Fluorine has been analyzed in the Fast Irradiation and Measurement System FIMS in the TRIGA Mark II reactor. The samples with weight ranging from 100 to 500 mg were irradiated and measured in 11 or 22 s periods. The applicability of the proposed method for widely different sample types is discussed. Results are divided into three main groups with regard to the sample type. The first group comprehends low level alumina, plants and other biological materials of organic origin, the second covers the medium level alumina sediments, sewage and soils, and the third the rocks with high alumina contents, and minerals.