Specifications and Grades of chemicals and reagents.pdf

Specifications and grades of chemicals and reagentss.

1. Specifications and Grades of
Chemicals and reagents
Noor Ul Mubarrah
Roll 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 all 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 following ways :
as numerical limits
approximate numerical limit
without an approximate numerical
limit.

5. Chemicals
Any substance that has defined composition is called
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 , tollen’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
NF 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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NF 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 called 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 bulk commerical and industrial
use.

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