CHROMATOGRAPHY Concepts and Contrasts

SECOND EDITION

James M. Miller Drew University

Madison, New Jersey

@ K E i C * E N C E A JOHN WILEY & SONS, INC., PUBLICATION

This Page Intentionally Left Blank

CHROMATOGRAPHY

This Page Intentionally Left Blank

CHROMATOGRAPHY Concepts and Contrasts

SECOND EDITION

James M. Miller Drew University

Madison, New Jersey

@ K E i C * E N C E A JOHN WILEY & SONS, INC., PUBLICATION

Copyright 0 2005 by John Wiley & Sons, Inc. All rights reserved

Published by John Wiley & Sons, Inc., Hoboken, New Jersey. Published simultaneously in Canada.

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Library of Congress Cataloging-in-Publication Data is available.

Miller, James M., 1933- Chromatography: concepts and contrasts / James M. Miller.-- 2nd ed.

Includes bibliographical reference and index. p. cm.

ISBN 0-471-47207-7 1. Chromatographic analysis. Title.

QD79.C4M55 2005 543'.8--dc22

2004003024

Printed in the United States of America

1 0 9 8 7 6 5 4 3 2 1

CONTENTS

Preface to Second Edition

Acknowledgments

Preface to the First Edition

Symbols, Abbreviations, and Acronyms

xiii

xv

xvii

xix

1 Impact of Industrial and Government Regulatory Practices on Analytical Chromatography 1

1.1 1.2

1.3

1.4 1.5

1.6

Locus of Chromatography in Chemical Industry / 3 Governmental Organizations / 4 National Institute of Standards and Technology

Food and Drug Administration (FDA) / 6 Environmental Protection Agency (EPA) / 11 Other organizations / 12 Nongovernmental Agencies / 12 Association of Analytical Communities International

ASTM International / 14 International Organization for Standardization

International Union of Pure and Applied Chemistry

Standards, Calibration, and NIST / 17 USP and Other Pharmacopoeias / 19 International Conference on Harmonization

International Guidelines for Analytical Laboratories / 22 Sources of Guidelines / 23 Method of Development, Validation, and Transfer / 24

(NIST) / 5

(AOAC) / 14

(ISO) / 16

(IUPAC) / 17

Guidlines / 21

V

Vi CONTENTS

Instrument Qualification / 29 21 CFR Part 11: Electronic Records and Electronic

Signatures / 30 1.7 Final Comments / 30

References / 31

2 Introduction to Chromatography

2.1 Brief History / 37 2.2 Definitions and Classsifications / 39

Separation / 39 Chromatography / 41 Chromatographic Symbols / 45 Normal Distribution / 51 Other Terms / 53

References / 64 2.3 Summary / 64

3 Band Broadening and Kinetics

3.1 Configurations of the Stationary Phase / 67 Characteristics of Column Packings / 68 Column Volume Characteristics / 73

Original Van Deemter Theory / 75 Other Rate Equations / 79 Van Deemter Plots / 83 Practical Consequences of the Rate Theory / 84 Reduced Rate Equation for HPLC (and GC) / 88 Redefinition of H / 90 References / 91

3.2 Rate Theory / 75

4 Physical Forces and Interactions

4.1 Intermolecular and Interionic Forces / 93 Sorption Isotherms / 94 Types of Forces / 96 Size Exclusion-Molecular Sieving / 100

Hildebrand’s Solubility Parameter / 104 Snyder’s Solvent Parameter / 104 References / 107

4.2 4.3 Some Models / 102

35

67

93

CONTENTS vii

5 Optimization and the Achievement of Separation

5.1 Kinetics and Zone Broadening / 109 5.2 Thermodynamics and Zone Migration / 111 5.2 Achievement of Separation / 111 5.4 Optimization of Separations / 112

