A new and sensitive reaction rate method for spectrophotometric determination of trace amounts of thiourea in different water samples based on an induction period

摘要

Thiourea (TU) has various industrial, agricultural and analytical applications. TU has been labeled as having carcinogenic activity. Hypothyroidism was induced in animals by using TU. A simple and sensitive spectrophotometric reaction rate method was proposed for the determination of trace amounts of TU. The method is based on the inhibitory effect of TU on the rate of meta cresol purple (MCP) with bromate in the presence of bromide. The reaction progress was followed by monitoring the absorbance of MCP at 525?nm. The effects of different variables on the sensitivity of the proposed method were studied and optimized. Under optimum conditions a linear relationship between induction period time and TU concentration was found in the concentration range of 0.10 – 6.0?μg?mL?1 of TU. The detection limit (3σ) of 0.020?μg?mL?1 was found. The relative standard deviations for six replicate determinations of 0.10, 2.0 and 5.0?μg?mL?1 of TU were 2.3%, 1.8% and 1.1%, respectively. In this study a new reaction system was proposed for the kinetic spectrophotometric determination of TU in water samples. The new method not only benefit from high selectivity and sensitivity, but also it has the advantage of fast and simple operation.