Limit Test of Iron – Complete Practical Guide for Pharmacy Students
Limit Test of Iron is one of the most important inorganic pharmaceutical chemistry practicals. It is frequently asked in B.Pharm & D.Pharm practical exams, viva voce, and written theory papers. This post is part of the PharmaEasyNotes – Limit Test Series, designed to help students understand, write, and score better. 📌 Aim of the Test To determine whether the amount of iron impurity present in a given substance is within the prescribed pharmacopoeial limit. 🧪 Principle of Limit Test of Iron Iron present in the sample is converted into thioglycolic acid complex in an alkaline medium. 🔹 Iron reacts with thioglycolic acid 🔹 Produces a pink to reddish-purple color 🔹 The intensity of color is compared with a standard iron solution ✔ If the test solution color is not more intense than the standard, the sample passes the test. 🧫 Reagents Required Test solution Standard iron solution Thioglycolic acid Ammonia solution Distilled water ⚗️ Procedure (Step-by-Step) Take the given test so...