Analytical Chemistry 7th Edition PDF

ANALYTICAL CHEMISTRY SEVENTH EDITION Gary D. Christian University of Washington Purnendu K. (Sandy) Dasgupta University of Texas at Arlington Kevin A. Schug University of Texas at Arlington...

ANALYTICAL CHEMISTRY SEVENTH EDITION Gary D. Christian University of Washington Purnendu K. (Sandy) Dasgupta University of Texas at Arlington Kevin A. Schug University of Texas at Arlington To Nikola from Gary—for your interests in science. You have a bright future,wherever your interests and talents take you Philip W. West from Sandy—wherever you are Phil, sipping your martini with 1 ppm vermouth, you know how it was: For he said, I will give you, A shelter from the storm.... Dad from Kevin—well its not hardcore P. Chem., but it is still quite useful. Thanks for your love, support, and guidance through the years VP & Publisher: Petra Recter Editorial Assistant: Ashley Gayle/Katherine Bull Senior Marketing Manager: Kristine Ruff Designer: Kenji Ngieng Associate Production Manager: Joyce Poh This book was set in 10.5 Times Roman by Laserwords Private Limited and printed and bound by Courier Kendallville. The cover was printed by Courier Kendallville. This book is printed on acid free paper. Founded in 1807, John Wiley & Sons, Inc. has been a valued source of knowledge and understanding for more than 200 years, helping people around the world meet their needs and fulfill their aspirations. Our company is built on a foundation of principles that include responsibility to the communities we serve and where we live and work. In 2008, we launched a Corporate Citizenship Initiative, a global effort to address the environmental, social, economic, and ethical challenges we face in our business. Among the issues we are addressing are carbon impact, paper specifications and procurement, ethical conduct within our business and among our vendors, and community and charitable support. For more information, please visit our website: www.wiley.com/go/citizenship. Copyright  2014, 2004 John Wiley & Sons, Inc. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, scanning or otherwise, except as permitted under Sections 107 or 108 of the 1976 United States Copyright Act, without either the prior written permission of the Publisher, or authorization through payment of the appropriate per-copy fee to the Copyright Clearance Center, Inc. 222 Rosewood Drive, Danvers, MA 01923, website www.copyright.com. Requests to the Publisher for permission should be addressed to the Permissions Department, John Wiley & Sons, Inc., 111 River Street, Hoboken, NJ 07030-5774, (201)748-6011, fax (201)748-6008, website http://www.wiley.com/go/permissions. Evaluation copies are provided to qualified academics and professionals for review purposes only, for use in their courses during the next academic year. These copies are licensed and may not be sold or transferred to a third party. Upon completion of the review period, please return the evaluation copy to Wiley. Return instructions and a free of charge return mailing label are available at www.wiley.com/go/returnlabel. If you have chosen to adopt this textbook for use in your course, please accept this book as your complimentary desk copy. Outside of the United States, please contact your local sales representative. Library of Congress Cataloging-in-Publication Data Christian, Gary D., author. Analytical chemistry. -- Seventh edition / Gary D. Christian, University of Washington, Purnendu K. (Sandy) Dasgupta, University of Texas at Arlington, Kevin A. Schug, University of Texas at Arlington. pages cm Includes index. ISBN 978-0-470-88757-8 (hardback : alk. paper) 1. Chemistry, Analytic--Quantitative--Textbooks. I. Dasgupta, Purnendu, author. II. Schug, Kevin, author. III. Title. QD101.2.C57 2014 543--dc23 2013019926 Printed in the United States of America 10 9 8 7 6 5 4 3 2 1  Contents Chapter 1 Chapter 3 Analytical Objectives, or: What Analytical Statistics and Data Handling in Analytical Chemists Do 1 Chemistry 62 1.1 What Is Analytical Science?, 2 3.1 Accuracy and Precision: There Is a 1.2 Qualitative and Quantitative Analysis: Difference, 62 What Does Each Tell Us?, 3 3.2 Determinate Errors—They Are Systematic, 63 1.3 Getting Started: The Analytical Process, 6 3.3 Indeterminate Errors—They Are Random, 64 1.4 Validation of a Method—You Have to 3.4 Significant Figures: How Many Numbers Prove It Works!, 15 Do You Need?, 65 1.5 Analyze Versus Determine—They Are 3.5 Rounding Off, 71 Different, 16 3.6 Ways of Expressing Accuracy, 71 1.6 Some Useful Websites, 16 3.7 Standard Deviation—The Most Important Statistic, 72 3.8 Propagation of Errors—Not Just Additive, 75 Chapter 2 3.9 Significant Figures and Propagation of Error, 81 Basic Tools and Operations of Analytical 3.10 Control Charts, 83 Chemistry 20 3.11 The Confidence Limit—How Sure Are You?, 84 3.12 Tests of Significance—Is There a 2.1 The Laboratory Notebook—Your Critical Difference?, 86 Record, 20 3.13 Rejection of a Result: The Q Test, 95 2.2 Laboratory Materials and Reagents, 23 3.14 Statistics for Small Data Sets, 98 2.3 The Analytical Balance—The 3.15 Linear Least Squares—How to Plot the Indispensible Tool, 23 Right Straight Line, 99 2.4 Volumetric Glassware—Also Indispensible, 30 3.16 Correlation Coefficient and Coefficient of 2.5 Preparation of Standard Base Solutions, 42 Determination, 104 2.6 Preparation of Standard Acid Solutions, 42 3.17 Detection Limits—There Is No Such 2.7 Other Apparatus—Handling and Treating Thing as Zero, 105 Samples, 43 3.18 Statistics of Sampling—How Many 2.8 Igniting Precipitates—Gravimetric Analysis, 48 Samples, How Large?, 107 2.9 Obtaining the Sample—Is It Solid, Liquid, 3.19 Powering a Study: Power Analysis, 110 or Gas?, 49 3.20 Use of Spreadsheets in Analytical 2.10 Operations of Drying and Preparing a Chemistry, 112 Solution of the Analyte, 51 3.21 Using Spreadsheets for Plotting Calibration 2.11 Laboratory Safety, 57 Curves, 117 iii iv CONTENTS 3.22 Slope, Intercept, and Coefficient of 6.5 Temperature Effects on Equilibrium Determination, 118 Constants, 192 3.23 LINEST for Additional Statistics, 119 6.6 Pressure Effects on Equilibria, 192 3.24 Statistics Software Packages, 120 6.7 Concentration Effects on Equilibria, 193 6.8 Catalysts, 193 6.9 Completeness of Reactions, 193 Chapter 4 6.10 Equilibrium Constants for Dissociating or Combining Species—Weak Electrolytes Good Laboratory Practice: Quality Assurance and and Precipitates, 194 Method Validation 132 6.11 Calculations Using Equilibrium Constants—Composition at Equilibrium?, 195 4.1 What Is Good Laboratory Practice?, 133 6.12 The Common Ion Effect—Shifting the 4.2 Validation of Analytical Methods, 134 Equilibrium, 203 4.3 Quality Assurance—Does the Method Still 6.13 Systematic Approach to Equilibrium Work?, 143 Calculations—How to Solve Any 4.4 Laboratory Accreditation, 144 Equilibrium Problem, 204 4.5 Electronic Records and Electronic 6.14 Some Hints for Applying the Systematic Signatures: 21 CFR, Part 11, 145 Approach for Equilibrium Calculations, 208 4.6 Some Official Organizations, 146 6.15 Heterogeneous Equilibria—Solids Don’t Count, 211 6.16 Activity and Activity Coefficients— Chapter 5 Concentration Is Not the Whole Story, 211 6.17 The Diverse Ion Effect: The Stoichiometric Calculations: The Workhorse of Thermodynamic Equilibrium Constant and the Analyst 149 Activity Coefficients, 217 5.1 Review of the Fundamentals, 149 5.2 How Do We Express Concentrations Chapter 7 of Solutions?, 152 5.3 Expressions of Analytical Results—So Acid–Base Equilibria 222 Many Ways, 159 7.1 The Early History of Acid—Base 5.4 Volumetric Analysis: How Do We Make Concepts, 222 Stoichiometric Calculations?, 166 7.2 Acid–Base Theories—Not All Are 5.5 Volumetric Calculations—Let’s Use Created Equal, 223 Molarity, 169 7.3 Acid–Base Equilibria in Water, 225 5.6 Titer—How to Make Rapid Routine 7.4 The pH Scale, 227 Calculations, 179 7.5 pH at Elevated Temperatures: Blood pH, 231 5.7 Weight Relationships—You Need These 7.6 Weak Acids and Bases—What Is the pH?, 232 for Gravimetric Calculations, 180 7.7 Salts of Weak Acids and Bases—They Aren’t Neutral, 234 7.8 Buffers—Keeping the pH Constant Chapter 6 (or Nearly So), 238 General Concepts of Chemical Equilibrium 188 7.9 Polyprotic Acids and Their Salts, 245 7.10 Ladder Diagrams, 247 6.1 Chemical Reactions: The Rate Concept, 188 7.11 Fractions of Dissociating Species at a 6.2 Types of Equilibria, 190 Given pH: α Values—How Much of Each 6.3 Gibbs Free Energy and the Equilibrium Species?, 248 Constant, 191 7.12 Salts of Polyprotic Acids—Acid, Base, or 6.4 Le Châtelier’s Principle, 192 Both?, 255 CONTENTS v 7.13 Physiological Buffers—They Keep You 9.5 Other Uses of Complexes, 336 Alive, 261 9.6 Cumulative Formation Constants β and 7.14 Buffers for Biological and Clinical Concentrations of Specific Species in Measurements, 263 Stepwise Formed Complexes, 336 7.15 Diverse Ion Effect on Acids and Bases: c Ka and c Kb —Salts Change the pH, 266 7.16 log C—pH Diagrams, 266 Chapter 10 7.17 Exact pH Calculators, 269 Gravimetric Analysis and Precipitation Equilibria 342 