A natural reagent in the application of spectrophotometric determination of aluminum

A new method of the quantitative determination of Al3+ was developed based on the different colors between anthocyanin itself extracted from the red cabbage and the product of the complexation that Al3+ reacted with anthocyanin.Anthocyanin colored with Al3+ in acetic acid-sodium acetate buffer at pH 4.7.The maximum absorption wavelength of the complex was 580nm.A good linear relationship between the absorbance and the concentration of Al3+ in the range of 0.1 ～ 1.0 mg/25 mL was obtained with the correlation coefficient of R2 = 0.9995.The molar absorption coefficient of the complex is 236 L·mol-1·cm-1.The precision of replicate measurements was 2.2% at Al concentrations of 25μg·mL-1.A quantitative detection limit of 0.059 mg/25 mL-1 was obtained.The analytical procedure was critically evaluated by analysing certified soil reference materials(GBW07408) and determining the recovery of Al in the materials.Excellent agreement between the experimental values and the certified concentrations and the recoveries of 98% ～109% by addition of the standard solution in the digestion solution of the soil reference materials were obtained.Because of less interference ions,short colored time,stable complex,accurate and reliable characteristics,this method can be used for the quantitative determination of trace amounts and low levels of aluminum.