Analytical Applns. of Ultrasound [Techs, Anal. Chem V. 26]

412 Pages·2007·6.41 MB·English

by  Lola Luque de Castro

TECHNIQUES AND INSTRUMENTATION IN ANALYTICAL CHEMISTRY — VOLUME 26
ANALYTICAL APPLICATIONS
OF ULTRASOUND
TECHNIQUES AND INSTRUMENTATION IN ANALYTICAL CHEMISTRY
Volume 1 Evaluation and Optimization of Laboratory Methods and Analytical Procedures.
A Survey of Statistical and Mathematical Techniques
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by D.M.Desiderio
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in Automated Chemical Control
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edited by D.Barceló
Volume 14 Analytical Applications of Circular Dichroism
edited by N.Purdie and H.Brittain
Volume 15 Trace Element Analysis in Biological Specimens
edited by R.F.M Herber and M.Stoeppler
Volume 16 Flow-through (Bio) Chemical Sensors
by M.Valcárcel and M.D.Luque de Castro
Volume 17 Quality Assurance for Environmental Analysis
edited by Ph.Quevauviller,E.A.Maier and B.Griepink
Volume 18 Instrumental Methods in Food Analysis
edited by J.R.J.Paré and N.M.R.Bélanger
Volume 19 Trace Determination of Pesticides and their Degradation Products in Water
by D.Barceló and M.-C.Hennion
Volume 20 Analytical Pyrolysis and Natural Organic Polymers
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Volume 22 Interlaboratory Studies and Certified Reference Materials for Environmental Analysis:
the BCR approach
by Ph.Quevauviller and E.A.Maier
Volume 23 Molecularly Imprinted Polymers
Man-Made Mimics of Antibodies and their Applications in Analytical Chemistry
edited by B.Sellergren
Volume 24 Acceleration and Automation of Solid Sample Treatment
M.D.Luque de Castro and J.L.Luque GarcíÌa
Volume 25 Analytical Pyrolysis of Synthetic Organic Polymers
S.C.Moldoveanu
Volume 26 Analytical Applications of Ultrasound
M.D.Luque de Castro and F.Priego Capote
TECHNIQUES AND INSTRUMENTATION IN ANALYTICAL CHEMISTRY — VOLUME 26
ANALYTICAL
APPLICATIONS OF
ULTRASOUND
M.D. Luque de Castro and F. Priego Capote
Department of Analytical Chemistry, Marie Curie Building
Campus of Rabanales, University of Córdoba, 14071
Córdoba, Spain
Amsterdam – Boston – Heidelberg – London – New York – Oxford
Paris – San Diego – San Francisco – Singapore – Sydney – Tokyo
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Library of Congress Cataloging-in-Publication Data
A catalog record for this book is available from the Library of Congress
British Library Cataloguing in Publication Data
Luque de Castro,M.D.
Analytical applications of ultrasound.– (Techniques and instrumentation in
analytical chemistry;v.26)
1.Ultrasonics 2.Chemistry,Analytic
I.Title II.Capote,F.Priego
543.1’9
ISBN-13: 978-0-444-52825-4 (this volume)
ISBN-10: 0-444-52825-3 (this volume)
ISSN 0167-9244 (series)
For information on all Elsevier publications
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v
FOREWORD
Ultrasound is an energy source that has potential for enhancing many steps in an analy-
sis,yet analytical chemists generally have limited knowledge of this.Over forty years ago,
I remember using an ultrasonic probe to disrupt cells in biological samples,not realizing
this type of energy has many other useful applications.In fact,I was pleasantly surprised
when the ultrasonic toothbrush (another type of probe) appeared on the market (invented
by a University of Washington dentist) and thought, why didn’t I think of that! This book
lays the foundation for practicing analytical chemists to think similarly of ways to exploit
ultrasound energy.
Professor Luque de Castro and Dr. Priego Capote have assembled a vast amount of
information about ultrasound,and this unique book is timely,given advances in ultrasound
equipment and demonstrations of how this energy has been used to enhance various
steps of analyses,which suggest that more can be done.
What can ultrasound be used for? It depends in part on the imagination of the analyst.
But just some examples are:
• cleaning of apparatus;
• assisting sample dissolution;
• facilitating filtration;
• degassing;
• assisting derivatization reactions;
• detection systems;and
• non-destructive testing.
Given the limited literature on analytical applications of ultrasound,the authors provide
information from other sources that suggest ways in which we can use it in the analytical
laboratory.They discuss the principles of ultrasound and the variables we must consider
in adapting ultrasound to different problems.
