EXP333

=Researcher= Matthew McBride =Objective= To determine the extinction coefficient of trans-dibenzalacetone in ethanol =Procedure= Dissolve a known amount of trans-dibenzalacetone in ethanol and calculate the extinction coefficient using UV/Vis Spectroscopy and Beer's law. =Results= Lambda 2 UV/Spectrometer Results [|Spreadsheet] with results λ max: 329 nm Absorption units at λ max (A): 0.755 (corrected for baseline) Pathlength (L): 1 cm Concentration (c): 2.121e-5 M Calculated extinction coefficient (ε) of trans-dibenzalacetone in ethanol using Beer's Law (A=εLc): 35596

Lambda 35 UV/Spectrometer Results [|UV/Vis Spectrum] λ max: 327 nm Absorption units at λ max (A): 0.756606 (cannot look at spectrum to obtain this number, but must look at .jdx file directly) Pathlength (L): 1 cm Concentration (c): 2.121e-5 M Calculated extinction coefficient (ε) of trans-dibenzalacetone in ethanol using Beer's Law (A=εLc): 35667 =Discussion= Both spectrometers provided the same value and this is similar to the value that was found in literature. =Conclusion= The extinction coefficient of trans-dibenzalacetone in ethanol is about 35000 =Log=

2012-08-07
15:35 Added 0.0497 g of trans-dibenzalacetone (Product 284A from UCEXP284) to a 10 mL volumetric flask. 15:47 The flask was filled with ethanol and the crystals were dissolved into the solution. This was a 0.0212128 M solution and Solution A. 15:50 1 mL of Solution A was transferred to a 10 mL volumetric flask and the flask was filled with ethanol to create Solution A_10dilution. The solution was inverted to mix and each flask was washed 3x prior to use. 1 mL of Solution A_10dilution was transferred to a 10 mL volumetric flask and filled with ethanol to create Solution A_100dilution. The solution was inverted to mix. 1 mL of Solution A_100dilution was transferred to a 10 mL volumetric flask and filled with ethanol to create Solution A_1000dilution. The solution was inverted to mix. A 1 cm pathlength cuvette was filled with Solution A_1000dilution and another cuvette was filled with ethanol. The sample was analyzed in dual beam mode using the Lambda 2 UV/Vis Spectrometer by manually selecting wavelengths and then the absorbance at each wavelength was recorded. The sample was also analyzed in dual beam mode using the Lambda 35 UV/Vis Spectrometer and the spectrum of the file was saved as ONSEXP333A_1000dilution.