RP-HPLC method development for the simultaneous determination of timolol maleate and human serum albumin in albumin nanoparticles.

An isocratic high-performance liquid chromatographic method was developed and validated for the simultaneous determination of human serum albumin (HSA) and timolol in albumin nanoparticles. This method involved a reversed-phase-C18 column thermostated at 25 °C, UV detection at 276 nm, flow rate of 1.0 ml/min and a mobile phase compounded by 0.05% (v/v) trifluoroacetic acid in water/0.05% (v/v) trifluoroacetic acid in an acetonitrile (40:60, v/v) solution. The elution times for albumin and timolol were 1.84 ± 0.05 min and 2.67 ± 0.04 min, respectively. Calibration curves were linear from 0.2 to 100 mg/ml for HSA and 0.01 to 1 mg/ml for timolol. Limits of quantification were 0.2 mg/ml for HSA and 0.01 mg/ml for timolol. The values of accuracy and precision of intra- and inter-day variation studies were within acceptable limits, according to the US Food and Drug Administration Guidance for Industry. The described method has proved to be useful to give accurate measurements of human serum albumin and timolol from albumin nanoparticles to determine the percentage of encapsulation and the process yield.