在线离子交换分离流动注射光度法测定铅

FI-PHOTOMETRIC DETERMINATION OF LEAD WITH ON-LINE ION-EXCHANGE SEPARATION

提出流动注射在线离子交换分离光度法测定痕量铅的方法。在一定酸度条件下,试样流经D401螯合树脂分离除去某些共存离子,利用H3PO4洗脱交换在树脂上的Pb2+,然后在聚乙烯醇、阿拉伯胶存在下与KI生成PbI42-,并与乙基罗丹明B反应,生成紫红色缔合物,于590nm波长处测定吸光度。在选定的试验条件下,铅含量0～2.5μg·ml-1范围内符合比耳定律。RSD为1.4％。采样频率为40次·h-1,对废水样中痕量铅进行测定,结果满意。

Manifold of a flow injection analyzer for the determination of microamounts of lead with on-line ion-exchange separation was described. The sample solution buffered at pH 5. 6 with HOAc-NaOAc was passed through an ion-exchange column packed with D401 chelate-resin. Lead(Ⅱ) ion was adsorbed on the resin and separated from most of the co-existing ions. Lead(Ⅱ) on the resin was stripped with 1. 5mol · L-1 H3PQ4 as eluant. Lead(Ⅱ) in the eluant was reacted with KI in the presence of PVA and gum arabic forming anionic complex of PbI42- which was further reacted with ethyl rhodamine B to form a reddish violet ion association complex having it absorption maxima at 590nm. Under the optimum condition, linear relationship between the absorbance and the concentration of lead in the range of 0-2. 5μg of Pb2+ per ml of solution were obtained. Detection limit of the method was found to be 0. 032μg ·ml-1(n=20). The RSD's (n=11) obtained at the concentration level of 0. 5μg · ml-1 was 1. 4%. The method has been satisfactorily applied to the analysis of waste water. Sampling frequency of this method was 40 samples per hour.