米面中痕量铍的微波消解-固相萃取/石墨炉原子吸收光谱法分析

Determination of Beryllium in Rice and Flour by Microwave Digestion Combined with Solid Phase Extraction and Graphite Furnace Atomic Absorption Spectrometry

建立了微波消解-固相萃取／石墨炉原子吸收法富集并测定米面中痕量铍的方法。采用微波消解制样，7．（2’-胂酸基-5’-羧酸）苯偶氮-8-羟基喹啉-5-磺酸（H2L）与Be^2＋螯合形成BeL络合物，C18固相萃取柱（C18-SPE）富集BeL，石墨炉原子吸收法测定C18柱洗脱液中的BeL。最佳实验条件为：采用50μL pH3．0的50g/LH2L水溶液与样品中的铍螯合15min，水相上柱，用2mL50％（体积分数）甲醇溶液洗脱。结果表明，方法的线性范围为0．05～14μg/L，检出限为0．02μg/L，对实际米面样品测定的加标回收率为90％-110％，可用于食品等复杂基质中痕量铍的测定。

A graphite furnace atomic absorption spectrometry（ GF -AAS） method for the determination of Be^2＋ in food sample was established by pre-extraction using 7-（ 2＇-arsenazo acid-5＇-carboxylic acid） phenylazo-8-hydroxyl-quinoline-5-sulfonic acid（H2L） as extraction agent. The separation and enrichment of Be ion in food samples was performed on a C18-solid phase extraction（ Cls-SPE） column. The optimum experimental conditions were using 50 μL 50 g/L H2L to react with Be ion in pH 3.0 buffer for 15 rain, with flow rate of 1.5 mL/min. The analyte was eluted by 2.0 mL 50% （ by volume） methanol solution. The calibration curve showed a good linearity over the Be concentration in the range of 0.05 - 14 μg/L with a detection limit of 0. 02 μg/L. The method was applied to the determination of Be in rice and flavor samples and the results obtained were in good agreement with those of ICP - AES method. The method was probably employed in the determination of Be^2＋ in food with complex matrix.