In this study, cation chromatography was performed to analyze high-concentration potassium contained in reduced-sodium edible salts. Regarding conditions, the eluent was set at a concentration of 30 mmol/L methanesulfonic acid, and potassium, sodium, magnesium, and calcium ions were observed to be well separated. Interference by other elements became negligible within 30 minutes. The recovery rate of potassium was 99.8-100.2 ％. In addition, good linearity was obtained in the potassium calibration curve at a concentration range of 1-50 mg/L. Validity could be confirmed from the accuracy, parallel precision of the results of this analysis method. This developed method can be applied as a rapid and effective analysis method for reduced-sodium edible salts containing high concentrations of potassium.

We developed a simple flow-injection analytical （FIA） system to determine boron in natural water samples fluorometrically. The system had two newly-developed components: one was the flow system using small and low-power consumption micro-ring pumps, and the other was a compact fluorometric detector using an ultra-violet light-emitting diode （UV-LED） with a photocurrent integration circuit. These components contributed to the cost reduction and downsizing of the system. The detector dimensions and mass were 125×90× 60 mm and 400 g, respectively. The fluorometric reagent for boron was chromotropic acid, reported as a highly sensitive reagent. Parameters for the system, such as reaction coil length, and sample injection volume, were optimized. After optimization, its linear dynamic range and the limit of detection （LOD） for boron were 0 to 0.5 mg L^－1 and 0.017 mg L^－1, respectively. The sample throughput was 20 h^－1. We successfully applied this FIA system to determine boron in river and seawater samples.

High growth conditions for sterile Ulva, green algae, were evaluated for an efficient culture. A culture device simulating the sea was prepared, and the maximum conditions for a specific growth rate was verified using the photosynthetic photon flux density （PPFD） of the bottom of the culture tank as an index instead of the Leaf Area Index （LAI）. As a result, the specific growth rate showed the highest value at the average PPFD of 20.6 µmol m^－2 s^－1 for one week on the bottom of the culture tank, and the specific growth rate decreased significantly at 4.0 µmol m^－2 s^－1. From these data, a method for controlling the density of sterile Ulva using the PPFD of the bottom surface as an index will lead to a culture control method that can maintain a high growth rate for sterile Ulva without the complicated LAI measurement. Based on these data, we newly proposed a type of efficient sterile Ulva production using enriched seawater.

An accelerated test method to evaluate the caking of salt products in a short time by controlling the fluctuation cycle of relative humidity was considered. Caking phenomenon is caused by dissolving and re-crystallizing due to moisture adsorption and release, and is affected not only by the amount of moisture intake but also by the rate of moisture adsorption. Specifically, a correlation between the amount of change in moisture content during adsorption and release accumulated over time and the caking strength was observed. Accordingly, by re-setting the relative humidity fluctuation cycle, methods that increase the rate of caking strength to three times that of standard conditions were created. As a result, the conventional testing time of 56 days could be shortened to 20 days. Using this method, an evaluation of caking characteristics for various common salt samples is thought to be possible in the future.

In this study, the relationship between the added amount of salt and the change in KCl content of salt appropriate for commercially available low sodium salt as used in the manufacture of salted ume （Japanese apricot） and the preservative quality of the resulting product was considered. When the added amount of salt was 9 ％, yeast and mold were detected in the sun-dried salted ume, suggesting a low （insufficient） preservation effect of the salt. On the other hand, when the amount of salt in sun-dried salted ume was maintained at 18 ％, which is appropriate for commercially available low sodium salt where KCl is added as a substitute for NaCl, general viable cells and molds and yeasts were not detected. This suggests that KCl inhibits the propagation of microorganisms as equally well as NaCl. Consequently, it follows that low sodium salted ume can be manufactured using salts with different amounts of KCl while maintaining the desired preservative effect.