Date of Award
Doctor of Philosophy
In the past few decades, there has been an increased need to analyze complex samples in the various areas of science. To meet this need, chemists have made substantial improvements in the separation capabilities of liquid chromatography (LC). Along with improved separations, complementary improvements in instrumen- tal techniques and detection methods are needed in order to achieve the optimum performance from the liquid chromatographic system. This dissertation reports improvements in instrumental techniques used in detection and in the methods by which detectors are used to obtain information;Part one describes the results of two projects in which new detec- tion techniques are demonstrated. Both of these techniques take advantage of the unique properties of lasers as light sources. The first technique is a laser-based three-dimensional detector which allows simultaneous monitoring of the refractive index, absorbance, and fluorescence from a flowing stream. Using the laser's ability to be focused to a very small spot, a one-microliter cell was built allow- ing compatibility with microbore column LC. The second technique is a laser-based absorbance detector which allows one to make differential absorbance measurements, optically, using Michelson interferometry. This optical arrangement also shows promise toward reducing the flicker noise of a light source;In part two, a novel detection method is shown to work with two common LC detectors: the absorbance detector and the electrical conductivity detector. The absorbance detector works as a universal detector when an absorbing eluent is used, allowing one to detect nonabsorbing analytes. This mode of detection, along with the new detection scheme, is shown to allow analytes to be quantified without the need for standards. The same detection scheme is demonstrated with the conductivity detector, with nonsuppressed ion chromatog- raphy. To show this scheme could work, we had to disprove a;common misconception that this detector cannot work with eluent ions having high equivalent conductance; ('1)DOE Report IS-T-1190. This work was performed under contract No. W-7405-Eng-82 with the U.S. Department of Energy.
Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/
Steven A. Wilson
Wilson, Steven A., "New detection methods and techniques with applications in liquid chromatography " (1985). Retrospective Theses and Dissertations. 8759.