Simplified method to quantify furosemide in urine by high-performance liquid chromatography and ultraviolet detection.

Simplified reversed-phase high-performance liquid chromatographic method with ultraviolet detection at 280 nm without extraction procedure is described to quantify furosemide in rabbit and human urine. An internal standard was not used. The lower limit of quantitation was 0.750 microg/ml using 50 microl urine samples (100 microl of total injection volume), and linear response was tested from 0.750 to 250 microg/ml in both humans and rabbits. Within and between-day accuracy and precision were always below 10% at all analyzed concentrations. Validation data showed that this method is linear, sensitive, selective, specific, accurate and reproducible.