@article{EngelhardLoehmannsroebenSchael2004,
  author    = {Engelhard, Sonja and L{\"o}hmannsr{\"o}ben, Hans-Gerd and Schael, Frank},
  title     = {Quantifying ethanol content of beer using interpretive near-infrared spectroscopy},
  issn      = {0003-7028},
  year      = {2004},
  abstract  = {On the basis of absorption measurements in the near-infrared (NIR) spectral range, a new method for the quantification of the ethanol content of beer is presented. Instead of the multivariate calibration models most commonly employed in NIR spectroscopic works, we use interpretive difference spectroscopy: Two wavelengths are selected according to the assignment of the absorption bands of the main substances of content of beer in the NIR region, and the difference between the absorbances at these wavelengths is used for ethanol quantification. Absorption spectra of the dominating beer ingredients are discussed and the calibration procedure with ethanol/water mixtures is shown. Robustness against the carbohydrate content of beer samples was demonstrated by analyzing solutions of ethanol and maltose in water. Validation of the method was performed with various beer samples with an ethanol concentration range between 0.5 and 7.7 vol \%. The pertinent advantage of the procedure developed in this work is the indication that the results are independent from seasonal variations of the ingredients, which is of high interest for products with natural ingredients such as beer},
  language  = {en}
}
@article{SchaelReichLoehmannsroeben2000,
  author    = {Schael, Frank and Reich, Oliver and L{\"o}hmannsr{\"o}ben, Hans-Gerd},
  title     = {Near infrared diode laser spectroscopy of organic compounds in turbid aqueous solutions},
  isbn      = {0-9528666-1-7},
  year      = {2000},
  abstract  = {Diffuse reflectance measurements and photon migration studies with near infrared (NIR) diode lasers were employed to elucidate experimental methods for determining absorption and scattering coefficients and species concentrations in highly scattering solutions. Applicability of theoretical approaches were established by investigating model systems with absorbing (e.g. ink, malachite green) and scattering (e.g. milk powder, caolinit) species in aqueous solution. While diffuse reflectance measurements practically requires calibration procedures, photon migration studies allow quantitative determination of absorption and scattering coefficients of turbid solutions consistent with absorptions coefficients obtained from Lambert-Beer's law. Furthermore, NIR absorption spectra of water, chlorinated hydrocarbons (chloroform, 1,2-dichloroethane, trichloroethene) and of various sugars (\$alpha\$-D-glucose, sucrose, maltose) are discussed. Spectral variations of NIR water absorption with temperature and solvents are exammined. Exemplary, NIR diode laser detection of water in acetone/water mixtures is performed.},
  language  = {en}
}