Medical brain notes 14

  INTRODUCTION In the earlier sections of this part, the various analytical methods based upon the measurements of mass and volume have been described at sufficient length with their typical applications in the analysis of pharmaceutical substances. Comparatively older methods of analysis, such as  colorimetry  is entirely based upon the interaction of specifically visible light with a sample. In this particular instance, just the visible portion of the electromagnetic radiation spectrum within the range of 400 and 700 nanometers (nm) to which a human eye is sensitive, has been employed. In a situation whereby the sample is made to interact with a wide spectrum of wavelengths in a given zone of electromagnetic radiation, consequently giving rise to a collection of measurement signals as a function of wavelength is termed as a  spectrum , ultimately putting forward the most common terminology  spectrochemical analysis  or  spectroscopy.

  THEORY 1.  ELECTROMAGNETIC SPECTRUM   It has been established beyond any reasonable doubt that the absorption and the emission of energy in the  electromagnetic spectrum  take place in distinct separate pockets or photons. The relationship existing between the energy of a photon and the frequency matching its propagation may be expressed as follows :                      E =  h ν          ...( a )   where,         E = Energy (in ergs),   v = Frequency (in cycles sec – 1 ), and   h  = Universal constant termed as Planck’s constant (6.6256 × 10   – 27   erg sec).   However, the relationship between wavelength and frequency may be expressed as follows :   ν  =   c / λ  ...( b ) where,  λ  = Wavelength (in cms),   c...