Novel method for indirect determination of iodine in marine products by atomic fluorescence spectrometry

A method for the determination of iodine based upon compound H2HgI4, formed between I− and Hg2+ in nitric acid and extracted in methyl isobutyl ketone(MIBK), was developed via atomic fluorescence spectrometry(AFS). After the compound is reduced with potassium borohydrid(KBH4), the resultant mercury vapor was injected into the instrument and iodine was, therefore, indirectly determined. Experimental parameters such as the conditions of extraction reagents, aqueous phase acidity, elemental mercury diffusion temperature in a vial and other factors were investigated and optimized. Under the optimum experimental conditions, this method shows a detection limit of 0.038 μg/L iodine and a linear relationship between 0.04–20 μg/L. The method was applied to determining the iodine content in marine duck eggs, kelps, laver and Ganoderma lucidum spirulina, showing a relative standard deviation(RSD) of 2.15% and the recoveries in the range of 98.1%–102.5%.