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The development of on-line digestion manifolds for the decomposition of solid samples having a predominantly organic matrix
Abstract
The goal of this research has been to enhance sample decomposition techniques through the coupling of flow technology with current sample digestion methodology in order to approach the characteristics of an ideal digestion system--one which is rapid, minimizes sample and reagent consumption, avoids analyte loss or contamination, rapidly transfers the resulting digest into the detector for measurement, and is amenable to automation. A stopped-flow, high pressure manifold incorporating a resistively heated thermal oven was developed for the on-line dissolution of slurried samples having a predominantly organic matrix. The manifold, which was directly coupled with a flame atomic absorption spectrometer, was determined to be most applicable to samples in which the analytes were loosely bound to the bulk material. This was a consequence of the limited oxidation potential of the system resulting from insufficient headspace volume for the expansion of nitrous oxides which are believed to be crucial intermediates in the digestion process, and rapid overpressurization of the manifold due to a lack of control over the rate of energy input to the system. A stopped-flow, high pressure manifold incorporating a microwave oven was subsequently developed to overcome the limitations of the thermal oven manifold. A microwave heated glass reaction column provided ample headspace for the expansion of gaseous reaction products and the use of power programming allowed for control of the energy flux introduced to the system. A dual stage manifold depressurization system was designed and interfaced via an autosampler to both a flame atomic absorption and an inductively coupled plasma atomic emission spectrometer for the determination of trace elements in solid samples. A study of the manifold operating parameters, such as flow rate, carrier stream composition, residence time, energy input, and gas-liquid separation was conducted in this work. Slurry sample preparation and handling and instrumental response to samples in concentrated acid matrices were also investigated.
Subject Area
Analytical chemistry
Recommended Citation
Gluodenis, Thomas Joseph, "The development of on-line digestion manifolds for the decomposition of solid samples having a predominantly organic matrix" (1993). Doctoral Dissertations Available from Proquest. AAI9408279.
https://scholarworks.umass.edu/dissertations/AAI9408279