当镍的共存质量浓度大于铬5 800倍时,对电感耦合等离子体原子发射光谱法(ICPAES)直接测定铬有明显的负干扰,而且干扰程度随着镍共存质量浓度的增大而增大。试验结果表明:将25.00mL 5.00×102μg/mL Ni(Ⅱ)、1.50mol/L NH4SCN的试液(pH 1.0),以0.5mL/min的流速通过3.00g强碱性阴离子交换纤维柱(=10mm),Ni(Ⅱ)能被纤维柱吸附,因铬在此条件下不被吸附而收集在待测流出液中,从而消除了镍基体对测定铬的干扰。方法中铬的测定下限为2.00×10-3μg/mL。按照实验方法对实际样品以及合成样中铬进行测定,合成样测定结果的相对误差绝对值不大于3.2%,实际样品回收率在93%~99%之间,测定总值的相对标准偏差(RSD,n=6)不大于2.9%。
The nickel had obvious negative interference to the direct determination of chromium by induc- tively coupled plasma atomic emission spectrometry (ICP-AES) when the mass concentration of coexisting nickel was 5 800 times higher than that of chromium. Moreover, the interference extent increased with the increase of mass concentration of coexisting nickel. 25.00 mL of 5.00 × 10^2 μg/mL Ni(Ⅱ) and 1.50 mol/L NH4SCN sample solution (pH 1.0) passed through 3.00 g of strong basic anion exchange fiber column (φ= 10 mm). The experimental results indicated that Ni(Ⅱ) could be adsorbed onto the fiber column, while chromium could not be adsorbed under this condition and be collected in the test solution. Therefore, the interference of nickel matrix to the determination of chromium was eliminated. The low limit of determina- tion was 2.00 × 10^-3 μg/mL. The content of chromium in actual samples and synthetic samples was deter- mined by the proposed method. The absolute value of relative error for determination results of synthetic samples was not more than 3.2%, and the recoveries of actual samples were between 93% and 99%. The relative standard deviation (RSD, n=6) was not more than 2.9%.