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Library of Congress Cataloging-in-Publication Data:

Silva Elipe, Maria Victoria, 1963-

LC-NMR and other hyphenated NMR techniques: overview and applications /

Maria Victoria Silva Elipe.

p. cm.

Includes bibliographical references and index.

ISBN 978-0-470-54834-9 (hardback)

1. Nuclear magnetic resonance spectroscopy–Industrial applications.

2. Organic compounds–Analysis. 3. Drug development. I. Title.

QD96.N8S54 2012

543′.66–dc23

2011018343

To my parents, Joaquin Silva Garcia and Maria Elipe Ruiz,
for their love, dedication, and memories that will last a lifetime.

To my husband, Regnar Llego Madarang, and my children,
Eva Silva Madarang and Regnar Silva Madarang, for their love.

Preface

Since the subject of nuclear magnetic resonance (NMR) was awarded its first Nobel Prize in 1952 due to its successful detection by Bloch and Purcell in 1945, the technology and its applications have developed tremendously. The first two decades were focused on technical developments of instrumentation and methodologies to apply to the structure determination of compounds. During the late 1970s, several research groups developed modifications of NMR probes to convert them to an online mode for the analysis of sample mixtures. However, with the hardware and software technology available at that time, it was difficult to hyphenate high-performance liquid chromatography (HPLC) and NMR to perform those analyses. During the past two decades, interest in sample mixture analysis and screening methods has been the driver for the latest developments and applications of hyphenated analytical techniques with NMR. Improvements in solvent suppression NMR techniques have facilitated the coupling to NMR of HPLC with reversed-phase columns, for what is known today as LC-NMR. Further technological developments have also supported the hyphenation of mass spectrometry (MS) to LC-NMR as LC-MS-NMR. In addition, other analytical separation techniques have been hyphenated to NMR. However, the only ones commercially available and commonly used are capillary HPLC (capLC) as capLC-NMR and solid-phase extraction (SPE) as SPE-NMR, including SPE hyphenated to MS-NMR as SPE-MS-NMR. Many laboratories in industry and academia have NMR as a hyphenated technique as part of their instrumentation to solve structural problems. This technology has become an important option for complex analysis.

The aim of this book is to provide an overview of the applications of hyphenated NMR techniques in industry and academia. The book is focused on understanding the pros and cons of NMR as a hyphenated and a nonhyphenated technique for the structural determination analysis of samples as organic materials. The purpose of the basic overview of the main concepts for structural elucidation by NMR and technical issues for online NMR is to facilitate an understanding of the pros and cons of the technique. A major emphasis of the book is on the application of hyphenated NMR in industry and academia. For completeness, the book has a chapter dedicated to the historical development of hyphenated NMR techniques, and another chapter focused on a comparison of other methodologies used to analyze sample mixtures.

The book begins with a description of basic NMR concepts for the structural elucidation of organic compounds, the historical development of NMR and hyphenated NMR in the structural elucidation world, followed by applications of hyphenated NMR as LC-NMR and LC-MS-NMR in industry and academia, such as to natural products, degradation products, impurity characterization, drug metabolism, food analysis, drug discovery, polymers, and others. Another chapter is dedicated to other analytical separation techniques hyphenated with NMR and MS-NMR, with special emphasis on capillary capLC and SPE due to be available commercially, and their applications compared to the other hyphenated NMR techniques. A special chapter is directed at understanding the applications of NMR online and off-line for structure elucidation, chiral analysis, in situ reaction monitoring, and analysis of sample mixtures by other NMR methodologies.

The audience for this book includes scientists in industry and academia who work and analyze complex sample mixtures in the areas of organic chemistry, medicinal chemistry, process chemistry, analytical chemistry, drug metabolism, separation science, natural products, chemical engineering, and others. In addition, the book contains the fundamentals of NMR and applications of hyphenated NMR techniques for college instructors to use as a complementary textbook for undergraduate and, especially, for graduate courses. The book is an excellent source of information and references for NMR basics, especially for applications of hyphenated NMR in industry and academia. The book also contains updated information on the latest advancements and applications of LC-NMR and other analytical techniques hyphenated with NMR focused on structural elucidation as of early 2011. The approach is based on explaining the basic pros and cons of the technique in a practical way, to make it easier for nonexperts in the field to understand the technology. Examples are provided, illustrated with figures and detailed explanations. Other books targeting those concepts have been used as reference material.

Previous to this book, I wrote some review articles and a book chapter. I gratefully acknowledge Elsevier for permitting me to use materials from one of the review articles [M.V. Silva Elipe, Advantages and Disadvantages of Nuclear Magnetic Resonance Spectroscopy as Hyphenated Technique, Anal. Chim. Acta 497 (2003), 1–25]. My sincere gratitude to Dr. Ray Bakhtiar (Drug Metabolism of MRL at Rahway) and Dr. Byron H. Arison (currently retired but previously at Drug Metabolism of MRL at Rahway) for their interest, support, and encouragement through constructive discussions, and to D. Knapp and U. Parikh (Medicinal Chemistry of MRL at Rahway) for technical help in online connection of radioactivity and MS detectors to an LC-NMR system. I am especially thankful to my father, Joaquin Silva Garcia, and my mother, Maria Elipe Ruiz, for their encouragement, love, and dedication to their children (the author and her siblings, Pedro Luis Silva Elipe and Maria Eva Silva Elipe). Last but not least, I thank my husband, Regnar Llego Madarang, for his support, and my children, Eva Silva Madarang and Regnar Silva Madarang, for their patience and support. There are not enough words to express my appreciation.

