The following are the precautions for using nucleic acid extraction reagents

I. Storage Conditions

1. Temperature Requirements
   • Most nucleic acid extraction reagents need to be stored at low temperatures, usually between 2 – 8°C. This is because some components of the reagents may degrade or have their activities altered at higher temperatures. For example, Proteinase K is prone to inactivation at high temperatures, and components in some buffers may undergo chemical changes due to increased temperature, affecting the performance of the reagents. If the reagents are kept at inappropriate temperatures for a long time, they will not function properly in subsequent nucleic acid extraction operations, affecting the quality and efficiency of nucleic acid extraction.
2. Avoiding Light Exposure
   • Some nucleic acid extraction reagents are sensitive to light and should be stored in a light – proof environment. Light may trigger certain chemical reactions in the reagents, causing the components to deteriorate. For instance, reagents containing photosensitive substances may undergo photolysis reactions under light, causing these substances to lose their original functions and thus affecting the extraction efficacy of the entire reagent.

II. Operating Environment

1. Aseptic Operation
   • Nucleic acid extraction operations should be carried out in an aseptic environment as much as possible. This is because exogenous microbial contamination may affect the purity of nucleic acid extraction. For example, bacteria in the environment may secrete nucleases, which will degrade the nucleic acid samples during extraction, resulting in a reduction in the amount or quality of the finally – extracted nucleic acids and affecting the results of subsequent tests or experiments. Before operation, the operating table should be disinfected, and operators should wear sterile gloves and masks, etc.
2. Preventing Nuclease Contamination
   • Since nucleases (especially RNase) can rapidly degrade nucleic acids, nuclease contamination must be prevented. On the one hand, dust in the operating environment, the skin and breath of operators may carry nucleases; on the other hand, if the experimental utensils used (such as pipettes, centrifuge tubes, etc.) have not been treated to be nuclease – free, nucleases may also be introduced. Therefore, experimental utensils should be specially treated to be nuclease – free before operation, and unnecessary operating actions should be minimized during the operation to prevent the invasion of external nucleases.

III. Sample Processing

1. Compatibility with Sample Types
   • Different nucleic acid extraction reagents are designed for specific types of samples. For example, there are reagents specifically for blood samples, tissue samples, swab samples, etc. Before using the reagents, it is necessary to ensure that the sample type matches the reagent. If an unmatched reagent is used, it may not be able to effectively lyse the sample cells to release nucleic acids, or may not be able to well remove impurities in the sample during extraction, thus affecting the quality and yield of nucleic acid extraction.
2. Control of Sample Volume
   • During operation, the sample volume should be strictly processed according to the specifications in the reagent instructions. If the sample volume is too large, the reagents may not be able to fully lyse all cells, leaving some nucleic acids unextracted; if the sample volume is too small, nucleic acid loss may occur during subsequent operations (such as washing and elution), or inaccurate test results may be obtained due to the small sample volume (for example, in the detection of trace nucleic acids, a too – small sample volume may lead to the failure to detect the target nucleic acids).

IV. Operating Procedures

1. Accurate Addition of Reagents
   • During the nucleic acid extraction process, various reagents, including lysis buffers, binding buffers, washing buffers, elution buffers, etc., should be added precisely. This is because inaccurate amounts of reagent addition may affect the binding of nucleic acids to carriers (such as magnetic beads or centrifugal column filter membranes), the removal of impurities, and the elution of nucleic acids. For example, if the amount of washing buffer added is insufficient, impurities may not be completely removed; inaccurate addition of elution buffer may result in incomplete elution of nucleic acids from the carriers, affecting the final concentration and quality of the obtained nucleic acids.
2. Strictly Adhering to the Operating Sequence
   • Nucleic acid extraction has a specific operating sequence that must be strictly followed. For example, in the magnetic bead method, usually, the sample is first lysed by adding a lysis buffer, then magnetic beads are added to bind nucleic acids, followed by washing operations, and finally elution. If the operating sequence is incorrect, nucleic acid extraction may fail. For example, adding magnetic beads before the sample is fully lysed will prevent nucleic acids from fully binding to the magnetic beads, reducing the extraction efficiency.

V. Shelf Life of Reagents

1. Paying Attention to the Expiration Date
   • Nucleic acid extraction reagents have a certain shelf life, and it is necessary to check whether the reagents are within the expiration date before use. Expired reagents may not be able to perform nucleic acid extraction normally due to component deterioration or inactivation. For example, some key components in the reagents (such as active groups in the binding buffer) may lose their activity over time, resulting in ineffective binding and separation of nucleic acids and making the quality of the extracted nucleic acids unqualified.
2. Observing the State of Reagents
   • The state of the reagents should also be observed before use. If the reagents show abnormal phenomena such as turbidity, precipitation, or discoloration, even within the expiration date, it may indicate that the reagents have deteriorated and should not be used. For example, if a reagent containing protein components shows turbidity or precipitation, it may be due to protein denaturation, and using such a reagent in this case will affect the effect of nucleic acid extraction.