“…Compared to the previously published sodium biphenyl methods for the determination of fluorine in organic compounds (12,13), in petroleum products (14), and in experimental biological samples having significantly high levels of organic fluorine compounds (15,16), the procedures described herein permit a smaller sample size, are simpler and more rapid to carry out, and are more economical. Further, the problem of low recoveries encountered by some in the analysis of certain fluorochemicals by the sodium biphenyl method (15) has been identified and resolved in this study.…”