In this study, we attempted to remove fluoride ion selectively from simulated iodine-containing wastewater using titanium oxide minerals for iodine production. The simulated iodine-containing wastewater contains fluoride ion (50 mg/L) and iodine (80 g/L) with pH 2 by adjusting using hydrochloric acid. Fluoride can be adsorbed selectively from the simulated iodine-containing wastewater to meet the quality standard for iodine production, and the fluoride adsorption rate is fast. The desorption of fluoride using alkaline solution, NaOH, is more than 90 ％, and the cycle stability of the adsorbent is high.

We investigated the application of Inductively Coupled Plasma Mass Spectrometry （ICP-MS）for the simultaneous analysis of Cu, As, Cd, and Pb in salt. The coexistence of NaCl reduced the intensity of the target elements. This prompted us to optimize the internal standard elements and utilize a matrix-matching methodology. The NaCl concentration of the measurement solution was decreased to below 1 ％ in order to achieve stability for continuous measurement. As for the form of arsenic, As ^III in salt is oxidized to As ^V in our pretreatment method using nitric acid. Using As ^V as the standard solution for the calibration curve enabled good quantification of the total amount of As. When measured at a NaCl concentration of 0.4 ％, the lower limit of quantification for Cu was 0.05 mg/kg, that for As was 0.02 mg/kg, that for Cd was 0.005 mg/kg, and that for Pb was 0.01 mg/kg.The lower limit of quantification for our method was less than 1/10 of the standards for the CODEX and de-icing salt agent. The results, in terms of accuracy, repeatability, and intermediate precision, confirmed the validity of our method using salt samples with the added target elements. For all elements, the method meets the criteria of the Ministry of Health, Labour and Welfare’s validation guidelines for analytical methods for hazardous substances in foods. In addition, a comparison of common salt and salt used as a de-icing agent using our method and ICP-OES showed that the difference between the two methods was within ±10 ％. The above results indicate that ICP-MS is a valid method for determining Cu, As, Cd, and Pb in salt. The ICP-MS method efficiently and sensitively measures harmful elements in salt.