Detection of Ions and Small Molecule Toxicants in Aqueous Media Using New Colorimetric and Fluorimetric Methods

Teresa Louise Mako, University of Rhode Island

Abstract

Ultrasensitive Detection of Nitrite through Implementation of N-(1-Naphthyl)ethylenediamine-Grafted Cellulose into a Paper-Based Device: Reported herein is the immobilization of N-(1-naphthyl)ethylenediamine on cellulose via an epichlorohydrin-based covalent attachment and the implementation of the functionalized cellulose into an ultrasensitive, paper-based device for nitrite detection. There is high demand for affordable, robust, sensitive, selective, and user-friendly detection methods for nitrite, a nutrient which is harmful at high concentrations in both marine environments and physiological systems. The reported functionalization procedure resulted in a 12.9-fold higher functionalization density than previously reported procedures using epichlorohydrin, and the subsequent device allows for nitrite detection limits in synthetic freshwater and real seawater of 0.26 μM and 0.22 μM, respectively. The sensor is efficient in a wide range of temperature, humidity, turbidity, and salinity conditions and was successfully applied to real water samples. Highly Sensitive and Subtraction-Free Dual Detection of Nitrate and Nitrite using the Griess Assay and a Paper-Based Device: Reported herein is the development of a novel paper-based sensor for the dual detection of nitrate and nitrite, using the N-(1-naphthyl)ethylenediamine-functionalized paper disclosed in Chapter 1. The detection of nitrate requires that nitrate be reduced to nitrite before reaction with indicator molecules. The majority of colorimetric and spectrophotometric detection schemes cannot differentiate reduced nitrate from any nitrite present in the sample. This compounded sensor readout requires the subtraction of nitrite signal in order to quantify nitrate in the sample which is difficult to accomplish with the naked eye. However, the immobilization of N-(1-naphthyl)ethylenediamine in the detection zones and the subsequent immobilization of the colored product has allowed for a subtraction-free nitrate readout. With the introduction of a cadmium/platinum chloride reduction zone into the sensor, this subtraction-free method has achieved nitrite and nitrate detection limits of 1.1 μM and 0.61 μM, respectively. Design, Implementation, and Evaluation of Paper-Based Devices for the Detection of Acetaminophen and Phenacetin in an Advanced Undergraduate Laboratory: Reported herein is a multi-disciplinary experiment for senior-level undergraduate teaching laboratories in the synthesis of the analytes acetaminophen and phenacetin, the fabrication of paper-based devices using low-complexity techniques, and the application of these devices for successful qualitative and quantitative detection of the analytes. This experiment includes elements of organic, analytical, and materials chemistry, as well as mechanical engineering, and provides a strong pedagogical experience for the undergraduate student participants. The experiment was tested over two years in an Advanced Organic Laboratory, and 90% of students over the two years successfully completed all experimental objectives. The modular nature of the reported experiments and inexpensive costs of materials and instrumentation significantly enhances the practical applicability of this experiment and the likelihood of widespread adaptation. Supramolecular Luminescent Sensors: There is great need for stand-alone luminescence-based chemosensors that exemplify selectivity, sensitivity, and applicability, and that overcome the challenges that arise from complex, real-world media. Discussed herein are recent developments toward that goal in the field of supramolecular luminescent macrocycle chemosensors. Specific focus is placed on the development of new macrocycle hosts since 2010, coupled with considerations of the underlying principles of supramolecular chemistry. A Polycationic Pillar[5]arene for the Binding and Removal of Organic Toxicants from Aqueous Media: The ability to bind and detect small molecule analytes with high levels of selectivity, sensitivity and broad applicability for a variety of analytes in multiple complex environments is an essential goal in analytical chemistry, with applications in public health, environmental remediation, and medical diagnostics. The use of supramolecular chemistry to accomplish such detection, by binding a target analyte in a supramolecular host and transducing that binding into a measurable signal, has notable advantages, including straightforward tunability of the supramolecular sensor as well as the ability to rationally design highly effective hosts through an understanding of non-covalent interactions in supramolecular complexes. Reported herein is the design and use of pillar[5]arenes to accomplish precisely such supramolecular detection. A water-soluble pillar[5]arene containing ten cationic peripheral arms bound small molecule toxicants in their hydrophobic cores with association constants on the orders of 105–106 M−1. When bound to a cationic exchange resin, the pillar[5]arene host allowed for effective toxicant removal and potential applications in water purification systems.

Subject Area

Chemistry|Organic chemistry|Analytical chemistry

Recommended Citation

Teresa Louise Mako, "Detection of Ions and Small Molecule Toxicants in Aqueous Media Using New Colorimetric and Fluorimetric Methods" (2019). Dissertations and Master's Theses (Campus Access). Paper AAI27666973.
https://digitalcommons.uri.edu/dissertations/AAI27666973

Share

COinS