Determination of water soluble fluoride from solid matrices. The fluoride is extracted from the dried sample with water in a single-stage shaking test at room temperature (20 ± 5 ° C) according to EN 12457-2. The extracted fluoride is analyzed with a spectrophotometer. The method is suitable for solid materials with a particle size <4 mm. Samples of larger particle size can be crushed prior to analysis, depending on the matrix. Please contact our expert if your sample has a large particle size and your samples require crushing prior to analysis. Results are given as mg of fluoride per kg of dried sample material. Dry matter content of the sample is also reported.