Analysis of Cations and Anions in Edible Salts by Ion Chromatography

In this study, we measured trace ions contained in edible salts, and evaluated their types, processes and characteristics using ion chromatography (IC). Under the optimal cationic IC conditions, potassium, magnesium, and calcium were detected within 17 minutes using a Shodex IC YS-50 as a separation column and 4.0 mM methanesulfonic acid as an eluent. On the other hand, fluoride, bromide, and sulfate were detected within 20 minutes under the optimal anionic IC conditions using a Shodex IC SI-35 4E as a separation column and 3.0 mM sodium carbonate/2.0 mM sodium bicarbonate mixture solutions as the eluent. The quantitation limits (S/N = 10) of each cation and anion were 30.2-60.3 μg L−1 and 3.4-22.7 μg L−1, respectively. The quantitation limits of analyte ions obtained by the present IC were expected to be applicable to analyses of trace ions in edible salts. In addition, the calibration curves of each ion at 0-50 mg L−1 showed a very close correlation (R2 = 0.999). A recovery test was carried out by adding 1 mg L−1 of each ion to 500 mg L−1 of edible salt dissolved in pure water. The recovery rates of each ion were 96.1-104.8 %. The developed method was applied for the determination of trace inorganic ions contained in edible salts. The content of each ion varied depending on the type and process. In particular, the content differences of magnesium, calcium, and bromide in sea salt and rock salt were distinct. For example, 55.2 mg/100 mg of bromide was detected from Seto Inland Sea salt. It was found that simultaneous determination of the 6 ions in edible salts was possible only using IC without using titration method and atomic absorption spectroscopy.