Objective Objective
Introduction Introduction
Nuclear magnetic resonance (NMR) is a
Nuclear magnetic resonance (NMR) is a physical phenomenonphysical phenomenon in whichin which nucleinuclei in ain a magneticmagnetic field
field absorb and re-emitabsorb and re-emit electromagnetic radiation.electromagnetic radiation. This energy is at a specificThis energy is at a specific resonanceresonance frequencyfrequency which depends on the strength of the magnetic field and the magnetic properties of the
which depends on the strength of the magnetic field and the magnetic properties of the isotopeisotope of of the atoms; in practical applications, the frequency is similar to
the atoms; in practical applications, the frequency is similar to VHFVHF andand UHFUHF televisiontelevision broadcasts
broadcasts (60(60 – –1000 MHz). NMR allows the observation of specific1000 MHz). NMR allows the observation of specific quantumquantum mechanical
mechanical magneticmagnetic properties of theproperties of the atomic nucleus.atomic nucleus. Many scientific techniques exploit NMRMany scientific techniques exploit NMR phenomena to study
phenomena to study molecular physics,molecular physics, crystals,crystals, and non-crystalline materials throughand non-crystalline materials through NMRNMR spectroscopy.
spectroscopy. NMR is also routinely used in advancedNMR is also routinely used in advanced medical imagingmedical imaging techniques, such astechniques, such as in
in magnetic resonance imagingmagnetic resonance imaging (MRI).(MRI). All isotopes that contain an odd number of
All isotopes that contain an odd number of protonsprotons and/or of and/or of neutronsneutrons (see(see Isotope)Isotope) have anhave an intrinsic
intrinsic magnetic momentmagnetic moment andand angular momentum,angular momentum, in other words a nonzeroin other words a nonzero spin,spin, whilewhile all
all nuclidesnuclides with even numbers of both have a total spin of zero. The most commonly studied nucleiwith even numbers of both have a total spin of zero. The most commonly studied nuclei are
are 1H1H andand 13C,13C, although nuclei from isotopes of many other elementsalthough nuclei from isotopes of many other elements (e.g.
(e.g. 2H,2H, 6Li,6Li, 10B,10B, 11B,11B, 14N,14N, 15N,15N, 17O,17O, 19F,19F, 23Na,23Na, 29Si,29Si, 31P,31P, 35Cl,35Cl, 113Cd,113Cd, 129Xe,129Xe, 195Pt)195Pt) have beenhave been studied by high-field NMR spectroscopy as
studied by high-field NMR spectroscopy as well.well. A key feature of NMR is that the
A key feature of NMR is that the resonanceresonance frequency of a particular substance is directlyfrequency of a particular substance is directly proportional to the strength of the applied magnetic field. It is this feature that is exploited in proportional to the strength of the applied magnetic field. It is this feature that is exploited in imaging techniques; if a sample is placed in a non-uniform magnetic field then the resonance imaging techniques; if a sample is placed in a non-uniform magnetic field then the resonance frequencies of the sample's nuclei depend on where in the field they are located. Since the frequencies of the sample's nuclei depend on where in the field they are located. Since the resolution of the imaging technique
resolution of the imaging technique depends on the magnitude of magnetic fielddepends on the magnitude of magnetic field gradient,gradient, manymany efforts are made to develop increased field strength, often using
efforts are made to develop increased field strength, often using superconductors.superconductors. The effectivenessThe effectiveness of NMR can also be improved using
of NMR can also be improved using hyperpolarization,hyperpolarization, and/or using two-dimensional, three-and/or using two-dimensional, three-dimensional and higher-three-dimensional multi-frequency techniques.
dimensional and higher-dimensional multi-frequency techniques. The principle of NMR
The principle of NMR usually involves two sequential steps:usually involves two sequential steps:
The alignment (polarization) of the magnetic nuclear spins in an applied, constantThe alignment (polarization) of the magnetic nuclear spins in an applied, constant magneticmagnetic
field fieldHH00..
The perturbation of this alignment of the nuclear spins by employing an electro-magnetic,The perturbation of this alignment of the nuclear spins by employing an electro-magnetic,
usually radio frequency (RF)
usually radio frequency (RF) pulse. The required perturbing frequency is dependent upon thepulse. The required perturbing frequency is dependent upon the static magnetic field (
static magnetic field (HH00) and the nuclei of observation.) and the nuclei of observation.
The two fields are usually chosen to be
The two fields are usually chosen to be perpendicularperpendicular to each other as to each other as this maximizes the NMRthis maximizes the NMR signal strength. The resulting response by the total magnetization (
signal strength. The resulting response by the total magnetization (MM) of the nuclear spins is the) of the nuclear spins is the
phenomenon that is exploited in
phenomenon that is exploited in NMR spectroscopyNMR spectroscopy andand magnetic resonance imaging.magnetic resonance imaging. Both useBoth use intense applied magnetic fields (
intense applied magnetic fields (HH00) in order to achieve dispersion and very high stability to) in order to achieve dispersion and very high stability to
delive
deliverspectral resolution,rspectral resolution, the details of which are described bythe details of which are described by chemical shifts,chemical shifts, thethe Zeeman effect,Zeeman effect, and
and Knight shiftsKnight shifts (in metals).(in metals).
