GC-MS determination of phenobarbitone entrapped in poly-epsilon-caprolactone nanocapsules

In order to evaluate the concentration of a hydrophilic drug, phenobarbitone, in a suspension of poly-epsilon-caprolactone nanocapsules, a gas chromatographic-mass spectrometric procedure, performed after methylation of the drug, was developed and validated. Free phenobarbitone (in solution in the liquid phase), released phenobarbitone (after opening the nanocapsules with ethyl acetate) and total entrapped phenobarbitone (after extraction with methylene chloride), were measured. Experimental results for four lots with various concentrations showed that the highest preparation of entrapped drug (80%) was obtained for a total concentration of 3.64 mg ml-1 in the nanocapsule suspension.