Analytical chemistry deals with determining the chemical composition of samples through qualitative and quantitative analysis. It has applications in fields like environmental science, clinical chemistry, and forensic science. Instrumental methods like spectroscopy, chromatography, and electroanalytical techniques are now commonly used for separation and analysis. These methods measure properties of samples like light absorption, emission spectra, electrical conductivity or potential to determine composition. Classical wet chemical methods like titration and gravimetry are also still used. Proper sampling, sample preparation, and control of instrumental factors are important for obtaining accurate results.

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Analytical Techniques
MCH521
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Introduction-Role of Analytical Chemistry
• Deals with methods for determining the
chemical composition of samples of matter .
• An interdisciplinary branch- deals with Organic,
Inorganic, Physical, Industrial and Bio-chemistry
and find applications in various other fields
• Environmental, Agricultural, Clinical chemistry,
solid state research, oceanography, forensic
science, defense and space research
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Applicationsof Instrumental Methods
Bioanalytical: biological molecules and/or
biological matrices (e.g., proteins, amino acids,
blood, urine)
Environmental: pesticides, pollution, air, water,
soil
Material science: polymers, characterization of
new materials
Forensic science (application of science to the
law): body fluids, DNA, gun shot residue, hair,
elemental analysis, drugs, alcohols, poisoning,
fingerprints, etc.
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Chemical Analysis
Determination of chemical composition of samples of matter
Two stages/types
• Qualitative-Gives the information about the
identity of atomic or molecular species or the
functional groups, by color, mp, bp, odour
• Quantitative Analysis- Provides numerical
information of analyte (provide exact amount or
conc.)
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Other Types of Chemical Analysis
• Proximate Analysis: The amount of each element in a
sample is determined with no concern to the actual
compounds present
• Partial Analysis: Deals with the determination of
selected constituents in the sample.
• Trace Constituents Analysis: type of partial analysis but
deals with the determination of specified components
present in very minute quantity.
• Complete Analysis: The proportion of each component
of the sample is to be determined.
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Stages of Analysis
Chemical analysis involves a series of steps and procedures-
• Sampling- depends on size and physical nature
• Prep of analytical sample- reduction of particle size, mixing,
drying
• Dissolution of sample- heating, ignition, fusion, use of solvent
• Removal of interferences- filtration, solvent extraction, ion,
exchange, chromatographic separation
• Sample measurements & control of instrumental
factors- standardization, calibration, optimization, response
• Results – calculations for the sample, statisticalevaluation
• and presentationof data- printout, plotting, graphs, storage
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Classification of Analytical Methods
• Classical Methods-MP, BP. Odour, color, gravimetric,
volumetric or titrimetric
• Instrumental methods-electro analytical, spectroscopic,
chromatographic and electrophoretic
• Non-destructive methods-electron probe microanalysis,
XRF
• Radioactive Methods-involves Measuring the intensity of
radiation
• Special methods:
Optical methods-Refractometry
Kinetic methods-rate of catalyzed reactions is monitored
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Classical Methods
Wet chemical methods such as
–Precipitation,extraction,distillation-
Separation
–B.P., M.P., color, solubilities in a series of
solvents, odors, optical activities
(polarimeter), refractive index
(refractometer)- For identification
–Gravimetric and titrimetric measurements–
For Quantification
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Soxhlet
extraction
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• Gravimetric Methods –mass of the analyte or
some compound produced from the analyte is
determined.
• Titrimetric Methods (volumetric) –volume or
mass of a standard reagent required to react
completely with the analyte is measured.
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Instrumental Methods
•Highly efficient chromatographicand
electrophoretictechniques replace distillation,
extraction and precipitationfor separation of
components of complex mixtures prior to their
qualitative or quantitative determination
•Measurements of physical properties of analyte such
as conductivity,electrode potential,light
absorptionor emission, mass-to-chargeratio,
fluorescenceetc. are made using instrumentation.
