Specifications and grades of chemicals and reagentss.

1. Specifications and Grades of
Chemicals and reagents
Noor Ul Mubarrah
Rol l no : 706051

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An act of identifying something precisely.
Specifications are a list of predefined criteria and their
corresponding test methods, which should be applied for
analysis.
Types of specification
There are two types of specification :
Assay specification
Impurity specification
Specification

3. Assay specification
Assay specifications or quantitative determination
of the principal or active constituent are included
most of the reagent chemicals and al l of the
standard-grade reference materials.
Assay Value
It is the content or concentration of a stated major
component in the reagent.

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Impurity specification
Specifications for impurities or
determination of minor constituents are
expressed in the fol lowing ways :
as numerical limits
approximate numerical limit
without an approximate numerical
limit.

5. Chemicals
Any substance that has defined composition is cal led
chemical.
A chemical is an element or a combination of elements.
For example oxygen in air and it is combination of two oxygen
elements.
Water is also a chemical.
Reagents
Any substance that is added to system to cause a chemical
reaction or to bring out a chemical reaction.
For example grignard reagent , tol len’s reagent etc

6. Primary and secondary standards
Chemicals can be graded based on various standards :
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Primary Standard
It is chemical or reagent
that is pure stable and
less reactive.
It is extremely pure.
Highly Stable.
Anhydrous.
Less hygroscopic.
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Secondary Standard
Its concentration has been
determined by comparison
with primary standard.
Not extremely pure.
Less stable.
Its solution remain stable.
Hygroscopic.

7. Grading of chemicals and reagent
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Grading system is used to show how pure a substance is.
Highest grades are provided to purest chemicals. As the
level of impurities increases , the grades begin to get low .
These impurities can be metal , water or other chemicals.
There are Seven Common grades for chemicals and regent.
ACS grade
Reagent grade
USP grade
N F grade
Laboratory grade
Purified grade
Technical grade

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ACS grade
American Chemical Society grade
It is of highest purity.
Used in labs and analytical applications where
quality factor is not ignored.
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Reagent grade
It is also of highest purity.
It is used in scientific assays where quality factor
is critical.
Used in food , drugs and medicine .

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USP grade
United States Pharmacopeia grade
It is of higher purity.
Used in food , drugs and medicine.
They must be reviewed to ensure that they are
appropriate for methodology.
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N F grade
National Formulary grade
It is of high purity.
Used in excipients and dietary supplements.

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Laboratory grade
It is of high purity.
Exact level of impurities are unknown.
Used in teaching and training purposes.
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Purified grade
They are also cal led chemical and commerical grade.
Used in qualitative testing and low grade applications.
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Technical grade
It is of lowest grade.
Supplied for bul k commerical and industrial
use.

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Hand ling of chemicals and reagents
Do not return chemicals to their original packaging.
Never use the wrong and unmarked reagents.
Always label al l chemical containers.
Chemicals must not be carried by the neck of the bottle.
Special precautions should be taken while hand ling concentrated acid
AAA principle : Always Add Acid in water never add water in acid.
Use protective equipment for eye protection.
Avoid intentional smel ling , inhaling and tasting of chemicals.
Avoid direct contact with chemicals.