Simultaneous determination of iodide and iodate in salty spices by liquid chromatography-inductively coupled plasma mass spectrometry (LC-ICP-MS)

Abstract

In this study, iodide and iodate species in food were simultaneously determined by LC-ICP-MS after sample treatment with Deion water based on ultrasonic extraction. The conditions of the instrument and the extraction procedure were investigated. The method was validated with calibration curves that have the coefficient of determination (R2) higher than 0.995. The method limits of detection (LOD) of iodide and iodate were 0.079 and 0.060 mg/kg respectively meeting the regulatory requirements for food safety management. The recoveries were in the range of 83.5 - 108% and the relative standard deviations (RSDr) were between 2.57 and 5.22%. These parameters met the requirements specified by AOAC. A total of 43 salty spice samples including table salts, iodized seasoning soup powders, seasoning seeds, oyster sauces, soy sauces, fish sauces were collected and analyzed for research purposes. The results showed that a high percentage (76.9%) of table salt and seasoning soup powder samples had total iodate and iodide content lower than the specified level. Meanwhile, other salty spice samples, especially seasoning seeds and soy sauces, had a significant content of iodide in the range of 2.0 to 13.2 mg/kg. This study has contributed to the preliminary assessment of the current status of iodine content in salty spice products collected in Hanoi city.