read the following statements :

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p) the surface area measurements using BET approach utilize argon gas for adsorption

q) full form of BET is brunauer, Emmett and teller

choose the correct answer

  1. p and q both are correct
  2. p is correct but q is incorrect
  3. q is correct but p is incorrect
  4. both p and q are in correct


Saraswathi.B's picture


q is correct but p is incorrect

Bulk flow, formulation homogeneity and surface area controlled processes such as dissolution and chemical reactivity are directly affected by size, shape and surface morphology of the drug particles. Each drug candidate should be tested during preformulation with the smallest particle size as is practical to facilities preparation of homogeneous samples and maximize the drugs surface area for inter actions.

The measurement of the surface area is made by brunauer, Emmett and teller (BET), nitrogen adsorption in which a layer of nitrogen molecules is adsorbed to the sample surface at -1960C. once surface adsorption has reached equilibrium, the sample is heated to room temperature and the nitrogen gas gets desorbed and its volume is measured and converted to the number of the adsorbed molecules through ideal gas laws.

Since the nitrogen gas is adsorbed or occupies with in the area of 16A2 so it is can measured the surface area per gram for each pre weighed sample. By determining the surface area at several partial pressure of nitrogen and extrapolation to zero nitrogen partial pressure yields the true mono layer surface area. While BET measurement are usually precise and quickly obtained with current commercial equipment, errors may arise from the use of impure gases and volatile surface impurities (hydrates).

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