Principles and Practice of Analytical Chemistry Principles and Practice of Analytical Chemistry Fo urth Edition F. w. FIFIELD and D. KEALEY Kingston University SPRINGER-SCIENCE+BUSINESS MEDIA, B.V. First edition 1975 Second edition 1983 Third edition 1990 This edition 1995 © 1995 Springer Science+Business Media Dordrecht Originally published by Chapman & HaU in 1995 Typeset in 10/12 pt Times by AFS Image Setters Ltd, Glasgow ISBN 978-1-4613-5912-8 ISBN 978-1-4615-2179-2 (eBook) DOI 10.1007/978-1-4615-2179-2 Apart from any fair dealing for the purposes of research or private study, or criticism or review, as permitted under the UK Copyright Designs and Patents Act, 1988, this publication may not be reproduced, stored, or transmitted, in any form or by any means, without the prior permission in writing of the publishers, or in the case of reprographic reproduction only in accordance with the terms of the licences issued by the Copyright Licensing Agency in the UK, or in accordance with the terms of licences issued by the appropriate Reproduction Rights Organization outside the UK. Enquiries concerning reproduction outside the terms stated here should be sent to the publishers at the Glasgow address printed on this page. The publisher makes no representation, express or implied, with regard to the accuracy of the information contained in this book and cannot accept any legal responsibility or liability for any errors or omissions that may be made. A catalogue record for this book is available from the British Library Library of Congress Catalog Card Number: 94-74246 00 Printed on acid-free text paper, manufactured in accordance with ANSIjNISO Z39.48-1992 (Permanence of Paper). Contents Preface ix Acknowledgements Xl CHAPTER 1 INTRODUCTION The scope of analytical chemistry. The function of analytical chemistry. Analytical problems and their solution. The nature of analytical methods. Trends in analytical methods and procedures. Glossary of terms. CHAPTER 2 THE ASSESSMENT OF ANALYTICAL DATA 14 2.1 Definitions and basic concepts 14 2.2 The nature and origin of errors 16 2.3 The evaluation of results and methods 18 The reliability of measurements. The analysis of data. The application of statistical tests. Limits of detection. Quality control charts. Standardization of analytical methods. Chemometrics. CHAPTER 3 pH, COMPLEXATION AND SOLUBILITY EQUILIBRIA 37 3.1 Chemical reactions in solution 38 Equilibrium constants. Kinetic factors in equilibria. 3.2 Solvents in analytical chemistry 42 Ionizing solvents. Non-ionizing solvents. 3.3 Acid-base equilibria 43 Weak acid and weak base equilibria. Buffers and pH control. The pH of salt solutions. 3.4 Complexation equilibria 50 The formation of complexes in solution. The chelate effect. 3.5 Solubility equilibria 53 Solubility products. CHAPTER 4 SEPARATION TECHNIQUES 55 4.1 Solvent extraction 56 Efficiency of extraction. Selectivity of extraction. Extraction systems. Extraction of uncharged metal chelates. Methods of extraction. Applications of solvent extraction. 4.2 Chromatography 75 4.2.1 Gas chromatography. 4.2.2 High performance liquid chroma tography. 4.2.3 Supercritical fluid chromatography. 4.2.4 Thin-layer chromatography. 4.2.5 Ion-exchange chromatography. 4.2.6 Gel permeation chromatography. v VI CONTENTS 4.3 Electrophoresis 164 Factors affecting ionic migration. Effect of temperature, pH and ionic strength. Electroosmosis. Supporting medium. Detection of separated components. Applications of tradional zone electrophoresis. High per formance capillary electrophoresis. CHAPTER 5 TITRIMETRY AND GRAVIMETRY 184 5.1 Titrimetry 184 Definitions. Titrimetric reactions. Acid-base titrations. Applications of acid-base titrations. Redox titrations. Applications of redox titrations. Complexometric titrations. EDTA . Applications of EDTA titrations. Titrations with complexing agents other than EDTA . Precipitation titrations. 5.2 Gravimetry 211 Precipitation reactions. Practical gravimetric procedures. Applications of gravimetry. CHAPTER 6 ELECTROCHEMICAL TECHNIQUES 223 6.1 Potentiometry 227 Electrode systems. Direct potentiometric measurements. Potentio metric titrations. Null-point potentiometry. Applications of potentio metry. 