Chapter 8 10.1 How to Perform a Successful Gravimetric Acid–Base Titrations 281 Analysis, 343 10.2 Gravimetric Calculations—How Much 8.1 Strong Acid versus Strong Base—The Analyte Is There?, 349 Easy Titrations, 282 10.3 Examples of Gravimetric Analysis, 353 8.2 The Charge Balance Method—An Excel 10.4 Organic Precipitates, 353 Exercise for the Titration of a Strong Acid and a Strong Base, 285 10.5 Precipitation Equilibria: The Solubility Product, 355 8.3 Detection of the End Point: Indicators, 288 10.6 Diverse Ion Effect on Solubility: Ksp and 8.4 Standard Acid and Base Solutions, 290 Activity Coefficients, 361 8.5 Weak Acid versus Strong Base—A Bit Less Straightforward, 290 8.6 Weak Base versus Strong Acid, 295 8.7 Titration of Sodium Carbonate—A Chapter 11 Diprotic Base, 296 Precipitation Reactions and Titrations 366 8.8 Using a Spreadsheet to Perform the 11.1 Effect of Acidity on Solubility of Sodium Carbonate—HCl Titration, 298 Precipitates: Conditional Solubility 8.9 Titration of Polyprotic Acids, 300 Product, 366 8.10 Mixtures of Acids or Bases, 302 11.2 Mass Balance Approach for Multiple 8.11 Equivalence Points from Derivatives of a Equilibria, 368 Titration Curve, 304 11.3 Effect of Complexation on Solubility: 8.12 Titration of Amino Acids—They Are Conditional Solubility Product, 372 Acids and Bases, 309 11.4 Precipitation Titrations, 374 8.13 Kjeldahl Analysis: Protein Determination, 310 8.14 Titrations Without Measuring Volumes, 312 Chapter 12 Chapter 9 Electrochemical Cells and Electrode Complexometric Reactions and Titrations 322 Potentials 383 9.1 Complexes and Formation 12.1 What Are Redox Reactions?, 384 Constants—How Stable Are Complexes?, 322 12.2 Electrochemical Cells—What 9.2 Chelates: EDTA—The Ultimate Titrating Electroanalytical Chemists Use, 384 Agent for Metals, 325 12.3 Nernst Equation—Effects of 9.3 Metal–EDTA Titration Curves, 331 Concentrations on Potentials, 390 9.4 Detection of the End Point: 12.4 Formal Potential—Use It for Defined Indicators—They Are Also Chelating Nonstandard Solution Conditions, 394 Agents, 334 12.5 Limitations of Electrode Potentials, 395 vi CONTENTS Chapter 13 14.6 Titrations with Other Oxidizing Agents, 452 14.7 Titrations with Other Reducing Agents, 454 Potentiometric Electrodes and Potentiometry 399 14.8 Preparing the Solution—Getting the Analyte in the Right Oxidation State before 13.1 Metal Electrodes for Measuring Titration, 454 the Metal Cation, 400 14.9 Potentiometric Titrations (Indirect 13.2 Metal–Metal Salt Electrodes for Potentiometry), 456 Measuring the Salt Anion, 401 13.3 Redox Electrodes—Inert Metals, 402 13.4 Voltaic Cells without Liquid Junction—For Maximum Accuracy, 404 Chapter 15 13.5 Voltaic Cells with Liquid Junction—The Voltammetry and Electrochemical Sensors 466 Practical Kind, 405 15.1 Voltammetry, 467 13.6 Reference Electrodes: The Saturated Calomel Electrode, 407 15.2 Amperometric Electrodes—Measurement of Oxygen, 472 13.7 Measurement of Potential, 409 15.3 Electrochemical Sensors: Chemically 13.8 Determination of Concentrations from Modified Electrodes, 472 Potential Measurements, 411 15.4 Ultramicroelectrodes, 474 13.9 Residual Liquid-Junction Potential—It Should Be Minimized, 411 15.5 Microfabricated Electrochemical Sensors, 474 13.10 Accuracy of Direct Potentiometric 15.6 Micro and Ultramicroelectrode Arrays, 475 Measurements—Voltage Error versus Activity Error, 412 13.11 Glass pH Electrode—Workhorse of Chapter 16 Chemists, 413 13.12 Standard Buffers—Reference for pH Spectrochemical Methods 477 Measurements, 418 16.1 Interaction of Electromagnetic Radiation 13.13 Accuracy of pH Measurements, 420 with Matter, 478 13.14 Using the pH Meter—How Does It Work?, 421 16.2 Electronic Spectra and Molecular Structure, 484 13.15 pH Measurement of Blood—Temperature 16.3 Infrared Absorption and Molecular Is Important, 422 Structure, 489 13.16 pH Measurements in Nonaqueous Solvents, 423 16.4 Near-Infrared Spectrometry for 13.17 Ion-Selective Electrodes, 424 Nondestructive Testing, 491 13.18 Chemical Analysis on Mars using 16.5 Spectral Databases—Identifying Ion-Selective Electrodes, 432 Unknowns, 493 16.6 Solvents for Spectrometry, 493 16.7 Quantitative Calculations, 494 Chapter 14 16.8 Spectrometric Instrumentation, 504 Redox and Potentiometric Titrations 437 16.9 Types of Instruments, 519 16.10 Array Spectrometers—Getting the Entire 14.1 First: Balance the Reduction–Oxidation Spectrum at Once, 522 Reaction, 437 16.11 Fourier Transform Infrared Spectrometers, 523 14.2 Calculation of the Equilibrium Constant of 16.12 Near-IR Instruments, 525 a Reaction—Needed to Calculate 16.13 Spectrometric Error in Measurements, 526 Equivalence Point Potentials, 438 16.14 Deviation from Beer’s Law, 527 14.3 Calculating Redox Titration Curves, 441 16.15 Fluorometry, 530 14.4 Visual Detection of the End Point, 445 16.16 Chemiluminescence, 538 14.5 Titrations Involving Iodine: Iodimetry and 16.17 Fiber-Optic Sensors, 540 Iodometry, 447 CONTENTS vii Chapter 17 Chapter 20 Atomic Spectrometric Methods 548 Gas Chromatography 619 17.1 Principles: Distribution between Ground 20.1 Performing GC Separations, 620 and Excited States—Most Atoms Are in 20.2 Gas Chromatography Columns, 623 the Ground State, 550 20.3 Gas Chromatography Detectors, 630 17.2 Flame Emission Spectrometry, 553 20.4 Temperature Selection, 638 17.3 Atomic Absorption Spectrometry, 556 20.5 Quantitative Measurements, 639 17.4 Sample Preparation—Sometimes 20.6 Headspace Analysis, 641 Minimal, 567 20.7 Thermal Desorption, 641 17.5 Internal Standard and Standard Addition 20.8 Purging and Trapping, 642 Calibration, 567 20.9 Small and Fast, 643 17.6 Atomic Emission Spectrometry: The Induction Coupled Plasma (ICP), 569 20.10 Separation of Chiral Compounds, 644 17.7 Atomic Fluorescence Spectrometry, 574 20.11 Two-Dimensional GC, 645 Chapter 18 Chapter 21 Sample Preparation: Solvent and Solid-Phase Liquid Chromatography and Electrophoresis 649 Extraction 579 21.1 High-Performance Liquid Chromatography, 651 21.2 Stationary Phases in HPLC, 654 18.1 Distribution Coefficient, 579 21.3 Equipment for HPLC, 665 18.2 Distribution Ratio, 580 21.4 Ion Chromatography, 692 18.3 Percent Extracted, 581 21.5 HPLC Method Development, 700 18.4 Solvent Extraction of Metals, 583 21.6 UHPLC and Fast LC, 701 18.5 Accelerated and Microwave-Assisted 21.7 Open Tubular Liquid Chromatography Extraction, 585 (OTLC), 702 18.6 Solid-Phase Extraction, 586 21.8 Thin-Layer Chromatography, 702 18.7 Microextraction, 590 21.9 Electrophoresis, 708 18.8 Solid-Phase Nanoextraction (SPNE), 593 21.10 Capillary Electrophoresis, 711 21.11 Electrophoresis Related Techniques, 724 Chapter 19 Chromatography: Principles and Theory 596 Chapter 22 19.1 Countercurrent Extraction: The Mass Spectrometry 735 Predecessor to Modern Liquid Chromatography, 598 22.1 Principles of Mass Spectrometry, 735 19.2 Principles of Chromatographic 22.2 Inlets and Ionization Sources, 740 Separations, 603 22.3 Gas Chromatography–Mass Spectrometry, 741 19.3 Classification of Chromatographic 22.4 Liquid Chromatography–Mass Techniques, 604 Spectrometry, 746 19.4 Theory of Column Efficiency in 22.5 Laser Desorption/Ionization, 750 Chromatography, 607 22.6 Secondary Ion Mass Spectrometry, 752 19.5 Chromatography Simulation 22.7 Inductively Coupled Plasma–Mass Software, 616 Spectrometry, 753 viii CONTENTS 22.8 Mass Analyzers and Detectors, 753 Available on textbook website: www.wiley.com/college/christian 22.9 Hybrid Instruments and Tandem Mass Spectrometry, 764 Chapter G Century of the Gene—Genomics and Chapter 23 Proteomics: DNA Sequencing and Protein Profiling G1 Kinetic Methods of Analysis 769 G.1 Of What Are We Made?, G1 G.2 What Is DNA?, G3 23.1 Kinetics—The Basics, 769 G.3 Human Genome Project, G3 23.2 Catalysis, 771 G.4 How Are Genes Sequenced?, G5 23.3 Enzyme Catalysis, 772 G.5 Replicating DNA: The Polymerase Chain Reaction, G6 Chapter 24 G.6 Plasmids and Bacterial Artificial Chromosomes (BACs), G7 Automation in Measurements 784 G.7 DNA Sequencing, G8 G.8 Whole Genome Shotgun Sequencing, G11 24.1 Principles of Automation, 784 G.9 Single-Nucleotide Polymorphisms, G11 24.2 Automated Instruments: Process Control, 785 G.10 DNA Chips, G12 24.3 Automatic Instruments, 787 G.11 Draft Genome, G13 24.4 Flow Injection Analysis, 789 G.12 Genomes and Proteomics: The Rest of the 24.5 Sequential Injection Analysis, 791 Story, G13 24.6 Laboratory Information Management Systems, 792 APPENDIX A LITERATURE OF ANALYTICAL Available on textbook website: www.wiley.com/college/christian CHEMISTRY 794 Chapter 25 Clinical Chemistry C1 APPENDIX B REVIEW OF MATHEMATICAL OPERATIONS: 25.1 Composition of Blood, C1 EXPONENTS, LOGARITHMS, AND THE QUADRATIC 25.2 Collection and Preservation of Samples, C3 FORMULA 797 25.3 Clinical Analysis—Common Determinations, C4 25.4 Immunoassay, C6 APPENDIX C TABLES OF CONSTANTS 801 Table C.1 Dissociation Constants for Acids, 801 Available on textbook website: www.wiley.com/college/christian Table C.2a Dissociation Constants for Basic Chapter 26 Species, 802 Environmental Sampling and Analysis EN1 Table C.2b Acid Dissociation Constants