Total Hardness Analysis in Water
Total Hardness Determination (EDTA Titrimetric Method) 1. Purpose This Standard Operating Procedure (SOP) describes a validated method for the determination of Total Hardness in water and wastewater samples using the EDTA titrimetric method. The procedure is designed to produce accurate, precise, and reproducible results suitable for routine laboratory analysis and regulatory monitoring. 2. Scope This method applies to the analysis of drinking water, surface water, groundwater, and wastewater samples in which calcium (Ca²⁺) and magnesium (Mg²⁺) are the primary contributors to hardness. 3. Principle of the Method Total hardness in water is caused mainly by dissolved calcium and magnesium salts. The determination is based on complexometric titration using Ethylenediaminetetraacetic Acid (EDTA) as the titrant. At a controlled pH of 10.0 ± 0.1 , calcium and magnesium ions react with Eriochrome Black T (EBT) indicator to form a wine‑red colored complex. During titration, EDTA prefere...