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Spectrophotometry – Basic Instrumentation

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  Spectrophotometry – Basic Instrumentation Objective: To understand the basic principle of spectrophotometry and the working of a UV-Vis spectrophotometer by measuring absorbance of a colored solution at a specific wavelength.   Principle: Spectrophotometry is based on the principle that molecules absorb light at specific wavelengths. The amount of light absorbed is proportional to the concentration of the solution (Beer-Lambert Law). Beer-Lambert Law : A = ε c l Where:   A = Absorbance ,  ε =  Molar absorptivity (L·mol⁻¹·cm⁻¹),  c  = Concentration (mol·L⁻¹),  l  =  Path length (cm)   Materials Required: ·           UV-Visible Spectrophotometer ·           Cuvettes (quartz or plastic, depending on wavelength) ·           Distilled water ·           C...
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Study of Cell Structure by Temporary Mounts of an Onion Peel

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  Experiment No: Study of Cell Structure by Temporary Mounts of an Onion Peel   Objective: To prepare a stained temporary mount of an onion peel and to record observations and draw labeled diagrams. Apparatus and materials required: Onion, glass-slide, watch glass, cover slip, forceps, needles, brush, blade, filter paper, safranin, glycerine, dropper, water, and a compound microscope.   Theory: All living organisms are made up of cells. The shape, size and the number of these units vary in organisms. The three major components of a cell are the cell membrane, cytoplasm and nucleus. In a plant cell, a cell wall surrounds the cell membrane.   Procedure: 1.   Take an onion and remove its outer most peel. 2.   Now cut a small part from an inner scale leaf with the help of a blade. 3.    Separate a thin, transparent peel from the convex surface of the scale leaf with the help of forceps. 4.   Keep this peel in a watch g...
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Light Microscopy

  Light Microscopy for Observing Bacterial Morphology Using Permanent Slides   Objective: To observe and identify the morphological characteristics of bacteria (such as shape and arrangement) using a compound light microscope and permanent stained slides .   Principle: Light microscopy uses visible light to magnify images of small specimens. In bacterial studies, staining techniques (e.g., Gram staining) enhance contrast, allowing for better observation of morphology —such as coccus , bacillus , spirillum , and their arrangements (e.g., diplo-, strepto-, staphylo-).   Materials Required: ·          Compound light microscope ·          Permanent bacterial slides ·          Immersion oil (for 100× objective) ·          Lens cleaning tissue ·        ...
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SEPARATION OF COMPOUNDS FROM A MIXTURE USING TLC

  SEPARATION OF COMPOUNDS FROM A MIXTURE USING TLC Objective: To separate and identify individual compounds from a given mixture using Thin Layer Chromatography (TLC) technique. Principle: Thin Layer Chromatography is based on the differential adsorption of compounds on a stationary phase and their differential solubility in a mobile phase. ·          The stationary phase is a thin layer of adsorbent (e.g., silica gel or alumina) on a glass or plastic plate. ·          The mobile phase is a solvent or solvent mixture that moves up the plate via capillary action. ·          Compounds move at different rates depending on their polarity and affinity to the stationary and mobile phases. Materials Required: ·          TLC plate (silica gel-coated) ·          Developi...
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