Spectrophotometric investigation of the uranyl–phenylephrine system

Abstract

Using spectrophotometric methods and pH-metric measurements, it was found that the uranyl ion and phenylephrine form a 1:2 complex in the pH region 2.50 – 4.25 with two absorption maxima at 314.2 nm and 340.6 nm. The thermodynamic stability constant at I = 0 and T = 298 K (room temperature) of the UO2(II)–phenylephrine complex, [UO2(C9H12O2N)2]2+, is log β20= 14.0 and ΔGÆ2 = –79.6 kJ mol-1. A linear dependence of the absorbance at 340.6 nm on the concentration of phenylephrine was obtained in the range from 0.0025 mol dm-3 to 0.0245 mol dm-3 using a solution of 0.025 mol dm-3 UO2(NO3)2 at pH = 3.90 and I = 0.075 mol dm-3. The measurement error was 2.1 %.

Keywords

• complex
• uranyl ion
• phenylephrine
• thermodynamic stability constant