Centrifugal tube for concentrating DNA (deoxyribonucleic acid) solution by using drying agent

The centrifugal tube for concentrating the DNA solution by using the drying agent comprises a tube body and a tube cover which is in threaded connection with the tube body, a columnar drying box is arranged in the tube cover; a drying agent is placed in the columnar drying box, through holes are formed in the side wall and the bottom end face of the columnar drying box, and hydrophilic filtering membranes are arranged on the side wall and the bottom end face of the columnar drying box; the top end face of the columnar drying box is fixedly connected with one end of a first sliding rod, a first sliding hole is formed in the pipe cover, the other end of the first sliding rod extends out of the first sliding hole and is in sliding fit with the first sliding hole, a plurality of annular grooves are formed in the outer wall of the first sliding rod at equal intervals, and a limiting assembly is further installed on the pipe cover. The clamping limiting end of the limiting assembly can be clamped to the annular gro