Determination of voriconazole in aqueous humor by liquid chromatography–electrospray ionization-mass spectrometry

A novel method based on liquid chromatography–mass spectrometry with electrospray ionization (LC–MS) has been developed for analysis of voriconazole in aqueous humor. The separation was achieved on a reversed-phase C18 column eluted by 70% acetonitrile–30% water–0.01% TFA. The correlation between the concentration of voriconazole to peak area was linear (r2=0.9990) between 0.04 and 60 ng, with a coefficient of variance of less than 3%. Limit of quantitation (LOQ) was estimated to be 5 ng/ml voriconazole with an injection volume of 2 μl of aqueous humor. Both intra-day and inter-day imprecision were less than 3% over the whole analytical range. Parallel analyses of voriconazole samples by LC–MS and by high-performance liquid chromatography (HPLC)–UV showed that the two methods were highly correlated (r2=0.9985). LC–MS was used to the determine voriconazole levels achieved in the aqueous humor of the rabbit eye, following topical application of 5 or 10 μg voriconazole in the form of eyedrops for 11 days b.i.d. The lower dosage produced an aqueous humor concentration of 7.29±5.84 μg/ml, while the higher dosage produced a concentration of 14.56±12.90 μg/ml.