What procedure must be performed on dirty fluoride samples prior to analysis?

In analyzing dirty fluoride samples, the correct procedure to perform prior to analysis is distillation. Distillation is a method used to separate components based on differences in boiling points, and it is particularly useful in purifying a liquid by removing impurities and concentrating the desired analyte.

In the context of fluoride analysis, distillation helps eliminate contaminants and other volatile substances that may interfere with the assay results. By vaporizing the fluoride-containing solution and then condensing the vapor back into a liquid, the distillation process effectively purifies the sample, allowing for more accurate and reliable measurements of fluoride concentration.

While filtration, centrifugation, and neutralization can also play roles in sample preparation, they do not specifically target the purification required for precise fluoride analysis as effectively as distillation does in this context. Filtration may remove particulates, centrifugation can separate components based on density, and neutralization is relevant for adjusting pH but does not inherently purify the sample in the same way distillation does.