The operation procedures of nucleic acid extraction kits vary slightly depending on different types. Taking the magnetic bead-based nucleic acid extraction kit as an example, the general operation procedures are as follows:

Biological Sample Collection: Appropriate biological samples, such as blood, saliva, tissues, and cells, are collected according to the detection purpose. If the nucleic acids cannot be extracted in a timely manner, the samples need to be stored under appropriate conditions to prevent nucleic acid degradation.
Sample Pretreatment: For cell or tissue samples, crushing and lysis treatments are required. For example, tissue samples can be homogenized using a homogenizer, and cell samples can be lysed by adding a cell lysis buffer and then using methods like shaking or vortexing to break the cells and release the nucleic acids.

Binding Reaction: Add magnetic beads and a binding buffer to the pretreated samples. The functional groups on the surface of the magnetic beads can bind specifically to the nucleic acids. Gently invert or vortex the mixture to ensure full contact between the magnetic beads and the nucleic acids. Under certain temperature and time conditions, the nucleic acids will be adsorbed onto the magnetic beads.
Washing and Impurity Removal: Place the samples on a magnetic stand. Under the action of the magnetic field, the magnetic beads will gather on one side of the tube wall. Carefully aspirate the supernatant to remove the unbound impurities. Then add a washing buffer to wash the surface of the magnetic beads to remove residual impurities such as proteins and polysaccharides. Generally, this washing step needs to be repeated 2 – 3 times.

Adding Elution Buffer: Remove the magnetic beads with adsorbed nucleic acids from the magnetic stand and add an appropriate amount of elution buffer. The components in the elution buffer can disrupt the binding force between the magnetic beads and the nucleic acids.
Nucleic Acid Elution: Gently pipette or agitate to make the nucleic acids detach from the magnetic beads and enter the elution buffer. Place the samples on the magnetic stand again. The magnetic beads will be adsorbed to the side of the tube wall, and the supernatant is the extracted nucleic acid solution. Carefully aspirate the supernatant and transfer it to a new centrifuge tube.

Concentration and Purity Detection: Use methods such as an ultraviolet spectrophotometer or fluorescence quantification to detect the concentration and purity of the extracted nucleic acids. Calculate the ratio of A260/A280 by measuring the absorbance at wavelengths of 260 nm and 280 nm to evaluate the purity of the nucleic acids. Generally, the ratio for pure DNA is around 1.8, and that for pure RNA is around 2.0.
Preservation: If the extracted nucleic acids are not to be used immediately, appropriate preservation conditions need to be selected according to the type of nucleic acids and experimental requirements. DNA can generally be stored at -20 °C or -80 °C for long-term preservation. RNA is more prone to degradation and usually needs to be stored at -80 °C with an appropriate amount of RNase inhibitor added to prevent RNA degradation.