Definition of Term
Definition of Term
Gravimetric Analysis is a quantitative method based on the measurement of the mass of a final product to determine the amount of an original analyte.
If you know the exact weight of a pure precipitate and its chemical formula, you can calculate exactly how much of the drug was in the starting sample using stoichiometric factors.
Core Principle
Core Principle
The principle of gravimetric analysis is based on stoichiometry and conservation of mass.
If a compound with known composition is formed quantitatively, the amount of analyte can be determined from the mass of that compound.
Instead of measuring volume like titration, gravimetry measures weight of a compound that contains the analyte.
In most pharmaceutical gravimetric procedures, the analyte is:
· Converted into an insoluble compound
· Filtered
· Dried or ignited
· Weighed
The measured mass is then used to calculate the amount of analyte in the original sample.
When a Volumetric assay gives a borderline result, Gravimetry is the "referee." Because it relies on mass which is an absolute SI unit, rather than volume which changes with temperature. Gravimetric is more accurate.