References / 115

6 Comparisons Between Chromatographic Modes

109

117

6.1

6.2

6.3 6.4

Gas Chromatography Compared to Liquid Chromatography / 117 Gases Compared to Liquids / 118 Gas Compressibility in GC / 119 Permeability / 121 Efficiency and Speed / 122 Supercritical Fluids and Supercritical Fluid Chromatography / 124 Mobile-Phase Properties / 127 Stationary-Phase Properties / 130 Instrumentation / 130 Density Programming / 130 Applications / 131 Summary / 134 Reduced Parameters / 134 Columnar and Planar Configurations / 135 Peaks Compared to Bands / 135 Retardation Factors / 136 References / 139

7.1

7.2

7.3

7 Gas Chromatography 141

Early History, Theories, and Classifications / 141 Kovats Index / 144 Rohrschneider/McReynolds Constants / 146 Methods for Selecting Stationary Phases / 147 Instrumentation for Capillary GC / 148 Mobile Phase / 148 Injection Ports and Valves / 150 Open Tubular Columns / 153 Detectors / 157 Instrumentation for Packed-Column GC / 165 Packed-Column Injection Ports / 165 Packed Columns and Stationary Phases / 166

Viii CONTENTS

7.4

7.5

7.6

7.7

Stationary Phase / 168 Typical Liquids / 169 Temperature Effects / 170 Programmed Temperature GC / 172 Special Topics / 177 Fast GC / 177 Programmed Temperature Vaporizers and Large-Volume

Injections / 177 Gas Chromatography Analysis of Nonvolatiles / 178 Inorganic GC / 178 Simulated Distillation / 179 Summary and Evaluation / 179 References / 180

8 Liquid Chromatography in Columns

8.1

8.2

8.3

8.4

Introductory Classifications / 184 Phase Polarities: Normal Versus Reversed / 184 Liquid-Solid (LSC) Versus Liquid-Liquid (LLC)

Low-Pressure Versus High-pressure Liquid Chromatography / 186 Isocratic Versus Gradient Elution / 188 Stationary Phase / 190 Mobile Phase / 191 Classification of HPLC Modes / 194 Liquid-Solid Chromatography / 194 Bonded-Phase Chromatography / 198 Ion Exchange Chromatography / 213 Size Exclusion Chromatography / 226 Instrumentation / 234 Pumping Systems and the Mobile Phase / 234 Sampling / 238 Columns / 240 Detectors / 244 Reversed-Phase Method Development and Optimization / 249 Overlapping Resolution Mapping / 249 Phase Selection Diagrams / 254 Buffer Effects / 256 Gradient Elution / 256 Computer Methods / 258 Troubleshooting and Tips / 259

Chromatography / 185

183

CONTENTS iX

8.5

8.6

8.7

8.8

RP-HPLC Alternatives for the Pharmaceutical Industry / 261 Preparative LC / 262 Sample Cleanup / 263 Low-Pressure Preparative LC / 263 High-pressure Preparative LC / 26.5 Special Topics / 266 Performance Qualification Kit / 266 Pseudophase or Micellar LC / 267 Other Topics / 268 Summary and Evaluation / 268 References / 270

9 Quantitation: Detectors and Methods

9.1

9.2

9.3

Detectors / 278 Classification of Detectors / 278 Detector Characteristics / 285 Summary of Detector Terms / 295 Data Acquisition and Processing / 296 Peak Height versus Peak Area / 296 Measurement of Areas / 297 Sources of Error / 299 Quantitative Analysis / 299 Standards and Calibration / 299 Classification of Methods / 300 Concluding Comments / 305 References / 306

10 Chromatography with Mass Spectral Detection (GC/MS and LC/MS)

10.1 Basics of Mass Spectrometry / 310 Ion Sources / 311 Analyzers / 318 Other MS Topics / 322

10.2 Gas Chromatography/Mass Spectrometry / 323 10.3 Liquid Chromatography/Mass Spectrometry / 324 10.4 Other Hyphenated Methods / 326

