engleski

Flow-injection Spectrophotometric Determination of Tiopronin Based on Coupled Redox-Complexation Reaction

A flow injection spectrophotometric procedure for determination of N-(2–mercaptopropionyl)- glycine (MPG) tropronin has been proposed. Determination was based on the coupled redox-complexation reaction between MPG, Fe(III) and 2, 4, 6-trypyridyl-S-triazine (TPTZ). Firstly, MPG reduced Fe(III) to Fe(II), which was rapidly converted to the highly stable, deep-blue coloured Fe(TPTZ)2 2+. This coloured complex was monitored at 593 nm. Optimal conditions for determination of MPG were obtained applying the univariate method. A linear calibration curve was established in MPG concentration range 6.0 × 10–6–2.0 × 10–4 mol L–1 with regression equation y = 4675 x – 0.0195 (R2 = 0.9999) (n = 9) and detection limit of 4.0 × 10–6. Analytical frequency was 60 h–1. The proposed method was simple, rapid, sensitive and reproducible (RSD 0.5%, n = 10). It can be applied to determination of up to nanomolar levels of MPG in pharmaceutical preparations. Usual excipients used as additives in pharmaceuticals did not interfere with determination.

tiopronin; N-(2-Mercaptopropionyl)-glycine; flow-injection spectrophotometry

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