The book is divided into two parts.Part I deals with the use ofultrasound in sample prepa-
ration,including general aspects of sample preparation of solids,liquids and heterogeneous
samples (Chapter 2), and ultrasound to assist digestion (Chapter 3), leaching (Chapter 4),
handling of heterogeneous systems – slurry formation,aggregation,filtration,nebulization,
defoaming, degassing (Chapter 5), liquid–liquid extraction, homogenization, emulsification
(Chapter 6), and chemical reactions (Chapter 7). Chapter 8 discusses topics such as
ultrasound-assisted levitation and its applications, and ultrasound-assisted electroanalyti-
cal techniques. Part II deals with the use of ultrasound in detection. Chapter 9 describes
types of ultrasound-based detection techniques,based on sample–ultrasound interactions,
including transmission, pulse echo, interferometric, resonance, back-scatter Rayleigh
surface wave and diffraction measurements, among others. Chapter 10 presents exam-
ples on applications of ultrasound-based detection techniques.
This book provides a wealth of information for those interested in exploiting ultrasound
to enhance different steps in an analysis and is a recommended reading.
Gary D.Christian
Department of Chemistry
University of Washington
Seattle, WA 98195-1700 USA
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vii
PREFACE
Ultrasound is a ubiquitous form of energy known and used, albeit to a rather disparate
extent, in many areas of chemistry. Thus, in organic chemistry, ultrasound is used so
widely – particularly to facilitate synthetic reactions – that it has been the subject matter
of a number of books.By contrast,no dedicated book on the use of this type of energy
in analytical chemistry had previously been published. This is quite surprising as ultra-
sound can be of help virtually throughout the analytical process;however,it can be easily
understood if one considers that few analytical chemists are aware of its enormous
potential and even fewer have used it for analytical purposes.
In fact, as shown in this book, ultrasound can facilitate to a greater or lesser extent
almost every step of the analytical process or even preliminary operations such as clean-
ing labware or degassing solvents.Thus,in relation to solid samples,ultrasound can dra-
matically expedite dissolution,digestion,leaching and slurry formation;and facilitate the
formation of a solid phase by crystallization or agglomeration, or its separation by filtra-
tion,for example.As regards liquid samples,ultrasound can facilitate or accelerate emul-
sification;the extraction,formation or separation of a gas;and a variety of derivatization
(complex formation,hydrolysis,redox) reactions.In addition,ultrasound is the underlying
principle of some detection techniques widely used in medicine but very scarcely known
by analytical chemists.
The authors’primary aim in writing this book was to provide an overview of appropri-
ate length to help analytical chemists assess the potential uses of ultrasound in a variety
of chemical fields.Another aim was to discuss ultrasound-based detection techniques in
a systematic manner in order to clear the enormous confusion around some concepts.
The authors would like to apologize in advance for any significant omissions resulting from
the vast scope of the topic and the absence of analytical chemists with whom to discuss
some specially elusive aspects of ultrasound. As long as readers believe the book
provides them with an up-to-date, balanced description of the potential of ultrasound in
analytical chemistry,the authors’will feel rewarded for the effort.
Finally,the authors would like to express their gratitude to Antonio Losada,MSc,for his
linguistic revision of the manuscript.
