Analysis of Key Points for Classification, Storage, and Quality Control Management of Commonly Used Reagents in Biological Laboratories

I. Main Categories and Functional Roles of Commonly Used Reagents

There are many types of reagents commonly used in biological laboratories, which can generally be classified by purpose into basic buffers, enzymes and substrates, nucleic acid isolation and electrophoresis reagents, protein detection reagents, cell culture-related reagents, and staining and preservation reagents. Basic buffers such as phosphate-buffered saline and Tris-HCl buffer mainly maintain the pH and ionic strength of the reaction system; enzyme reagents include restriction endonucleases, DNA polymerases, reverse transcriptases, etc., and their activity units, storage temperatures, and requirements regarding repeated freeze-thaw cycles are generally clearly stated in the product instructions. Nucleic acid isolation reagents usually involve lysis buffer, phenol-chloroform, isopropanol, ethanol, and magnetic bead suspensions, and different methods differ in purity, yield, and processing time. Commonly used protein detection reagents such as BCA, Bradford, SDS-PAGE gel preparation components, and luminescent substrates require attention to batch-to-batch sensitivity and background signal. Fetal bovine serum, trypsin, dual antibiotics, and culture medium supplements commonly used in cell culture have high requirements for sterility, endotoxin, and mycoplasma control. For staining and preservation reagents such as trypan blue, propidium iodide, and DMSO, special attention must be paid to working concentration and protection.

Reagents of the same type often come in multiple specifications and purity grades, such as molecular biology grade, cell culture grade, and analytical reagent grade. Laboratory personnel should select the appropriate grade according to methodological requirements, rather than simply pursuing high purity or low price. For critical steps, it is recommended to perform small-scale validation before formal experiments to confirm that blank, negative, and positive controls perform as expected.

II. Key Quality Control Points in Storage and Aliquoting

The stability of reagents commonly used in biological laboratories is significantly affected by temperature, light, humidity, and repeated freeze-thaw cycles. Enzymes, antibodies, and cytokines are usually required to be stored at -20°C or -80°C and should avoid repeated freeze-thaw cycles; flammable reagents such as ethanol and isopropanol used for nucleic acid precipitation should be stored in explosion-proof cabinets or in cool, well-ventilated places. Buffers and culture media are generally stored at 4°C or room temperature according to the instructions, and the opening date and expiration date must be recorded after opening. For powdered reagents that are prone to deliquescence and oxidation, they should be promptly sealed and placed in a dry environment after use.

Aliquoting is an effective way to reduce the risk of contamination and degradation. For large-package liquid reagents, they can be aliquoted into single-use portions in a clean environment or biological safety cabinet to reduce repeated opening of the container. Aliquot containers should preferably be made of low-adsorption, low-temperature-resistant materials and labeled with the name, concentration, aliquot date, and operator. Different reagents must not share tips, pipettes, or spatulas to avoid cross-contamination. Working solutions should be labeled with the preparation date and storage conditions, and even if they appear normal, they should not continue to be used in critical experiments beyond the recommended period of use.

III. Safe Use and Compliance Management

Some reagents commonly used in biological laboratories are corrosive, flammable, reproductively toxic, or acutely toxic, such as formaldehyde, DEPC, β-mercaptoethanol, and ethidium bromide substitutes. Before use, the safety data sheet should be consulted to understand hazard classification, storage incompatibilities, and spill disposal methods. Volatile or powdered substances should preferably be weighed in a fume hood, wearing appropriate gloves and goggles. Culture media containing antibiotics, cell culture supernatants, and utensils that have contacted biological samples should be collected and disposed of in categories according to laboratory waste management requirements and must not be discharged directly into drains.

For procurement, suppliers with complete qualifications and the ability to provide quality certificates and batch information should be selected. For experiments related to in vitro diagnostics or drug development, attention should also be paid to raw material sources, animal-derived statements, and RNase/DNase-free statements. During reagent acceptance, the integrity of packaging, label information, storage conditions, and arrival temperature records should be checked; if abnormalities are found, the reagents should be isolated and the supplier contacted. Laboratories may establish a reagent ledger or electronic management system, set safety stock levels for commonly used reagents, and label and prioritize products nearing expiration to reduce waste from expiration.

IV. Common Problems and Optimization Recommendations

In daily experiments, reagent-related abnormalities often manifest as high blanks, diffuse bands, decreased amplification efficiency, and poor cell condition. At this point, it is not enough to adjust only the experimental procedure; a systematic investigation should also be conducted into whether reagents are expired, contaminated, whether the pH has shifted, and whether the ionic strength is appropriate. For example, blurred nucleic acid electrophoresis bands may be related to excessive use of electrophoresis buffer or an incorrect gel preparation ratio; contamination in cell culture may be related to incomplete sterilization of serum, trypsin, or culture medium.

Optimizing the management of reagents commonly used in biological laboratories can be approached from three levels: first, establish an acceptance and verification system for critical reagents, performing parallel comparisons between new and old batches; second, standardize the water quality used for preparation, prioritizing ultrapure water or deionized water, and regularly monitoring conductivity; third, record environmental temperature and humidity and refrigerator temperatures, and install temperature alarm devices.