According to the People's Republic of China GB15346-94 chemical reagent packaging standard provisions: 9.1.1.M provisions: required to indicate the period of validity must indicate the period of validity; Production date or batch number.

Classification of chemical reagents in China:

Excellent purity (GR, green label) : high principal component content, high purity, suitable for accurate analysis and research work, some can be used as a reference material.

Analytical purity (AR, red label) : high principal component content, high purity, low interference impurities, suitable for industrial analysis and chemical experiments.

Chemical pure (CP, blue label) : high principal component content, high purity, interference impurities, suitable for chemical experiments and synthetic preparation.

Experimental pure (LR, yellow label) : high principal component content, poor purity, impurity content is not selected, only suitable for general chemical experiments and synthetic preparation.

Indicators and dyes (ID or SR, purple label) : Specific sensitivity required.

Designated grade (ZD) : Chemical reagents customized for specific users according to the quality control indicators required by users.

Electronic pure (MOS) : Suitable for the production of electronic products, the content of electrical impurities is very low.

Equivalent reagent (3N, 4N, 5N) : the principal component content was 99.9%, 99.99%, 99.999% or more.

Chemical reagent expiration date: Chemical reagents in the storage, transportation and sales process will be affected by temperature, light irradiation, air and water and other external factors, prone to delixiation, mycin, discoloration, polymerization, oxidation, volatilization, sublimation and decomposition of physical and chemical changes, so that it can not be used. Therefore, it is necessary to use reasonable packaging, appropriate storage conditions and transportation methods to ensure that chemical reagents do not deteriorate during storage, transportation and sales. Some special requirements for storage and transportation should be handled according to special requirements. Some chemical reagents have a certain shelf life and must be paid attention to when using.

The expiration date of chemical reagents varies greatly with the change of chemical properties. Under normal circumstances, the chemical properties of stable substances, the longer the preservation period, the preservation conditions are simple. The initial judgment of the stability of a substance can follow the following principles:

Inorganic compounds, as long as properly kept, intact packaging, can be used for a long time. However, those substances that are easy to oxidize and delix can only be stored for a short time (1 to 5 years) under light, shade and dry conditions, depending on whether the packaging and storage conditions are in line with regulations.

Organic small molecular weight compounds are generally more volatile, the packaging is better sealed, and can be stored for a long time. However, easy oxidation, thermal decomposition, easy polymerization, photosensitive substances, etc., can only be stored for a short time (1 to 5 years) under light, shade, and dry conditions, depending on whether the packaging and storage conditions meet the requirements.

Organic polymers, especially fats, polysaccharides, proteins, enzymes, peptides and other living materials, are highly susceptible to the effects of microorganisms, temperature, and light, and lose their activity, or deteriorate, therefore, it is necessary to refrigerate (freeze) storage, and the time is shorter.

Reference substances, standard substances and high-purity substances, in principle, should be stored in strict accordance with the preservation provisions, to ensure that the packaging is intact, to avoid the impact of the chemical environment, and the storage time should not be too long. In general, the reference substance must be used within the expiry date.