This book deals with various subject matters of analytical and instrumental techniques. Its intention is to serve as valuable text-and reference book to the undergraduates, postgraduates and the researchers in the field of agriculture, horticulture, food science, home science, forestry, biochemistry, biotechnology, agricultural chemicals and other allied fields. I believe that this book will prove to be of utility and bring clarity to the readers.

Acids are chemical substances that are sour in taste and highly corrosive. The term ‘Acid’ was derived from a Latin word ‘acidus’, meaning ‘sour’. They emit sharp odour and transform litmus colour from blue to red. They lose their properties when alkalis are added to them. However, in this process, alkalis also lose their alkaline properties.

Volumetric analysis, also known as titrimetric analysis, is an analytical method of estimating the concentration of a known solute (analyte) in a solution by measuring the volume of a second known solution of known concentration (standard solution), that reacts completely with the known solute of unknown concentration. The prerequisite of titration is that the two different analytes, present in solution form, must involve in a fast chemical reaction. The standard solution is more commonly known as ‘titrant’ and the solution whose concentration needs to be determined is frequently called ‘titrand’.

Indicators are the natural or synthetic chemical compounds that are used to detect the equivalence point in a volumetric analysis where unknown compound in a solution form is quantitatively estimated with the help of a known standard solution. The equivalence point, also known as the stoichiometric end point, is the point or stage of a titration reaction where the equivalent amount of the reacting substances are mixed together, and this point is identified by monitoring the rate of change in pH, conductivity, flow of current, adsorption, fluorescence, changing of solution colour, occurrence or disappearance of turbidity, flocculation or deflocculation, etc.

Centrifugation is a technique that promotes accelerated settling of particles in a solid-liquid mixture by the application of centrifugal force. The device that accelerates the separation with the help of centrifugal force is known as ‘Centrifuge’. The centrifuge consists of a fixed base or frame and a rotating part in which the mixture is placed and is then spun at high speed.

Electrophoresis is an important separation technique for the charged molecules. Biologically important molecules, such as amino acids, peptides, proteins nucleotides, nucleic acids which carry electrical charge as they possess certain ionizable functional groups may be separated and identified from a mixture with the help of this technique. Some compounds that are non-polar in nature and do not possess any charge may be transformed to charge carrying derivatives. Thus, phosphate derivatives of carbohydrates may be separated and characterized utilizing electrophoretic techniques.

Interaction of radiant energy, exhibiting the properties of both waves and particles, with matter is dealt in spectroscopy. Matter may be defined as material, existing in solid or liquid or gaseous phase, which is composed of molecules, atoms, or ions. Atoms, molecules, and ions, irrespective of their physical state, remain in constant motion in a matter. Molecules may rotate, vibrate, and move from place to place in space. While radiant energy interacts with matter, these molecular motions are influenced to some extent. It is observed that radiations from ultraviolet and visible range of electromagnetic spectrum lead to the movement of bonding electrons from lowest energy state (ground state) to higher energy state (excited state) in the molecules, while absorption of IR radiation causes the molecule to vibrate more. Such changes, referred to as transition, are responsible for changing the molecular energy level.

Mass spectrometry (MS) is a powerful and versatile analytical technique through which mass of an atom, or a molecule is assessed. It helps for identification and structure elucidation of various complex compounds. The instrument used is known as Mass Spectrometer. It serves the purpose of qualitative identification, confirmation as well as the quantification of an atom or a molecule. MS identification is conclusive because the mass spectrum of each substance is unique. In general, MS instruments are composed of a sample inlet, an ionization source, a molecule accelerator, a detector, an amplifier, and a recorder (Figure 7.1)

Research related to biochemical analysis has been greatly benefited due to the development of chromatographic technique, since this technique makes it possible to resolve mixtures of closely related substances on a milligram to picogram range and to identify individual components by comparison with reference standard compounds. Chromatography ‘gives information where other analytical means have failed’ [Tswett, M. (1906) The macro-chemical and micro-chemical detection of carotene. Ber. Deut. Botan.Ges. 24 : 384- 393].

An atom consists of a positively charged nucleus surrounded by a cloud of negatively charged electrons. The positive nuclear charge is due to the presence of protons which carry a mass of 1 and a charge of +1. Besides protons in the nucleus, there are neutrons which are heavier than protons. They carry no charge. Comparatively electrons have no mass (1836 times lesser than that of a proton) but they carry a charge of –1. Hence, the whole mass of an atom is likely to be concentrated in the nucleus.