6.2 Polarography, stripping voltammetry and amperometric techniques 243 Diffusion currents. Half-wave potentials. Characteristics of the DME. Quantitative analysis. Modes of operation used in polarography. The dissolved oxygen electrode and biochemical enzyme sensors. Amperometric titrations. Applications of polarography and ampero metric titrations. 6.3 Electrogravimetry and coulometry 257 Coulometry. Coulometry at constant potential. Coulometric titrations. Applications of coulometric titrations. 6.4 Conductometric titrations 261 Ionic conductances. CHAPTER 7 AN INTRODUCTION TO ANALYTICAL SPECTROMETRY 267 Electromagnetic radiation. Atomic and molecular energy. The absorption and emission of electromagnetic radiation. The complexity of spectra and the intensity of spectral lines. Analytical spectrometry. Instrumentation. CHAPTER 8 ATOMIC SPECTROMETRY 282 8.1 Arc/spark atomic (optical) emission spectrometry 287 Instrumentation. Sample preparation. Qualitative and quantitative analysis. Interferences and errors associated with the excitation process. Applications of arc/spark emission spectrometry. 8.2 Glow discharge atomic emission spectrometry 294 Instrumentation. Applications. CONTENTS VB 8.3 Plasma emission spectrometry 296 Instrumentation. Sample introduction for plasma sources. Analytical measurements. Applications of plasma emission spectrometry. 8.4 Inductively coupled plasma-mass spectrometry (ICP-MS) 304 Principles. Instrumentation. Applications. 8.5 Flame emission spectrometry 308 Instrumentation. Flame characteristics. Flame processes. Emission spectra. Quantitative measurements and interferences. Applications of flame photometry and flame atomic emission spectrometry. 8.6 Atomic absorption spectrometry 317 Absorption of characteristic radiation. Instrumentation. Sample vaporization. Quantitative measurements and interferences. Atomic fluorescence spectrometry. 8.7 X-ray emission spectrometry 331 X-ray processes. Instrumentation. Applications of X-ray emission spectrometry. CHAPTER 9 MOLECULAR SPECTROMETRY 351 9.1 Visible and ultraviolet spectrometry 361 Poly atomic organic molecules. Metal complexes. Qualitative analysis - the identification of structural features. Quantitative analysis - absorptiometry. Choice of colorimetric and spectrophotometric procedures. Fluorimetry. Applications of UV/visible spectrometry and fluorimetry. 9.2 Infrared spectrometry 377 Diatomic molecules. Poly atomic molecules. Characteristic vibration frequencies. Factors affecting group frequencies. Qualitative analysis - the identification of structural features. Quantitative analysis. Sampling procedures. Applications of infrared spectrometry. 9.3 N ucIear magnetic resonance spectrometry (nmr) 393 Instrumentation. The nmr process. Chemical shift. Spin-spin coupling. Carbon-13 nmr. Pulsed Fourier transform nmr (ft-nmr). Quantitative analysis - the identification of structural features. Quantitative analysis. Applications of nmr spectrometry. 9.4 Mass spectrometry 425 Instrumentation. Principle of mass spectrometry. Characteristics and interpretation of molecular mass spectra. Applications of mass spectro metry. 9.5 Spectrometric identification of organic compounds 436 CHAPTER 10 RADIOCHEMICAL METHODS IN ANALYSIS 447 10.1 Nuclear structure and nuclear reactions 448 Decay reactions. The kinetics of decay reactions. Bombardment reactions and the growth of radioactivity. 10.2 Instrumentation and measurement of radioactivity 455 Radiation detectors. Some important electronic circuits. The statistics of radioactive measurements. viii CONTENTS 10.3 Analytical uses of radionucleides 465 Chemical pathway studies. Radioisotope dilution methods. Radio immunoassay. Radioactivation analysis. Environmental monitoring. CHAPTER 11 THERMAL TECHNIQUES 475 11.1 Thermogravimetry 477 Instrumentation. Applications ofTG. 11.2 Differential thermal analysis (DTA ) 482 Instrumentation. Applications of DTA 11.3 Differential scanning calorimetry (DSC) 489 Instrumentation. Applications of DSC. DTA and DSC. 11.4 Thermomechanical analysis (TMA) and dynamic mechanical analysis (DMA) 493 Instrumentation. Applications of TMA. Dynamic mechanical analysis. 