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 (Δ F ) 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. Copyright © 2010 John Wiley & Sons, Ltd.