Liquid Chromatography/Nuclear Magnetic Resonance / 327

10.5 Summary / 328 References / 328

277

309

X CONTENTS

11 Liquid Chromatography on Plane Surfaces

11.1 Paper Chromatography / 331 11.2 Thin-Layer Chromatography / 333

Manual TLC / 333 Instrumental TLC / 341

11.3 Other Topics / 347 Preparative TLC / 347 Multidimensional TLC / 347

References / 350 11.4 Literature Summary and Applications / 348

331

12 Qualitative Analysis

12.1 Retention Parameters / 353 Relative Retention Parameters / 355 Two-Column Plots / 355

Chemical Methods / 358 Instrumental Methods / 358 References / 362

12.2 Other Methods of Qualitative Analysis / 357

13 Capillary Electrophoresis and Capillary Electrochromatography

13.1 Principles of Electrophoresis / 366 Fundamental Equations / 366 Weak Acids and Bases / 367 Complex Formation / 369 Electrolyte Concentration / 369 Electroosmosis / 370 Diffusion / 370 Adsorption / 371

13.2 Zone Electrophoresis / 371 13.3 Capillary Electrophoresis / 372

Capillary Zone Electrophoresis / 376 Micellar Electrokinetic Chromatography / 380

References / 383 13.4 Capillary Electrochromatography / 380

14 Sample Preparation

14.1 Extraction / 390 Simple Liquid-Liquid Extraction / 391 Liquid-Solid Extraction / 402

353

365

387

CONTENTS Xi

Assisted Liquid-Solid Extraction / 402 Supercritical Fluid Extraction / 404 Solid-Phase Extraction / 405 Solid-Phase Microextraction / 407 Stir-Bar Sorptive Extraction / 410 Other Extraction Methods / 410 Headspace Methods / 410

14.2 Dialysis / 411 14.3 Derivatization / 412

Methods / 413 Examples / 415 References / 417

15 Special Applications

15.1 Multidimensional Chromatography / 423 Gas Chromatography/Gas Chromatography / 425 Liquid Chromatography/Gas Chromatography / 427 Liquid Chromatography/Liquid Chromatography / 431 Other Combinations / 432

Affinity Chromatography / 434 Proteins, Peptides, and Proteomics / 438 Other Large Biomolecules / 440 Hydrophobic Interaction Chromatography / 442

Stereochemical Nomenclature and Conventions / 443 Disastereoismeric Separations / 445 Chiral Stationary Phases / 446 Chiral Mobile Phases / 453 Additional Chiral Methods / 453

Other Chromatographic Methods / 454 Field-Flow Fractionation / 455 Microfludic Devices for Chromatography and

Electrophoresis (Lab-on-a-Chip) / 455 References / 456

15.2 Biological Applications / 433

15.3 Chiral Separations / 443

15.4 Other Topics / 454

423

16 Selection of a Method

16.1 Methods of Attack / 463

463

Xii CONTENTS

16.2 The Internet / 464 Literature Searching / 464 Other Sources of Information on the Internet / 465

16.3 Experimental Approach / 466 Volatile Samples / 468 Nonvolatile Samples / 468

References / 471 Some Internet Web Sites of Interest to

16.4 Summary / 471

Chromatographers / 472

Appendix A ICH Glossary

Appendix B

Index

475

479

485

PREFACE TO THE SECOND EDITION

This new, second edition has the same rationale, organization, objectives, and academic level as the first edition. It is based on the premise that chromatog- raphy (the concepts) should be described and taught in a unified manner that emphasizes the similarities and differences (the contrasts). The academic level remains at the third year undergraduate, and the subject of chromatog- raphy is built on fundamentals well-known to third-year students, topics like liquid-liquid extraction, ion exchange processes, and equilibrium theory. The text attempts to show the connections between these principles, already familiar to the students, and chromatography.

Even though chromatography has become a mature science, the material from the first edition was badly out of date. Many new developments made in the intervening 15 years needed to be added. The process of updating has also resulted in an expansion, in part by inclusion of more information about topics like multidimensional chromatography, chiral separations, mass spec- trometric detection, and biological applications. Liquid chromatography (LC) in columns is still the largest topic with coverage of normal and reversed phase systems, bonded phases and monolithic stationary phases, ion ex- change, size exclusion, and affinity chromatography. The emergence of capillary electrochromatography (CEC) from the combination of HPLC and capillary zone electrophoresis has necessitated a short introduction to elec- trophoresis. Further broadening of the coverage has resulted from a new chapter on sample preparation which includes many forms of extraction including solid phase extraction (SPE) and solid phase microextraction (SPME), among others. The overall result is a book that covers most of the separation methods used in the analytical laboratory today, so it could be useful in courses covering the wider field of separation science, not just chromatography.

