Determination of phosphonoformate (foscarnet) in biological fluids by ion-pair reversed-phase liquid chromatography

Bioanalytical liquid chromatographic methods for the determination of phosphonoformate (foscarnet) have been developed. Biological fluids, after simple pre-treatment (ultrafiltration and/or treatment with charcoal), were injected into a reversed-phase liquid chromatographic system with electrochemical detection. Foscarnet was retained as an ion pair with tetrahexylammonium; addition of pyrophosphate was necessary in order to obtain an acceptable peak. This additive could also be used for the fine regulation of the retention to achieve the necessary selectivity.