Ultrasensitive and highly selective determination of iodate by reversed-phase ion pair HPLC–amperometric detector after online electrochemical reduction to iodide

We developed an ultrasensitive and highly selective method to quantify iodate (IO3–) in iodized salt and biological samples. In the high-performance liquid chromatography (HPLC) system, IO3– was injected with sampler and reduced to iodide (I–) online using a Coulomb detector (CD) as a pre-column reactor, retained by C18 column with the help of ion pairs, and then determined by an amperometric detector (AD). For analysis of IO3–, several parameters and reactive conditions of Coulomb detector, including applied potential, pH value, and salt concentration, were optimized to obtain the best reduction efficiency. The optimized HPLC–CD-AD method was found to be linear over a wide range of IO3– concentration (0.05–0.25 μg/mL) with appreciable recovery rates (86.90– 94.70%) of quality controls at excellent detection limits (100 pg) and acceptable variability. The analysis of IO3– in actual samples, such as urine of volunteers, iodized salt, and seawater, discovered that the method has high selectivity and little interference. It can be concluded that the proposed method was ultrasensitive and highly selective in the trace detection of IO3.