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Types of Instrumental Methods
1. Spectroscopic methods:
a. Atomic spectroscopy
b. Molecular spectroscopy
2. Chromatographic and Electrophorectic
methods
3. Electro-analytical Methods
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1.SPECTROSCOPIC METHODS
Interaction of matter with electromagnetic
radiations (Xrays,UV,VIS,IR,Micro, Radio)
These methods depends on:
• Measurement of amount of radiant energy of
a particular wavelength absorbed or emitted
by the sample
• Bending, scattering or delayed emission of
radiant energy
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THE ELECTROMAGNETIC SPECTRUMTHE ELECTROMAGNETIC SPECTRUM
low highFrequency ()
Energy highlow
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(i)-Absorptionmethods
• Usually classified according to the wavelength
involved as Visible, UV, or IR Spectrophotometry
• e.g. AAS Spectroscopy involves atomizing the
specimen, often by spraying a solution of the
sample into a flame and then studying the
absorption of radiation from an electric lamp
producing the spectrum of the element to be
determined
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(ii)-Emission methods
Samples are subjected to heat or electrical
treatment so that atoms are raised to excited
states causing them to emit energy
The intensity of this energy is then measured
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Some common techniques are:
Flame photometry- solution of the sample is injected into
the flame
Emission spectroscopy- sample is subjected to an ICPlasma
and then examining the emitted light
Fluorimetry-substance is taken in a fluorescent reagent
and excited using UV-VIS radiations
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(iii)-Magnetic resonance spectroscopy
• NMR is concerned with the study of interaction of
energy with spin active nuclei which have
permanent magnetic moments and quantized
nuclear spin states (many atomic nuclei spin about
an axis and generate their own magnetic field)
• Electron spin resonance (ESR): electrons in the free
radicals, atoms, ions or molecules (having unpaired
electrons) change their spin under the influence of
applied magnetic field and spectra arising is called
ESR spectra
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(iv)-Scattering methods
Nephalometric and turbidimetric methods
measure the amount of light stopped or
scattered by a suspension
• Turbidimetry- the intensity of light transmitted
through the sample is measured
• Nephalometry-reflection & scattering of beam
by colloidal solution, the intensity of the
scattered light is measured
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(v)-Photoelectron spectrosopy (PES)
• In PES, a beam of photons of known energy is
allowed to fall on the sample
• and kin. energy of the ejected e- is measured.
• It can be done either using X-ray photons
(XPES) or UV Photons (UVPES)
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(vi)-Mass spectrometry
• It involves the ionization of atoms and
molecules by a combined action of electric
and magnetic fields and then appearance of
mass spectra.
• Position and intensity of signals in mass
spectrum are measured (mass to charge
ratio)
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2.ELECTROANALYTICAL METHODS
Study of change in the electrical properties of the system
These methods involve measurement of current,
voltage, potential or resistance in relation to the
conc. of a certain species in solution
• Electrogravimetry
• Coulometry
• Potentiometrictechniques
• Conductometric techniques
• Voltametric techniques (Amperometric, Polarography)
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2.Electroanalytical Methods
METHOD PRINCIPAL PROPERTY
MEASURED
1. Electrogravimetry Electrolysis is carried out Material
deposited on
electrode is
weighed
2. Coulometry Amount of electrical
current & time over which
it flows is a measure of
the substance producing
current
Current and time
3. Potentiometric
techniques
Measurement of potential
of an electrode in
equilibrium with an ion to
be determined
Electrode
potential
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2.Electroanalytical Methods
METHOD PRINCIPAL PROPERTY
MEASURED
4.
Conductometric
techniques
Change in electrical
conductivity of a
solution during
chemical reaction
Electrical
conductivity
Electrical
resistance
5. Volta metric
techniques
(Amperometric,
Polarography)
Measurement of
current at a micro-
electrode at a
specified voltage
Current at a
specified
voltage
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3.Chromatographic methods
• These are essentially separation
processes for mixtures of substances
• but equipped with modern detector
systems
• They are also used to identify the
components of mixtures.
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