Determination of Total Iodine Concentration in Aquatic Environments Using Cathodic Stripping Voltammetry Combined with Sodium Hypochlorite (NaClO) Oxidation

摘要

An easy and fast method for the determination of total iodine in environmental samples by cathodic stripping voltammetry combined with sodium-hydrochlorous-induced oxidation (NaClO oxidation) has been developed. Adequate conditions for NaClO oxidation of 40 - 50oC over 2 h were determined, using three representative environmental samples (reference soil, seabed sediment, seaweed). By analyzing a mixture of thyroxin and a reference soil material, an overall recovery of > 97% for total iodine in the concentration range of 1 - 7 μmol/g was obtained. This method was compared with alkaline extraction and combustion methods for solid (reference soil, seabed sediments, seaweed, and filter) and aqueous environmental samples. Alkaline extraction exhibited lower recovery of iodine compared with the NaClO oxidation method, indicating insufficient extraction and/or interference on determination. Combustion method also showed lower iodine recovery for some samples, probably due to a trapping efficiency and incomplete combustion of organic matter.