Researcher

Matthew McBride

Objective

To determine the extinction coefficient for 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

UV/Vis Spectrums: For Solution A_10000dilution
Spectrum of Solution A_10000dilution in E1 mode
Spectrum of Ethanol in E1 mode
Spectrum of difference (Solution A_10000dilution - ethanol)
λ max: 328 nm
Absorption units at λ max (A): 0.141815 (cannot look at spectrum to obtain this number, but must look at .jdx file directly)
Pathlength (L): 1 cm
Concentration (c): 2.0886e-6 M
Calculated extinction coefficient (ε) of trans-dibenzalacetone in ethanol using Beer's Law (A=εLc): 67899

Discussion

The volumetric flasks were not washed throughly enough to provide an accurate measurement from the dilutions.

Conclusion

Calculated extinction coefficient (ε) of trans-dibenzalacetone in ethanol was 67899, but this number is higher than some of the 33000 number that has been reported in literature.

Log

2012-08-06

9:36 0.0607 g of trans-dibenzalacetone (Product 284A from UCEXP284) was added to a 5-dram vial.
9:46 A new bottle of ethanol was opened and 9.7907 g (density of 0.7893 g/mL, so 12.4043 mL) was added to the 5-dram vial. All of the crystals were observed to dissolve. This was Solution A (0.020886 M).
9:55 1 mL of Solution A was added to a 10 mL volumetric flask and the flask was filled with ethanol. The solution was inverted several times to mix. This was Solution A_10dilution.
10:05 1 mL of Solution A_10dilution was added to a 10 mL volumetric flask and the flask was filled with ethanol. The solution was inverted several times to mix. This was Solution A_100dilution.
10:12 1 mL of Solution A_100dilution was added to a 10 mL volumetric flask and the flask was filled with ethanol. The solution was inverted several times to mix. This was Solution A_1000dilution.
10:21 1 mL of Solution A_1000dilution was added to a 10 mL volumetric flask and the flask was filled with ethanol. The solution was inverted several times to mix. This was Solution A_10000dilution.
12:37 3 mL of Solution A_10000dilution was added to a 1 cm pathlength cuvette and analyzed by UV/Vis spectroscopy. The sample was analyzed in E1 mode and both the blank (ethanol) and the sample were analyzed using the same cuvette.