Another addition is a unique new chapter on industrial and governmental regulatory practices. It introduces students to agencies like FDA, EPA, and NIST as well as the USP, ASTM, AOAC, ISO, ICH, and IUPAC. The

xiii

XiV PREFACE TO THE SECOND EDITION

information should be helpful in building a bridge between academe and the industrial/governmental workplace. Subjects defined and discussed include method development, method validation, instrument qualification, standard operating procedures (SOPS), and system suitability. This chapter has been placed first in the text, but for many, it should not be read first, at least not all of it. It has too many abbreviations and new topics. Rather it should serve as a reference chapter, being consulted many times in the study of chro- matography, and in the end, it may serve as a good summary of current chromatographic practice.

This book contains many acronyms and abbreviations that will tend to overwhelm students as they start to use the book. Unfortunately, that is the real-world experience, and rather than refrain from using them, I have attempted to minimize confusion by providing a complete listing beginning on page xix, accompanied by a comprehensive index. Also, these symbols and abbreviations are repeated often throughout the text for those who choose to read chapters out of the sequential order in which they are presented.

Complete coverage of chromatography is attempted, but space did not permit some topics to be described in depth; depth is provided in the form of references which can lead the reader to more information. The book includes nearly a thousand references and many Internet Web sites. By taking advantage of these additional sources of information, upperlevcl courses should find the text suitable for their use. It can serve as a framework and outline which is readily expanded and supplemented.

In the following Acknowledgments, I have named some colleagues to whom I am especially grateful, but I would be remiss if I did not salute all of those who have taught, mentored, and supported me during my career. Thanks to all of you.

JAMES M. MILLER

Madison, New Jersey September 2004

ACKNOWLEDGMENTS

There are many persons to whom I am indebted for their help in producing this publication. I can’t name all of them, but I want to single out a few. The staff at Wiley has been very cooperative and helpful, especially Heather Bergman. My special thanks go to a select few colleagues who reviewed this edition in every stage of development and made significant contributions to its content and accuracy. I am especially proud that three of them are former students and.alumni of Drew University. All are listed here and have my enthusiastic appreciation. They deserve the credit for the quality; any errors there may be in this monograph are mine, not theirs.

Judy P. Boehlert Boehlert Associates, LLC Park Ridge, New Jersey Member of USP’s Council of Experts, 2000-2005 Jonathan Crowther Ortho-Clinical Diagnostics Raritan, New Jersey John G. Hoogerheide Pfizer Analytical R & D, Pfizer, Inc. Kalamazoo, Michigan David Locke Department of Chemistry Queens College, CUNY Flushing, New York Ron Majors Agilent Technologies Wilmington, Delaware Harold McNair Department of Chemistry Virginia Tech Blacksburg, Virginia

xvi ACKNOWLEDGMENTS

Lee Polite Axion Analytical Laboratories Chicago, Illinois Vincent T. Remcho Department of Chemistry Oregon State University Corvallis, Oregon Joseph Sherma Department of Chemistry Lafayette College Easton, Pennsylvania

J.M.M

PREFACE TO THE FIRST EDITION

Chromatography has become the premier technique for separations and analyses. The three most important types of chromatography are gas chro- matography (GC), liquid chromatography in columns (LC), and thin-layer chromatography (TLC). Because of the large amount of information available about each of them, these individual techniques are often treated separately in monographs. However, they do share a common theoretical base, and the most efficient education of a novice would be a unified study. Furthermore, a scientist working with one of the techniques may need to switch to another one, and that could be more easily accomplished if he/she were acquainted with the theories common to the two techniques.

