Lugol solution

Lugol’s Solution is an aqueous iodine solution used in medical, microbiological, and laboratory settings for disinfection, staining, and iodine supplementation. It was first formulated in 1829 by French physician Jean Lugol.

🏭⚗️ Production
Lugol’s solution is prepared by dissolving elemental iodine (I₂) and potassium iodide (KI) in distilled water. The standard concentration includes 5% iodine and 10% potassium iodide. The potassium iodide increases the solubility of iodine in water. The solution is stored in dark containers to protect it from light degradation.

🔬 Properties
This reagent appears as a dark brown to reddish-brown liquid with a sharp iodine odor. It is acidic and water-soluble. When in contact with starch, Lugol’s solution forms a deep blue or purple complex, a reaction commonly used in iodine-starch tests. It also acts as a mordant in Gram staining procedures.

🧪 Applications
Lugol’s solution is used in microbiology as a mordant in Gram staining to fix the crystal violet stain within Gram-positive bacteria. It is also applied in medicine for disinfecting skin before surgery, treating iodine deficiency, and preparing the thyroid before surgery in certain cases. In food science, it is used for starch detection.

⚠️ Safety
Lugol’s solution is generally safe in small doses but may cause irritation to the skin, eyes, and mucous membranes. Overexposure can affect thyroid function. Handle with care, wear gloves and eye protection, and store in a cool, dark place away from oxidizing agents.