Figure 6: Migration of hydrogen gas from hydrogen-water in a polyethylene (PE)-made storage container to the outside water. Note: (A) Hydrogen-water in a PE storage container was 50 mL, and the water outside the container in the interior of a stainless-steel-made tank was 150 mL, commonly at 20°C. The oxidation-reduction potential (ORP) and dissolved hydrogen concentration (DH) of hydrogen-water in a PE storage container at the start was –410 mV and was 970 μg/L, respectively whereas those of water outside the container were 190 mV and 0 μg/L. After 12 hours, DHs (B) and ORPs (C) were almost the same between the inside and the outside of a storage container. Measurements for each hour were performed more than three times and typically the mean values were shown.