Optimized determination of lycopene in canine plasma using reversed-phase high-performance liquid chromatography.

An isocratic high-performance liquid chromatographic method with detection at 472 nm was developed, optimized and validated for the determination of lycopene in canine plasma. Ethyl-beta-apo-8'-carotenoate was used as internal standard. A Hypersil BDS RP-C18 column (150 mm x 4.6 mm), 5 microm particle size, was equilibrated with a mobile phase composed of acetonitrile and methanol (50:50, v/v). Its flow rate was 1.5 ml/min. The elution time for lycopene and ethyl-beta-apo-8'-carotenoate was approximately 11 and 5 min, respectively. Calibration curves of lycopene were linear in the concentration range of 3-200 ng/ml in plasma. Limits of detection and quantification in plasma were 1 and 4 ng/ml, respectively. Recovery was greater than 97%. Intra- and inter-day relative standard deviation for lycopene in plasma was less than 1.8 and 3.1%, respectively. This method was applied to the determination of lycopene plasma levels after single dose administration to dogs.