This monograph attempts a unified approach to chromatography and emphasizes the similarities and differences between the major divisions-GC, LC, and TLC. Thus the title is Chromatography: Concepts and Contrasts. In addition to the advantages mentioned above, the unified approach permits the use of one set of terms and symbols that should make learning easier. Another consequence of this approach is that the chapters covering the three main topics (GC, LC, TLC) do not stand alone; rather, they build on the introductory chapters, which cover the common principles. Hopefully, the book is short enough that the novice can afford the time to begin at the beginning and read through to the chapter that covers the information on the topic he/she is seeking.

The unified approach was taken in my earlier book, Separation Methods in Chemical Analysis, and some of the material in that book has been repeated. This monograph is more narrow in coverage, of course, and has been updated with the latest information on chromatography. It is an elementary introduction to the topic, but one that is quite comprehensive. In most cases, references are provided for further information, and this book should serve as a good reference text. It includes many practical operating hints. These are presented as evidence of the applicability of the theory and not as hints without rationales. Modern LC is the newest of the three techniques and the

xvii

XViii PREFACE TO THE FIRST EDITION

one requiring the most description, so Chapter 9 on LC is the longest one. Chapter 11 describes some special techniques, including chiral separations and derivatization. The final chapter, Chapter 12, provides some suggestions for selecting a chromatographic method.

Although the book is introductory and elementary, some background in chemistry will be needed in order to understand the chemical systems described. The better the reader’s background in the theory of chemistry, the more meaningful will be the sections that deal with chromatographic theory. A person with a minimal background will probably want to skip lightly over some of the theory, while a chemist may want to delve into the theory more deeply by reading some of the references provided. Only the most basic and necessary information is presented here in order to keep this book as simple as possible.

The book is intended to appeal to a wide audience-academic and industrial scientists, students in both formal coursework and informal private study, and chemists and nonchemists. The academic use is best suited for the undergraduate level, but with additional assignments from the references, it could probably be used at the lower graduate level. In industry, it could be used by scientists entering any of the fields of chromatography, or it could serve as an updating for those in the field.

I want to express my appreciation to a large number of people, beginning with the many scientists on whose work I have drawn in the preparation of this monograph. Many of them have taken time to communicate with me privately and I appreciate their kind efforts. Several colleagues have read parts of the manuscript and offered useful suggestions, and I am deeply indebted to them. Thanks also to my students, at Drew and elsewhere, who suffered with early versions of the manuscript and offered helpful criticisms. Special thanks for sabbatical support go to Drew University and Sandoz, Inc.

JAMES M. MILLER

Madison, New Jersey November 1987

SY M BOLS, ABBREVIATIONS, AND ACRONYMS

A

A, As AC ACN ACS

ALSSA A D

ANDA AND1 AOAC APHA API ASEGO ASTM

AWWA BP, BPC C CBER

ccc CD CDER

CDC CDS CE CEC

Area (Peak area) Cross-sectional area (of a column or tube) Surface area of an adsorbent Affinity chromatography; sometimes also HPAC Acetonitrile American Chemical Society Analog-to-digital Analytical and Life Science Systems Association (formerly Analytical Instrument Association) Abbreviated new drug application Analytical Data Exchange Association of Analytical Communities International American Public Health Association Atmospheric pressure ionization (MS) Accelerated solvent extraction ASTM International, formerly American Society for Test- ing & Materials American Water Works Association Bonded phase; bonded phase chromatography Concentration, usually molar, M Center for Biologics Evaluation and Research (Division of FDA) Countercurrent chromatography Cyclodextrin Center for Drug Evaluation and Research (Division of FDA) Centers for Disease Control and Prevention Chromatography data system Capillary electrophoresis Capillary electrochromatography

xix

XX SYMBOLS, ABBREVIATIONS, AND ACRONYMS

CFR Code of Federal Regulations CGMP: cGMP Current good manufacturing practice (GMP is used in this

