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UNIT I, Chapter . 1, ..., INTRODUCTION TO, PHARMACEUTICAL ANALYSIS, • OBJECTIVES •, To illuminate relevance and significance of Analytical Chemistry to Pharmaceutical, Sciences., To aware regarding different techniques of analysis on the basis of their classification., To clarify the basic principle of different analytical techniques., To learn the different methods used for expressing the concentration., To learn about primary and secondary standards along with its characteristics., To know the procedure for preparation of various standard solutions and standardization, of it., 1.1 INTRODUCTION, Chemistry (generally called Central Science) is deals with the study of matter, including its, composition and structure, its physical properties, and its reactivity. Chemistry is, measurement based science discipline which generally based on number of other fields like, organic chemistry, inorganic chemistry, biochemistry, physical chemistry, and analytical, chemistry., • Organic Chemistry is the area of chemistry that involves the study of carbon and its, compounds, • Inorganic Chemistry is the study of the synthesis, reactions, structures and, properties of compounds of the elements., Biochemistry is said to be a hybrid science as it contain Bio (Biology science of, living organisms) and chemistry (science of atoms and molecules), so biochemistry is, the science of the atoms and molecules in living organisms (such as DNA and, proteins)., Physical Chemistry deals with the study of the physico chemical characteristics of, the substance without changing its composition., 1.1, 1
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Introduction to Pharmaceutical Analysis, Pharmaceutical Analysis, Analytical Chemistry deals with methods for determining the chemical composition c, sample. Analytical Chemistry is found to be useful tool in nearly all aspects of chemistry yia, agricultural, clinical, environmental, forensic, manufacturing, metallurgical,, pharmaceutical chemistry. The techniques of this science are used to identify the substance, which may be present in a material and to determine the exact amounts of the identifier, substance., and, Chemical analysis may be classified into four kinds:, (i) Proximate Analysis: It determines the amount of each element in a sample with no, concern as to the actual compounds present., (ii) Partial Analysis: It deals with the determination of designated constituents in the, sample., (iii) Trace Constituent Analysis: A specialized instance of partial analysis in which we are, worried about the determination of specified components present in very minute, quantity, (iv) Complete Analysis: It determines the proportion of each component of the sample., Chemical analysis are often classified on the basis of sample size:, (i) Macro Analysis: The analysis deals with quantities of 0.1 g or more., (ii) Meso (semimicro) Analysis: This analysis dealing with quantities ranging from, 0.01 to 0.1 g., (iii) Micro Analysis: This analysis deals with quantities in the range 0.001 g to, 0.01 g., (iv) Submicro Analysis: This analysis deals with samples in the range 0.0001, 0.001 g., g to, (v) Ultramicro Analysis: This analysis deals with quantities below 0.0001 g., Major Constituent: A major constituent is one accounting for 1-100%., Minor Conștituent: A minor constituent is existing in this range of 0.01 - 1%., Trace Constituent: A trace constituent is presented at absorption of less than 0.01%., 1.2 PHARMACEUTICAL ANALYSIS AND ITS SCOPE, The pharmaceutical analysis is a branch of chemistry, which deals with the process or, sequences of processes to identify and/or quantify a substance or drug, the component of, pharmaceutical solution or mixture or the determination of the structure of chemical, compound used in the formulation of pharmaceutical product., Some specific uses of analysis are mentioned as follows :, (). The examination of raw material, in-process and finished product., (i) Separation, determination and quantitation of impurity., (ii) To check the strength and concentration of the chemical compound., (iv) Used for identification and characterization of chemical compound., 1.2
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Pharmaceutical Analysis, Introduction to Pharmaceutical Analysis, (v) To determine the molecular weight of the chemical compound., (vi) Used for structural elucidation of synthetic compound., (vii) Quantitative analysis of air, water and soil samples is carried out to determine the, level of pollution., (vii) In farming, nature of soil and level of fertilizer application is analyzed., (ix) In geology, composition of the rock and soil is carried out., 1.3 DIFFERENT TECHNIQUES OF ANALYSIS, Analysis is broadly divided into two types:, Qualitative Analysis: It gives information about the identity of atomic and molecular, species or the functional groups in samples. It is used only to determine the presence, and absence of the compound., Quantitative Analysis: It establishes the relative amount of one or more of the, species (analyte) in numerical terms. It measures the concentration or amount of each, substance in a sample., Analytical Method, Qualitative and/or quantitative analysis are carried out for one or more analytes using a, specified technique/analytical method., Classification of Analytical Methods, Various methods of analysis can be broadly classified into two categories; Classical, methods and Instrumental methods., Classical Methods:, These are based on traditional method of analysis and may be divided as:, (a) Qualitative: Use for identification by colour, odours, boiling points, melting point,, limit test etc., (b) Quantitative: Use for determination of mass or volume (e.g. volumetric and, gravimetric analysis)., Volumetric Analysis is used to determine the exact volume of the solution of known, concentration required to react completely with the solution of the substance to be, analysed., (i) Neutralization acid-base titration: It involves neutralization acid base reaction in, presence of water as solvent., (ii) Non-aqueous acid-base titration: It involves reaction in between acid and base in, presence of non-aqueous solvent i.e. organic solvents., (ii) Complexometric titration: It is complex formation reaction. In this titration the, reacting substance reacts with standard solution to form a soluble but very slightly, dissociated complex., 1.3, 3
