Shelf life of chemical reagents
Unlike food and medicine, chemical reagents do not have strict shelf life. Generally, chemical reagents do not have specific requirements and limits for shelf life. This is related to the fact that the shelf life of chemical reagents is affected by many factors; it should be based on chemical properties, storage conditions, etc., combined with the actual work. Judging whether the reagent has deteriorated and whether it can continue to be used.
The effect of the properties of chemical reagents on the validity period
Chemical reagents generally do not indicate the shelf life, and the determination of whether the reagents have deteriorated is mainly based on experience and comparison of old and new reagents.
The validity period of chemical reagents varies greatly with the change of chemical properties of chemicals. In general, substances with stable chemical properties have longer shelf life and simpler storage conditions.
Generally follow the following principles:
- Inorganic compounds
Inorganic compounds can theoretically be used for a long time as long as they are properly stored and the packaging is intact. However, it is easy to be oxidized (such as sulfite, phenol, ferrous salt, iodide, sulfide, etc., should be stored in a sealed solid or crystal, not long-term storage; aqueous solution of sulfite and hydrosulfuric acid should be sealed and stored; potassium, sodium, white phosphorus It is necessary to use liquid sealing form), substances that are easy to deliquescence, and can only be stored for a short period of time (1 to 5 years) under dark, cool and dry conditions, depending on whether the packaging and storage conditions meet the regulations.
- Organic small molecular weight compounds
Organic small molecular weight compounds are generally more volatile, and the packaging is better in airtightness, and can be stored for a long time (3 to 5 years). However, it is easy to be oxidized, decomposed by heat, easy to polymerize, and photosensitive substances, etc., in the dark, cool and dry conditions, it can only be stored for a short period of time (1 to 5 years), depending on whether the packaging and storage conditions meet the regulations.
- Organic polymers
Organic polymers, especially living materials such as oils, polysaccharides, proteins, enzymes, and peptides, are easily affected by microorganisms, temperature, and light, and lose their activity, or deteriorate. shorter.
- Reference materials, reference materials and high-purity materials
In principle, reference materials, reference materials and high-purity materials should be stored in strict accordance with the preservation regulations to ensure that the packaging is intact, to avoid being affected by the chemical environment, and the storage time should not be too long. In general, the reference substance must be used within the validity period. The storage time is generally not more than 2 months under normal conditions (15℃~25℃). More than two months to be re-calibrated or checked before use.
- Culture medium
Medium: Prepare and sterilize the medium according to the regulations, cool it to room temperature, and store it in a dark place (stored in the refrigerator as much as possible). The prepared medium should be used up within 1 month.
Unless otherwise specified, the validity period of test solution, buffer solution and indicator (liquid) is half a year.
The mobile phase and purified water for liquid phase are valid for 15 days. It depends on the ratio of organic phase to water phase.
Unless otherwise specified, liquid reagents are valid for one year after opening, and solid reagents are valid for three years after opening.
