Table Of ContentDK6024_half-series-title.qxd 2/13/06 3:04 PM Page i
Instrumental Methods
in Metal Ion Speciation
Imran Ali
National Institute of Hydrology
Roorkee, India
Hassan Y. Aboul-Enein
King Faisal Specialist Hospital and Research Centre
Riyadh, Saudi Arabia
Boca Raton London New York
A CRC title, part of the Taylor & Francis imprint, a member of the
Taylor & Francis Group, the academic division of T&F Informa plc.
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Published in 2006 by
CRC Press
Taylor & Francis Group
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Boca Raton, FL 33487-2742
© 2006 by Taylor & Francis Group, LLC
CRC Press is an imprint of Taylor & Francis Group
No claim to original U.S. Government works
Printed in the United States of America on acid-free paper
10 987 6 5 4 3 2 1
International Standard Book Number-10: 0-8493-3736-4 (Hardcover)
International Standard Book Number-13: 978-0-8493-3736-9 (Hardcover)
Library of Congress Card Number 2005054894
This book contains information obtained from authentic and highly regarded sources. Reprinted material is
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Library of Congress Cataloging-in-Publication Data
Ali, Imran.
Instrumental methods in metal ion speciation : chromatography, capillary electrophoresis,
spectroscopy, electrochemistry / by Imran Ali and Hassan Y. Aboul-Enein.
p. cm.
Includes bibliographical references and index.
ISBN 0-8493-3736-4 (alk. paper)
1. Metal ions--Toxicology. 2. Metal ions--Identification. 3. Metal ions--Classification. I.
Aboul-Enein, Hassan Y. II. Title.
RA1231.M52A45 2005
615.9’253--dc222005054894
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Dedications
Dedicated to the memory of my late parents:
Basheer Ahmed and Mehmudan Begum
Imran Ali
To my loving family — Nagla, Youssef, Faisal, and Basil
— for your support and enlightenment
Hassan Y. Aboul-Enein
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Preface
Transition metal ions, lanthanides, and actinides are widely distributed in envi-
ronmental and biological materials. These metal ions exist in various oxidation
states, having different physical and chemical properties leading to different
toxicities. Many reports are available in the literature on the analysis of total
concentrations of metal ions, but the data presented may not be reliable and may
be incorrect due to the different toxicities of various oxidation states a particular
metal ion can have, which confuses the toxicity concept. Therefore, to predict
the exact toxicities of metal ion species, the determination of the concentrations
of all species is required and essential. Knowledge of metal ion speciation is
essential for environmental and industrial chemists, scientists from various dis-
ciplines, and regulatory authorities. Therefore, the separation and identification
of metal ion species (speciation) is important and demanding in this developing
world.
This book deals with the distribution, toxicities, and state-of-the-art tech-
niques in metal ion speciation by gas chromatography, liquid chromatography
(high-performance liquid chromatography [HPLC], ion chromatography [IC],
ion-pair chromatography [IPC], micellar electrokinetic chromatography [MEKC],
size exclusion chromatography [SEC], chiral chromatography [CC], capillary
electrochromatography [CEC], and supercritical fluid chromatography [SFC]),
capillary electrophoresis (CE), and electrochemical and radiochemical methods.
This book describes metal ion speciation in detail with a main emphasis on
experimental methodologies. Moreover, we attempt to explain the optimization
techniques for metal ion speciation that will be helpful in designing future exper-
iments in this area. The importance and uniqueness of this book lies in the fact
that, unlike other books on this subject, it focuses only on metal ion speciation
(analysis of different species of a particular metal ion). We hope that it will be
a useful reference for scientists, researchers, academicians, and graduate students
working in the field of metal ion speciation. This book will also fulfill the
requirements of regulatory authorities for formulating the regulations and legis-
lations to control the distribution of different metal ion species into our environ-
ment and other living entities.
