DESIGN AND EVALUATION OF AN IMAGE DISSECTOR-BASED DERIVATIVE SPECTROPHOTOMETER (FILTERING, DIGITAL, ALGORITHMS)
Abstract
A derivative spectrometer was constructed with an image dissector tube as detector and the characteristics of the system were evaluated for derivative spectroscopy. The precision scanning and positional accuracy of the image dissector detector contributed significantly to producing undistorted derivatives. The high sensitivity and low photometric errors extend the spectrometers useable range to greater than 3 absorbance units. The derivatives are computed directly from intensity versus wavelength data recorded in a conventional scanning mode. The quantitative results indicate that this approach can provide information that is similar in quality to that obtained by electronic or wavelength-modulated derivative spectrometers. This method of generating derivatives required modification of the data smoothing algorithms, and the evaluation of the modified algorithm suggests that they have reduced distortion. Computational time is critical to this approach, leading to the generation of a system of integer based arithmetic routines that resulted in computational times that were faster by a factor of 4 to 8. Potential applicability of this derivative spectrometer to analytical problems was illustrated by the examination of mixtures of polyaromatic hydrocarbons. Data from the spectrometer indicates that two component mixtures can be resolved, with a limit of detection in the range of 0.003 ug/ml.
Degree
Ph.D.
Subject Area
Analytical chemistry
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