for Basic Species, 803 26.1 Getting a Meaningful Sample, EN1 Table C.3 Solubility Product Constants, 803 26.2 Air Sample Collection and Analysis, EN2 Table C.4 Formation Constants for Some 26.3 Water Sample Collection and Analysis, EN9 EDTA Metal Chelates, 805 26.4 Soil and Sediment Sampling, EN11 Table C.5 Some Standard and Formal Reduction Electrode Potentials, 806 26.5 Sample Preparation for Trace Organics, EN12 26.6 Contaminated Land Sites—What Needs to Available on textbook website: www.wiley.com/college/christian Be Analyzed?, EN12 26.7 EPA Methods and Performance-Based APPENDIX D SAFETY IN THE LABORATORY S1 Analyses, EN13 CONTENTS ix Available on textbook website: www.wiley.com/college/christian Experiment 13 Determination of Chloride in a Soluble Chloride: Fajans’ Method, E23 APPENDIX E PERIODIC TABLES ON THE WEB P1 Potentiometric Measurements Experiment 14 Determination of the pH of Hair APPENDIX F ANSWERS TO PROBLEMS 808 Shampoos, E24 Experiment 15 Potentiometric Determination of Fluoride in Drinking Water Using Available on textbook website: www.wiley.com/college/christian a Fluoride Ion-Selective Electrode, E25 Experiments E1 Reduction–Oxidation Titrations Experiment 16 Analysis of an Iron Alloy or Ore Use of Apparatus by Titration with Potassium Experiment 1 Use of the Analytical Balance, E1 Dichromate, E27 Experiment 2 Use of the Pipet and Buret and Experiment 17 Analysis of Commercial Statistical Analysis, E2 Hypochlorite or Peroxide Solution Experiment 3 Analysis of Volumetric by Iodometric Titration, E30 Measurements Using Experiment 18 Iodometric Determination of Spectrophotometric Microplate Copper, E32 Readers and Spreadsheet Experiment 19 Determination of Antimony by Calculations, E4 Titration with Iodine, E34 Gravimetry Experiment 20 Microscale Quantitative Analysis Experiment 4 Gravimetric Determination of of Hard-Water Samples Using an Chloride, E6 Indirect Potassium Permanganate Redox Titration, E36 Experiment 5 Gravimetric Determination of SO3 in a Soluble Sulfate, E9 Potentiometric Titrations Experiment 6 Gravimetric Determination of Experiment 21 pH Titration of Unknown Soda Nickel in a Nichrome Alloy, E11 Ash, E38 Acid–Base Titrations Experiment 22 Potentiometric Titration of a Experiment 7 Determination of Replaceable Mixture of Chloride and Iodide, E40 Hydrogen in Acid by Titration with Sodium Hydroxide, E12 Spectrochemical Measurements Experiment 23 Spectrophotometric Determination Experiment 8 Determination of Total Alkalinity of Iron, E41 of Soda Ash, E14 Experiment 24 Spectrophotometric Determination Experiment 9 Determination of Aspirin Using of Iron in Vitamin Tablets Using a Back Titration, E16 96 Well Plate Reader, E43 Experiment 10 Determination of Hydrogen Experiment 25 Determination of Nitrate Nitrogen Carbonate in Blood Using in Water, E46 Back-Titration, E18 Experiment 26 Spectrophotometric Determination Complexometric Titration of Lead on Leaves Using Solvent Experiment 11 Determination of Water Hardness Extraction, E47 with EDTA, E19 Experiment 27 Spectrophotometric Determination of Inorganic Phosphorus in Serum, E48 Precipitation Titrations Experiment 28 Spectrophotometric Determination Experiment 12 Determination of Silver in an of Manganese and Chromium in Alloy: Volhard’s Method, E21 Mixture, E50 x CONTENTS Experiment 29 Spectrophotometric Determination Experiment 39 Analysis of Analgesics Using of Manganese in Steel Using a 96 High-Performance Liquid Well Plate Reader, E52 Chromatography, E71 Experiment 30 Ultraviolet Spectrophotometric Determination of Aspirin, Mass Spectrometry Phenacetin, and Caffeine in APC Experiment 40 Capillary Gas Tablets Using Solvent Extraction, E54 Chromatography-Mass Experiment 31 Infrared Determination of a Spectrometry, E72 Mixture of Xylene Isomers, E56 Kinetic Analysis Experiment 32 Fluorometric Determination of Experiment 41 Enzymatic Determination of Riboflavin (Vitamin B2 ), E57 Glucose in Blood, E74 Atomic Spectrometry Measurements Flow Injection Analysis Experiment 33 Determination of Calcium by Experiment 42 Characterization of Physical Atomic Absorption Parameters of a Flow Injection Spectrophotometry, E57 Analysis System, E76 Experiment 34 Flame Emission Spectrometric Experiment 43 Single-Line FIA: Determination of Sodium, E60 Spectrophotometric Determination Solid-Phase Extraction and Chromatography of Chloride, E79 Experiment 44 Three-Line FIA: Experiment 35 Solid-Phase Extraction with Spectrophotometric Determination Preconcentration, Elution, and of Phosphate, E80 Spectrophotometric Analysis, E61 Experiment 36 Thin-Layer Chromatography Team Experiments Separation of Amino Acids, E67 Experiment 45 Method Validation and Quality Experiment 37 Gas Chromatographic Analysis of Control Study, E82 a Tertiary Mixture, E69 Experiment 46 Proficiency Testing: Experiment 38 Qualitative and Quantitative Determination of z Values of Analysis of Fruit Juices for Class Experiments, E84 Vitamin C Using High-Performance Liquid Chromatography, E70 Index 815  Preface “Teachers open the door, but it is up to you to enter” —Anonymous T his edition has two new coauthors, Purnendu (Sandy) Dasgupta and Kevin Schug, both from the University of Texas at Arlington. So the authorship now spans three generations of analytical chemists who have each brought their considerable expertise in both teaching and research interests to this book. While all chapters have ultimately been revised and updated by all authors, the three authors have spearheaded different tasks. Among the most notable changes are the following: The addition of a dedicated chapter on mass spectrometry (Chapter 22) by Kevin. Sandy provided complete rewrites of the chapters on spectrochemical methods (Chapter 16) and atomic spectrometric methods (Chapter 17), and gas and liquid chromatography (Chapters 20 and 21), and added many new Excel problems and exercises. Gary compiled and organized all old and new supplementary materials for the textbook companion website and added QR codes for selected website materials, and he prepared the PowerPoint presentations of figures and tables. WHO SHOULD USE THIS TEXT? This text is designed for college students majoring in chemistry and in fields related to chemistry. It is written for an undergraduate quantitative analysis course. It necessarily contains more material than normally can be covered in a one-semester or one-quarter course, so that your instructor can select those topics deemed most important. Some of the remaining sections may serve as supplemental material. Depending on how a quantitative analysis and instrumental analysis sequence is designed, it may serve for both courses. In any event, we hope you will take time to read some sections that look interesting to you that are not formally covered. They can certainly serve as a reference for the future. WHAT IS ANALYTICAL CHEMISTRY? Analytical chemistry is concerned with the chemical characterization of matter, both qualitative and quantitative. It is important in nearly every aspect of our lives because chemicals make up everything we use. This text deals with the principles and techniques of quantitative analysis, that is, how to determine how much of a specific substance is contained in a sample. You will learn how to design an analytical method, based on what information is needed or requested (it is important to know what that is, and why!), how to obtain a laboratory sample that is representative of the whole, how to prepare it for analysis, what measurement tools are available, and the statistical significance of the analysis. xi xii PREFACE Analytical chemistry becomes meaningful when you realize that a blood analysis may provide information that saves a patient’s life, or that quality control analysis assures that a manufacturer does not lose money from a defective product. WHAT’S NEW TO THIS EDITION? This seventh edition is extensively rewritten, offering new and updated material. The goal was to provide the student with a foundation of the analytical process, tools, and computational methods and resources, and to illustrate with problems that bring realism to the practice and importance of analytical chemistry. We take advantage of digital technologies to provide supplementary material, including videos, website materials, spreadsheet calculations, and so forth (more on these below). We introduce the chapters with examples of representative uses of a technique, what its unique capabilities may be, and indicate what techniques may be preferred or limited in scope. The beginning of each chapter lists key learning objectives for the chapter, with page numbers for specific objectives. This will help students focus on the core concepts as they read the chapter. Here are some of the new things: Professors Favorite Examples and Problems. We asked professors and prac- ticing analytical chemists from around the world to suggest new analytical examples and problems, especially as they relate to real world practice, that we could include in this new edition. It is with appreciation and pleasure that we thank the many that have generously