原子光谱法直接测定纯铝材中的砷,受到铝基体的干扰.实验表明,当被测试液中Al的质量浓度大于等于As的5 000倍时,测量误差大于5%.为了降低被测试液中铝的浓度以消除干扰,利用对Al3+吸附作用强的强酸型阳离子交换纤维作为固相萃取剂,通过对萃取剂用量、萃取温度、pH值等条件的研究,得到以下方法:0.900 0 g强酸型阳离子交换纤维在55 ℃,pH 2.0的试液中,对Al3+进行超声辅助萃取5 min,此时以砷酸形式存在的砷不被萃取而留在试液中供测定.结果表明,10.00 mL含砷1.00 μg,铝20.0 mg的试液经过分离后,其中砷未见损失,而残留铝质量浓度约为砷的2 000倍,已不干扰ICP-AES测定As.方法检出限(3 s)为0.027 μg·mL-1,方法定量下限(10 s)为0.091 μg·mL-1.本方法已用于合成样、铝制饮料易拉罐和烘烤食品用铝箔等样品中As的测定,标准加入的回收率98.3%~105%;RSD(n=3) 0.1％~4.3％;结果显示,在本实验所测的铝易拉罐和烘烤用铝箔样品中,砷的含量均低于国家标准(GB/T 3190—2008)的限定值.

Determination of arsenic in pure aluminum by inductively coupled plasma atomic emission spectrometry was interfered by aluminum matrix.The experiment showed that when the mass concentration of Al was greater than or equal to 5 000 times the As in the test solution,the measurement error was greater than 5%.In order to eliminate the interference,strong acid cation exchange fiber (SACEF) was used as solid phase extraction agent to adsorb Al3+.The extraction conditions included amount of SACEF,extraction time,temperature and pH were investigated.The optimal extraction conditions were that 0.900 0 g SACEF was used to extract the aluminum from the sample solution of pH 2.0 at 55 ℃ for 5 min with the ultrasonic assist,and in this case,the arsenic in the form of arsenic acid was not extracted and left in the solution for the determination.The results showed that after treating 10.00 mL test solution containing 1.00 μg arsenic and 20.0 mg aluminum,arsenic did not lose.The mass concentration of residual aluminum in the raffinate was about 2 000 times the As,which had not interfered the determination of arsenic.The detection limit (3 s) was 0.027 μg·mL-1 and quantification limit (10 s) was 0.091 μg·mL-1.The proposed method was successfully applied to the separation and determination of arsenic in the synthetic samples,the aluminum cans and the barbecue aluminum foil.Recovery was in the range of 98.3%~105% and RSD (n=3) was in the range of 0.1%~4.3%.The results showed that the content of arsenic in the aluminum cans and the aluminum barbecue foil was below the limited value of national standard (GB/T 3190—2008).