FAAS Determination of Trace Amount of Iron in Huaiqing Chinese Medicines with Cloud Point Extraction

Trace amount of Fe was separated and enriched from the sample solution buffered at pH 4.0 in the form of hydrophobic coordination complex with DDTC by cloud point extraction using Triton X-114 as surfactant.The surfactant phase was diluted and made up to 0.6 mL with 0.01 mol·L-1 HCl and the content of Fe was determined by FAAS. Influential factors to cloud point extraction, and interferences of co-existing ions were studied and optimized. Detection limit (3σ) of the method was found to be 0.4 μg·L-1. The proposed method was applied to the determination of Fe in samples of Huaiqing Chinese medicines (Huaiqing Chinese yam, radices rehmanniae, achyranthes and chrysanthemum), and values of recovery obtained by standard addition method were in the range of 90.7%-111.2% with RSD′s (n=6) in the range of 2.5%-4.5%.