The document discusses complexometric titration, a volumetric analysis technique used to determine concentrations of different metal ions using ligands to form colored complexes. It explains the types of ligands, chelating agents, and their applications, including the use of EDTA as a versatile chelating agent for water hardness analysis and heavy metal poisoning treatment. The document also details various titration methods, indicators, and concepts such as masking and demasking agents.

1. Pharmaceutical analysis
Complexometric Titration
BY- VIRENDRA VAISHNAV
APOLLO COLLEGE OF
PHARMACY , DURG

2. Introduction
 TITRATION – A technique in which solution of known concentration
used to determine the concentaration of unknown solution.
 CONDITION FOR TITRATION :-
 Rapid reaction
 Well designed stoichiometry
 Large equilibrium constant

3. COMPLEXOMETRy
COMPLEXOMETRIC TITRATION – (chelatometry) is a form of volumetric
analysis in which the formation of a colored complex is used to
indicate the end point of a titration.
 Used for the determination of a mixture of different metal ions in
solution
 It also involves formation of complex
 Ligands are used for complexation
COMPLEX - Metal ion+ Ligand [ M + L = ML ]

4. LIGAND
 The neutral molecules or ion which are directly attached to central metal ion
or atom through co-ordinate bond in the complex ion is called Ligands.
 Ligand should have atleast one pair of electron
 Ligand should be capable to donate their lon pair of electron to central
metal ion
 Ligand act as lewis base & Metal ion act as lewis acid
TYPES OF LIGAND – On the basis of number of donating lone pair
 Monodentate ( NH3 , H2O , Cl )
 Bidentate ( ethylenediamine & oxalate ion )
 Polydentate or Multidentate ( SCN , EDTA )

5. Chelating agents
 Multidentate ligands are called Chelates .
 Chelating agents are chemical compounds that react with metal ions to
form a stable, water-soluble complex.
 They are also known as chelants, chelators, or sequestering agents.
 Chelating agents have a ring-like center which forms at least two bonds
with the metal ion allowing it to be excreted
 Chelating agents may also be used in the treatment of heavy metal
poisoning.
 Example - EDTA ( Ethylene diamine tetra acetate or acetic acid )

6. EDTA (Ethtlene Diamine TetraAcetate)
 EDTA is a versatile chelating agent.
 It was synthesised for the first time in 1935 by Ferdinand Munz .
 It can form four or six bonds with a metal ion, and it forms chelates
with both transition-metal ions and main-group ions.
 EDTA deactivates these enzymes by removing the metal ions from
them and forming stable chelates with them.

7. Types of complexometric reaction
DIRECT TITRATION - It is simplest and the most convenient method in which the
standard solution of EDTA is slowly added to the metal ion solution till the end
point is achieved
 The solution containing the metal ion is buffered to an appropriate pH at
which the stability constant of the metal-EDTA complex is large.
BACK TITRATION - This involves addition of a known excess of EDTA to the
metal ion (buffered to an appropriate pH). Then, the excess EDT A is titrated
with a standard solution of a different metal ion
 The choice of a second metal ion is important as it must not displace the
analyte metal ion from its EDTA complex.
INDICATORS - Common indicators are organic dyes such as Fast Sulphon
Black, Eriochrome Black T, Eriochrome Red B, Patton Reeder, or Murexide.

8. Hardness of Water
 The hardness is due to both Ca and Mg salts but the two are
determined together in the titration.
 The total Ca and Mg is titrated with standard EDTA solution using
eriochrome black –T as indicator.

9. Masking & demasking agent
MASKING AGENT - a reagent that protects some component of the
analyte from reaction with EDTA.
 Masking used to prevent one element from interfering in the analysis of
another element .
DEMASKING AGENT -Demasking is the process inwhich the masked
substance regains its ability to enter into a particular reaction.
 It is used to counteract the effect of a masking agent .

10. THANK YOU