Introduction to Pharmaceutical Analysis
Pharmaceutical Analysis is a branch of Practical Chemistry that involved process of Identification, Determination, Qualification and Purification of a chemical substances. This is mainly used for the separation of the components from the mixture and for the determination of the structure of the compounds.
The Substances may be a single compound or a mixture of a compound and it may be in any of the dosage form. The substances used as Pharmaceutical are Animals, Plants, Microorganisms, Minerals and Various Synthetic Compound.
Based upon the determination type, there are mainly two types of analytical methods. They are as follows:
- Qualitative Analysis
- Quantitative Analysis
It is performed to establish composition of natural/synthetic substances. These tests are performed to indicate whether the substance or compound is present in the sample or not.
The techniques are mainly used to quantify any compound or substance in the sample. These techniques are based in;
- The quantitative performance of suitable chemical reaction and either measuring the amount of reagent added to complete the reaction or measuring the amount of reaction product obtained.
- The characteristic movement of a substance through a defined medium under controlled conditions.
- Electrical measurement.
- Measurement of some spectroscopic properties of the compound.
Various types of Qualitative analysis:
- Chemical methods:
- Volumetric or Titrimetric methods
- Gravimetric methods
- Gasometric analysis
- Electrical methods
- Instrumental methods
- Biological and microbiological
1. Titrimetric or Volumetric Methods:
Titrimetric or Volumetric analysis is a widely-used quantitative analytical method. This method involves the measurement of volume of a solution of known concentration which is used to determine the concentration of the analyte. This method requires simple and less apparatus and they are susceptible of high accuracy.
Various types of Titrimetric Methods or Volumetric Methods are:
- Acid-base titrations (neutralization reactions)
- Complex metric titrations
- Precipitation titrations
- Oxidation reduction titrations
- Non aqueous titrations
2. Gravimetric Analysis:
Gravimetric analysis is a technique through which the amount of an analyte (the ion being analyzed) can be determined through the measurement of mass. The principle behind gravimetric analysis is that the mass of an ion in a pure compound can be determined and then used to find the mass percent of the same ion in a known quantity of an impure compound.
3. Gasometric Analysis:
Gasometric Analysis involves measurement of the volume of gas absorbed in a chemical reaction.
Some of the gases which are analysed by Gasometry are CO2, N2O, cyclopropane, amyl nitrate, ethylene, N2, helium etc.
Electrical methods, also called electro analysis, these methods of analysis involve the measurement of electric current, voltage or resistance in relation to the concentration of some species in the solution. The measurements provide qualitative or quantitative information.
Electrical methods of analysis include:
Potentiometry measures electrical potential of an electrode in equilibrium with an ion to be determined. Conductometry measures electrical conductivity of an electrode with a reference electrode while Polarography, Voltametry and Amperometry measures electrical current at a micro-electrode.
Instrumental Method of Analysis:
Instrumental method involves measurement of some physical properties of the compound or a substance. These methods are employed for determination of minor or trace concentration of element in the sample.
Instrumental methods are preferred due to their selectivity, high speed, accuracy and simplicity of analysis. Any change in the properties of the system are detected by measurement of absorbance, specific rotation, refractive index, migration difference, charge to mass ratio etc.
- Spectroscopic methods of analysis depend upon measurement of the amount of radiant energy of a particular wavelength emitted by the sample.
- Methods which include absorption of radiation are ultra violet, visible, infra-red, atomic absorption, nuclear magnetic resonance spectroscopy etc.
- Emission methods involve heating or electrical treatment of the sample so that the atoms are raised to the excited state to emit the energy and the intensity of this energy is measured. Emission methods include emission spectroscopy, flame photometry, flourimetry etc.
- Chromatographic techniques and electrophoretic methods are separation methods for the mixture of compounds, but also applied for identification of compounds of mixtures. Various chromatographic techniques are GC, HPLC, TLC, HPTLC, PC etc.
- Mass spectrometry involves vaporization of material using a high vaccum and the vapour is bombarded by a high energy electron beam. Vapour molecules undergo fragmentation to produce ions of varying size. These ions are differentiated by accelerating them in electrical field and then deflecting them in a magnetic field. Each kind of ion gives a peak in the mass spectrum.
Biological & Microbiological Methods:
Biological methods are used when potency of a drug or its derivative cannot be properly determined by any physical or chemical methods. They are called bio-assays.
Microbiological methods are used to observe potency of antibiotic or anti- microbial agents. In antimicrobial assay, inhibition of growth of bacteria of the sample is compared with that of the standard antibiotic. These methods include Cup Plate method and Turbidimetric analysis.
- Manufacturing industries require both qualitative and quantitative
- In the development of new products which contains mixtures other than the pure material, it is necessary to ascertain composition of mixture which shows the optimum characteristics for which the material has been developed.
- Raw materials are to be checked to ensure that the essential components are present within the predetermined range of composition and there are not any unusual substances present which might upset the manufacturing process or it may appear as a harmful impurity in the final product.
- Most of the industrial processes give rise to pollutants which may cause health related problems. So quantitative analysis of air, water and soil sample should be carried out to determine the level of pollution and to establish the safe limits for pollutants.