High-sensitivity spectrofluorimetric determination of tiopronin based on inhibition of hemoglobin

A highly sensitive and simple spectrofluorimetric method for the determination of tiopronin based on its inhibitory effect on the hemoglobin-catalyzed reaction of H(2)O(2) and L-tyrosine was developed. The concentration of tiopronin is linear with decreased fluorescence (ΔF) of the system under the optimal experimental conditions. The calibration graph is linear in the range 1.23 × 10(-8) to 3.06 × 10(-5) mol L(-1) with a detection limit of 6.13 × 10(-9) mol L(-1). The relative standard deviation was 4.38% for 11 determinations of 6.13 × 10(-6) mol L(-1). This method can be used for the determination of tiopronin in pharmaceuticals with satisfactory results.