Comparative assessment of iodine determination techniques in natural waters

Abstract

Iodine concentration limits in ground and surface waters vary from p-10 7 to p-10” 6 %. The sensitivity of the accepted standard methods of iodine determination is often insufficient. It is necessary to take into account the instability of iodine in natural environments and errors in the results of analyses related to the addition of reagents during analysis. One of the modern methods convenient for measurements in the field is ionometry using ion-selective electrodes. The range of measured concentrations is from Yu-6 to 10 7 mol/L. Despite all the advantages of the method, the measurement accuracy decreases if “interfering ions” are present in the water. In such cases, chemical additives have been developed to eliminate “interfering ions” and increase the selectivity of the electrodes. Accuracy and sensitivity can also be improved by applying new techniques and sensitive field instruments. One such method is being developed at the Department of Hydrogeology and Engineering Geology. Hydrochemical samples are converted to a solid state and then transmitted for X-ray spectral analysis. As a result, the accuracy of determination increases by one or two orders of magnitude compared to existing methods, which is important when determining micro concentrations of iodine. Other advantages of the method: simple and fast operation, any long storage of the sorbent without negative changes and absence of “interfering ions”. Analysis of a series of samples, for which positive results were obtained, was performed.