Low-concentration PCR product concentrating method used for direct sequencing

The invention relates to a low-concentration PCR product concentrated perborate and 2ul nucleic acid settling agent (artificially synthesized DNA sequence), and mixing evenly; adding a 2-2 method. The 2-2 method comprises the specific steps of adding 3M sodium acetate with 1/10 volume and pH of 5.2, absolute ethyl alcohol with 0.5 volume and 300 ul 40% PEG8000 into a PCR product to be purified, placing the solution at -20 DEG C for 10-30 min; conducting centrifugation at 4 DEG C and 12000 rpm for 10-20 min, and abandoning the supernatant; adding 1 ml 70% ethyl alcohol to be subjected to precooling at 4 DEG C, reversing evenly, conducting centrifugation at 4 DEG C and 12000 rpm for 2-10 min, and abandoning the supernatant; placing a centrifuge tube with a cover opened at room temperature, and making the remaining liquid fully volatilize; adding water or a TE solution to dissolve precipitated DNA. By the adoption of the method, the recycled product can be directly used for sequencing, the success rate of the lo