Determination of Iodides and Bromides in Associated Produced Groundwater by the Visual Test Method

A technique has been developed for the semiquantitative visual determination of iodide and bromide ions in their simultaneous presence in highly mineralized produced waters from oil and gas condensate fields. The technique is based on the oxidation of iodine to iodide with potassium iodate and bromide to bromine with potassium bromate, followed by the bromination of fluorescein with the formation of eosin. Both iodine and eosin were adsorbed by modified polyurethane foam tablets. The conditions for visual determination of the indicated analytical forms were investigated. The limit of quantification using the color scale was 3.2 mg/L for bromide ions and was 0.48 mg/L for iodide ions. The determination range was 5–80 mg/L for Br^– contents and 0.5–16 mg/L for I–. The semiquantitative method with visual detection is expressed and suitable for the analysis of associated produced groundwater: the analysis time is reduced threefold compared to the quantitative determination method using oxidation–reduction titration.