Degree Type

Dissertation

Date of Award

1993

Degree Name

Doctor of Philosophy

Department

Veterinary Pathology

Major

Toxicology

First Advisor

Gary D. Osweiler

Abstract

The objective of this project was to develop a rapid, simple and inexpensive quantitative analysis to confirm hydrogen sulfide toxicosis in livestock based on acid extraction of sulfide in a wash-bottle unit and potentiometric determination with an ion-selective electrode (ISE). A silver/sulfide ISE and double-junction reference electrode coupled to a digital pH/mV meter with an automatic temperature compensation probe provided rapid and stable measurement of sulfide down to 0.02 ppm S[superscript]-2 using a liter-beaker calibration technique. The analysis was further facilitated by sealing standardized solutions and extracted unknown samples in serum bottles after flushing with nitrogen gas and storing at 4°C;The wash-bottle developed during the research provided excellent sulfide recoveries from aqueous samples (87 to 96%), but extraction from animal tissues was plagued by sample coagulation, foaming and poor to excellent percent recoveries. Whole and clotted blood were the worst samples for coagulation and foaming problems, compared to brain, lung, serum or plasma. Diluting the sample prior to extraction, and acidifying with dilute acids prevented coagulation. Foaming was combated with a mineral oil-poloxalene mixture (50:50 v/v), redesigning the wash-bottle, and reducing the nitrogen flow rate. Mean percentage of spike recovered were: blood, 7 to 43; blood clot, 13; serum, 58; plasma, 80; brain, 83 to 101; and lung, 76 to 102;Poor sulfide recovery and concentrating ability of the extraction unit prevented estimating endogenous blood sulfide concentrations ( 0.05) from endogenous levels due to the large variance in the resulting sulfide estimates. Specimens should be collected as soon as possible, with steps taken to preserve the sulfide content (refrigeration, flash freezing, or zinc precipitation), rapid delivery to the laboratory under preservation, and prompt analysis.

DOI

https://doi.org/10.31274/rtd-180813-1819

Publisher

Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/

Copyright Owner

Scott Thompson Witte

Language

en

Proquest ID

AAI9321224

File Format

application/pdf

File Size

187 pages

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