provided interesting and valuable examples and problems. We call these Professor’s Favorite Examples, and Professor’s Favorite Problems, and they are annotated within the text by a margin element. We have included these in the text where appropriate and as space allows, and have placed some on the text website. We hope you find these interesting and, as appropriate, are challenged by them. Our special thanks go to the following colleagues who have contributed problems, analytical examples, updates, and experiments: Christine Blaine, Carthage College Gary Hieftje, Indiana University Andre Campiglia, University of Central Thomas Isenhour, Old Dominion University Florida Peter Kissinger, Purdue University David Chen, University of British Columbia Samuel P. Kounaves, Tufts University Christa L. Colyer, Wake Forest University Ulrich Krull, University of Toronto Michael DeGranpre, University of Montana Thomas Leach, University of Washington Mary Kate Donais, Saint Anselm College Dong Soo Lee, Yonsei University, Seoul, Tarek Farhat, University of Memphis Korea Carlos Garcia, The University of Texas at Milton L. Lee, Brigham Young University San Antonio Wen-Yee Lee, University of Texas at El Paso Steven Goates, BrighhamYoung University Shaorong Liu, University of Oklahoma Amanda Grannas, Villanova University Fred McLafferty, Cornell University Peter Griffiths, University of Idaho Michael D. Morris, University of Michigan Christopher Harrison, San Diego State University Noel Motta, University of Puerto Rico, Rı́o Piedras James Harynuk, University of Alberta Christopher Palmer, University of Montana Fred Hawkridge, Virginia Commonwealth University Dimitris Pappas, Texas Tech University Yi He, John Jay College of Criminal Justice, Aleeta Powe, University of Louisville The City University of New York Alberto Rojas-Hernández, Universidad Autó- Charles Henry, Colorado State University noma Metropolitana-Iztapalapa, Mexico PREFACE xiii Alexander Scheeline, University of Illinois Galina Talanova, Howard University W. Rudolph Seitz, University of New Yijun Tang, University of Wisconsin, Hampshire Oshkosh Paul S. Simone, Jr., University of Memphis Jon Thompson, Texas Tech University Nicholas Snow, Seton Hall University Kris Varazo, Francis Marion University Wes Steiner, Eastern Washington University Akos Vertes, George Washington University Apryll M. Stalcup, City University of Dublin, Bin Wang, Marshall University Ireland George Wilson, University of Kansas Robert Synovec, University of Washington Richard Zare, Stanford University Mass spectrometry, especially when used as a hyphenated technique with chro- matography, is increasingly a routine and powerful analytical tool, and a new chapter (Chapter 22) is dedicated to this topic. Likewise, liquid chromatog- raphy, including ion chromatography for anion determinations, is one of the most widely used techniques today, even surpassing gas chromatography. There are a wide variety of options of systems, instruments, columns, and detectors available, making selection of a suitable system or instrument a challenge for different applications. The present liquid chromatography chapter (Chapter 21) uniquely provides comprehensive coverage within the scope of an undergrad- uate text that not only gives the fundamentals of various techniques, how they evolved, and their operation, but also what the capabilities of different systems are and guidance for selecting a suitable system for a specific application. Revised chapters. All chapters have been revised, several extensively, especially those dealing with instrumentation to include recent technological innovations, as done for the liquid chromatography chapter. These include the spectrochemical chapter (16), the atomic spectrometric chapter (17), and the gas chromatog- raphy chapter (20). State-of-the-art technologies are covered. Some of this material and that of other chapters may be appropriate to use in an Instrumental Analysis course, as well as providing the basics for the quantitative analysis course; your instructor may assign selected sections for your course. Historical information is added throughout to put into perspective how the tools we have were developed and evolved. Some is this is included in margin pictures and notes, showing pioneers in development of our profession. Videos of Excel Programs. Major additions to the text and the text’s website supplemental material include powerful Excel programs to perform complicated calculations, and to create plots of titration curves, alpha vs. pH, logC vs. pH, etc. We have included video tutorials created by students of Professor Dasgupta to illustrate the use of many of these. The following videos, by chapter and in order of page appearance, with page numbers listed, are available on the text website. We have also created QR Codes for these in each chapter (see below) for those who want to access them on their smartphones. You will find these useful as you experiment with Excel and its power. Chapter 3 7. Error bars, 102 1. Solver, 87 8. Introduction to Excel, 113 2. Data Analysis Regression, 87, 120 9. Absolute Cell Reference, 115 3. F-test, 88 10. Average, 116 4. t-test for Paired Samples, 94 11. STDEV, 116 5. Paired t-test from Excel, 94 12. Intercept Slope and r-square, 119 6. Plotting in Excel, 102, 118 13. LINEST, 120 xiv PREFACE Chapter 6 Chapter 8 1. Goal Seek Equilibrium, 201 1. Excel H3 PO4 titration curve, 302 2. Goal Seek Problem 6.2, 219 Chapter 9 Chapter 7 1. H4 Y alpha plot Excel 1, 328 1. Goal Seek pH NH4 F, 238 2. H4 Y alpha plot Excel 2, 328 2. Goal Seek mixture, 244 3. Example 9.6, 339 Thanks are due to the following students at the University of Texas as Arlington for their contributions: Barry Akhigbe, Jyoti Birjah, Rubi Gurung, Aisha Hegab, Akinde Kadjo, Karli Kirk, Heena Patel, Devika Shakya, and Mahesh Thakurathi. OTHER MODIFICATIONS TO EXISTING CONTENT It has been almost ten years since the last edition was published and since that time, much has changed! This seventh edition of Analytical Chemistry is extensively revised and updated, with new materials, new problems and examples, and new references. Spreadsheets. Detailed instructions are given on how to use and take advantage of spreadsheets in analytical calculations, plotting, and data processing. But the introductory material has been moved to the end of Chapter 3 as a separate unit, so that it can be assigned independently if desired, or treated as auxiliary material. The use of Excel Goal Seek and Excel Solver is introduced for solving complex problems and constructing titration curves (see below). Mastery of these powerful tools will allow students to tackle complex problems. Several useful programs introduced in the chapters are placed on the text website and instructions are given for applying these for plotting titration curves, derivative titrations, etc. by simply inputting equilibrium constant data, concentrations, and volumes. References. There are numerous recommended references given in each chapter, and we hope you will find them interesting reading. The late Tomas Hirschfeld said you should read the very old literature and the very new to know the field. We have deleted a number of outdated references, updating them with new ones. Many references are for classical, pioneering reports, forming the basis of current methodologies, and these remain. Material moved to the text website. As detailed elsewhere, we have moved certain parts to the text website as supplemental material and to make room for updating material on the techniques to be used. This includes: The single pan balance (Chapter 2) and normality calculations (Chapter 5), which may still be used, but in a limited capacity. The experiments. Auxiliary spreadsheet calculations from different chapters are posted on the website. Chapters dealing with specific applications of analytical chemistry are now on the text website for those interested in pursuing these topics. These are Clinical Chemistry (Chapter 25), and Environmental Sampling and Analysis (Chapter 26). Analytical chemistry played a key role in the completion of the historic Human Genome Project, and the Genomics and Proteomics chapter documents how. This material is not mainstream in the quantitative analysis course, so it has been moved to the website as Chapter G. It is available there for the interested student or for professor assignment. PREFACE xv SPREADSHEETS Spreadsheets (using Excel) are introduced and used throughout the text for performing computations, statistical analysis, and graphing. Many titration curves are derived using spreadsheets, as are the calculations of α-values and plots of α-pH curves, and of logarithm concentration diagrams. The spreadsheet presentations are given in a “user-friendly” fashion to make it easier for you to follow how they are set up. We provide a list of the different types of spreadsheets that are used throughout the text, by topic, after the Table of Contents. GOAL SEEK We have introduced the use of Goal Seek, a powerful Excel tool, for solving complex problems. Goal Seek performs “trial and error” or successive approximation calculations to arrive at an answer. It is useful when one parameter needs to be varied in a calculation, as is the case for most equilibrium calculations. An introduction to Goal Seek is given in Section 6.11 in Chapter 6. Example applications are given on the text website, and we list these after the Table of Contents. SOLVER Excel Solver is an even more versatile tool. Goal Seek can only solve one parameter in a single equation, and does not allow for incorporating constraints in the parameter we want to solve. Solver, on the other hand, can solve for more than one parameter (or more than one equation) at a time. Example applications are given on the text website, with descriptions in the text. See the list after the Table of Contents. An introduction to its use is given in Example 7.21. REGRESSION FUNCTION IN EXCEL DATA ANALYSIS Possibly the most powerful tool to calculate all regression related parameters for a calibration plot is the “Regression” function in Data Analysis. It not only provides the results for r, r2 , intercept, and slope (which it lists as X variable 1), it also provides their standard errors and upper and lower limits at the 95% confidence level. It also provides an option for fitting the straight line through the origin (when you know for certain that the response at zero concentration is zero by checking a box “constant is zero”). A video illustrating its use is in the website of the book, Chapter 3, titled Data Analysis Regression. A description of how to use it is given in Chapter 16 at the end of Section 16.7, and example applications are given in Chapter 20, Section 20.5, and Chapter 23 for Examples 23.1 and Example 23.2. READY TO USE PROGRAMS As listed above, there are numerous supplemental materials on the text website, including Excel spreadsheets for different calculations. Many of these are for specific examples and are tutorial in nature. But several are suited to apply to different applications, simply by inputting data and not having to set up the calculation program. Examples include calculating titration curves and their derivatives, or for solving either quadratic or simultaneous equations. We list here a number that you should find useful. You can find them under the particular chapter on the website. Chapter 2 Glassware calibration, Table 2.4 xvi PREFACE Chapter 6 Calculate activity coefficients, equations 6.19 and 6.20 (Auxiliary data) Quadratic equation solution (Example 6.1) (See also Goal Seek for solving quadratic equations) Chapter 7 Stig Johannson pH calculator. For calculating pH of complex mixtures. Easy to use. CurtiPotpH calculator (Ivano Gutz) for calculating pH of complex mixtures, as well as constructing pH related curves. Learning curve higher, but very powerful. logC-pH Master Spreadsheet. See Section 7.16 on how to use it. Chapter 8 Derivative titrations—Easy method (Section 8.11) Universal Acid Titrator—Alex Scheeline—Easy method (Section 8.11). For polyprotic acid titration curves. Master Spreadsheet for titrations of weak bases—Easy method Chapter 10 Solving simultaneous equations (Example 10.5) Chapter 14 Derivative titration plots (for near the endpoint) Chapter 16 Calculation of unknown from calibration curve plot Standard deviation of sample concentration Two component Beer’s Law solution Chapter 17 Standard additions plot and unknown calculation Chapter 20 Internal standard calibration plot and unknown calculation (Section 20.5) EXPERIMENTS There are 46 experiments, grouped by topic, illustrating most of the measurement techniques presented in the text, and they can be downloaded from the text website. Each contains a description of the principles and chemical reactions involved, so the student gains an overview of what is being determined and how. Solutions and reagents to prepare in advance of the experiment are listed, so experiments can be performed efficiently. All experiments, particularly the volumetric ones, have been designed to minimize waste by preparing the minimum volumes of reagents, like titrants, required to complete the experiment. Two team experiments are included (Experiments 45 and 46) to illustrate the principles presented in Chapter 4 on statistical validation. One is on method validation and quality control, in which different members of teams perform different parts of the validation for a chosen experiment. The other is on proficiency testing in which students calculate the z-values for all the student results of one or more class experiments and each student compares their z-value to see how well they have performed. PREFACE xvii New experiments were contributed by users and colleagues. Included are three experiments from Professor Christopher Palmer, University of Montana using a spectrophotometric microplate reader (Experiments 3, 24, and 29). Experiment Video Resource. Professor Christopher Harrison from San Diego State University has a YouTube “Channel” of videos of different types of experi- ments, some illustrating laboratory and titration techniques: http://www.youtube.com/ user/crharrison. We would recommend that students be encouraged to look at the ones dealing with buret rinsing, pipetting, and aliquoting a sample, before they begin experiments. Also, they will find useful the examples of acid-base titrations illustrating methyl red or phenolphthalein indicator change at end points. There are a few specific experiments that may be related to ones from the textbook, for example, EDTA titration of calcium or Fajan’s titration of chloride. The video of glucose analysis gives a good illustration of the starch end point, which is used in iodometric titrations. SUPPLEMENTARY MATERIALS FOR THE INSTRUCTOR AND THE STUDENT WEBSITE URLs and QR CODES. There are some 200 website URLs, i.e., website addresses, given throughout the text for access to useful supplemental material. To efficiently access the websites, lists of all the URLs are posted on the text website for each chapter. These lists can be used to access the websites without typing the URLs. The lists of URLs for each chapter are also added as QR codes at the beginning of each chapter, facilitating access on smartphones. QR codes for selected ones are also given on the text pages where they appear (see below). We list in the QR code here all the chapter URL lists. QR codes are created for selected website materials in several chapters, as referred to in the chapter text. This will allow access to supplemental material using a smartphone, iPad, etc. So by accessing QR codes in a given chapter, one can browse for the videos and the selected URL links, alongside other valuable materials. Complete URL list TEXT COMPANION WEBSITE John Wiley & Sons, Inc. maintains a companion website for your Analytical Chemistry textbook that contains additional valuable supplemental material. The website may be accessed at: www.wiley.com/college/christian Materials on the website include supplemental materials for different chapters that expand on abbreviated presentations in the text. Following is a list of the types of materials on the website: Videos URLs Supplemental Material: WORD, PDFs, Excel, PowerPoint, JPEG POWERPOINT SLIDES All figures and tables in the text are posted on the text website as PowerPoint slides for each chapter, with notes on each for the instructor, and can be downloaded for preparation of PowerPoint presentations. SOLUTIONS MANUAL A comprehensive saleable solutions manual is available for use by instructors and students in which all problems are completely worked out and all questions are xviii PREFACE answered, a total of 824. More information on the solutions manual can be found at www.wiley.com, including where/how to purchase it. Answers for spreadsheet problems, which include the spreadsheets, are given on the text website. Answers to all problems are given in Appendix F. A WORD OF THANKS The production of your text involved the assistance and expertise of numerous people. Special thanks go to the users of the text who have contributed comments and suggestions for changes and improvements; these are always welcome. A number of colleagues served as reviewers of the text and manuscript and have aided immeasurably in providing specific suggestions for revision. They, naturally, express opposing views sometimes on a subject or placement of a chapter or section, but collectively have assured a near optimum outcome that we hope you find easy and enjoyable to read and study. First, Professors Louise Sowers, Stockton College; Gloria McGee, Xavier University; and Craig Taylor, Oakland University; and Lecturer Michelle Brooks, University of Maryland and Senior Lecturer Jill Robinson, Indiana University offered advice for revision and improvements of the 6th edition. Second, Professors Neil Barnett, Deakin University, Australia; Carlos Garcia, The University of Texas at San Antonio; Amanda Grannas, Villanova University; Gary Long, Virginia Tech; Alexander Scheeline, University of Illinois; and Mathew Wise, Condordia University, proofed the draft chapter manuscripts of