ABSTRACT
The current reference method for the determination of fluorine in plant tissue involves high temperature ashing and alkaline fusion with the subsequent release of fluorine by microdistillation and either colorimetric or Potentiometric analysis (1,2). These methods are complex and time-consuming. This method employs a simple extraction followed by direct analysis with the fluoride specific-ion electrode and electrometer (3). The results are comparable to the reference method although there has been no collaborative study done between referee laboratories. Plant tissue is prepared in a manner similar to the reference method, drying in a forced-draft oven, and grinding to a uniform size. The dried, ground tissue is then weighed into a plastic tube, a solution of perchloric acid is added, and the mixture is heated and shaken. The fluoride content of the solution is then measured directly in the tube by insertion of the specific-ion electrode into the stirred solution and reading the output of the electrometer.
