Direct Determination of Fluoride in Sea Water with a Fluoride Selective Ion Electrode by a Method of Standard Additions

In natural water systems, variable matrices can provide considerable problems In analytical methods based on calibration procedures with standard solutions. For the determination of fluoride in sea water by a selective ion electrode, a modified method of standard additions Is shown to provide a direct and simple means for determining fluoride without the need for addition of buffers and/or complex calibration procedures. Data obtained under a variety of conditions are presented to validate the method using both synthetic and natural sea water. The presence of fluoride complexing metal ions such as alumlnum(III) and iron(III) was shown not to Interfere in the determination.