Highly sensitive methods for determination of fluoride in biological samples

A total of 40 samples of shell ashes from chicken eggs and 15 samples of chicken plasma. have been investigated for amounts of fluoride. Two different methods have been applied. Egg samples were analysed with a spectrophotometric method (Alizarin: cerium: fluoride complex with detection at lambda = 620 nm), following prior distillation of the samples in sulfuric media. Plasma samples were analysed by suppressed ion chromatography (IC) with conductivity detection. In this case, it was necessary to develop a cleaning method for the samples before their injection into the chromatographic system. The detection limits obtained were 25 ng mL(-1) for the colorimetric method and 50 ng mL-1 in the case of the chromatographic method. Both methods were successfully applied to the analysis of the samples, and the obtained results were in accordance with the results obtained with the ion selective electrode (ISE) method. On the other hand, the proposed methods turn out to be a sensitive alternative when problems with sample size or cationic interferences are present.