A new, innovative, simple method to determine the concentration of phosphate and sulphate ions in an aqueous extract of plants using conductometric titration

Abstract Determining phosphate (PO 4 −3 ) and sulphate (SO 4 −2 ) is highly significant in agricultural sciences and practices for the sustainable growth of crops. Their deficiencies have reflective properties on the transcriptome and many metabolic pathways. Therefore, this study planned to monitor concentrations of both ions for the first time through conductometric titration using BaCl 2 . For this purpose, the leaves of Spinacia oleracea L., Thorn Apple , and Rangoon Creeper plants were collected from Karachi and transported to the Department of Chemistry, University of Karachi, where they were washed thoroughly to remove any dust particles, dried, and crushed in deionized water and filtered. A known concentration of barium chloride (BaCl 2 ) as a single reagent was prepared to be applied to an aqueous plant extract test sample containing an unknown amount of phosphate and sulphate ions. The 50 ml of extract was taken into the beaker and subjected to titration with a known concentration of BaCl 2 conductometrically. Results showed that as precipitation started, the conductivity of the extract solution decreased with the addition of the BaCl 2 and reached a point where further addition did not affect it. The precipitate was tested two times, initially and at the end of the reaction, by adding HCl and HNO 3 to validate the presence of these ions in leaves aqueous extract. Chemical analysis of the precipitate initially suggested that phosphate is separated first due to its low solubility product (Ksp) value and then sulphate. Moreover, the concentration of both ions at the end of the reaction was determined through the derivative graph of the conductivity curve and standard curve method after the separation of ions by HCl and HNO 3 . It was concluded that this simple technique may be used to ascertain the concentration of both ions required for plant growth under various stress conditions.