GF-AAS Determination of Trace Amounts of Pb and Cd in Seawater with Enrichment on Strong Alkaline Anion Exchange Fiber

The sample of sea water (500 mL) was adjusted to pH 5 and 8-hydroxyquinoline was added to chelate with Pb²⁺ and Cd²⁺ in the solution. The chelates of Pb²⁺ and Cd²⁺ were then quantitatively enrich on the SPE column pack with 0.5 g of strong anion exchange fiber, with a flow rate of 10 mL·min^-1. The chelates of Pb and Cd on the SPE column were eluted with 10 mL of 1.0 mol·L^-1 HNO₃ solution, and their contents in the eluate were determined by GF-AAS. Linear relationships between values of absorbance and mass concentration of Pb and Cd were obtained in definite ranges, with detection limit of 0.019, 0.012 μg·L^-1 respectively. Values of recovery for the 2 elements found by standard addition method were in the range of 94.3%-99.9%, and values of RSD's (n=6) in the range of 1.2%-3.4%.