Methods of Analysis:

Chemical analysis is mainly used to identify or the amount of a particular substance in a

sample. When this method is only used to identify the only in a substance that is called

qualitative chemical analysis. But when the amount of a particular substance in a sample is

determine called quantitative chemical analysis.

Types of chemical analysis:

The chemical analysis methods may be divided into classical and instrumental analysis. Classical

or non instrumental analysis methods is the group of analytical methods that only require the use

of chemical, a balance, calibrated glassware, funnels and burners etc. The example of classical

methods is gravimetric quantitative analysis and volumetric chemical analysis.

Gravimetric quantitative chemical analysis:

It is used for critical measurement of the product of a chemical reaction, or a measurement of

mass change during chemical reaction to determine the amount of chemical reactant in the

sample that is made with an accurate balance. A classical gravimetric analysis usually consists of

a precipitation of a salt of the assayed substance. The ppt is collected by filtration dried and

weighed.

Gravimetric quantitative chemical analysis:

Volumetric chemical analysis depends upon critical measurement of volume of a chemical

reactant to determine the concentration of the sample. Volumetric analyses are titrations methods

in which a solution of one of the chemical reactants in burette is added to a solution of a second

chemical reactant. The solution in the burette is called titrant and solution in the reaction vessels

is called titrand. The sample can be either titrant or titrand. The volume of titrant added at the

end point of the titration is measured and use to calculate the concentration of the sample. A

classical volumetric analysis uses a chemical indicator to locate the end point of those titrations

in which no color change is observed.

Instrumental methods of chemical analysis:

The instrumental methods of chemical analysis requires the use of an analytical instrument in

addition to the common laboratory apparatus such as spectrophotometer, atomic absorption

spectrophotometer etc. But if we use a laboratory instrument to help in locating the endpoint i.e.

pH meter, conductometer.

Analytical instruments are devices that measure a physical or chemical property of the sample or

that measure some factor that enables determination of a property of the sample. The

instrumental methods of chemical analysis are divided into three categories according to the

property of the assayed substance that is measured or used during the assay such as spectral

methods, elctroanalytical and separation methods.

Spectral methods (Spectroscopic methods):

The spectral methods use or measure some form of radiation during assay i.e. measure

the interaction of radiation with the matter such as absorption spectrophotometry, Flame

emission and Atomic emission spectrophotometry, Infrared spectroscopy, Raman spectroscopy,

Visible spectrophometry and colorimetry, Ultraviolet spectroscopy, Nuclear magnetic

spectroscopy, Electron Spin Resonance Spectroscopy, Mass Spectrometry, X-ray spectroscopy.

Electroanalytical methods:

The electroanalytical methods apply an electrical signal to the sample or monitor an

electrical property of the sample such as Amperometry, conductometry, coulometry,

electrogravimetry, potentiometry and Voltametry.

Separation methods:

The separation methods rely on separation of the components of a sample prior to

measure the property of the components such as chromatography, Electrophoresis and Mass

spectrometry.

Spectroscopic or spectral methods of analysis:

This branch of science deals with the study of interaction of electromagnetic radiation

with matter. In this case the amount of light absorbed, emitted or scattered by a sample.

Electromagnetic radiation is a form of energy that posses the properties of both discrete particles

named as photons and of waves. EMR is transmitted through space at the enormous velocity and

requires no supporting medium such as air like sound waves which needs a medium for

transportation. Example light which occupies only a small region of EMR.

E = hυ

Where E is energy of a single photon of the EMR, υ is the frequency of the wave and h is palnk’s

constant 6.625 x 10-14 J. s.

Wave properties of electromagnetic radiation:

Electromagnetic radiation is an alternating electrical and magnetic force field in space

has both electric and magnetic components. The both components oscillate in planes

perpendicular to each other and perpendicular to the direction of propagation of the radiation.