Studies on the Eu and Evans Blue Spectrophotometric Determination of Neomycin and tobramycin

In acid solution, Eu(Ⅲ) and evans blue(EB) react with neomycin sulfate(NEO) and tobramycin sulfate(TOB), to form three ingredient blue ion association complexes. The maximum absorption wavelength was at 668 nm(NEO) and 670 nm(TOB), the linear ranges were 0～15.5 μg·mL~(-1)(NEO)and 0～15.0 μg·mL~(-1)(TOB), and their molar absorptivities (e) were 1.19×10~(5)(NEO) and 9.05×10~(4)(TOB)L·mol~(-1)·cm~(-1). The maximum fading wavelength was located at 608 nm, the linear ranges were 0～16.5 μg·mL~(-1)(NEO)and 0～16.0 μg·mL~(-1)(TOB)with molar absorptivities(e) of 1.54×10~(5)(NEO) and 1.08×1~(5)(TOB)L·mol~(-1)·cm~(-1). When the dual-wavelengths overlapping absorption spectrometry was used to determine the concentrations of neomycin and tobramycin, and their molar absorptivities e were 2.73×10~(5)(NEO)and 2.00×10~(5)(TOB)L·mol~(-1)·cm~(-1). The optimum reaction conditions and the analytical performance were studied. The method has been applied to the determination of the content of neomycin and tobramycin in commercial medicine and human urine with satisfactory results.