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NON-TRADITIONAL CALIBRATION STRATEGIES FOR APPLICATIONS IN ATOMIC SPECTROMETRY

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abstract
Calibration is one of the most important steps of any analytical chemistry procedure. The selection of an appropriate calibration strategy, therefore, is of utmost importance when beginning any analysis. In the field of analytical chemistry, there are three most commonly used calibration methods: external standard calibration (EC), internal standard calibration (IS), and standard additions (SA). Careful consideration should be made when selecting a calibration method, as each of these three have their benefits and drawbacks. EC works best in applications in which the matrix of the sample is nearly identical to the matrix of the standard solutions. This typically means the sample needs to be in a very clean matrix. However, this is commonly not the case. IS works to correct for variations in sample volume, transport, and other problems associated with physical characteristics of the sample. SA is commonly used when the matrix of the sample is very complex, which EC and IS cannot correct for. While SA is one of the most sought after for correcting for major problems associated with matrix effects, it is very time consuming and labor intensive. Several alternative calibration methods have been proposed for overcoming the limitations of EC, IS, and SA. These calibration methods typically aim to either: (a) improve accuracy and precision, (b) increase sample throughput, (c) simplify sample preparation, or (d) minimize reagent consumption and waste. One of the more recently proposed methods is standard dilution analysis (SDA). SDA works by combining the main principles of IS and SA calibration into one novel calibration strategy. Two solutions, containing sample and standard, and sample and blank, are mixed with each other, and data is collected throughout the mixing process. Though the technique works very well, in its original form, there were some drawbacks, including relatively low sample throughput, difficult data processing, and the inability to automate the technique. In each of the works illustrated here, we find alternative ways to use SA to improve accuracy, and improve SDA to achieve higher sample throughput while keeping the high accuracy of the method. The performance of the extrapolation, interpolation, reversed-axis and normalization approaches in SA were evaluated and compared. The problems related with data processing and automation of SDA were addressed by adding a second IS species to the sample preparation procedure, and fashioning a mixing chamber for automated mixing. Sample throughput issues were addressed by developing a matrix-matched, two-point calibration technique based on the theory of SDA calibration. The applicability of the newly developed technique was explored over a wide range of concentrations, and the ultimate linearity of the calibration was further explored.
subject
contributor
Sloop, John T (author)
Jones, Bradley T (committee chair)
Calloway, Clifton P (committee member)
Colyer, Christa L (committee member)
Geyer, Scott M (committee member)
King, Stephen B (committee member)
date
2021-06-03T08:35:45Z (accessioned)
2021-06-03T08:35:45Z (available)
2021 (issued)
degree
Chemistry (discipline)
identifier
http://hdl.handle.net/10339/98775 (uri)
language
en (iso)
publisher
Wake Forest University
title
NON-TRADITIONAL CALIBRATION STRATEGIES FOR APPLICATIONS IN ATOMIC SPECTROMETRY
type
Dissertation

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