铝(Ⅲ)-铝试剂-溴化十六烷基三甲胺体系共振瑞利散射法测定痕量铝

Determination of trace aluminum by resonance Rayleigh scattering method with aluminum(Ⅲ)-aluminoncetyltrimethylammonium bromide system

铝是广泛应用于工业生产各个领域的重要金属材料,愈来愈多的铝化合物随废水排入水体,因此测定水中铝的含量很有必要。研究了铝(Ⅲ)-铝试剂-溴化十六烷基三甲铵体系的共振瑞利散射光谱,优化了体系的最佳条件,考察了体系的其他离子干扰情况,初步探讨了反应机理,并据此建立了共振瑞利散射法测定铝的方法。试验表明,在弱酸性介质中,铝与铝试剂(ATA)形成配阴离子,然后再与溴化十六烷基三甲胺(CTMAB)通过静电引力及疏水作用力形成离子缔合物,从而引起体系的共振瑞利散射强度增加。在598.1nm处,Al(Ⅲ)的质量浓度在0.02~0.16μg/mL范围内与其对应的共振瑞利散射强度呈良好的线性关系,相关系数为0.998 9。方法检出限为1.8ng/mL。对实际水样进行了分析检测,铝测定结果的相对标准偏差(RSD,n=6)均不大于1.1%,回收率为93.5%~100.8%,测定值与原子吸收光谱法(AAS)测定值基本一致。

Aluminum is a class of important metal material that has been widely used in many fields in industrial production.More and more aluminum compounds are discharged into water system along with the wastewater.Therefore,it is very necessary to determine the content of aluminum in water.The resonance Rayleigh scattering spectrum of aluminum(Ⅲ)-aluminon-cetyltrimethylammonium bromide system was investigated.The determination conditions were optimized.The interference of other ions in system was investigated.The reaction mechanism was preliminarily discussed.The determination method of aluminum by resonance Rayleigh scattering was finally established.The results indicated that aluminum could form complex anion with aluminon(aurin tricarboxylic acid,ATA)in weakly acid medium.Then the ion association complex was formed between complex anion and cetyltrimethylammonium bromide(CTMAB)via electrostatic attraction and hydrophobic interaction,leading to the increase of resonance Rayleigh scattering intensity of system.The mass concentration of Al(Ⅲ)in range of 0.02-0.16μg/mL showed good linearity to the corresponding resonance Rayleigh scattering intensity at 598.1 nm with correlation coefficient of0.998 9.The detection limit was 1.8ng/mL.The proposed method was applied for the analysis of actual water sample.The relative standard deviation(RSD,n=6)was not more than 1.1%.The recoveries were between 93.5%and 100.8%.The determination results were consistent with those obtained by atomic absorption spectrometry(AAS).