According to the different ethanol content in the preparation, it can also be divided into two situations: ① Those with ethanol content less than 30%: take the test product, shake it, adjust the temperature to 20℃, accurately measure 25ml, and place 150ml to separate the solution In the funnel, add the same amount of water, add sodium chloride to saturate it, then add petroleum ether , shake 1 to 3 times, about 25ml each time, dissolve the volatile substances that hinder the measurement into the petroleum ether, and wait for two.
    Separate the liquid, divide the lower layer of water and place it in a 150-200ml distillation flask.
    Wash the petroleum ether layer with a saturated solution of sodium chloride 3 times, each with 10ml.
    The washing liquid is incorporated into the distillation flask, according to the first method above ( Method ①) Distillation and determination; ② Those with ethanol content higher than 30%: Take the test product, shake it, adjust the temperature to 20℃, accurately measure 25ml, put it in a 250ml separatory funnel, add about 50ml of water, and add it as above
    Saturate it with sodium chloride and extract 1 to 3 times with petroleum ether .
    Divide the lower layer of water and distill and measure according to the first method (method ②) above
    .


    After adding petroleum ether to the test product and shaking, if emulsification occurs, or the distillate is still turbid after being treated with petroleum ether, another test product can be taken, diluted with water, and distilled according to the first method.
    The obtained distillate was processed, distilled and measured according to this method

    .
    If the test product is a water cotton gel, water can be used instead of saturated sodium chloride solution

    .

    (3) The third method: This method is used to determine the amount of ethanol in preparations containing free ammonia or volatile acids
    .
    If the test product contains free ammonia, you can add dilute sulfuric acid to make it slightly acidic; if it contains volatile acid, you can add
    sodium hydroxide test solution to make it slightly alkaline
    .
    Then according to the first method of distillation, determination

    .
    If it contains volatile oil at the same time, in addition to the above-mentioned treatment method, and according to the second method

    .
    If the test product contains soap, add excessive sulfuric acid to decompose the soap, and then determine according to law

    .

    3.
    Matters needing attention

    (1) If the distillate of any method is turbid, add talc or calcium carbonate to shake, filter to make the solution clear, and then determine the relative density
    .

    (2) During distillation, if foam occurs, sulfuric acid or phosphoric acid can be added to the test product to make it strong acid
    .
    Or add a little excess of
    calcium chloride solution, or add a small amount of paraffin before distilling
    .

    4.
    Results and Judgment

    (1) If the amount of ethanol in the test solution is within the limit specified in the standard, it is judged to meet the requirements (Table 15-27)
    .

    (2) If the standard does not clearly stipulate which method is used to determine the amount of ethanol, it is recommended to use gas chromatography to determine the amount of ethanol
    .
    The data determined by gas chromatography shall prevail

    .

    (3) Unless otherwise specified, if the result of the distillation method is inconsistent with the gas chromatography method, the result of the gas chromatography method shall prevail
    .

    5.
    Records and calculations

    (1) Record the sampling volume, temperature and balance model of the test product
    .

    (2) Record sample preparation methods and relative density measurement results
    .

    (3) Record the ethanol content found in the ethanol relative density table
    .

    (4) Calculate the percentage (%) (v/v) of the ethanol content of the test product at 20°C
    .
    Calculate according to the following formula

    .

    Ethanol content (%) = Find the relative density data of the test product in the ethanol relative density table.
    If the ethanol content is less than 30%, the corresponding ethanol percentage content can be found; if the ethanol content is more than 30% If you multiply the percentage of ethanol contained by 2, you get it

    .

    Table 15-27 Relative density table of ethanol

     

     

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