This document discusses primary and secondary standards used in pharmaceutical analysis. It defines a primary standard as a highly pure reagent or chemical used to prepare standard solutions of known concentration that do not require further standardization. Primary standards should be stable, pure, and soluble. Secondary standards are substances whose concentration has been determined by comparison to a primary standard. Secondary standards have less purity and stability than primary standards but their solutions remain stable for long periods of time. The document provides examples of properties primary and secondary standards should possess.

1. Miss. Rahee B Chougule
Assistant Professor
Department of Pharmaceutical Chemistry

2. Standards:-
In Pharmaceutical Analysis, the word standard means a
material containing a substance of our interest with a known
concentration. We can express this with definite numbers
with proper units.
 Functions
• To provide a reference using which we can determine
unknown concentration of solution
• To standardization of volumetric solutions
• Preparation of secondary standard
• To calibrate an instrument

3. Standards
Primary
Standards
Secondary
Standards
Primary and Secondary Standards

4. Primary Standards
A solution with accurately known concentration is called
as standard solutions
Highly pure reagents or chemicals are used to prepare
standard solutions which dose not require further
standardization, is known as primary standard
solutions
 A primary standard is a chemical or reagent
which has certain properties such a
1. primary standard substances should be easily available,
purified and dried.
2. It should be almost 100% pure.
3. The total amount impurities should not exceed 0.01 to 0.02%

5. 4. Primary standard substances should be stable at normal
atmospheric conditions.
5. It should not be hygroscopic.
6. Equivalent weight and molecular weight to these substances
should be high to reduce the weighing errors as higher weight leads
to reduction in the weighing error.
7. Reaction of the standard solution with the reactant should be
instant and stoichiometric for easy calculations.
8. Theoretical equivalence point and practical end point should be
equal

6. 9. Primary standard substances should be completely soluble under
the experimental conditions
10. It should be free from any hydrated water moiety
11. Titration error with it should be negligible.

8.  Secondary standards
These are the substances used for the standardization and
whose concentration has been determined by comparison
with the primary standard
 A secondary standard is a chemical or reagent
which has certain properties such as
(a)It has less purity than primary standard
(b)Less stable and more reactive than primary standard
(c)But its solution remains stable for a long time
(d)Titrated against primary standard

10. Books Referred:-
1. Dr. H. N. More, Dr. K. R. Mahadik et al., “Pharmaceutical Analysis” volume – I.
2. Dr. K. S. Jain, Ms. D. K. Kadam et al., “Pharmaceutical Analysis” Niral Publication.