Abstract: A method for fluorinating a filter for a pipette tip, the filter being made of a solid porous structure made of polyolefin. The method comprises the following steps: (a) placing the filter in an enclosure, (b) creating a vacuum in the enclosure, and (c) bringing the filter into contact with a fluorination agent injected into the enclosure in a gaseous state, the fluorination agent being made up of difluorine F2, the difluorine F2 being injected into the enclosure at a partial pressure between 100 Pa and 10000 Pa and step (c) being done at a temperature between 0° C. and 100° C. A pipette tip comprising a filter modified by the fluorination method, a method for producing such a tip, as well as a withdrawing pipette equipped with such a tip.