Development and validation of a rapid test kit for iodine detection in salt

Iodine deficiency disorders are widespread among vulnerable populations in Pakistan. To combat this menace, the Universal Salt Iodization program needs regular monitoring throughout the salt supply chain. Traditional titration methods are limited by accessibility, cost, and time, making rapid test tools a more practical alternative for household surveys. In this context, the current study was designed to develop a rapid test kit for on-the-spot analysis of salt samples and validate it against standard reference methods by applying single- and multiple-observer study designs. Results indicated that the regression plot analysis of the developed kit produced an excellent average R2 value of 0.9949. Percent yield/recovery of the titration method and the rapid test kit was achieved at 97.66% and 88.7-102.4%, along with a maximum value of coefficient of variance of 2.84 and 3.45, respectively. Moreover, the limit of detection/sensitivity was higher for multiple-observer designs (97.08%) as compared to the single-observer design (82.09%). The limit of quantification/specificity declined sharply for the multiple-observer design (40.4%) against the single-observer design (69.7%). This study revealed that despite yielding low specificity for multiple observers and occasional overestimations, the developed kit demonstrated strong potential as a sustainable and efficient alternative tool for iodine testing, thereby supporting and enhancing the overall impact of the salt iodization program in the country.