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Introduction to Pharmaceutical Analys, Pharmaceutical Analysis, Ph, (iv) Precipitation titration: It is precipitation formation reaction. In this titration t, reacting substance reacts with standards solution to form a precipitate or slight, soluble salt., (v) Oxidation-reduction titration: In this titration simultaneous oxidation-reductic cl, reaction occurs. It includes all the methods where one reacting substance is oxidize, while other get reduced., Gravimetric Analysis is quantitative determination of an analyte based on the mass of, solid by the process of isolating definite compound of element in pure form. In th, technique substance under determination is converted into an insoluble precipitate which, collected and weighed., Instrumental Methods:, These methods are based upon the measurement of some physical properties a, conductivity, electrode potential, light absorption or emission, mass-to-charge ratio and, fluorescence of substance. When non-instrumental method is not possible, instrumenta, method is the only answer to the problem., The instrumental methods have advantages of being less time consuming over classica, methods. Various factors such as cost of instruments, sensitivity, accuracy, precision and, reproducibility have to be taken into considerations before selecting method for analysis., Qualitative: Chromatography, electrophoresis and identification by measuring physica, property (e.g. spectroscopy, electrode potential)., Quantitative: Use for measuring property and determining its relationship to, concentration (e.g. spectrophotometry, mass spectrometry) often, same instrumental methoc, used for qualitative and quantitative analysis., Advantages of Instrumental Methods:, 1. A small amount of a sample is required for analysis., 2. Determination is comparatively fast., 3. Various complex mixtures can be analysed with or without their separation., 4. High sensitivity and selectivity., 5. Results obtained by instrumental method are reliable and accurate., Limitation of Instrumental Methods:, 1. Instrumental methods are comparatively costly., 2. Need of regular maintenance of instrument, 3. Skilled personnel required., 4. Specialized training is required for handling instrument., 5. The sensitivity and accuracy depends upon the type of instrument., 6. Selectivity of instrument is required for specific samples., 7. Some time cross checking of results with other methods is needed., 1.4, 4
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Pharmaceutical Analysis, Introduction to Pharmaceutical Analysis, Types of Instrumental Methods:, There are many techniques available for the analysis of analytes, which can be broadly, classified as:, (A) Electro analytical methods (chemical potential + electrons), (B) Analytical separation methods (chemical equilibrium + detectors), (C) Analytical spectroscopic methods (chemical energy + photons), (D) Miscellaneous methods, 1.3.1 Electro Analytical Methods, Electrochemical methods are powerful and versatile analytical techniques that offer high, sensitivity, accuracy, and precision with relatively low cost instrumentation., 1. Potentiometry is useful means of characterizing an acid of which the potential is, measured across the analyte without using indicator. It gives information about the, composition of the sample through the potential appearing between two electrodes., 2. Voltammetry is the study of current as a function of applied potential. It is used to, designate the current-voltage measurement obtained at a given electrode., 3. Coulometry use for determination of the amount of matter transformed during, an electrolysis reaction by measuring the amount of electricity (in Coulombs C'), consumed or produced, 4. Polarography is a special case of voltammetry referring to the current-voltage, measurement acquired using dropping mercury electrode with a constant flow of, mercury drop., 5. Amperometry used for determination of any analyte concentration by measurement, of the current generated in a suitable chemical reaction., 6. Conductometry is measurement of electrical conductivity of ionic solutions by, applying an electric field between two electrodes., 7. Electrogravimetry is based on an analysis that is carried out by passing an electric, current for a sufficient length of time to ensure complete oxidation or reduction of, the analyte to a single product of known composition. It is a method used to, separate and quantify ions of a substance, usually a metal., Examples : Cd, Cu, Ni, Ag, Sn, Zn., 1.3.2 Analytical Separation Methods, Chromatographic is a method of separating a mixture of compound into individual, compound through equilibrium distribution between two phases viz, a stationary phase and, a mobile phase. Chromatography is based on the difference in the rate at which the, compound of a mixture moves through a porous medium under the influence of some, solvent or gas., Chromatographic methods broadly classified on the basis of separation takes place on a, planar surface or in a column. In column chromatography, the stationary phase is placed n, 1.5
