Pharmaceutical Analysis- Alkalimetry Titration
Alkalimetry Titration Presentation
Alkalimetry
“The term alkalimetry refers to that part of volumetric chemical analysis which enables us to work out the concentration of an acid solution using an alkaline solution at a known concentration and a suitable indicator.”
Alkalimetry (cont.) Alkalimetry is used in the determination of many different inorganic, organic and biological substances which have acid properties. Some examples are: 1. determining acidity of oil; 2. determining acidity of milk; 3. determining volatile acidity in wine.
ALKALIMETRY IN NON-AQUEOUS TITRATIONS
A plethora of weakly acidic pharmaceutical substances may be titrated effectively by making use of a suitable non-aqueous solvent with a sharp end-point. The wide spectrum of such organic compounds in clude: anhydrides, acids, amino acids, acid halides, enols, barbiturates, xanthines, sulphonamides, phenols, imides and lastly the organic salts of inorganic acids.
3. Alkalimetry
“The term alkalimetry refers to that part of volumetric
chemical analysis which enables us to work out the
concentration of an acid solution using an alkaline
solution at a known concentration and a suitable
indicator.”
Introduction
4. Alkalimetry (cont.)
Alkalimetry is used in the determination of many
different inorganic, organic and biological substances
which have acid properties. Some examples are:
1. determining acidity of oil;
2. determining acidity of milk;
3. determining volatile acidity in wine.
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5. Alkalimetry and Acidimetry
Alkalimetry and acidimetry are a kind of
volumetric analysis in which the fundamental
reaction is a neutralization reaction. Alkalimetry is
the specialized analytic use of acid-base titration
to determine the concentration of a basic
(synonymous to alkaline) substance. Acidimetry,
sometimes spelled acidometry, is the same
concept of specialized analytic acid-base titration,
but for an acidic substance.
6. Alkalimetry used to
determine the
concentration of acid
substances using standard
Acidimetry used to
determine the
concentration of base
substances using standard
acid.
Alkalimetry Acidimetry
Alkalimetry and Acidimetry
7. Alkalimetric titration
Alkalimetry, is the same concept of specialized
analytic acid-base titration, but for an acidic substance
using standard base.
• Example: The titration of acetic acid (HC₂H₂O₂) with
NaOH. During this titration, as the OH- reacts with the
H* from acetic acid, the acetate ion (C₂H₂O₂) is
formed. This conjugate base reacts with water to form
a slightly basic solution.
8. • Acidic substances are usually determined
quantitatively by methods similar to those used
for the quantitative determinations of bases.
• However, two methods are generally adopted for
the assay of acidic substances, namely:
9. • (a) Direct Titration Methods:
• It is accomplished by directly titrating an exact quantity
of the acid, acid salt or other acidic substance with
standard alkali solutions.
• (b) Residual Titration Methods:
• It is carried out by the addition of an excess of the
standard alkali solution and subsequently determining
the amount in excess residual titration with standard
acid solution.
10. Solvents:
Most commonly used solvents are ethylene di amine, acetone chloroform
and morphine.
These solvents either increase the strength of acid or do not interfere in
the reactions.
11. Titrant:
• In the titration of weak acidic compounds, methoxide of alkali metals like
potassium, sodium, lithium are used as titrant.
• Potassium methoxide and sodium methoxide are stronger titrant but it is
not used because it produce the gelatinous product.
• So, lithium methoxide in toluene and methanol prefer as titrant.
13. ALKALIMETRY IN NON-AQUEOUS
TITRATIONS
A plethora of weakly acidic pharmaceutical substances may be
titrated effectively by making use of a suitable non-aqueous
solvent with a sharp end-point. The wide spectrum of such
organic compounds in clude: anhydrides, acids, amino acids,
acid halides, enols, barbiturates, xanthines, sulphonamides,
phenols, imides and lastly the organic salts of inorganic acids.
