Ana Chem UNIT 2: CHEMICALS, APPARATUS, AND UNIT OPERATIONS OF ANALYTICAL CHEMISTRY

Reagent Grade Chemicals

A grade of commercial chemicals with a high

purity level that can be used in chemical

analysis to ensure that they do not introduce

impurities or contaminants that could interfere

with the accuracy and reliability of analytical

measurements.

Reagent Grade Chemicals

Used to manufacture food and medicines and

are suitable for use in numerous high-purity

laboratory and analytical applications.

Reagent Grade Chemicals

conform to the minimum standards set forth

by the Reagent Chemical Committee of the

American Chemical Society (ACS)1

96-98%

Reagent Grade Chemicals are around_______ pure, almost equal in

purity to ACS grade

Primary-Standard Grade

Extremely pure or has extraordinary purity,

which means that it should be a chemical of

high grade of purity, preferably 99.98%

National Institute of Standards and

Technology (NIST)

The _____________________________ is an excellent source for

primary standards.

National Bureau of Standards.

The National Institute of Standards and

Technology (NIST) is the current name of

what was formerly the _________________________.

The National Institute of Standards and

Technology (NIST)

This agency also prepares and sells

reference standards, which are complex

substances that have been exhaustively

analyzed.

Primary-Standard Grade

It is a reagent that is extremely pure, stable,

has no waters of hydration and has high

molecular weight.

Primary-Standard Grade

It is a highly purified compound that serve as

a reference material in all volumetric method.

The accuracy of method is critically

dependent on the properties of this

compound.

▪ High purity.

▪ Stability toward air.

▪ Absence of hydrated water.

▪ Readily available at modest cost.

▪ Reasonable solubility in titration medium.

▪ Reasonably large molar mass

Important requirements for primary standard

are:

Special-Purpose Reagent Chemicals

Chemicals that have been prepared for a

specific application are also available.

Special-Purpose Reagent Chemicals

Used for specific applications especially when

advanced and hi-tech instruments are

involved.

Special-Purpose Reagent Chemicals

are prepared for a specific application such

as solvents for spectrophotometry and high-

performance liquid chromatography.

PCR (Polymerase Chain Reaction) Reagents

Enzymes like DNA polymerase, buffers, and

nucleotide solutions specifically designed for PCR

are examples of special-purpose reagents. They

are essential for DNA amplification in molecular

biology

ELISA (Enzyme-Linked Immunosorbent Assay) Kits

often come with special-purpose

reagents, including enzyme-conjugated

antibodies, substrate solutions, and wash buffers.

These reagents are optimized for the detection of

specific biomolecules.

Molecular Biology Enzymes

Restriction enzymes,

ligases, and reverse transcriptase used in

molecular biology techniques are often provided

as special-purpose reagents. They are critical for

DNA manipulation and analysis.

High-Performance Liquid Chromatography (HPLC)

Standards

Certified reference standards used for

calibration and validation in HPLC are special-

purpose reagents. They ensure the accuracy of

analytical measurements.

Titration Solutions

Reagents used in titration

methods, such as standardized solutions of acids

or bases, can be considered special-purpose

reagents. They are crucial for accurately

determining the concentration of unknown

substances.

1. Purity and Grade:

2. Compatibility

3. Storage Requirements

4. Supplier Reliability

5. Alternative Selection

RULES IN SELECTING REAGENTS

Bumping

is the sudden, often violent boiling that

tends to spatter solution out of its container.

Graduated pipettes or Measuring Pipette

They are a class of macro pipettes that are

distinguished by a series of graduations

that indicate different volumes. These

pipettes come in a variety of shapes and

sizes, and they all use suction to transfer

liquid.

mother liquor.

Liquid from which a substance precipitates or

crystallizes is called the ______________

titrant

Reagent of known concentration is called

titrand

substance being titrated is termed the

Direct titration

titrant reacts directly with an

analyte

Back titration

is a process in which the excess of

standard solution used to react with an analyte is

determined by titration with a second standard

solution.

Titration error

The difference between the

observed end point and the true equivalence

point in a titration