一种天然显色剂在光度法测定铝中的应用

A natural reagent in the application of spectrophotometric determination of aluminum

自紫甘蓝中提取的花青素与Al3+发生络合反应的产物颜色与花青素本身不同,利用该性质可以建立一种定量测定Al3+的新方法。花青素在pH 4.7的乙酸-乙酸钠缓冲体系中与Al3+显色,络合物最大吸收波长580nm。Al3+含量在0.1～1.0 mg/25 mL范围内与吸光度呈良好的线性关系,相关系数R2=0.9995,络合物摩尔吸光系数236 L.mol-1.cm-1,铝离子浓度为25μg/mL时方法相对标准偏差2.1%,定量检出限0.059 mg/25 mL。方法应用于国家土壤标准样品(GBW07408)的测定,土壤样品加标回收率在98%～109%之间。方法可用于低常量和微量铝的定量测定。

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.