Iodine determination in table salts by digital images analysis

Abstract

For human health reasons the World Health Organization (WHO) stated in 2014 that the amount of iodine present on table salts should lie within the range of 15 to 65 mg per kilogram of salt, depending on the salt intake levels presented in each population. This means that booth industrial laboratories (for quality control) and governmental agencies (for external quality control) should perform iodide quantification in table salts. The main method for this determination is based on volumetric analyses or WYD iodine checker. This work proposes an alternative approach for the quantification of iodine in table salt samples, that combine the good accuracy and precision obtained by titrimetric methods with the convenience of using a spectrophotometer, using just a polyurethane foam and a scanner, trough digital image analysis. The results here obtained indicate that the proposed method offers satisfactory precision and accuracy as well as sufficient sensitivity to address the resolutions provided by the WHO and the Brazilian legislation relating to iodine content in table salts. The limit of detection (LOD) was calculated as 3.94 mg kg⁻¹ and the limit of quantification (LOQ) as 13.2 mg kg⁻¹. When compared to the standard iodometric method, the developed method presented no statistical difference at 95% confidence level.