analytical chemistry

154 Pages·2012·8.1 MB·English

ANALYTICAL CHEMISTRY
Edited by Ira S. Krull
ANALYTICAL CHEMISTRY

Edited by Ira S. Krull
Analytical Chemistry
http://dx.doi.org/10.5772/3086
Edited by Ira S. Krull

Contributors
Christophe B.Y. Cordella, S. A. Akinyemi, W. M. Gitari, A. Akinlua, L. F. Petrik, Njegomir Radić,
Lea Kukoc-Modun, Miguel Valcárcel, Izydor Apostol, Ira Krull, Drew Kelner, Ion Neda, Paulina
Vlazan, Raluca Oana Pop, Paula Sfarloaga, Ioan Grozescu, Adina-Elena Segneanu

Published by InTech
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Copyright © 2012 InTech
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Typesetting InTech Prepress, Novi Sad
Cover InTech Design Team

First published October, 2012
Printed in Croatia

A free online edition of this book is available at www.intechopen.com
Additional hard copies can be obtained from [email protected]

Analytical Chemistry, Edited by Ira S. Krull
p. cm.
ISBN 978-953-51-0837-5

Contents

Preface VII
Chapter 1 PCA: The Basic Building Block of Chemometrics 1
Christophe B.Y. Cordella
Chapter 2 Mineralogy and Geochemistry of Sub-Bituminous Coal
and Its Combustion Products from Mpumalanga Province,
South Africa 47
S. A. Akinyemi, W. M. Gitari, A. Akinlua and L. F. Petrik
Chapter 3 Kinetic Methods of Analysis with Potentiometric
and Spectrophotometric Detectors –
Our Laboratory Experiences 71
Njegomir Radić and Lea Kukoc-Modun
Chapter 4 Analytical Chemistry Today and Tomorrow 93
Miguel Valcárcel
Chapter 5 Analytical Method Validation for Biopharmaceuticals 115
Izydor Apostol, Ira Krull and Drew Kelner
Chapter 6 Peptide and Amino Acids Separation
and Identification from Natural Products 135
Ion Neda, Paulina Vlazan, Raluca Oana Pop,
Paula Sfarloaga, Ioan Grozescu and Adina-Elena Segneanu

Preface

The book, Analytical Chemistry, deals with some of the more important areas of the
title's subject matter, which we hope will enable our readers to better appreciate just
some of the numerous topics of importance in Analytical Chemistry today. The topics
being covered herein deal with the following topics: 1) Principal Component Analysis:
The Basic Building Block of Chemometrics; 2) Mineralogy and Geochemistry of Sub-
bituminous Coal; 3) Kinetic Methods of Analysis with Potentiometric and
Spectrophotometric Detectors; 4) Analytical Chemistry - Today and Tomorrow,
Biochemical and Chemical Information, Basic Standards, Analytical Properties and
Challenges; 5) Analytical Method Validation in Biotechnology Today, Method
Validation, ICH/FDA Requirements, and Related Topics; and 6) Peptide and Amino
Acid Separations and Identification - Chromatography, Spectrometry and Other
Detection Methods. These topics are up-to-date, thoroughly referenced and literature
cited to the present time, and truly review the major and most important topics and
areas in each of these subjects. They should find widespread acceptance and studious
involvement on the part of many readers interested in such generally important areas
of Analytical Chemistry today. Analytical Chemistry has come to assume a
tremendously important part of many, if not most, research areas in chemistry,
biochemistry, biomedicine, medical science, proteomics, peptidomics, metabolomics,
protein/peptide analysis, forensic science, and innumerable other areas of current,
scientific research and development in modern times. As such, it behooves all those
involved in these and other research and development areas to keep themselves up-to-
date and current in the very latest developments in these and other areas of Analytical
Chemistry.

Ira S. Krull
Chemistry and Chemical Biology,
Northeastern University,
Boston,
USA

