User:Mary Mendoza/Notebook/CHEM 581: Experimental Chemistry I/2014/10/01

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Malachite Green Diffusion through PVA-clay film

  • I prepared 20 ppm malachite green from a 195 ppm malachite green stock solution provided by Dr. Hartings.
  • Using dilution equation, the volume of 195 ppm of malachite green required to make 25 mL of 20 ppm was calculated to be 2.56 mL.
  • Using a vernier caliper, the thickness of the PVA-clay film used for diffusion is 0.51 mm; the film weighed 0.8846 g.
  • The diffusion assembly was prepared according to the picture below, containing 10 mL of 20 ppm Malachite green on the left chamber and 10 mL of distilled, deionized water:
Status at 9:16 AM
Status at 9:16 AM
Status at 7:38 PM
Status at 7:38 PM


  • 10 uL of the 20 ppm Malachite green stock was diluted into 200 uL of DI water. This mixture was transferred into a 200 uL quartz, fluorescence cuvette; the absorbance was measured as the zero time for the diffusion curve. The absorbance of 200 uL of DI water was directly measured as the zero mark for the diffusion curve.
  • At the 5 minute mark, 200 uL was taken from each chamber and placed in an eppendorf tube. 10 uL from the 200 uL was diluted into 200 uL of DI water. The absorbance was measured from 200-800 nm.
  • The remaining, unused, and undiluted samples were returned to each, respective chamber to prevent disrupting the chemical equilibrium.
  • Additional absorbance measurements were taken in the following times:
    • 15 minutes
    • 30 minutes
    • 60 minutes
    • 120 minutes
    • 150 minutes
  • To produce a better diffusion curve, additional collections were performed at the following times; 459, 616, 1426, 1733, 1799, and 2294 minutes.