Instrumental method

INSTRUMENTAL METHODS OF CHEMICAL ANALYSIS

These are the quantitative methods of analysis that use, as principal measuring devices, instruments other than those employed in conventional gravimetric and volumetric determination.

The main basis for this method of analysis is the physical property of any particular element or compound being analysed. These properties include

• • • • •  Mass / Volume

        • Specific gravity, surface tension, viscosity, velocity of sound

        • Properties involving interaction with radiant energy – Absorption, scattering, emission.

        • Electric properties such as half cell potential, current voltage charactertistics, E.C, dielectric constant and magnetic susceptibility.

        • Thermal properties:  Thermal conductivity, heat of reactions, transition temperature.

        • Nuclear properties – Radioactivity, isotopic mass etc.

Advantages of Instrumental methods                      

• Time saving

• Large number of samples can be handled at a time.

• Variety of methods available.  Hence, we can choose alternate methods.

• Instruments have higher sensitivity and there is minimum personal error.

• Wider applicability – solids as well as liquids can be determined. 

Classification                 

• Electrometric methods: Electrolysis, potentiometry, conductometry, polarography.

• Optical methods : colorimetry, turbidimetry, spectrophotmetry, flame photometry, spectrography, polarimetry, X-ray emission, refractrometry

• Thermal methods

• Gas volumetric methods – adsorption, combustion.