Maria Victoria Silva Elipe

Thousand Oaks, California

Abbreviations, Symbols, and Units

ACN | acetonitrile
ACN-d3 | deuterated acetonitrile
API | atmospheric pressure ionization, active principal ingredient
APCI | atmospheric pressure chemical ionization
B | applied magnetic field along x or y axis
Beff | effective magnetic field
bd | broad doublet
B₀ | applied magnetic field along z axis
bs | broad singlet
bt | broad triplet
°C | degree Celsius or centigrade
capLC | capillary liquid chromatography
CAT | computer of averaging transients
CD | circular dichroism
CD₃CN | deuterated acetonitrile
CD₃OD | deuterated methanol
CE | capillary electrophoresis
CEC | capillary electrochromatography
CHPLC | capillary high-performace liquid chromatography
CI | chemical ionization
cIPT | capillary isotachophoresis
cm | centimeter
COSY | correlation spectroscopy
CW | continuous wave
CYP | cytochrome P450 enzyme
CZE | capillary zone electrophoresis
d | doublet
D | deuterium
1D | one dimension
2D | two dimensions
Da | dalton
dd | doublet of doublets
ddd | doublet of doublet of doublets
DEPT | distortionless enhancement by polarization transfer
DEPT-135 | distortionless enhancement by polarization transfer at 135° angle
DEPTQ | distortionless enhancement by polarization transfer, including the detection of quaternary nuclei
DI | direct injection
DMSO-d6 | dimethyl-d6 sulfoxide
DNP | dynamic nuclear polarization
D₂O | deuterated water or deuterium oxide
DOSY | diffusion-ordered spectroscopy
DQF | double quantum filter
dt | doublet of triples
E | energy
EOF | electroosmotic flow
EPR | electron paramagnetic resonance
ERETIC | electronic reference to access in vivo concentrations
ESI | electrospray ionization
FIA | flow injection analysis
FID | free induction decay
FT | Fourier transform
GC | gas chromatography
GHz | gigahertz
GPC | gel permeation chromatography
GSH | glutathione
h | Planck's constant
HETCOR | heteronuclear correlation spectroscopy
HMBC | heteronuclear multiple bond correlation
HMQC | heteronuclear multiple quantum correlation
HOD | residual water from deuterated solvents
HPLC | high-performance liquid chromatography
HSQC | heteronuclear single quantum coherence
Hz | hertz
I | nuclear spin
ICH | International Conference of Harmonisation of Technical Requirements
INADEQUATE | incredible natural abundance double quantum transfer experiment
INEPT | intensive nuclei enhanced by polarization transfer
IR | infrared
J | coupling constant
k | Boltzmann constant
K | kelvin
LC | liquid chromatography
LOD | limit of detection
μL | microliter
mL | milliliter
m | meter; multiplet
mm | millimeter
M | molar; molecular ion
mM | millimolar
μM | micromolar
ms | millisecond
MEK | methyl ethyl ketone
MHz | megahertz
MS | mass spectrometry
MSPD | matrix solid-phase dispersion
MW | molecular weight
m/z | mass over charge
NMR | nuclear magnetic resonance
NOE | nuclear Overhauser effect
NOESY | nuclear Overhauser effect spectroscopy
oct | octet
PAT | process analytical technology
PCA | principal components analysis
pCEC | pressured capillary electrochromatography
PEEK | poly(ether ether ketone)
PKDM | pharmacokinetics drug metabolism
ppm | part per million
q | quartet
qNMR | quantitation NMR
qui | quintet
RDC | residual dipolar coupling
RF | radio frequency
ROE | rotating frame Overhauser effect
ROESY | rotating frame Overhauser effect spectroscopy
RT | room temperature
s | seconds; singlet
SEC | size-exclusion chromatography
SFE | supercritical fluid extraction
SFC | supercritical fluid chromatography
S/N | signal-to-noise ratio
SPE | solid-phase extraction
spt | septet
sxt | sextet
t | triplet
T | temperature, tesla
T₁ | spin-lattice or longitudinal relaxation time
T₂ | spin-spin or transverse relaxation time
td | triplet of doublets
TIC | total ion chromatogram
TMS | tetramethylsilane
TOCSY | total correlation spectroscopy
UF | ultrafast
UV | ultraviolet
WET | water suppression enhanced through T₁ effects
γ | gyromagnetic ratio
δ | chemical shift
ν | frequency
σ | shielding constant
τc | correlation time
ω₀ | Lamour frequency

Chapter 1

Basic Concepts of NMR Spectroscopy

1.1 Introduction

Nuclear magnetic resonance, known widely as NMR spectroscopy, is a powerful technique applied extensively to the structural elucidation of organic compounds. Since its discovery in the early twentieth century, NMR has been in wide use while evolving to what it is today. Understanding the basic concepts in interpreting NMR spectra is fundamental for the structural analysis of organic compounds. In this chapter we introduce the reader to the basic concepts of NMR data interpretation. The major topics discussed provide information on the chemical structures of organic compounds, and the connectivities and correlations of atoms through bonds and space. Understanding how to interpret NMR data from hyphenated and nonhyphenated NMR instruments is essential. This chapter is not intended to explain the theory of NMR with mathematical equations and algorithms, as these can be found elsewhere [1–4]. In addition, more detailed information from a practical perspective with less focus on mathematical algorithms is available in the literature [5–16].

Lesen Sie weiter in der vollständigen Ausgabe!

Lesen Sie weiter in der vollständigen Ausgabe!

Lesen Sie weiter in der vollständigen Ausgabe!

Lesen Sie weiter in der vollständigen Ausgabe!

Lesen Sie weiter in der vollständigen Ausgabe!

Lesen Sie weiter in der vollständigen Ausgabe!

Lesen Sie weiter in der vollständigen Ausgabe!