11.5 Pyrolysis - gas chromatography 497 Instrumentation. CHAPTER 12 OVERALL ANALYTICAL PROCEDURES AND THEIR AUTOMATION 504 12.1 Sampling and sample pretreatment 504 Representative samples and sample storage. Sample concentration and clean-up: solid phase extraction. 12.2 Examples of analytical problems and procedures 509 1: Evaluation of methods for the determination of fluoride in water samples. 2: Analysis ofa competitive product. 3: The assessment ofthe heavy metal pollution in a river estuary. 4: The analysis of hydrocarbon products in a catalytic reforming study. 12.3 The automation of analytical procedures. 519 The automation of repetitive analysis. Constant monitoring and on line analysis. Laboratory robotics. CHAPTER 13 THE ROLE OF COMPUTERS AND MICRO PROCESSORS IN ANALYTICAL CHEMISTRY 528 13.1 Introduction 528 Instrument optimization. Data recording and storage. Data processing and data analysis (chemometrics). Laboratory management. Expert systems. 13.2 Computers and microprocessors 534 Mini-and microcomputers. Microprocessors. 13.3 Instrument- computer interfaces 537 13.4 The scope of microprocessor control and computers in analytical laboratories 542 1. A microprocessor-controlled potentiometric titrator. 2. An infrared spectrometer interfaced to a dedicated microcomputer. 3. A computing integrator for chromatographic analysis. 4. A microprocessor-based X-ray or ')I-ray spectrometer. Index 551 Preface to the fourth edition There have been significant advances in both analytical instrumentation and computerised data handling during the five years since the third edition was published in 1990. Windows-based computer software is now widely available for instrument control and real-time data processing and the use of laboratory information and management systems (LIMS) has become commonplace. Whilst most analytical techniques have undergone steady improvements in instrument design, high-performance capillary electrophoresis (HPCE or CE) and two dimensional nuclear magnetic resonance spectrometry (2D-NMR) have developed into major forces in separation science and structural analysis respectively. The powerful and versatile separation technique of CE promises to rival high-performance liquid chromatography, particularly in the separ ation of low levels of substances of biological interest. The spectral inform ation provided by various modes of 2D-NMR is enabling far more complex molecules to be studied than hitherto. The electrophoresis section of chapter 3 and the NMR section of chapter 9 have therefore been considerably expanded in the fourth edition along with a revision of aspects of atomic spectrometry (chapter 8). New material has been included on fluorescence spectrometry (chapter 9), the use of Kovats Retention Indices in gas chroma tography (chapter 3) and solid phase extraction for sample cleanup and concentration (chapter 12). Additions to high performance liquid chroma tography (chapter 3) reflect the growing importance of chiral stationary phases, solvent optimization and pH control, continuous regeneration car tridges for ion chromatography and HPLC-MS. Throughout the book there have been numerous other changes and additions to enhance clarity and presentation including a number of new or improved diagrams and some additional worked examples on the statistical assessment of analytical data (chapter 2). x PREFACE TO FOURTH EDITION The earlier editions have been widely used by both undergraduate and postgraduate students of analytical chemistry, and the fourth edition should continue to provide a sound basis for this readership. Industrial trainees and those in related disciplines who require a knowledge of analytical chemistry will find this a suitable text for reading and reference purposes. We continue to benefit from discussions with many of our colleagues at Kingston University, and particularly with Mr. P. 1. Haines whose knowledge of thermal techniques has proved invaluable. The Publisher's reviewers and users of the book continue to be a source of helpful and much appreciated comments. OK FWF