Development and Validation of a Diethyl Phosphite Content in Foscarnet Sodium USP by GC MS Technique

A simple, rapid, selective, and reproducible Gas chromatographic mass spectrometry (GC-MS) method has been developed and validated for the estimation of Diethyl Phosphite content in Foscarnet Sodium USP Drug substance. The drugs were estimated using HP-5, Length-30 M, Internal diameter 0.32 mm; Film thickness 1 μ at a total flow rate of 11.9 ml/min, and column flow of 1.49 ml/min was used for the separation. Flow control mode was pressure. Column oven temperature 70°C and injector temperature 220°C. Oven program modified for proper elution of peak. The linearity range used was 0.025-0.120µg/ml and (Rt) was 6.7 min. The correlation coefficient values were found to be 0.997. Precession studies showed % RSD values less than 15.0% for all the selected concentrations. The percentage recovery of Diethyl phosphite from LOQ to 150% was found in range of 100.7 -116.7%. The content results of Phophite content were within the limits of less than 0.12 ppm. The method was validated as per the International Conference on Harmonization (ICH) guidelines. The developed method was successfully used for the quantitative analysis of commercially available dosage forms.