[Development and Applicability of Analytical Methods for Quantifying Cyanide and Bromic Acid in Mineral Waters]

We developed and evaluated methods of quantifying cyanide (cyanide ion and cyanogen chloride) and bromic acid in mineral waters (MW). After performance evaluation, recovery studies were performed on 110 kinds of MW products to examine the applicability of the methods. The approximate proportion of the MW samples, in which the recovery rate of these anionic compounds was within 90 to 110%, was 95% in the cyanide ion and bromic acid analysis and 45% in the cyanogen chloride analysis. We observed low rates of recovery of cyanogen chloride from some MW products with pH values around neutral. To increase the recovery rate, we propose adding phosphoric acid buffer to adjust the pH of these MW samples. The retention times for bromic acid in some MW products differed from that in standard solution. We concluded that carbonic acid influences the retention times. It may be necessary to to exclude carbon dioxide from the MW samples by degassing to synchronize the retention times of bromic acid in the MW samples and the standard solution.