this edition and offered further suggestions for enhancing the text. Dr. Ronald Majors, a leading chromatography expert from Agilent Technologies, offered advice on the liquid chromatography chapter. The professionals at John Wiley & Sons have been responsible for producing a high quality book. Petra Recter, Vice President, Publisher, Chemistry and Physics, Global Education, shepherded the whole process from beginning to end. Her Editorial Assistants Lauren Stauber, Ashley Gayle, and Katherine Bull were key in taking care of many details, with efficiency and accuracy. Joyce Poh was the production editor, arranging copyediting to printing, attending to many details, and assuring a quality final product. Laserwords Pvt Ltd was responsible for artwork in your text. We appreciate the efforts of Marketing Manager, Kristy Ruff, in making sure the text is available to all potential users. It has been a real pleasure for all of us working with this team of professionals and others in a long but rewarding process. We each owe special thanks to our families for their patience during our long hours of attention to this undertaking. Gary’s wife, Sue, his companion for over 50 years, has been through seven editions, and remains his strong supporter, even now. Purnendu owes his wife, Kajori, and his students, much for essentially taking off from all but the absolute essentials for the last three years. He also thanks Akinde Kadjo in particular for doing many of the drawings. Kevin’s wife, Dani, put up with yet another “interesting project” and lent her support in the form of keeping the kids at bay and making sure her husband was well fed while working on the text. GARY D. CHRISTIAN Seattle, Washington PURNENDU K. (SANDY) DASGUPTA KEVIN A. SCHUG Arlington, Texas September, 2013 “To teach is to learn twice.” —Joseph Joubert List of Spreadsheets Used Throughout the Text The use of spreadsheets for plotting curves and perform- Slope, Intercept and Coefficient of Determination ing calculations is introduced in different chapters. Listed (without a plot) (Section 3.22; Chapter 3, Problems 47, in the Preface are several that are ready to use for differ- 51, 52) ent applications. Following is a list of the various other LINEST for Additional Statistics (Section 3.23, applications of Microsoft Excel, by category, for easy Figure 3.11) reference for different uses. All spreadsheets are given in Ten functions: slope, std. devn., R2 , F, sum sq. regr., the text website. The Problem spreadsheets are only in intercept, std. devn., std. error of estimate, d.f., sum sq. the website; others are in the text but also in the website. resid. You should always practice preparing assigned spread- sheets before referring to the website. You can save the Plotting α vs. pH Curves (Figure 7.2, H3 PO4 ), 251 spreadsheets in your website to your desktop for use.. Plotting log C vs. pH Curves Use of Spreadsheets (Section 3.20) Chapter 7, Problem 66 (HOAc) Filling the Cell Contents, 112 Plotting log C vs. pH Curves Using Alpha Values Saving the Spreadsheet, 113 (Section 7.16) Printing the Spreadsheet, 113 Chapter 7, Problem 69 (Malic acid, H2 A) Relative vs. Absolute Cell References, 114 Chapter 7, Problem 73 (H3 PO4 , H3 A) Use of Excel Statistical Functions (Paste functions), 115 Plotting Titration Curves Useful Syntaxes: LOG10; PRODUCT; POWER; SQRT; AVERAGE; MEDIAN; STDEV; VAR, 116 HCl vs. NaOH (Figure 8.1), 283, 285 HCl vs. NaOH, Charge Balance (Section 8.2), 285 Statistics Calculations HOAc vs. NaOH (Section 8.5), 293 Standard Deviation: Chapter 3, Problems 14, 15, Hg2+ vs. EDTA: Chapter 9, Problem 24 16, 22, 24 SCN− and Cl− vs. AgNO3 : Chapter 11, Problem 12 Confidence Limit: Chapter 3, Problems 22, 24, Fe2+ vs. Ce4+ (Figure 14.1): Example 14.3 25, 29 Derivative Titrations (Section 8.11), 305; Chapter Pooled Standard Deviation: Chapter 3, Problem 34 14, 458 F-Test: Chapter 3, Problems 31, 33, 35. t-Test: Chapter 3, Problems 37, 38 Plotting log K’ vs. pH (Figure 9.2): Chapter 9, t-Test, multiple samples: Chapter 3, Problem 53 Problem 23. Propagation of Error: Chapter 3, Problems 18 (add/subtract), 19 (multiply/divide) Plotting β-values vs. [ligand] (Ni(NH3 )6 2+ beta- values vs. [NH3 ]): Using Spreadsheets for Plotting Calibration Chapter 9, Problem 25 Curves Trendline; Least squares equation; R2 (Section 3.21, Spreadsheet Calculations/Plots Figure 3.10) Glassware Calibration (Table 2.4), 38 xix xx LIST OF SPREADSHEETS USED THROUGHOUT THE TEXT Weight in Vacuum Error vs. Sample Density (Chapter 2) Example 7.7 Goal Seek solution (pH HOAc) Gravimetric Calculations Example 7.8 Goal Seek solution (pH NH3 ) Spreadsheet Examples-Grav. calcn. %Fe, 378 Example 7.9 Goal Seek solution (pH NaOAc) Chapter 10, Problem 40 (Example 10.2, %P2 O5 ) Example 7.10 Goal Seek solution (pH NH4 Cl) Solubility BaSO4 vs. [Ba2+ ] Plot (Figure 10.3): Chapter 7 video Goal Seek pH NH4 F, 238 Chapter 10, Problem 41 Chapter 7 video Goal Seek mixture (NaOH + H2 CO3 ), Solubility vs. Ionic Strength Plot (Figure 10.4): 244 Chapter 10, Problem 42 Example 7.19 Charge balance and Goal Seek to calc Van Deemter Plot: Chapter 19, Problem 13 H3 PO4 pH (See the example for details of setting up the spreadsheet) EXCEL SOLVER FOR PROBLEM SOLVING Example 7.19b Goal Seek solution (pH H3 PO4 + NaOAc + K2 HPO4 ) (See Example 7.19 discussion for spreadsheet This program can be used to solve several parameters setup) or equations at a time. An introduction is given in Example 7.21. 77PFP Goal Seek calculations—there are three tabs (Chapter 7, Problem 77). See 77PFP solution on the Chapter 3 video Solver (solving quadratic equation, website for a detailed description of the problem solution Example 6.1) and appropriate equations. Example 7.21 Solver pH calculations of multiple solutions Example 9.6—Goal Seek (complexation equilibria); (H3 PO4 , NaH2 PO4 , Na2 HPO4 , Na3 PO4 ); 258 (Section 9.6), 339 (See the example for the equation Example 7.24 Solver calculation (buffer setup) composition), 264 Example 11.1 Goal Seek (solubility of CaC2 O4 in 0.001M Solubility from Ksp : Chapter 10, Problem 43 HCl) (Example 10.9) Example 11.2 Goal Seek (charge balance, solubility of MA in 0.1M HCl) GOAL SEEK FOR PROBLEM SOLVING Example 11.5 Goal Seek (solubility of MX in presence of complexing ligand L) The spreadsheets listed below are on the text website for the particular chapter. The page numbers refer to cor- responding discussions on setting up the programs. See Section 6.11 for introduction to and application of Goal REGRESSION FUNCTION IN EXCEL DATA Seek. It can be used to solve one parameter in an equation, ANALYSIS as in most equilibrium problems. This Excel tool calculates all regression related param- Excel Goal Seek for Trial and Error Problem Solving eters for a calibration plot. It provides the results for r, (Section 6.11): r2 , intercept, and slope, and also provides their standard Equilibrium problem—introduction to Goal Seek, 197; errors and upper and lower limits at the 95% confidence Practice Goal Seek—setup, answer level. Goal Seek to Solve an Equation (Example 6.1—quadratic Chapter 3 video Data Analysis Regression; 87, 120 equation), 199 Chapter 16, end of Section 16.7, Excel Exercise. Describes Solving a quadratic equation by Goal Seek—setup the use of the Excel Regression function in Data Analysis Goal Seek answer quadratic equation to readily calculate a calibration curve and its uncertainty, Chapter 6 video Goal Seek Equilibrium, 201 and then apply this to calculate an unknown concentration Goal Seek shortcomings (how to get around them)—setup and its uncertainty from its absorbance; 502 (Example 6.4); 202 Section 20.5, GC internal standard determination, 640 Goal Seek answer Example 6.4 Chapter 20, Problem 11. GC internal standard determi- Solving Example 6.13 Using Goal Seek (charge balance); nation 210 Example 23.1, Lineweaver-Burk Km determination Chapter 6 video Goal Seek Problem 6.2 Example 23.2, Calculating unknown concentration from Goal Seek answer Problem 26 (quadratic equation), reaction rate Chapter 6 Problem 23.17, Lineweaver-Burk Km determination  About the Authors Gary Christian grew up Oregon, and has had a lifelong interest in teaching and research, inspired by great teachers throughout his education. He received his B.S. degree from the University of Oregon and Ph. D. degree from the University of Maryland. He began his career at Walter Reed Army Institute of Research, where he developed an interest in clinical and bioanalytical chemistry. He joined the University of Kentucky in 1967, and in 1972 moved to the University of Washington, where he is Emeritus Professor, and Divisional Dean of Sciences Emeritus. Gary wrote the first edition of this text in 1971. He is pleased that Professors Dasgupta and Schug have joined him in this new edition. They bring expertise and experience that markedly enhance and update the book in many ways. Gary is the recipient of numerous national and international awards in recognition of his teaching and research activities, including the American Chemical Society (ACS) Division of Analytical Chemistry