CHED 347 |
| We describe a method for quantifying tocopherol TLC spots from vitamin E samples developed on C-18 plates with bonded 254 nm fluorophors. The plate fluorescence background signal fo is first fitted with a 2D quadratic function using selected background pixel regions. The empirical absorbance A = -log(f/fo) is then calculated at each pixel in the spot image regions. Next a Levenberg-Marquardt nonlinear procedure is used to fit the overlapping spots to 2D Gaussian profiles for each component. Finally, analytical integration of the Gaussian profiles provides data for calibration plots and sample analyses. Uncertainties are estimated using a combination of linear fit formulas and Monte Carlo methods. The LabVIEW/Vision software environment (National Instruments) enables systematic control of the process from image acquisition to final calculations. Quantitative TLC methods are particularly suitable for cases such as this where rigorous isolation and purification requirements can easily lead to analyte decomposition. |
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Undergraduate Research Poster Session: Analytical Chemistry
11:00 AM-1:00 PM, Monday, March 26, 2007 Hyatt Regency Chicago -- Riverside Center, Poster
Division of Chemical Education |