Determination methods and general steps of Chinese medicine content (1)

1.

(1) Chemical analysis method

The chemical quantitative analysis method is an analysis method based on the chemical reaction of substances, mainly including titration analysis method and gravimetric analysis method

The chemical analysis method is used to determine the content of ingredients in traditional Chinese medicine preparations.

(2) Instrumental analysis method

Instrumental analysis is an analysis method based on certain physical properties and physicochemical properties of substances

According to the relationship between a certain physical property (such as specific gravity, phase transition temperature, refractive index, optical rotation, and spectral characteristics) of the measured substance and its composition, a qualitative or quantitative analysis method without chemical reaction is called physical analysis

1.

2.

(1) Potential analysis method: an analysis method that uses electromotive force (or potential) as an electrical parameter

(2) Conductivity analysis method: a quantitative analysis method with solution conductivity as an electrical parameter

(3) Electrolytic analysis method: One of them is an analysis method that uses electrons as a precipitant, and is based on electrolysis of a sample solution to make the measured product analyzed and weighed.

The coulomb analysis method that uses electricity as an electrical parameter can also be classified as electrolysis

(4) Amperometric method: an analysis method that uses current-potential curves as electrical parameters.

3.

(3) Macro, semi-trace, trace and ultra-trace analysis

According to the amount of sample (sampling amount), the analysis method can be divided into constant (>0.

It should also be pointed out that according to the percentage of the measured component, it can be roughly divided into constant component (>1%) analysis, trace component (0.

2.

The content determination of traditional Chinese medicine ingredients generally includes the following steps:

(1) Sampling

1.
The sample to be analyzed by the sampling method of medicinal materials and decoction pieces should be representative in composition and content, and can represent the totality of the analyte
.
Take a representative sample using a specific method or procedure
.
The 2015 edition of the Chinese Pharmacopoeia (General Rules 0211) clearly stipulates the sampling methods of medicinal materials and decoction pieces
.
The sampling method of medicinal materials and decoction pieces refers to the sampling method of medicinal materials or decoction pieces samples for inspection
.

The principle of sampling samples for inspection from the same batch of medicinal materials and decoction pieces packages: if the total package is less than 5 pieces, sampling one by one; 5～99 pieces, randomly sampling 5 pieces; 100～1000 pieces, sampling at a rate of 5% ; If more than 1000 pieces are sampled, 1% will be sampled; valuable medicinal materials and decoction pieces will be sampled piece by piece regardless of the number of packages
.

At least one sample should be taken from 2 to 3 different parts of each package; the large package should be taken from a depth of less than 10cm in different parts; for broken, powdered or medicinal materials and decoction pieces with a size of less than 1cm , Samplers (probes) can be used to sample samples; for medicinal materials with larger packages or larger individuals, representative samples can be sampled according to actual conditions
.
The sampling amount of each package: 100~500g for general medicinal materials and decoction pieces; 25-50g for powdered medicinal materials and decoction pieces; 5-10g for precious medicinal materials and decoction pieces
.

Mix the extracted samples, that is, the total amount of the extracted samples
.
If the total amount of samples taken exceeds several times the test quantity, you can re-sampling according to the quarter method, that is, spread all the samples into squares, divide them into four equal parts according to the diagonal "×", and take two diagonally; The above operation is repeated several times until the final remaining quantity can meet the sample quantity for inspection
.

The final sample volume for testing shall generally not be less than 3 times the volume required for testing, that is, 1/3 is for laboratory analysis, the other 1/3 is for review, and the remaining 1/3 is retained for storage with a shelf life of at least One year
.

2.
The sampling method of traditional Chinese medicine preparations, unless otherwise specified, generally the determination of Chinese patent medicines is to take the samples under the check of the difference in packing quantity or weight to ensure a certain degree of uniformity
.
The sampling volume of various Chinese medicine preparations is sufficient for at least 3 tests
.
Valuable drugs can be sampled as appropriate
.

Powdered Chinese medicine preparations (powders and granules are generally sampled 100g, which can be sampled on the upper, middle and lower 3 layers of the package or at equal intervals, mix them evenly, and take out the required test amount according to the "quarter method"; liquid Traditional Chinese medicine preparations (oral liquids, liquids, wines, syrups), the general sampling quantity is 200ml, mix and sample; solid traditional Chinese medicine preparations (pills, tablets), the general tablet takes 200 tablets, and the granules are made before the tablets are formed Can take 100g; generally 10 pills; capsules should be sampled at least 20 capsules according to the pharmacopoeia, pour out the medicines and carefully scrape off the medicines attached to the capsules, combine, mix and weigh the empty capsules.
The total weight minus is the weight of the contents of the capsule.
The general sampling volume is 100g; the injection should be sampled twice.
After preparation, take a sample before filling, melting and sterilizing.
The sterilized injection should be The original method is carried out, and only after passing the analysis and inspection, it can be used for medicinal purposes; the sample size of the sealed Ambe is generally 200; other dosage forms of Chinese medicine preparations can be randomly selected according to the specific situation
.