Imran Ali
Roorkee, India
[email protected]
Hassan Y. Aboul-Enein
Riyadh, Saudi Arabia
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About the Book
This book describes distribution, toxicities, and techniques of metal ion specia-
tion. The techniques discussed are gas and liquid chromatography, capillary
electrophoresis, electrochemical and radiochemical methods. The different liquid
chromatographic approaches discussed are high-performance liquid chromatog-
raphy (HPLC), ion chromatography (IC), ion-pair chromatography (IPC), micel-
lar electrokinetic chromatography (MEKC), size exclusion chromatography
(SEC), chiral chromatography (CC), capillary electrochromatography (CEC), and
supercritical fluid chromatography (SFC). This book is divided into 12 chapters:
the first chapter is an introduction to the principles of metal ion speciation
followed by Chapter 2 through Chapter 11 that discuss the distribution, toxicity,
sample preparation, and metal ion speciation into the environmental and biolog-
ical samples using the above-mentioned techniques. Chapter 12 describes the
perspectives of metal ion speciation and legislation. The optimization of the
experimental parameters of the analytical techniques is discussed; hence, this
book may be considered as an applied text in the area of metal ion speciation.
This book is unique in the area of metal ion speciation, as it deals exclusively
with metal ion speciation. By fulfilling the needs of the scientific community for
an information resource focusing on metal ion speciation, it will become a
necessary reference source for scientists, academicians, researchers, and others
in such diverse positions as regulators, material industries specialists, clinicians
and nutritional experts, agriculturalists, and environmentalists.
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Acknowledgments
I express my deepest respect and gratitude and love to my wife Seema Imran
who has helped and supported me in my efforts to carry out this work. My loving
and sweet thanks also go to my dearest son Al-Arsh Basheer Baichain who has
given me continual freshness and inspiration during the completion of this difficult
job. I would also like to acknowledge my other family members and relatives
who have helped me directly and indirectly during this period.
I also sincerely thank Professor Vinod K. Gupta, Chemistry Department,
Indian Institute of Technology, Roorkee, India, who helped me to complete this
book. Moreover, his moral support, which I received continuously, was monu-
mental and will be forever treasured. Finally, the administration of National
Institute of Hydrology, Roorkee, India, is also acknowledged for permitting me
to write this book.
Imran Ali
I would like to express my thanks to the administration of King Faisal Specialist
Hospital and Research Centre for their support of this work. Special thanks are
extended to the editorial staff of Taylor & Francis publishers for their assistance
in publishing this book. I am particularly grateful to my wife, Nagla El-
Mojadaddy, for her forbearance and support throughout the preparation of this
book. It is to her that I extend my deepest gratitude.
Hassan Y. Aboul-Enein
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The Authors
Hassan Y. Aboul-Enein is a Principal Scientist and the Head of the Pharmaceutical
Analysis and Drug Development Laboratory, Centre for Clinical Research, at King
Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia. He is the
author or coauthor of over 600 refereed journal articles, 30 book chapters, and 270
conference presentations. He is the author or coauthor of seven books, including
Chiral Separation by Liquid Chromatography and Related Technologies (Marcel
Dekker, Inc., New York), The Impact of Stereochemistry on Drug Development and
Use (John Wiley & Sons, New York), Chiral Pollutants: Distribution, Toxicity and
Analysis by Chromatography and Capillary Electrophoresis (John Wiley & Sons,
Chichester, UK), among others. He is a member of the editorial boards of several
journals, including Analytica Chimica Acta, Chirality, Biomedical Chromatography,
Analytical Letters, Journal of Liquid Chromatography and Related Technologies,
Biopolymers, Biosensors and Bioelectronics, to mention a few. Professor Aboul-
Enein is a member of the World Health Organization’s (WHO) advisory panel on
international pharmacopeia and pharmaceutical preparations and a Fellow of the
Royal Society of Chemistry (United Kingdom). He earned his B.Sc. degree (1964)
in pharmacy and pharmaceutical chemistry from Cairo University, Cairo, Egypt,
and his M.Sc. (1969) and Ph.D. (1971) degrees in pharmaceutical and medicinal
chemistry from the University of Mississippi, U.S. Professor Aboul-Enein’s current
research interests are in the field of pharmaceutical and biomedical analysis and
drug development with special emphasis on chiral chromatography, ion-selective
electrodes, and other separation techniques.