Award for Excellence in Teaching and the ACS Fisher Award in Analytical Chemistry, and received an Honorary Doctorate Degree from Chiang Mai University. The University of Maryland inducted him into their distinguished alumni Circle of Discovery. He has authored five other books, including Instrumental Analysis, and over 300 research papers, and has been Editor-in-Chief of the international analytical chemistry journal, Talanta, since 1989. Purnendu K. (Sandy) Dasgupta is a native of India and was educated in a college founded by Irish missionaries and graduated with honors in Chemistry in 1968. After a MSc in Inorganic Chemistry in 1970 from the University of Burdwan and a brief stint as a researcher at the Indian Association for the Cultivation of Science (where Raman made his celebrated discovery), he came as a graduate student to Louisiana State University at Baton Rouge in 1973. Sandy received his PhD in Analytical Chemistry with a minor in Electrical Engineering from LSU in 1977 and managed to get a diploma as a TV mechanic while a graduate student. He joined the California Primate Research Center at the University of California at Davis as an Aerosol research Chemist in 1979 to be part of a research team studying inhalation toxicology of air pollutants. In his mother tongue, Bengali, he was once a well-published poet and a fledgling novelist but seemingly finally found his love of analytical chemistry as salvation. He joined Texas Tech in 1981 and was designated a Horn Professor in 1992, named after the first president of the University, the youngest person to be so honored at the time. He remained at Texas Tech for 25 years, joining the University of Texas at Arlington in 2007 as the Department Chair. He has stepped down as Chair, and currently holds the Jenkins Garrett Professorship. Sandy has written more than 400 papers/book chapters, and holds 23 US patents, many of which have been commercialized. His work has been recognized by the Dow Chemical Traylor Creativity Award, the Ion Chromatography Symposium xxi xxii ABOUT THE AUTHORS Outstanding Achievement Award (twice), the Benedetti-Pichler Memorial Award in Microchemistry, American Chemical Society Award in Chromatography, Dal Nogare Award in the Separation Sciences, Honor Proclamation of the State of Texas Senate and so on. He is the one of the Editors of Analytica Chimica Acta, a major international journal in analytical chemistry. He is best known for his work in atmospheric measurements, ion chromatography, the environmental occurrence of perchlorate and its effect on iodine nutrition, and complete instrumentation systems. He is a big champion of the role of spreadsheet programs in teaching analytical chemistry. Kevin Schug was born and raised in Blacksburg, Virginia. The son of a physical chemistry Professor at Virginia Tech, he grew up running around the halls of a chemistry building and looking over his father’s shoulder at chemistry texts. He pursued and received his B.S. degree in Chemistry from the College of William & Mary in 1998, and his Ph.D. degree in Chemistry under the direction of Professor Harold McNair at Virginia Tech in 2002. Following two years as a post-doctoral fellow with Professor Wolfgang Lindner at the University of Vienna (Austria), he joined the faculty in the Department of Chemistry & Biochemistry at The University of Texas at Arlington in 2005, where he is currently the Shimadzu Distinguished Professor of Analytical Chemistry. The research in Kevin’s group spans fundamental and applied aspects of sample preparation, separation science, and mass spectrometry. He also manages a second group, which focuses their efforts on chemical education research. He has been the recipient of several awards, including the Eli Lilly ACACC Young Investigator in Analytical Chemistry award, the LCGC Emerging Leader in Separation Science award, and the American Chemical Society Division of Analytical Chemistry Award for Young Investigators in Separation Science. At present, he has authored or coauthored 65 scientific peer-reviewed manuscripts. Kevin is a member of the Editorial Advisory Boards for Analytica Chimica Acta and LCGC Magazine, and is a regular contributor to LCGC on-line articles. He is also Associate Editor of the Journal of Separation Science.  Chapter One ANALYTICAL OBJECTIVES, OR: WHAT ANALYTICAL CHEMISTS DO “Unless our knowledge is measured and expressed in numbers, it does not amount to much.” —Lord Kelvin Chapter 1 URLs Learning Objectives WHAT ARE SOME OF THE KEY THINGS WE WILL LEARN FROM THIS CHAPTER? Analytical science deals with the chemical characterization of You must select the appropriate method for measurement, matter—what, how much?, p. 2 p. 12 The analyst must know what information is really needed, and Validation is important, p. 15 obtain a representative sample, pp. 6, 9 There are many useful websites dealing with analytical chem- Few measurements are specific, so operations are performed istry, p. 16 to achieve high selectivity, p. 11 Analytical chemistry is concerned with the chemical characterization of matter and the answer to two important questions: what is it (qualitative analysis) and how much is it (quantitative analysis). Chemicals make up everything we use or consume, and knowledge of the chemical composition of many substances is important in our daily lives. Analytical chemistry plays an important role in nearly all aspects of chemistry, for example, agricultural, clinical, environmental, forensic, manufacturing, metallurgical, and pharmaceutical chemistry. The nitrogen content of a fertilizer determines its value. Foods must be analyzed for contaminants (e.g., pesticide residues) and for essential nutrients (e.g., vitamin content). The air we breathe must be analyzed for toxic gases Lord Kelvin (William Thomson, (e.g., carbon monoxide). Blood glucose must be monitored in diabetics (and, in fact, 1824–1907) most diseases are diagnosed by chemical analysis). The presence of trace elements from gun powder on a perpetrator’s hand will prove a gun was fired by that hand. The quality of manufactured products often depends on proper chemical proportions, and measurement of the constituents is a necessary part of quality assurance. The Everything is made of chemicals. carbon content of steel will influence its quality. The purity of drugs will influence Analytical chemists determine their efficacy. what and how much. In this text, we will describe the tools and techniques for performing these different types of analyses. There is much useful supplemental material on the text website, including Excel programs that you can use, and videos to illustrate their use. You should first read the Preface to learn what is available to you, and then take advantage of some of the tools. 1 2 CHAPTER 1 ANALYTICAL OBJECTIVES, OR: WHAT ANALYTICAL CHEMISTS DO 1.1 What Is Analytical Science? The above description of analytical chemistry provides an overview of the discipline of analytical chemistry. There have been various attempts to more specifically define the discipline. The late Charles N. Reilley said: “Analytical chemistry is what analytical chemists do” (Reference 2). The discipline has expanded beyond the bounds of just chemistry, and many have advocated using the name analytical science to describe the field. This term is used in a National Science Foundation report from workshops on “Curricular Developments in the Analytical Sciences.” Even this term falls short of recognition of the role of instrumentation development and application. One suggestion is that we use the term analytical science and technology (Reference 3). The Federation of European Chemical Societies held a contest in 1992 to define analytical chemistry, and the following suggestion by K. Cammann was selected [Fresenius’ J. Anal. Chem., 343 (1992) 812–813]. Analytical Chemistry provides the methods and tools needed for insight into our material world... for answering four basic questions about a material sample: What? Where? How much? What arrangement, structure or form? These cover qualitative, spatial, quantitative, and speciation aspects of analytical science. The Division of Analytical Chemistry of the American Chemical Society developed a definition of analytical chemistry, reproduced in part here: Analytical Chemistry seeks ever improved means of measuring the chemical compo- sition of natural and artificial materials. The techniques of this science are used to identify the substances which may be present in a material and to determine the exact amounts of the identified substance. Analytical chemists serve the needs of many fields: In medicine, analytical chemistry is the basis for clinical laboratory tests which help physicians diagnose disease and chart progress in recovery. In industry, analytical chemistry provides the means of testing raw materials and for assuring the quality of finished products whose chemical composition is critical. Many household products, fuels, paints, pharmaceuticals, etc. are analyzed by the procedures developed by analytical chemists before being sold to the consumer. Environmental quality is often evaluated by testing for suspected contaminants using the techniques of analytical chemistry. The nutritional value of food is determined by chemical analysis for major components such as protein and carbohydrates and trace components such as vitamins and minerals. Indeed, even the calories in food are often calculated from its chemical analysis. Analytical chemists also make important contributions to fields as diverse as forensics, archaeology, and space science. An interesting article published by a leading analytical chemist, G. E. F. Lundell, from the National Bureau of Standards in 1935 entitled “The Analysis of Things As They Are”, describes why we do analyses and the analytical process (Industrial and Engineering Chemistry, Analytical Edition, 5(4) (1933) 221–225). The article is posted on the text website. 