电感耦合等离子体原子发射光谱法测定某些特殊试样中痕量铬(Ⅵ)-共沉淀法快速分离铬(Ⅲ)

ICP-AES Determination of Cr(Ⅵ) in Certain Special Samples-Preliminary Separation of Cr(Ⅲ) by co-Precipitation

摘要: 电感耦合等离子体原子发射光谱法(ICP-AES)应用于某些特殊试样(特别试液背景色泽很深或略带混浊者)中铬(Ⅵ)的测定.试样溶液中共存的铬(Ⅲ)及一些其他金属离子的干扰,借在pH 9.5的氨性溶液中以Fe(Ⅲ)离子作载体共沉淀分离予以消除,用ICP-AES法测定滤液中铬(Ⅵ).试验表明:铬(Ⅲ)共存量达100 mg·L-1时,经沉淀分离后不影响铬(Ⅵ)的测定,铬(Ⅵ)的回收率接近100%.此方法的检出限(3σ)为0.054 mg·L-1,应用所提出的方法测定了一种黄色油漆中在铬(Ⅲ)共存下的铬(Ⅵ),平行7次测定,相对标准偏差为1.3%.

Abstract: ICP-AES was applied to the determination of Cr(Ⅵ) in certain special samples,especially those with deep color or slight turbidity.Interferences of Cr(Ⅲ) and some other co-existing metal ions were eliminated by precipitation with aq.ammonia at pH 9.5 using Fe(Ⅲ) ion as carrier,and Cr(Ⅵ) was determined in the filtrate by ICP-AES.It was proved that 100 mg·L-1 of Cr(Ⅲ) were tolerable and the recovery of Cr(Ⅵ) obtained,after precipitation were very near to 100%.Detection limit (3σ) of the method was found to be 0.054 mg·L-1.The proposed method was used for the determination of Cr(Ⅵ) in presence of Cr(Ⅲ) in a sample of yellow colored paint which was digested with conc.HNO3 preliminarity,the value of RSD′s (n=7) obtained were 1.3%.