Which of the following is more suitable for plasma free DNA extraction kit magnetic bead method and column extraction method?

The recovery rate and complete fragment gender only depend on the promotion of the reagent kit. After arrival, it is recommended to perform a spiked verification: take a known concentration of short fragment DNA and add it to 200 microliters of plasma, extract it and quantify it with Qubit, then use qPCR to amplify the short fragment internal reference, and compare the Ct difference before and after passing through the column/magnetic bead. If tumor early screening is performed, it is best to first centrifuge the plasma twice to remove leukocyte genomic DNA contamination, otherwise the background of large fragments will be high. Using a small volume and preheating the eluent at 56 ℃ during elution can improve the yield. The magnetic bead method is easier to control batch consistency in operation, but it is important to note that the drying time should not be too long, otherwise the magnetic beads will clump and lose fragments.

200 microliters of plasma is a low starting amount, and I will give priority to the magnetic bead method kit specifically for cfDNA. The magnetic bead method usually retains small pieces of DNA better than the general column method, and the manual operation is also stable, as long as the magnetic frame is equipped to avoid the loss of magnetic beads. Column extraction is not unusable, but special columns with carrier RNA and low elution volume of cfDNA should be selected, otherwise the recovery rate of low-concentration samples will fluctuate easily. Focus on whether the instructions clearly support low-volume plasma and whether the elution volume is about 30-60 microliters, and the product can be qPCR directly. If it arrives within two weeks, several domestic cfDNA manufacturers and import agents can generally meet it.

When selecting, don't just look at the brand. Ask clearly whether the lysis and binding conditions are suitable for short fragments, whether proteinase K must be added, and whether the reagents are pre-dispensed. Magnetic bead-based methods can be performed manually or automated. When the sample volume is not large, manual operation is sufficient, but the magnetic rack must be compatible with 1.5/2 mL tubes. Imported options such as Qiagen and Thermo have mature dedicated circulating nucleic acid extraction kits, and some domestic magnetic bead-based methods focused on cfDNA can also be considered. It is recommended to ask the distributor to provide trial packs or small sizes, and first use your actual samples to compare extraction concentration and qPCR Ct values. If the lead time is within two weeks, confirm that shipment is from a domestic warehouse, not overseas replenishment.