This document provides instructions for estimating the amount of nickel (Ni) in a sample using complexometric titration with EDTA. The procedure involves: 1) Standardizing a solution of EDTA against zinc sulfate to determine its concentration. 2) Dissolving a nickel sample and filtering the solution. 3) Titrating an aliquot of the nickel solution against EDTA using murexide indicator, which changes color from yellow to red at the endpoint. 4) Calculating the concentration of nickel in the original sample and percentage of nickel in the complex from titration results.