Dr. Imran Ali is presently a scientist at the National Institute of Hydrology,
Roorkee, India. He earned his M.Sc. (1986) and Ph.D. (1990) degrees from the
University of Roorkee, India (now the Indian Institute of Technology, Roorkee,
India). His research areas of interest are chiral analysis of biological and envi-
ronmental active chiral compounds and metal ion speciation using chromato-
graphic and capillary electrophoresis techniques. He also has expertise in water
quality and wastewater treatment methodologies. Dr. Ali is author and coauthor
of more than 100 journal articles and book and encyclopedia chapters. He is the
coauthor of two books: Chiral Separations by Liquid Chromatography and
Related Technologies (Marcel Dekker, Inc., New York) and Chiral Pollutants:
Distribution, Toxicity and Analysis by Chromatography and Capillary Electro-
phoresis (John Wiley & Sons, Chichester, UK). Dr. Ali was awarded a Khosla
Research Award in 1987 by the Indian Institute of Technology, Roorkee, India,
for his work on the chiral resolution of amino acids. He is a life member of the
Indian Science Congress Association, India.
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Contents
Chapter 1 Introduction......................................................................................1
1.1 Importance of the Environment ..................................................................1
1.2 Environmental Pollutants ............................................................................2
1.3 Metal Ions Speciation..................................................................................2
1.4 Metal Ion Speciation and the Environment ................................................4
1.5 Methods Of Metal Ion Speciation...............................................................5
1.5.1 Chromatographic Methods..............................................................7
1.5.2 Capillary Electrophoretic Method...................................................9
1.5.3 Spectroscopic and Other Methods ................................................11
1.6 Detection in Chromatography and Capillary Electrophoresis..................11
References ...........................................................................................................13
Chapter 2 Metal Ion Species: Sources and Distribution ...............................17
2.1 Sources of Contamination.........................................................................18
2.2 Distribution of Metal Ions.........................................................................20
2.2.1 Distribution in Water .....................................................................20
2.2.2 Distribution in Sediment ...............................................................22
2.2.3 Distribution in Soil........................................................................23
2.2.4 Distribution in Air .........................................................................24
2.2.5 Distribution in Aquatic Biota........................................................24
2.2.6 Distribution in Terrestrial Biota ....................................................26
2.3 Mechanisms of Metal Ions Contamination...............................................33
2.4 Conclusion.................................................................................................34
References ...........................................................................................................34
Chapter 3 Metal Ion Species: Toxicities, Biotransformation, and
Biodegradation...............................................................................41
3.1 Modes of Bioactivity and Toxicities of Metal Ions..................................43
3.2 Toxicities of Metal Ions ............................................................................47
3.2.1 Aluminum (Al)..............................................................................48
3.2.2 Arsenic (As)...................................................................................50
3.2.3 Cadmium (Cd)...............................................................................52
3.2.4 Cobalt (Co)....................................................................................52
3.2.5 Chromium (Cr)..............................................................................53
3.2.6 Copper (Cu)...................................................................................55
3.2.7 Lead (Pb) .......................................................................................55
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3.2.8 Mercury (Hg).................................................................................56
3.2.9 Selenium (Se) ................................................................................58
3.2.10 Tin (Sn)..........................................................................................60
3.2.11 Miscellaneous Metal Ions .............................................................60
3.3 Biotransformation of Metal Ions...............................................................63
3.4 Biodegradation of Metal Ions ...................................................................65
3.5 Essentiality versus Toxicity of Metal Ions................................................68
3.6 Conclusion.................................................................................................69
References ...........................................................................................................70
Chapter 4 Sample Preparation........................................................................73
4.1 Sampling....................................................................................................74
4.1.1 Environmental Samples.................................................................74
4.1.1.1 Air....................................................................................75
4.1.1.2 Water ...............................................................................76
4.1.1.3 Sediments and Soils........................................................77
4.1.2 Biological Samples........................................................................77
4.1.2.1 Blood ...............................................................................78
4.1.2.2 Urine................................................................................78
4.1.2.3 Tissues.............................................................................78
