Trisodium phosphonoformate (PFA) is a broad spectrum antiviral drug with low toxicity. Based on the weakbasic property of PFA (pKb

13.51)

nonaqueous titration was used for the determination of PFA in solid sample

while molybdenum blue spectrophotometry was adopted for the determination of PFA in solution and cream. Themethod was not interfered with by additives in preparations. The average recovery of PFA from solid sample

solution and cream was 99.78 % ± 0.32 %

99.94 %±0.46 % and 99.48 % ± 0.50 %

respectively.