Two different synchronous spectrofluorimetric approaches for simultaneous determination of febuxostat and ibuprofen: application to human plasma

Two green, sensitive and simple synchronous spectrofluorimetric methods were developed for the simultaneous estimation of febuxostat and ibuprofen for the first time. Method I is constant-wavelength synchronous spectrofluorimetry where febuxostat and ibuprofen were recorded at 329 and 258 nm, respectively using Δλ of 40 nm. Method II is constant-energy synchronous spectrofluorimetry using a wave-number interval of -4000 cm−1. All measurements were performed in a borate buffer of pH 7 and distilled water for dilution which increased the method greenness. The two methods were rectilinear over the concentration ranges of 30.0-700.0 ng mL-1 and 0.5-9.0 µg mL-1 in method I and 20.0-500.0 ng mL-1 and 0.1-8.0 µg mL-1 in method II for febuxostat and ibuprofen, respectively. High sensitivity was attained for the two drugs with LODs down to 0.40 and 5.6 ng mL-1 in method I and 0.25 and 3.4 ng mL-1 in method II for febuxostat and ibuprofen, respectively. Recovery percentages were in the range of 9...