CI CITAC

CRM CRV CSP CSTL

CVM CZE D

d

4

d f dP

DAD

DL DQ E P

Ea

ECD EI EKC ELSD EOF EPA EPC ESI F

f FDA FFF

book for CGMP and GMP) Chemical ionization (MS) Cooperation on International Traceability in Analytical Chemistry Certified reference material Critical value Chiral stationary phase Chemical Science and Technology Laboratory (Division of NIST) Center for Veterinary Medicine (Division of FDA) Capillary zone electrophoresis Diffusion coefficient; for example D,, diff. coeff. for a solute in a liquid or minimum detectability Distance between two peak maxima (in resolution equa- tion) Diameter of a column (inside) Diode array detector Film thickness Diameter of a particle (of stationary phase or solid sup- port) Detection limit Design qualification Peak height or electric field strength (voltage) Free energy at constant V and T Surface energy of an adsorbent (see Snyder solvent param- eter) Electron capture detector or electrochemical detector Electron impact ionization (MS) Electrokinetic chromatography Evaporative light scattering detector Electroosmotic flow Environmental Protection Agency Electronic pressure control (GC) Electrospray ionization (MS) Flow rate: F, at outlet; F, corrected outlet flow; F, average corrected outlet flow Detector response factor Food and Drug Administration Field flow fractionation

SYMBOLS, ABBREVIATIONS, AND ACRONYMS xxi

FFPC FID FPD FR FTIR GAMP GC GGP GLC GLP GMP GPO GSC GXP ,G 27 H HIC HILIC HPLC HPTLC HS h I I IC ICH i.d. IEC IIC IPC

IQ IR IS I S 0 ISRP IUPAC

j K , Ke,

Forced flow planar chromatography (TLC) Flame ionization detector Flame photometric detector Federal Register Fourier transform infrared spectroscopy Good automated manufacturing practice Gas chromatography Good guidance practices (of the FDA) Gas-liquid chromatography Good laboratory practice Good manufacturing practice Government printing office Gas-solid chromatography Any or all of the good practices Gibbs free energy at constant P and T Enthalpy Plate height or peak dispersivity; formerly HETP Hydrophobic interaction chromatography Hydrophilic interaction chromatography High performance liquid chromatography High performance thin layer chromatography Headspace; headspace sampling Reduced plate height Retention index of Kovats; also sometimes A1 Ionic strength Ion chromatography International Conference on Harmonization Inside diameter (of a column or tube) Ion exchange chromatography Ion interaction chromatography Ion pair chromatography; often called IIC, ion interaction chromatography Installation qualification Infrared spectroscopy Internal standard International Organization for Standardization Internal surface reversed phase supports International Union of Pure and Applied Chemistry Pressure correction factor (in GC) Acid ionization constant Constant; equilibrium constant

xxii SYMBOLS, ABBREVIATIONS, AND ACRONYMS

Kc KP k L 1

LC

LIMS LLC LLE LLME

LOD LOQ LSC LSE LVI MAE MDQ MDV MEKC MIP MN MP MRA MS MSD MW MWCO N N

Neff N i i m

NDA NF NIOSH NIST NMR NPD NPLC

Distribution constant Partition constant Retention factor Length, for example, column length Distance from one end of a capillary to the detector window Liquid chromatography; sometimes used to refer to low pressure LC Laboratory information management system Liquid-liquid chromatography Liquid-liquid extraction Liquid-liquid microextraction; also called LPME, SDME, and SME Limit of detection Limit of quantitation Liquid-solid chromatography Liquid-solid extraction Large volume injection (GC) Microwave assisted extraction Minimum detectable quantity Minimum detectable value Micellar electrokinetic chromatography Molecular imprint polymers Number average molecular weight Mobile phase Mutual recognition arrangement Mass spectrometry Mass selective detector (MS) Molecular weight (mass) Molecular weight cut off Plate number Noise (detector) Effective plate number Plate number limit New drug application National Formulary National Institute of Occupational Safety and Health National Institute of Standards and Technology Nuclear magnetic resonance (spectrometry) Nitrogen-phosphorus detector Normal phase liquid chromatography

SYMBOLS, ABBREVIATIONS, AND ACRONYMS xxiii

NTIS 0.d. ODS OECD 00s OPLC OQ ORD ORM OSHA OT ov P P'

