Content determination methods included in the general rules of "Chinese Pharmacopoeia" (3)

Four, volume analysis (titration analysis method)

The volumetric analysis method is to drop a reagent solution with a known concentration and an accurate standard solution into the solution of the substance to be tested, until the added reagent and the substance to be tested quantitatively react according to the stoichiometric relationship, and then according to the standard solution used Volume and concentration, calculate the content of the substance to be tested

The volumetric analysis method is classified according to the type of chemical reaction: including acid-base titration, coordination titration (complex titration), precipitation titration, redox titration, etc.

Most titration analysis is carried out in aqueous solution.

(1) Acid-base titration

It is an analytical method based on the proton transfer reaction

(2) Precipitation titration method

It is a method of titration using precipitation reaction, which is divided into silver measurement method, sodium tetraphenylborate method and potassium ferrocyanide method.

(3) Coordination titration

It is a titration analysis method based on coordination reaction

(4) Redox titration method

It is a titration analysis method based on the electron transfer between the oxidant and the reducing agent in the solution.

Five, gravimetric analysis

The analytical method to determine the content of the measured component based on the weighed weight

(1) Volatilization method

The volatilization method is a method for determining the content of volatile components by using the measured components to be volatile or can be quantitatively converted into volatile substances

(2) Extraction method

The extraction method is based on the difference of the solubility of the tested components in the two immiscible phases to achieve the purpose of separation

(3) Precipitation method

The precipitation method is a method of using precipitation reaction to quantitatively convert the tested components into insoluble compounds, which are separated from the solution in the form of precipitation, and then filtered, washed, dried or ignited, and finally weighed to calculate the content

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