The Authors
Córdoba, May 2006
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ix
CONTENTS
Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
V
Preface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
VII
1. Introduction: Fundamentals of Ultrasound and Basis of
its Analytical Uses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1. INTRODUCTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2. PHYSICALPRINCIPLESOFULTRASOUND. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.2.1. Factors influencing cavitation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.3. CHEMICALASPECTSOFULTRASOUND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
1.3.1. Some rules of sonochemistry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
1.4. TYPESOFANALYTICALLYUSEFULULTRASOUNDDEVICES: ADVANTAGESAND
DISADVANTAGES. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
1.4.1. The piezoelectric transducer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
1.4.2. Commercial ultrasound apparatus for analytical applications. . . . . . . . . . . . 14
1.4.3. Maintenance and troubleshooting of ultrasound devices . . . . . . . . . . . . . . . 27
1.5. ULTRASONICS, HEARINGANDHEALTH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
1.6. USINGULTRASOUNDTOASSISTVARIOUSSTEPSOFTHEANALYTICALPROCESS . . . . 31
References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
2. Generalities on Ultrasound-Assisted Sample Preparation . . . . . . . . 35
2.1. GENERALITIESONSAMPLEPREPARATION: THECONCEPTOF
“SAMPLEPREPARATION”. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
2.2. PREPARATIONOFSOLIDSAMPLES. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
2.2.1. Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
2.2.2. Misused terms. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
2.3. PREPARATIONOFLIQUIDSAMPLES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
2.3.1. Ultrasound-assisted liquid sample preparation involving
chemical reactions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
2.3.2. Ultrasound-assisted liquid sample preparation without chemical reaction . . 45
2.4. PREPARATIONOFHETEROGENEOUSSAMPLES. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
2.4.1. Ultrasound-assisted filtration and aggregation . . . . . . . . . . . . . . . . . . . . . . . 46
2.4.2. Ultrasound-assisted dissolution of the solid phase in heterogeneous
samples. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
2.4.3. Ultrasound-assisted formation of a solid phase: sonocrystallization and
sonoprecipitation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
2.4.4. Ultrasound-assisted gas–liquid systems. . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
2.5. DISCRETEVERSUSCONTINUOUSAPPROACHESTOULTRASOUND-ASSISTEDSAMPLE
PREPARATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
2.5.1. Commercial and custom equipments for ultrasound-assisted sample
preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
x Contents
2.6. ANALYTICALUSESOFULTRASOUNDPRIORTOSAMPLEPREPARATION . . . . . . . . . . . 56
2.6.1. Ultrasound-assisted cleaning. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
2.6.2. Ultrasound-assisted degassing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
2.6.3. Ultrasonic atomization. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
3. Ultrasound-Assisted Sample Digestion. . . . . . . . . . . . . . . . . . . . . . . 69
3.1. INTRODUCTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
3.2. INFLUENCEOFULTRASOUNDONSAMPLEDIGESTION. . . . . . . . . . . . . . . . . . . . . . . . 70
3.2.1. Effects involved in ultrasound-assisted sample digestion. . . . . . . . . . . . . . . 70
3.2.2. Variables affecting ultrasound-assisted sample digestion. . . . . . . . . . . . . . . 71
3.3. ULTRASOUND-ASSISTEDSOFTDIGESTION(USASD). . . . . . . . . . . . . . . . . . . . . . . . 75
3.3.1. Scope of ultrasound-assisted soft digestion . . . . . . . . . . . . . . . . . . . . . . . . . 75
3.3.2. Experimental checking of USASD mechanisms . . . . . . . . . . . . . . . . . . . . . . 77
3.3.3. Applications of USASD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
3.4. ULTRASOUND-ASSISTEDSTRONGDIGESTION(USASTD) . . . . . . . . . . . . . . . . . . . . 82
3.4.1. Scope of USASTD. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
3.4.2. Digestion media. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
3.4.3. Applications of USASTD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
3.4.4. Synergistic effects of ultrasound and other auxiliary energies
on strong digestion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
3.5. ULTRASOUND-ASSISTEDENZYMATICDIGESTION . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
3.5.1. Effect of ultrasound on enzymatic digestion . . . . . . . . . . . . . . . . . . . . . . . . . 91
3.5.2. Applications of ultrasound-assisted enzymatic digestion . . . . . . . . . . . . . . . 92
3.6. ULTRASOUND-ASSISTEDCELLDISRUPTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
4. Ultrasound-Assisted Leaching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
4.1. INTRODUCTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
4.2. USEOFULTRASONICBATHSVERSUSULTRASONICPROBESFORLEACHING. . . . . . . 101
4.3. DISCRETEVERSUSCONTINUOUSULTRASOUND-ASSISTEDLEACHING. . . . . . . . . . . . 101
4.3.1. Discrete and continuous ultrasound-assisted leaching. . . . . . . . . . . . . . . . 101
4.3.2. Comparison of DUSAL and CUSAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
4.3.3. Variables affecting DUSAL and CUSAL . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
4.3.4. Approaches for CUSAL. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
4.4. COUPLINGCUSALTOOTHERSTEPSOFTHEANALYTICALPROCESS. . . . . . . . . . . 113
4.4.1. Off-line coupling of leaching to subsequent steps of the
analytical process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
4.4.2. On-line coupling of leaching to subsequent steps of the
analytical process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
4.5. ULTRASOUND-ASSISTEDLEACHINGVERSUSOTHERLEACHINGALTERNATIVES . . . . . 120
4.5.1. Ultrasound-assisted leaching versusconventional Soxhlet leaching . . . . . 122
4.5.2. Ultrasound-assisted leaching versussupercritical fluid leaching. . . . . . . . . 123
4.5.3. Ultrasound-assisted leaching versusmicrowave-assisted leaching . . . . . . 124