Zaijun Li, Yuling Yang, Jian Tang, Jiaomai Pan
College of Chemical and Material Engineering, Southern Yangtze University, Wuxi 214036, China(1).
Talanta. 2003 May 28;60(1):123-30. doi: 10.1016/S0039-9140(03)00115-2.
A highly sensitive and selective spectrophotometric method for determination of trace lead in water after pre-concentration using mercaptosephadex (MS-50) has been developed, the method based on the color reaction of lead(II) with dibromohydroxylphenylporphyrin. Under optimal condition, lead(II) reacts with the reagent to form a 1:2 yellow complex in presence of TritonX-100, which has a maximum absorption peak at 479 nm. The color reaction can complete rapidly and remain stable for 24 h in room temperature. The molar absorption coefficient of the lead complex, the limit of quantification, the limit of detection and relative standard deviations were found to be 2.35x10(5) l mol(-1) cm(-1), 4.3, 1.4 ng ml(-1) and 1.0%, respectively. The absorbance of the lead complex at 479 nm is linear up to 0.48 mug ml(-1) of lead(II). The effect of various co-existing ions in water were examined seriously. No interference was observed. Moreover, a simple pre-concentration method for trace lead in water was also studied using MS-50. It was found that trace lead in water can be adsorbed in 1.0 mol l(-1) HCl and dissociated from MS-50 with 4.0 mol l(-1) HCl quantitatively, that improves the selectivity and the sensitivity of method (its detection limit (3 s) changed into 0.2 ng ml(-1) of lead) obviously. The proposed method has been applied to determine trace lead in water samples with satisfactory results.
建立了一种高灵敏度和选择性的分光光度法，用于在使用巯基葡聚糖（MS - 50）预富集后测定水中的痕量铅。该方法基于铅（II）与二溴羟基苯基卟啉的显色反应。在最佳条件下，铅（II）与试剂在TritonX - 100存在下反应形成1:2的黄色络合物，其在479 nm处有最大吸收峰。显色反应能迅速完成，在室温下可稳定24小时。铅络合物的摩尔吸收系数、定量限、检测限和相对标准偏差分别为2.35×10⁵ l·mol⁻¹·cm⁻¹、4.3、1.4 ng·ml⁻¹和1.0%。铅络合物在479 nm处的吸光度在铅（II）浓度高达0.48 μg·ml⁻¹时呈线性关系。认真研究了水中各种共存离子的影响，未观察到干扰。此外，还研究了使用MS - 50对水中痕量铅的一种简单预富集方法。发现水中的痕量铅能在1.0 mol·l⁻¹ HCl中被吸附，并能用4.0 mol·l⁻¹ HCl从MS - 50中定量解离，这明显提高了方法的选择性和灵敏度（其检测限（3s）变为0.2 ng·ml⁻¹的铅）。所提出的方法已应用于测定水样中的痕量铅，结果令人满意。