Chapter 1
PCA: The Basic Building Block of Chemometrics
Christophe B.Y. Cordella
Additional information is available at the end of the chapter
http://dx.doi.org/10.5772/51429
1. Introduction
Modern analytical instruments generate large amounts of data. An infrared (IR) spectrum may
include several thousands of data points (wave number). In a GC-MS (Gas Chromatography-
Mass spectrometry) analysis, it is common to obtain in a single analysis 600,000 digital values
whose size amounts to about 2.5 megabytes or more. There are different methods for dealing
with this huge quantity of information. The simplest one is to ignore the bulk of the available
data. For example, in the case of a spectroscopic analysis, the spectrum can be reduced to
maxima of intensity of some characteristic bands. In the case analysed by GC-MS, the
recording is, accordingly, for a special unit of mass and not the full range of units of mass.
Until recently, it was indeed impossible to fully explore a large set of data, and many
potentially useful pieces of information remained unrevealed. Nowadays, the systematic use
of computers makes it possible to completely process huge data collections, with a minimum
loss of information. By the intensive use of chemometric tools, it becomes possible to gain a
deeper insight and a more complete interpretation of this data. The main objectives of
multivariate methods in analytical chemistry include data reduction, grouping and the
classification of observations and the modelling of relationships that may exist between
variables. The predictive aspect is also an important component of some methods of
multivariate analysis. It is actually important to predict whether a new observation belongs to
any pre-defined qualitative groups or else to estimate some quantitative feature such as
chemical concentration. This chapter presents an essential multivariate method, namely
principal component analysis (PCA). In order to better understand the fundamentals, we first
return to the historical origins of this technique. Then, we will show - via pedagogical
examples - the importance of PCA in comparison to traditional univariate data processing
methods. With PCA, we move from the one-dimensional vision of a problem to its
multidimensional version. Multiway extensions of PCA, PARAFAC and Tucker3 models are
exposed in a second part of this chapter with brief historical and bibliographical elements. A
PARAFAC example on real data is presented in order to illustrate the interest in this powerful
technique for handling high dimensional data.
2 Analytical Chemistry
2. General considerations and historical introduction
The origin of PCA is confounded with that of linear regression. In 1870, Sir Lord Francis
Galton worked on the measurement of the physical features of human populations. He
assumed that many physical traits are transmitted by heredity. From theoretical assumptions,
he supposed that the height of children with exceptionally tall parents will, eventually, tend to
have a height close to the mean of the entire population. This assumption greatly disturbed
Lord Galton, who interpreted it as a "move to mediocrity," in other words as a kind of
regression of the human race. This led him in 1889 to formulate his law of universal regression
which gave birth to the statistical tool of linear regression. Nowadays, the word "regression" is
still in use in statistical science (but obviously without any connotation of the regression of the
human race). Around 30 years later, Karl Pearson,1 who was one of Galton’s disciples,
exploited the statistical work of his mentor and built up the mathematical framework of linear
regression. In doing so, he laid down the basis of the correlation calculation, which plays an
important role in PCA. Correlation and linear regression were exploited later on in the fields of
psychometrics, biometrics and, much later on, in chemometrics.
Thirty-two years later, Harold Hotelling2 made use of correlation in the same spirit as
Pearson and imagined a graphical presentation of the results that was easier to interpret
than tables of numbers. At this time, Hotelling was concerned with the economic games of
companies. He worked on the concept of economic competition and introduced a notion of
spatial competition in duopoly. This refers to an economic situation where many "players"
offer similar products or services in possibly overlapping trading areas. Their potential
customers are thus in a situation of choice between different available products. This can
lead to illegal agreements between companies. Harold Hotelling was already looking at
solving this problem. In 1933, he wrote in the Journal of Educational Psychology a fundamental
article entitled "Analysis of a Complex of Statistical Variables with Principal Components,"
which finally introduced the use of special variables called principal components. These new
variables allow for the easier viewing of the intrinsic characteristics of observations.
PCA (also known as Karhunen-Love or Hotelling transform) is a member of those
descriptive methods called multidimensional factorial methods. It has seen many
improvements, including those developed in France by the group headed by Jean-Paul
Benzécri3 in the 1960s. This group exploited in particular geometry and graphs. Since PCA is

1 Famous for his contributions to the foundation of modern statistics (2 test, linear regression, principal components
analysis), Karl Pearson (1857-1936), English mathematician, taught mathematics at London University from 1884 to
1933 and was the editor of The Annals of Eugenics (1925 to 1936). As a good disciple of Francis Galton (1822-1911),
Pearson continues the statistical work of his mentor which leads him to lay the foundation for calculating correlations
(on the basis of principal component analysis) and will mark the beginning of a new science of biometrics.
2 Harold Hotelling: American economist and statistician (1895-1973). Professor of Economics at Columbia University,
he is responsible for significant contributions in statistics in the first half of the 20th century, such as the calculation of
variation, the production functions based on profit maximization, the using the t distribution for the validation of
assumptions that lead to the calculation of the confidence interval.
3 French statistician. Alumnus of the Ecole Normale Superieure, professor at the Institute of Statistics, University of
Paris. Founder of the French school of data analysis in the years 1960-1990, Jean-Paul Benzécri developed statistical