PROBLEMS OF IODIDE IONS DETERMINATION IN MULTIVITAMINS BY INDUCTIVELY COUPLED PLASMA ATOMIC-EMISSION SPECTROMETRY

The article looks into the main problems of determination of iodine trace amounts in multivitamins by inductively coupled plasma-atomic emission spectrometry (ICP-AES), i.e. spectral overlaps attributable to macro-components, and the background effect of organic compounds. The article suggests potential ways of solving these problems. It was shown that there was a minimal overlap of iodine spectral lines by emission lines of multivitamins macro-components at the non-priority wavelength of 182.276 nm. The iodine detection limit (LOD) and limit of quantification (LOQ) were experimentally determined for ICP-AES at different wavelengths. It was demonstrated that LOD and LOQ of iodide ion were much higher in solutions containing a complex organic and multi-element matrix then in water solutions, which calls for the use of spiking in iodine assays. A comparative analysis was performed in which the content of iodine was determined in the multivitamin product Multi-tabs Junior by ICP-AES and by the reference method of inductively coupled plasma-mass spectrometry (ICP-MS). It was demonstrated that the increase in plasma power to 1500 W, the use of spiking which minimizes the background interference of organic compounds, and the use of non-priority wavelength (182.276 nm) make it possible to obtain results of iodine determination in mulitivitamins by ICP-AES which are comparable to the results obtained by the reference method. 

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