P

PAGE PAH PC PDMS PF PFE

P O

PDA

PH PK PLOT

PPb PPm PQ psi PTGC PTV

P W

12 4 QA QC QL YZ R

National Technical Information Service Outside diameter (of column or tube) Octadecylsilyl Organization for Economic Cooperation and Development Out of specification Overpressurized layer chromatography (TLC) Operational qualification Office of research and development Overlapping resolution mapping Occupational Safety and Health Administration Open tubular (type of column) Ohio Valley Speciality Chemical (line of GC stat. phases) Pressure; Pi, inlet pressure; Po, outlet pressure Polarity index Partial pressure Vapor pressure, at equilibrium Polyacrylamide gel electrophoresis Polycyclic aromatic hydrocarbon Paper chromatography or personal computer Polydimethylsiloxane (polymer class) Pharmacopeial Forum Pressurized fluid extraction, also called accelerated solvent extraction (ASE) Photodiode array (detector) Acidity scale; - log a H +

Porous-layer open tubular (column) Parts per billion Parts per million Performance qualification Pounds per square inch (pressure) Programmed temperature gas chromatography Programmed temperature vaporization Vapor pressure of water Fraction extracted Configuration factor (in rate equation) Quality assurance Quality control Quantitation Limit Gas constant Retardation factor (columns)

- logK

XXiV SYMBOLS, ABBREVIATIONS, AND ACRONYMS

r RAM R & D

RF R M

RS RRF

rc RI RM RPLC RSD RTIL S S"

SBSE SCOT SDS SEC SFC SFE SIM SN SOP SP SPE SPME SRM ss STP T T' t TCD

t D

THF TF TFA TIC TLC

Radius Restricted access media Research & Development Retardation factor (TLC) Martin retention parameter Relative response factor (for detectors) Resolution Radius of a column (inside) Refractive index (detector) Reference material Reversed phase liquid chromatography Relative standard deviation Room temperature ionic liquids Sensitivity (of a detector) Adsorption energy of a solute (see Snyder solvent parame- ter) Stir bar sorptive extraction Support-coated open tubular (column) Sodium dodecylsulfate Size exclusion chromatography Supercritical fluid chromatography Supercritical fluid extraction Single ion monitoring (MS) Separation number (see TZ) Standard operating procedure Stationary phase Solid phase extraction Solid phase microextraction Standard reference material System suitability Special technical publication (of ASTM) Temperature Significant temperature (in PTGC) Time Thermal conductivity detector Dwell time (LC) Tetrahydrofuran Tailing factor Trifluoroacetic acid Total ion chromatogram (MS) Thin-layer chromatography

SYMBOLS, ABBREVIATIONS, AND ACRONYMS XXV

t M

TOF

t R

t k TSI TZ

uc USA USDA USP USP/NF uv UV/Vis V V

U

v, VD

VM

V N

VR VR v; VS

K S

VWD

UEOF

'ion

W

U

w b

w h

Wi

WCOT WEF X Z

Hold-up time Time of flight (mass spectrometer) Retention time Adjusted retention time Thermospray ionization (MS) Trennzahl number Velocity of the mobile phase; u F = velocity of MP front Unified chromatography United States of America United States Department of Agriculture United States Pharmacopeia United States Pharmacopeia/National Formulary Ultraviolet; ultraviolet absorption detector Ultraviolet/visible (spectrophometry) Volume or voltage Molal volume Adsorbent surface volume (see Snyder solvent parameter) Dwell volume (LC) Volume of the mobile phase; hold-up volume; V,, volume of MP gas; V,, volume of MP liquid (also volume of SP liquid) Net retention volume Retention volume Adjusted retention volume Corrected retention volume (GC) Volume of the stationary phase; VL, volume of SP liquid; Vs, volume of SP solid Volume of solid support Variable wavelength detector Velocity of an analyte Electroosmotic flow velocity Electrophoretic velocity of an ionized analyte Weight; W, is the weight of an unknown; etc. Width of a peak at the base Width of a peak at half-height Width of a peak at the inflection point Wall-coated open tubular (column) Water Environment Federation Mole fraction Charge on an ion

