Determination of trace iodide in iodised table salt on silver sulfate-modified carbon paste electrode by differential pulse voltammetry with electrochemical solid phase nano-extraction.

Electrochemical solid phase nano-extraction, a novel sample preparation technique, was used for the determination of trace iodide in iodised table salt based on the silver sulfate nanoparticle-modified carbon paste electrode. Electrochemical solid phase nano-extraction was realized in the exchange between the sulfate anion in nanoparticles and an iodide anion from aqueous solution. The released silver cation serves as the electrochemical probe for the determination of iodide. The extraction follows a Freundlich adsorption isotherm, and can be used in the detection of iodide in the concentration range 5.0x10(-12)-4.0x10(-9)M. The amount of iodide in iodised table salt was determined as 0.875+/-0.002microg/g, which is about 2.5% of the addition amount of iodate with a relative deviation of 5.92% and a standard addition recovery of 90-110%. The large amounts of chloride and iodate did not interfere with the detection.