Micro-emulsion Spectrophotometric Determination of Iron in Aluminum Alloy by the Associated System of Fe(III)-Thiocyanate-Ethyl Rhodamine B

A micro-emulsion spectrophotometric method for determination of iron in aluminum alloy was proposed.Fe(Ⅲ) was reacted with 3.00 mL of 2 mol·L~(-1) KSCN solution and 3.00 mL of 1.0×10~(-3)mol·L~(-1) ethyl rhodamine B in 0.5 mol·L~(-1) H_2SO_4 solution in the presence of 0.8 mL of 5 g·L~(-1) gum arabic and 0.70 mL of micro-emulsion solution.An association complex was formed between the anionic complex of[Fe(CN)_6]~(3-) and the cation of ethyl rhodamine B(ERB~- ),which was solubilized by solutions of gum arabic and micro-emulsion. Linear relationship between values of absorbance and mass concentration of Fe(Ⅲ) was found in the range of 0.026 - 0.36 mg·L~(-1).Apparent molar absorptivity of the associated system found was 1.08×10~5'L·mol~(-1)·cm~(-1) at the wavelength of its absorption maximum 620 nm.The proposed method was applied to the determination of Fe in samples of aluminum alloy,giving values of RSD's(n=5) less than 2%.