Determination of Magnesium, Calcium and Sulphate Ion Impurities in Commercial Edible Salt

Natural elemental impurities are recognized as a threat for safety and quality of edible salt and have adverse effects on public health. In the current study, fifty samples of packages containing 1 kg of salt from 25 different brands were collected from retailers in Semnan city (Iran). The concentrations of main impurities of edible salt including magnesium (Mg), calcium (Ca), and sulphate (SO4 ^-2) ions were quantified by the aid of an Ion Chromatography with conductivity detector. According to findings, the maximum concentrations of Mg, Ca, and SO4 ^-2 ions in salt samples were 0.067, 0.226, and 0.888 % w/w (dry matter basis), respectively. In addition, the concentration of Mg in 16%, Ca in 4%, and SO4 ^-2 in 28% of samples suppressed the acceptable limit proposed by the Institute of Standards and Industrial Research of Iran (ISIRI) (0.15% for Ca, 0.03% for Mg, and 0.46% for SO4 ^-2 ). Moreover, the maximum and minimum levels of purity in the salt samples were recorded as 99.940 and 97.730%, respectively. Moreover, the purity in 12% of the investigated samples was lower than that of the minimum acceptable limit suggested by ISIRI, while the purity of 97% samples met the acceptable Codex Alimentarius limit (97% Min). Based on results of the current investigation, the routine purification processes used in some factories of Iran did not reduce impurities. Hence, purification process bedsides constant monitoring and safety management should be improved to promote the health quality of edible salt.