Document Type

Dissertation - Open Access

Award Date

2020

Degree Name

Doctor of Philosophy (PhD)

Department / School

Chemistry and Biochemistry

First Advisor

Brian Logue

Keywords

ATOEA, CN-fishing, Cyanide, Sensor, Toxic, Inhaled Hazard

Abstract

Toxic inhalation hazards (TIHs), such as methyl isocyanate (MIC) and hydrogen cyanide (HCN), are noxious gases and vapors that are harmful, and often deadly, to humans. However, because of their low cost and high reactivity, they are extensively used for industrial productions, creating risk of exposure for both industrial workers (e.g., occupational exposure) and civilians (e.g., accidental release during transport). The illicit use of TIHs, including as terrorist agents, is also concerning. Considering the rapid toxicity of TIHs and the danger they pose to both human and animal lives, there is a critical need to develop of analytical methods for the analysis of TIH metabolites and therapeutic agents to verify their exposed and to help in further development of these therapeutics. One therapeutic strategy for TIH exposure is inhibition of the transient receptor potential ankyrin 1 (TRPA1) ion channel, since some TIH toxic effects are triggered by activation of this channel. Antagonists of TRPA1 have shown near complete attenuation of the noxious effects from TIH exposure. One of the TRPA1 antagonists, A-967079, has shown impressive efficacy, high selectivity, high potency, and oral bioavailability. However, no method for its analysis from any matrix is currently available. Hence, a simple HPLC-MS/MS method was developed and validated to quantify A-967079 in plasma. The method features an excellent LOD of 25 nM, a wide linear range (0.05–200 μM), and good accuracy and precision. The method was successfully applied to determine A-967079 from treated animals and it may facilitate the development of A-967079 as a therapeutic agent against the noxious effects of TIH exposure. While there are a number of known metabolites of cyanide (CN), the interaction of CN with glutathione has not been explored. Therefore, we studied the interaction of CN and GSH to identify the novel CN metabolite, 2-aminothiazoline-4-oxoaminoethanioc acid (ATOEA). The production of ATOEA from cyanide exposure was confirmed by detection of both ATOEA and ATOEA-13C15N in rabbit plasma (N = 11 animals) following administration of NaCN:K13C15N (1:1), with a similar amount of ATOEA and ATOEA- 13C15N formed (R2 = 0.9924, p < 0.05). An HPLC–MS/MS method was developed and validated to analyze ATOEA from plasma, producing a linear range of 0.5–50 μM, a limit of detection of 200 nM, and excellent precision and accuracy. ATOEA concentrations were significantly elevated in the plasma of animals following cyanide exposure. Using this method, we showed that ATOEA is produced from interaction of CN and GSH and can serve as a biomarker of CN exposure. A field portable detection method was developed to detect the CN metabolite, thiocyanate, from fish blood to verify CN-fishing (an illegal fishing technique practice in Southeast Asia that has detrimental effect on aquatic life). The cyanide sensor was adapted via oxidation of thiocyanate to cyanide using KMnO4, microdiffusion, reaction of the cyanide with naphthalene dialdehyde and taurine, and fluorescence analysis of the resulting β-isoindole product. The method presented here features an excellent LOD (29 μg/L) and an acceptable linear range (59-590 μg/L), good accuracy (100±20%) and good precision (< 20% relative standard deviation). The method was successfully applied to quantify thiocyanate from the blood of marine fish exposed to cyanide. The full development of the proposed sensor would allow rapid field and laboratory analysis of suspected cyanidecaught fish by government, aquarium trade and food agencies to help enforce this illegal practice.

Library of Congress Subject Headings

Pulmonary toxicology.
Analytical toxicology.
Metabolites.
Cyanides.
Cyanide-fishing.

Format

application/pdf

Number of Pages

114

Publisher

South Dakota State University

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Rights Statement

In Copyright