This lecture discusses pharmaceutical analysis techniques including titration of mixtures, estimation of magnesium sulfate and calcium gluconate. It focuses on the use of masking and demasking agents to estimate multiple metals in a solution. Masking agents like triethanolamine, thioglycerol and potassium cyanide form stronger complexes with metals, preventing their interaction with the titrant. Cyanide is an effective masking agent for metals like cadmium, zinc and copper. Demasking agents like formaldehyde-acetic acid and chloral hydrate can break these complexes to selectively estimate the masked metals. The combination of masking and demasking agents allows estimation of many metals in a single solution.