Principles Of Judging The Stability Of Chemical Reagents

To determine the stability of a substance preliminarily, the following principles can be followed:

Inorganic compounds can be used for a long time as long as they are properly stored and the packaging is intact. However, those substances that are easily oxidized and deliquescent 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 comply with the regulations.

Organic low-molecular-weight compounds are generally more volatile, and the packaging has better airtightness and can be stored for a long time. But it is easy to be oxidized, decomposed by heat, easy to polymerize, photosensitive substances, etc.

Organic polymers, especially life materials such as oils, polysaccharides, proteins, enzymes, peptides, etc., are extremely susceptible to the effects of microorganisms, temperature, and light, and lose their activity or deteriorate. Therefore, they must be stored in cold storage (frozen), and the time is too long. Shorter.

In principle, reference materials, standard materials and high-purity materials should be stored in strict accordance with the preservation regulations to ensure that the packaging is intact, 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 stability of most chemicals is still relatively good, and the specific conditions should be determined by actual use requirements. If the analysis data is used as a general understanding, or there are no specific and accurate requirements for the analysis results, such as general teaching experiments, the quality level of chemical reagents can be generally required. However, the factory test data is used to guide production, and the quality indicators of chemical reagents must not be ambiguous. As for the chemical reagents used in general synthetic preparation, in most cases, the use of industrial-grade chemical reagents is sufficient. However, the synthetic preparation of research-type and certain special chemicals, in some cases, has very strict requirements on the quality of raw materials and requires strict control.

In actual use, people are always accustomed to judging the effectiveness of chemical reagents by the date of production. In fact, it is absurd. For example, in a college of higher education, I once saw warehouse managers clean out all the chemical reagents that have been out of the factory for more than 2 years, and prepare to destroy them, because the reason is that they have expired. Not to mention the huge waste of funds, the destruction plan of the various chemical hazardous materials alone is enough to be prohibitive. What's more, commercial companies are not allowed to buy, to prevent businesses from "deceiving people", the situation is lamentable, and the situation is sad! Later, it is said that these large quantities of chemical reagents were "deeply dug and buried".

In short, the effectiveness of chemical reagents should first be judged based on the physical and chemical properties of the chemical reagents themselves, and then the storage conditions of the chemical reagents should be observed visually, and then the conclusion of whether they can be used can be made according to specific needs.