Document Type

Dissertation - Open Access

Award Date

2026

Degree Name

Doctor of Philosophy (PhD)

Department / School

Chemistry and Biochemistry

First Advisor

Brian Logue

Abstract

Environmental contaminants such as neonicotinoids and bisphenols are increasingly detected at ultratrace concentrations in environmental and consumer matrices, necessitating sensitive and efficient analytical methodologies. This dissertation presents the development, validation, and application of liquid chromatography–tandem mass spectrometry (LC–MS/MS) methods coupled with simplified sample preparation techniques. In Chapter 2, a direct aqueous injection (DAI) LC–MS/MS method was developed for the analysis of five neonicotinoids in surface water, eliminating extensive sample preparation. The method demonstrated strong linearity (R² = 0.993–0.998), with limits of detection (LOD) ranging from 0.5 to 4 ng/L and lower limits of quantification (LLOQ) of 10–50 ng/L. Accuracy (80–120%) and precision (< 15% RSD) met validation criteria. Matrix effects evaluated at dissolved organic matter concentrations of 2, 5, and 10 mg/L were minimal. Application to environmental samples resulted in detections of clothianidin (44.5 ng/L), imidacloprid (33.8 ng/L), and thiamethoxam (5.2 ng/L). In Chapter 3, an ice concentration linked with extractive stirrer (ICECLES)-based method was developed for bisphenol analysis in aqueous matrices, including thermal receipt paper extracts. The method demonstrated excellent linearity (R² ≥ 0.994), with LODs ranging from 0.196 to 0.782 ng/g and LOQs from 4.9 to 9.8 ng/g. Accuracy was within ±20% at low concentrations and ±15% at higher concentrations, with precision ≤15% RSD across all conditions. Application to receipt extracts revealed bisphenol A (0.23 µg/g) and bisphenol S (~610 µg/g), highlighting variability in consumer products. Overall, these methods provide robust, sensitive, and low-solvent alternatives for the determination of environmental contaminants in complex matrices.

Publisher

South Dakota State University

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Included in

Chemistry Commons

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Rights Statement

In Copyright