A Study on the Dual-wavelength Compensation Spectrophotometry and Its Application to Micro Ferrum Determination

A novel dual-wavelength compensation spectrophotometry was established and applied to the determination of micro ferrum with alzarin red S(ARS) as the chromogenic reagent.This method could determine the real absorbance of the chromogenic product in spectrophotometry through eliminating the destructive interference of discolored ARS on the resultant chromogenic product,Fe3.It could also determine the real absorbance of the discolored product in spectrophotometry through eliminating the destructive interference of Fe3 on the discolored ARS.The sum of the absolute chromogenic absorbance and discolored absorbance was taken as the signal determined by the spectrophotometry.The compensation coefficient fs of absorbance signal was 2.227 at wavelength of 423 nm(λN) and 555 nm (λp) and the molar absorptivity was 2.154×104 L·mol-1·cm-1,which was 2.135 times greater than that obtained by traditional method.The linear range was 0-2 mg·L-1.The proposed method was compared with the traditional method in terms of linear range and molar absorptivity.The results showed that the proposed method is superior to the traditional method.The method was also applied to the determination of ferrum in hair with satisfactory results.