1.2 QUALITATIVE AND QUANTITATIVE ANALYSIS: WHAT DOES EACH TELL US? 3 A brief overview of the importance of analytical chemistry in society, with examples that affect our lives, and the tools and capabilities, is given in the article, “What Analytical Chemists Do: A Personal Perspective,” by Gary Chris- tian, Chiang Mai Journal of Science, 32(2) (2005) 81–92: http://it.science.cmu.ac.th/ejournal/journalDetail.php?journal_id=202 Reading this before beginning this course will help place in context what you are learning. A reprint of the article is posted on the text website. What Analytical Chemists Do 1.2 Qualitative and Quantitative Analysis: What Does Each Tell Us? The discipline of analytical chemistry consists of qualitative analysis and quantitative Qualitative analysis tells us what analysis. The former deals with the identification of elements, ions, or compounds chemicals are present. present in a sample (we may be interested in whether only a given substance is Quantitative analysis tells us how present), while the latter deals with the determination of how much of one or more much. constituents is present. The sample may be solid, liquid, gas, or a mixture. The presence of gunpowder residue on a hand generally requires only qualitative knowledge, not of how much is there, but the price of coal will be determined by the percent of undesired sulfur impurity present. How Did Analytical Chemistry Originate? That is a very good question. Actually, some tools and basic chemical measure- ments date back to the earliest recorded history. Fire assays for gold are referred to in Zechariah 13:9, and the King of Babylon complained to the Egyptian Pharoah, Ammenophis the Fourth (1375–1350 BC), that gold he had received from the pharaoh was “less than its weight” after putting it in a furnace. The perceived value of gold, in fact, was probably a major incentive for acquiring analytical knowledge. Archimedes (287–212 BC) did nondestructive testing of the golden wreath of King Hieron II. He placed lumps of gold and silver equal in weight to the wreath in a jar full of water and measured the amount of water displaced by all three. The wreath displaced an amount between the gold and silver, proving it was not pure gold! Robert Boyle coined the term The balance is of such early origin that it was ascribed to the gods in the “analyst” in his book The Sceptical earliest documents found. The Babylonians created standard weights in 2600 BC Chymist in 1661 and considered them so important that their use was supervised by the priests. The alchemists accumulated the chemical knowledge that formed the basis for quantitative analysis as we know it today. Robert Boyle coined the term analyst in his 1661 book, The Sceptical Chymist. Antoine Lavoisier has been considered the “father of analytical chemistry” because of the careful quantitative experiments he performed on conservation of mass (using the analytical balance). (Lavoisier was actually a tax collector and dabbled in science on the side. He was guillotined on May 8, 1793, during the French Revolution because of his activities as a tax collector.) Gravimetry was developed in the seventeenth century, and titrimetry in the eighteenth and nineteenth centuries. The origin of titrimetry goes back to Antoine Lavoisier used a precision Geoffroy in 1729; he evaluated the quality of vinegar by noting the quantity balance for quantitative experiments of solid K2 CO3 that could be added before effervescence ceased (Reference 4). on the conservation of mass. He is Gay-Lussac, in 1829, assayed silver by titration with 0.05% relative accuracy considered the “father of and precision! quantitative analysis.” 4 CHAPTER 1 ANALYTICAL OBJECTIVES, OR: WHAT ANALYTICAL CHEMISTS DO Karl Remigius Fresenius (1818–1897) published a textbook on quantitative analysis in 1846, which went through six editions and became a standard in the field. He also founded the first journal in analytical chemistry, Zeitschrift Fur Analytische Chemie in 1862. A 2000-year-old balance. Han Dynasty 10 AD. Taiwan National Museum, Taipei. From collection of G. D. Christian. Textbooks of analytical chemistry began appearing in the 1800s. Karl Fre- senius published Anleitung zur Quantitaven Chemischen Analyse in Germany in 1845. Wilhelm Ostwald published an influential text on the scientific fundamen- tals of analytical chemistry in 1894 entitled Die wissenschaflichen Grundagen der analytischen Chemie, and this book introduced theoretical explanations of analytical phenomena using equilibrium constants (thank him for Chapter 6 and applications in other chapters). The twentieth century saw the evolution of instrumental techniques. Wilhelm Ostwald (1853–1932) Steven Popoff’s second edition of Quantitative Analysis in 1927 included published the influential text, Die Wissenschaflichen Grundlagen Der electroanalysis, conductimetric titrations, and colorimetric methods. Today, Analytischem Chemie (The scien- of course, analytical technology has progressed to include sophisticated and tific fundamentals of analytical powerful computer-controlled instrumentation and the ability to perform highly chemistry) in 1894. He introduced complex analyses and measurements at extremely low concentrations. theoretical explanations of analyti- This text will teach you the fundamentals and give you the tools to tackle cal phenomena and equilibrium most analytical problems. Happy journey. For more on the evolution of the field, constants. see Reference 8. Qualitative tests may be performed by selective chemical reactions or with the use of instrumentation. The formation of a white precipitate when adding a solution of silver nitrate in dilute nitric acid to a dissolved sample indicates the presence of a halide. Certain chemical reactions will produce colors to indicate the presence of classes of organic compounds, for example, ketones. Infrared spectra will give “fingerprints” of organic compounds or their functional groups. A clear distinction should be made between the terms selective and specific: A selective reaction or test is one that can occur with other substances but exhibits Few analyses are specific. a degree of preference for the substance of interest. Selectivity may be achieved A specific reaction or test is one that occurs only with the substance of interest. through proper preparation and measurement. Unfortunately, very few reactions are truly specific but many exhibit selectivity. Selectivity may be also achieved by a number of strategies. Some examples are: 1.2 QUALITATIVE AND QUANTITATIVE ANALYSIS: WHAT DOES EACH TELL US? 5 Sample preparation (e.g., extractions, precipitation) Instrumentation (selective detectors) Target analyte derivatization (e.g., derivatize specific functional groups) Chromatography, which separates the sample constituents For quantitative analysis, the typical sample composition will often be known (we know that blood contains glucose), or else the analyst will need to perform a qualitative test prior to performing the more difficult quantitative analysis. Modern chemical measurement systems often exhibit sufficient selectivity that a quantitative measurement can also serve as a qualitative measurement. However, simple qualitative tests are usually more rapid and less expensive than quantitative procedures. Qualitative analysis has historically been composed of two fields: inorganic and organic. The former is usually covered in introductory chemistry courses, whereas the latter is best left until after the student has had a course in organic chemistry. In comparing qualitative versus quantitative analysis, consider, for example, the sequence of analytical procedures followed in testing for banned substances at the Olympic Games. The list of prohibited substances includes about 500 different active constituents: stimulants, steroids, beta-blockers, diuretics, narcotics, analgesics, local anesthetics, and sedatives. Some are detectable only as their metabolites. Many athletes must be tested rapidly, and it is not practical to perform a detailed quantitative analysis on each. There are three phases in the analysis: the fast-screening phase, the identification phase, and possible quantification. In the fast-screeni