(2) Preparation of test solution

Chinese medicinal materials and Chinese medicinal preparations contain many chemical components.
Before qualitative and quantitative analysis, it is often necessary to extract, separate, and refine them before testing
.
The extraction principle eliminates the interference of invalid components and non-detected components as much as possible to improve the accuracy and sensitivity of the analysis:

1.
The solvent extraction method is a method in which an appropriate solvent is selected to dissolve the components to be measured
.
The so-called appropriate solvent is a solvent that has high solubility for the component to be tested, but low solubility or insoluble for unneeded components
.
The solubility of the chemical components of traditional Chinese medicine in the solvent is related to the nature of the solvent, and generally follows the principle of "similar compatibility"
.
When choosing a solvent, in addition to the high solubility of the component to be tested and low solubility for impurities, the selected solvent cannot chemically change with the component to be tested in the traditional Chinese medicine.
The solvent is easy to obtain and safe to use
.

(1) Commonly used extraction solvents: Commonly used extraction solvents can be divided into 3 categories according to their polarity, namely, polar solvents, non-polar solvents and medium-polar solvents
.

1) Polar solvent: Water is a typical polar solvent, which can dissolve ionic components, such as alkaloid salts, organic acid salts and other components (such as sugars, glycosides, starch, proteins, amino acids, polyhydroxy compounds, tannins and Inorganic salts, etc.
)
.
However, there are many impurities in the water extract, which brings a lot of trouble to further separation and concentration
.
In addition, it is also easy to enzymatically degrade glycosides, mildew and spoil
.

2) a non-polar solvent: non-polar solvents commonly used petroleum ether , diethyl ether , chloroform , ethyl acetate and the like
.
Solvents used to extract low-polar components, such as volatile oils, chlorophyll, resins, sterols, lactones, free alkaloids and certain aglycones
.

3) Medium polar solvents: Ethanol , methanol , acetone, etc.
are commonly used medium polar solvents
.
They have a wide range of solubility for various components, especially ethanol .
Except for the hydrophilic components such as protein, mucus, pectin, starch, etc.
, most of them can be dissolved in ethanol
.
The lipophilic components that are hard to dissolve in water have greater solubility in ethanol, and different concentrations of ethanol can also be used for extraction according to the nature of the extract
.
Extraction with ethanol has a shorter time than extraction with water, has less water-soluble impurities, has low toxicity, is inexpensive, is not easy to mold and deteriorate, and can be recycled
.
Therefore, ethanol is the most commonly used organic solvent
.
Methanol and ethanol are similar in nature, so be careful when using it because it is toxic
.

(2) Commonly used extraction methods

1) Cold soaking method: suitable for the extraction of thermally unstable active ingredients
.
The sample is placed in a test tube with a stopper, a certain amount of appropriate solvent is precisely added, shaken, and then left to stand, soak and extract
.
The amount of solvent is 6-20 times the weight of the sample and weighed
.
The soaking time is 12～48h.
During the soaking period, it should be shaken frequently, and then weighed after soaking
.

2) Continuous reflux extraction method: The sample is placed in a Soxhlet extractor for repeated reflux extraction for organic solvents that are easily volatile when exposed to heat
.
This method has high extraction efficiency, requires less solvent, and is not suitable for the extraction of thermally unstable components
.

3) Ultrasonic extraction method: The sample is placed in a suitable container, and the extraction solvent is added, and then placed in an ultrasonic oscillator for extraction
.
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.

2.
Steam distillation method The volatile oil or volatile components in traditional Chinese medicine (such as paeonol, etc.
) can be extracted by steam distillation method
.
After the distillate or distillate is salted out, it is extracted with ether.
After the ether is recovered from the extract, volatile oil or volatile components are obtained
.
In addition, some small molecular alkaloids, such as ephedrine, nicotine, arecoline, etc.
, can also be extracted by this method
.

3.
Sublimation method For some compounds with sublimation properties, sublimation method can be used to directly extract
.
Such as free hydroxyanthraquinone compounds, caffeine, cantharidin and so on
.

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