Detection of iodine in aqueous extract of plants through modified Mohr’s method

Abstract

This article explores the extraction of iodine contents in Ipomoea pes-caprae plants using the modified Mohr’s method applied to a biological extract prepared in an aqueous solution. The plants were collected from three coastal regions of the Arabian Sea at Karachi coast, privileged as iodine resource areas. The size of the stem, leaves, and flowers of collected plants was measured after transportation into the laboratory before preparation of aqueous extract. It was found to be significantly different in size from each other. The electrical conductivity of the biological extract was recorded through a conductometer. For this purpose, the extract of different parts of the I. pes-caprae plants was prepared, followed by heating and filtration, while silver nitrate (AgNO3) was used as a precipitating agent. It was interesting to note that when filtrate was titrated with AgNO3, the precipitate started to settle down. Results showed the lowest iodine concentration in the flowers of all tested plants, followed by the highest in the leaves. Conductometric precipitation reaction was influential in determining iodine in herbal medicinal plants. It was observed that the size of the plants and collection sites impacted the iodine concentration. It was lowest in I. pes-caprae, collected from sea view Karachi, while highest in plants of Hawksbay. The endpoint of this biochemical reaction was taken when conductivity started rising. The standard curve of KI was prepared to determine the concentration of iodine in plant samples through conductometric titration. Moreover, the presence of Iodine was confirmed through a chemical testing method using HNO3, NH4OH, and H2SO4, after a complete precipitation reaction. The iodine quantification was done using a spectrophotometer through hexane solvent after being treated with H2SO4.