Determination of potassium iodide in table salt

Abstract

The samples of table salt bought in Belgrade supermarkets are analyzed in this paper. The method of indirect iodometry was used in the process of the analysis, and received results were converted into the content of KI in mg/kg of salt. Beside the content of KI, the content of NaCl was also determined, counted to dry meter and water content, and received results were compared with the requests determined by Regulations of Table Salt Quality Meant for Human Diet and by manufacturers' declaration. Received results show that the volumetric method of indirect iodometry, applied in this analysis, is very reliable for determination of potassium iodine in table salt, because of its high precision and reproducibility of the analysis results. All received results show that the samples of table salt which can be bought in supermarkets are according to the demands given by Regulations. Only one sample (evaporated salt) has significantly less mass of KI than it is determined by Regulations, but also by manufacturer's declaration. Measured humidity in the samples of table salt received from sea salt (sample 1) is higher than humidity in the samples received from rock salt as the result of magnesium presence in sea salt, which is hygroscopic material. Although samples 5 and 6 also originate from sea salt, their smaller humidity is the result of additional heating and salt processing.

U radu su ispitivani uzorci kuhinjske soli koji se mogu nabaviti u beogradskim prodavnicama. U radu je primenjena metoda indirektne jodimetrije, a dobijeni rezultati su preračunavani na sadržaj KI u mg/kg soli. Osim sadržaja KI, određivan je i sadržaj NaCl, računato na suvu materiju i sadržaj vode, a dobijeni rezultati upoređeni su za zahtevima koji su predviđeni Pravilnikom o kvalitetu kuhinjske soli predviđenim za ljudsku ishranu i proizvođačkom deklaracijom. Dobijeni rezultati su pokazali da je volumetrijska metoda indirektne jodimetrije, primenjena u ovom radu, veoma pouzdana za određivanje kalijum-jodida u kuhinjskoj soli, usled velike preciznosti i reproduktivnosti rezultata ispitivanja. Svi dobijeni rezultati pokazali su da uzorci kuhinjske soli koji se mogu nabaviti u trgovini odgovaraju zahtevima Pravilnika, osim jednog uzorka (varena so) koji je sadržao znatno manju masu KI nego što je predviđeno Pravilnikom, ali i proizvođačkom deklaracijom. Izmerena vlažnost u uzorcima kuhinjske soli dobijene iz morske vode (uzorak 1.) veća je od vlažnosti u uzorcima dobijenim iz kamene soli kao posledica prisustva magnezijuma u morskoj vodi, koji je higroskopni materijal. Iako su i uzorci 5. i 6. poreklom iz morske vode, njihova mala vlažnost posledica je dodatnog zagrevanja i dorade soli.