XXVi SYMBOLS, ABBREVIATIONS, AND ACRONYMS

a

P Y

6

& O

e

YA

&

77

K

L

h

P pTAS

P i o n

P

v

0-

a 2 r

cp a) * 5 w

Separation factor Phase volume ratio Surface tension Activity coefficient for analyte A Hildebrand solubility parameter Porosity Snyder solvent parameter Viscosity Contact angle (in TLC) Permeability Dielectric constant Packing characteristic (in rate equation) or Wavelength (of a UV/Vis spectrometer) Dipole moment Micro total analysis system Electrophoretic ion mobility Reduced velocity Polarizability Standard deviation or quarter-zone width Variance Time constant (detector) Volume fraction (Hildebrand solubility parameter) Flow resistance parameter Obstruction factor (rate equation) Packing factor (rate equation) Zeta potential

IMPACT OF INDUSTRIAL AND GOVERNMENTAL

REG U LATORY PRACTl C ES ON ANALYTICAL

CHROMATOGRAPHY

Chromatography is a proven method for separating complex samples into their constituent parts, and it is undoubtedly the most important procedure for isolating and purifying chemicals. Using data from the first half of 2003, Ryan estimated that nearly 5% of all chemical research in 2003 would involve chromatography. '

In addition, most chromatographic instrumentation is equipped with de- tectors, making chromatographs true instruments, devices capable of making measurements. Consequently, this monograph will deal not only with the principles of chromatography but also with the practice of quantitative analysis. It is this latter subject that has been greatly influenced by both industry and the federal government because of the need for standards and standardization that go hand-in-hand with governmental regulation. In the modern world, these issues extend to foreign countries as well and have given rise to international organizations and guidances/regulations that need to be recognized by chromatographers worldwide. Since much important informa- tion is available on the Internet, all scientists need to be knowledgeable about its retrieval and its impact on their work. In addition, much effort is being made internationally to provide a cooperative and harmonized ap- proach to analysis and analytical method development. Although this book is

Chrornutogruphy: Concepts und Contrusts, Second Edition. ISBN 0-471-47207-7 0 2005 John Wiley & Sons, Inc.

By James M. Miller

1

2 IMPACT OF INDUSTRIAL AND GOVERNMENTAL REGULATORY PRACTICES

written from the perspective of chromatographers in the United States, the principles are applicable internationally, and scientists would be well advised to recognize that fact and become aware of the developments outside their own countries.

Fortunately, the fundamental principles of chromatography and analytical chemistry in general are the same in academia, industry, and government, of course. Their common objective is to perform laboratory tests and proce- dures that are based on sound scientific principles. However, some industries operate under more stringent controls than others. For example, the pharma- ceutical industry in the United States is regulated by the Food and Drug Administration (FDA), which enforces federal regulations known as the Current Good Manufacturing Practices (CGMPs)?. These regulations were promulgated to ensure the safety and efficacy of drugs by setting forth minimum standards for manufacturing and testing. The GMPs are not prescriptive and, therefore, they have been supplemented by FDA guidance documents that provide more specific details on complying with the regula- tions. These guidances provide insight for the practice of good chromatogra- phy in all venues where analytical chemistry is performed, in the United States and abroad. While it is true that European and Asian counterparts are similarly regulated by their respective agencies, the fundamental analytical principles are the same and are becoming internationally codified.

Because these special regulations and guidances are often omitted from academic courses,' this chapter is presented to guide informed readers as they proceed to industrial and governmental employment. It also serves as a general introduction to quantitative analysis practices in chromatography by presenting and summarizing some basics of chromatographic measurement. This chapter examines:

The organization of analytical chemists in a typical industrial corpora-

The organization and regulatory agencies of the U.S. government and of

The effect of FDA regulation on the pharmaceutical practices in the

Some international guidelines for analytical chemistry in general and

tion

nongovernmental agencies

laboratory

analytical chromatography in particular.

*The official title of the FDA regulations includes the word Current so the abbreviation should be CGMP. Howevcr, some authors use ii lowercasc c and call them the cGMPs, and others shorten the name to just GMP. For simplicity, we will use GMP in most cases.