Document Type

Thesis - Open Access

Award Date

2016

Degree Name

Master of Science (MS)

Department / School

Chemistry and Biochemistry

First Advisor

Brian A. Logue

Keywords

fraction limit of detection, freeze concentration, ICECLES, signal enhancement, stir bar sorptive extraction, TD-GCMS

Abstract

Clean water is very important for human health. Therefore, drinking water contamination is a significant research concern, especially with the increasing global population. Some contaminants, such as pesticides, can cause health effects even at low levels. Therefore, trace and ultratrace analysis of contaminants in drinking water is essential. Ultratrace analysis typically requires highly effective sample preparation methods and/or highly sensitive instruments. There are currently advanced sample preparations techniques available to analytical chemists that may allow trace analysis of certain analytes. These include liquid-liquid extraction (LLE), solid phase extraction (SPE), solid phase micro extraction (SPME), and stir bar sorpitive extraction (SBSE). Even though these techniques have advantages, some analytes are still extremely difficult to analyse at the trace and ultratrace concentrations necessary to ensure safe drinking water. Therefore, a novel sample preparation method was developed as a combination of SBSE and FC to allow trace analysis of drinking water samples. The technique, ICE Concentration Linked with Extractive Stirrer (ICECLES), illustrated great advantages for ultra-trace analysis of multiple analytes. Parameters affecting the performance of ICECLES were evaluated using benzaldehyde, such as the initial concentration, stir speed and freeze rate. Extraction at low speeds resulted in higher extraction efficiency. However, the freeze rate and initial concentrations had a minor effect on ICECLES extraction efficiency. ICECLES produced linear range of benzaldehyde from 40-5000 nM, with R2 > 0.999, the accuracy was 100 ± 15%, and the precision was ≤ 16% RSD for the QCs. ICECLES provided greater extraction efficiency, signal enhancement (SE) and lower limits of detection (LOD) compared to SBSE method for each analyte tested. ICECLES was evaluated in five different analytes (2-butanol, benzaldehyde, benzyl Alcohol, dimethyl trisulfide and bromobenzene; with log Kow of 0.61, 1.1, 1.48, 1.87 and 2.9, respectively). ICECLES produced the highest SE for 2-butanol, 474 times than SBSE, and the SE generally correlated with decreasing log Kow. ICECLES was shown to be an excellent sample preparation method for analyzing triazine pesticides from aqueous samples. ICECLES achieved greater SE and extraction efficiency for all pesticides, especially for lower log Kow compounds, with trend: metamitron > deethyl-atrazine > deisopropyl-atrazine > metribuzin > atrazine inversely following the log Kow.

Library of Congress Subject Headings

Drinking water -- Analysis

Drinking water -- Contamination

Description

Includes bibliographical references (page 59-64)

Format

application/pdf

Number of Pages

77

Publisher

South Dakota State University

Download

Included in

Chemistry Commons

Share

COinS
 

Rights Statement

In Copyright