[Determination of fluorine in biological materials with ion-selective electrodes]

Fluorine was determined in faeces of experimental rats and in krill meal by the method of ion-selective electrode. Concentrated hydrochloric acid was added to the prepared samples, and then acetate buffer was added to obtain pH 5.0-5.5 The results were similar to those obtained according to AOAC. The recovery of fluorine added to the samples in amounts from 0.2 to 0.8 mg as sodium fluoride was 90 to 98%. The method may be used also for determination of fluorine level in biological materials.