Gravimetric Analysis, Summary as per D. Pharm syllabus.

1. GRAVIMETRIC ANALYSIS
1. Introduction
The term gravimetric pertains to a “weight
measurement”. It is an analytical method
which determine the amount of analyte by
measurement of the mass of a pure substance
containing the analyte.
2. Types of gravimetric analysis
Gravimetric analysis
Precipitation
Volatilization
3. Advantages of Gravimetric Analysis:
 Accurate and precise: Gravimetric analysis
is potentially more accurate and more
precise than volumetric analysis.
 Possible sources of errors can be checked:
Gravimetric analysis avoids problems with
temperature fluctuations, calibration errors,
and other problems associated with
volumetric analysis.
 Relatively in-expensive
4. Disadvantages of Gravimetric Analysis
 But there are potential problems with
gravimetric analysis that must be avoided to
get good results.
 Careful and time consuming.
 Scrupulously clean glassware.
 Very accurate weighing.
Prepared By – Kartik Tiwari (Lecturer)
Hygia College of Pharmacy, Lucknow (U.P)
Content as Per D. Pharm Syllabus
1. Preparation of the solution
2. Precipitation
3. Digestion
4. Filtration
5. Washing
6. Drying or ignition
7. Weighing
8. Calculation
5. Steps in a gravimetric analysis
Solvents are
evaporates from
analyte’s mixture by
heating method and
residue weigh.
Analytes are converted
into precipitate by using
an precipitating reagents.
Then precipitate filter,
dry and weigh.
Example: Ca determined
by calcium oxalate
precipitation.
1. Preparation of the solution
Analyte are dissolved in the solvent system in
which it is completely soluble.
2. Precipitation
Add sufficient precipitating reagent to the
solution for the formation of good precipitate.
3. Digestion
Precipitate stand in contact with mother liquor
(the solution from which it was precipitated), is
called digestion.
4. Filtration
Filter the solution containing analyte precipitate
by using filter paper (specially Sintered glass
filters).
5. Washing
Co-precipitated impurities especially those on
surface, removed by washing the precipitate.
6. Drying or ignition
To remove solvent and wash electrolytes and
drying process done by heating at 110 to 120°C
for 1 to 2 hrs.
7. Weighing
After drying precipitate is allowed to cool (in a
desiccator to absorb moisture), it is weighed (in
the crucible).
8. Calculation
G.F = g of analyte/ g of precipitate
G.F1 = G.F2 (Analyte will be same)
Where, G.F = Gravimetric Factor