Simple and rapid determination of trace iodide by cathodic stripping voltammetry

• A sensitive and simple electrochemical method to detect trace iodide was stablished.
• The effect of different surfactants in the preconcentration process was investigated.
• The formation of ion-associating compound remarkably increased the signal of iodide.
• This method is suitable to determine trace iodine in real samples.

This work establishes a highly sensitive and simple stripping voltammetric method for the direct determination of trace iodide. In the presence of abounding bromide and appropriate amount of cetylpyridine bromide (CPB), the iodine was accumulated on the glassy carbon electrode surface as ion association complex (CPBI2Br). After accumulation for a period of time, a linear sweep potential with negative scanning was applied and the I2 in CPBI2Br was reduced again into the solution. Under the optimization conditions, the stripping signals (peak current) were linear relationship with iodide concentration in range of 3.81×10−3 µg/mL to 0.114 μg/mL and 0.127 μg/mL to 2.54 μg/mL, with a detection limit of 1.02 ng/mL (S/N=3) for a accumulation time of 180 s. Determination of trace iodine in pharmaceutical sample, kelp and table salt were performed with high accuracy and satisfactory recovery results.

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