Analytical Techniques in Chemistry

Abstract

Introduction Analytical chemistry is an important branch that helps in qualitative and quantitative analyses. Qualitative analysis gives information regarding the presence or absence of a component, whereas quantitative analysis addresses the question of how much? Analytical chemistry is an interdisciplinary science that plays a vital role in all streams of chemistry such as organic, inorganic, physical, industrial and biochemistry. It is not only confined to qualitative and quantitative analyses but the advancement of science and development in the field of instrumentation has further quantified its scope. It finds extensive use in environmental science, agricultural science, pollution studies, oceanography, clinical chemistry, medical science, manufacturing industries, biological science, forensic science, and so on. Type of Analysis Three types of analyses can be carried out (a) Physical analysis (b) Chemical analysis (c) Instrumental analysis Physical Analysis The study of physical parameters such as color, smell, physical state, solubility, specific gravity, melting point and boiling point helps in the preliminary investigation of the compound. The physical properties can be measured by various chemical and instrumental methods, for instance, mass can be estimated by gravimetry, volume by volumetry, electric potential and electric current by conductometry, potentiometry, absorption or emission of radiation by spectroscopy, scattering of radiation by turbidimetry, nephelometry, refraction by refractometry, rotation by polarimetry and optical rotatory dispersion and diffraction by X-ray electron diffraction methods. These physical and physicochemical methods enable the qualitative and quantitative estimations of the compound. Chemical Analysis The qualitative and quantitative estimations of organic and inorganic compounds can be carried out chemically. Qualitative Estimation of Inorganic Compounds The qualitative analysis of inorganic compounds is carried out by determining the acid and basic radicals in the compound. For organic compounds, the aromatic and functional groups are determined by the use of specific reagents and compounds. The quantitative estimation of chemical reactions can be carried out by the following methods of analysis. (i) Gravimetric analysis In gravimetric analysis, the substance to be estimated is converted into an insoluble precipitate, which is collected, dried and weighed. The process involves several steps in which the sample is prepared, precipitated, filtered, washed, dried and weighed. If the sample is electrolyzed and the material deposited at one of the electrodes is weighed, then the process is called electrogravimetry. The weight of the sample obtained helps in quantitative estimation of the desired substance.