4.1.2.4 Plants ...............................................................................78
4.1.2.5 Foodstuffs........................................................................79
4.2 Preservation ...............................................................................................79
4.3 Filtration ....................................................................................................80
4.4 Digestion/Homogenization........................................................................83
4.5 Extraction...................................................................................................85
4.5.1 Extraction of Solid Samples..........................................................85
4.5.1.1 Homogenization Extraction ............................................85
4.5.1.2 Sonication Extraction......................................................86
4.5.1.3 Microwave-Assisted Extraction ......................................87
4.5.1.4 Soxhlet Extraction...........................................................88
4.5.1.5 Accelerated Solvent Extraction ......................................89
4.5.1.6 Supercritical Fluid Extraction.........................................91
4.5.2 Extraction of Liquid Samples .......................................................91
4.5.2.1 Liquid–Liquid Extraction................................................92
4.5.2.2 Solid-Phase Extraction....................................................98
4.5.2.3 Liquid Chromatographic Extraction.............................103
4.6 Membrane Methods in Sample Preparation ...........................................105
4.7 Enzymatic Hydrolysis .............................................................................107
4.8 Other Extraction Methods.......................................................................108
4.9 Cleanup....................................................................................................109
4.10 Preconcentration ......................................................................................110
4.11 Conclusion...............................................................................................112
References .........................................................................................................113
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Chapter 5 Speciation of Metal Ions by Gas Chromatography ....................121
5.1 Applications.............................................................................................122
5.1.1 Arsenic (As).................................................................................123
5.1.2 Lead (Pb) .....................................................................................124
5.1.3 Mercury (Hg)...............................................................................125
5.1.4 Tin (Sn)........................................................................................126
5.1.5 Miscellaneous Metal Ions ...........................................................127
5.1.6 Isotope Ratio................................................................................128
5.2 Optimization of Metal Ion Speciation ....................................................132
5.2.1 Stationary Phases.........................................................................132
5.2.2 Mobile Phases..............................................................................134
5.2.3 Temperature .................................................................................137
5.2.4 Nature of Metal Ion Species .......................................................141
5.2.5 Detection......................................................................................141
5.2.6 Other Parameters .........................................................................149
5.3 Derivatization of Metal Ions ...................................................................152
5.4 Mechanisms of Metal Ions Speciation....................................................157
5.5 Errors and Problems in Metal Ions Speciation.......................................157
5.6 Conclusion...............................................................................................158
References .........................................................................................................159
Chapter 6 Speciation of Metal Ions by Reversed-Phase High-Performance
Liquid Chromatography ..............................................................163
6.1 Applications.............................................................................................164
6.1.1 Arsenic (As).................................................................................164
6.1.2 Chromium (Cr)............................................................................165
6.1.3 Lead (Pb) .....................................................................................166
6.1.4 Mercury (Hg)...............................................................................166
6.1.5 Selenium (Se) ..............................................................................167
6.1.6 Tin (Sn)........................................................................................168
6.1.7 Miscellaneous Metal Ions ...........................................................169
6.2 Optimization of Metal Ion Speciation ....................................................169
6.2.1 Stationary Phases.........................................................................169
6.2.2 Mobile Phases..............................................................................174
6.2.3 pH of the Mobile Phase ..............................................................176
6.2.4 Detection......................................................................................177
6.2.5 Other Parameters .........................................................................184
6.3 Derivatization of Metal Ions ...................................................................185
6.4 Mechanisms of Metal Ions Speciation....................................................188
6.5 Conclusion...............................................................................................189
References .........................................................................................................189
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