NMR phenomena are also utilized in
NMR phenomena are also utilized in low-field NMR,low-field NMR, NMR spectroscopy and MRI in the NMR spectroscopy and MRI in the Earth'sEarth's magnetic field (referred to as
magnetic field (referred to as Earth's field NMR)Earth's field NMR), and in several types of , and in several types of magnetometers.magnetometers. Spectroscopy is the study of the interaction of electromagnetic radiation with matter. Nuclear Spectroscopy is the study of the interaction of electromagnetic radiation with matter. Nuclear magnetic resonance spectroscopy is the use of
and biological properties of matter. As a consequence, NMR spectroscopy finds applications in
several areas of science. NMR spectroscopy is routinely used by chemists to study chemical structure using simple one-dimensional techniques. Two-dimensional techniques are used to determine the structure of more complicated molecules. These techniques are replacing x-ray crystallography for the determination of protein structure. Time domain NMR spectroscopic techniques are used to probe molecular dynamics in solutions. So lid state NMR spectroscopy is used to determine the molecular structure of solids. Other scientists have developed NMR methods of measuring diffusion coefficients.
The versatility of NMR makes it pervasive in the sciences. Scientists and students are discovering that knowledge of the science and technology of NMR is essential for applying, as well as
developing, new applications for it. Unfortunately many of the dynamic concepts of NMR
spectroscopy are difficult for the novice to understand when static diagrams in hard copy texts are used. The chapters in this hypertext book on NMR are designed in such a way to incorporate both static and dynamic figures with hypertext. This book presents a comprehensive picture of the basic principles necessary to begin using NMR spectroscopy, and it will provide you with an understanding of the principles of NMR from the microscopic, macroscopic, and system perspectives.
Procedure
Part A: determination of the spectrum of each component
1. 30mg of aspirin, phenacetin and caffeine was weighted in the different conical vial.
2. About 0.5ml of deuterated chloroform CDCl3 was transferred with clean, dry Pasteur pipet to the sample.
3. The conical vial was swirl to help dissolve the sample.
4. The sample should have completely dissolve after swirling the conical vial and a little more solvent was added, if necessary to dissolve the sample fully.
5. The solution was transferred to the NMR tube using a clean, dry Pasteur pipet.
6. Once the solution has been transferred to the NMR tube, use a clean pipet to add enough deuterated chloroform to bring the total solution height to about 4cm from the bottom. 7. Cap the NMR tube and make sure that the cap is on straight and tight.
8. Invert the NMR tube several times to mix the contents. 9. The sample is ready to record its NMR spectrum.
10. Insert the NMR tube into its holder and adjust the depth by using the gauge provided. 11. For cleaning purpose, transfer the sample into the same conical vial, partially refilled with
acetone using a Pasteur pipet, carefully replace the cap and invert the tube several times to rinse it.
12. Remove the acetone and repeat it for 2 times and put the NMR glass tube into an oven for approximately 2 hours.
Part B: analysis of the APC tablet
1. Weight approximately 100mg of the tablet. 2. Prepare the sample as described in part A
Part C: determining the H NMR spectra
1. The instructor will describe how to operate NMR spectrometer because the controls vary considerably, depending on the manufacturer, model of the instrument, type and software in the computer.
Result
1. CAFFEINE
Spectrum(ppm) Type of bond splitting Number of bond
1. 7.444 Amide RCONH singlet 1
2. 3.818 R2N-CH Singlet 3
3. 3.488 NC-CH Singlet 3
4. 3.335 R-C=O-C singlet 2
2. PHENACETIN
SPECTRUM TYPE OF BOND splitting NUMBER OF BOND
1. 7.873 AMIDE RCONH Triplet 1
2. 7.383 AROMATIC Singlet 2
3. 6.889 AROMATIC
Quartet
24. 4.005 PhOCH Double 2
5. 2.085 RCOCH Triplet 4
3. ASPIRIN
SPECTRUM TYPE OF BOND Splitting NUMBER OF BOND
1. 8.200 AROMATIC
Double
1 2. 7.669 AROMATIC Double 1 3. 7.443 AROMATIC Triplet 1 4. 7.281 AROMATIC Triplet 1 5. 2.465 RCOCH Singlet 3 4. UNKNOWNSPECTRUM TYPE OF BOND Splitting NUMBER OF BOND
1. 8.155 AROMATIC Double 1
2. 7.672 AROMATIC Double 1
3. 7.401 AROMATIC Triplet 1
4. 7.173 AROMATIC Triplet 1
DISCUSSION
In this experiment, we will use NMR to determine the present of photon and it type of bond because NMR is a physical phenomenon in which nuclei in a magnetic field absorb and
re-emit electromagnetic radiation. This energy is at a specific resonance frequency which depends on the strength of the magnetic field and the magnetic properties of the isotope of the atoms; in
practical applications, the frequency is similar to VHF and UHF television broadcasts (60 –1000 MHz). NMR allows the observation of specific quantum mechanical magnetic properties of the atomic nucleus. Many scientific techniques exploit NMR phenomena to study molecular physics, crystals, and non-crystalline materials through NMR spectroscopy
Some error might occur because NMR is very sensitive and can detect very fine structural component. Any contamination can cause false result and wrong analysis. NMR also can detect organic and inorganic, qualitative and quantitative, and versatile. However NMR is very
expensive
, time consuming and require long time to interpret spectra. In the result, number of spectra depend on the position of photon in the compound which will cause the variety of spectra as resultIn nuclear magnetic resonance (NMR) spectroscopy, the chemical shift is the resonant frequency of a nucleus relative to a standard. Often the position and number of chemical shifts are diagnostic of the structure of a molecule. Chemical shifts are also used to describe signals in other forms of
spectroscopy such as photoemission spectroscopy.
Some atomic nuclei possess a magnetic moment (nuclear spin), which gives rise to different energy levels and resonance frequencies in a magnetic field. The total magnetic field experienced by a nucleus includes local magnetic fields induced by currents of electrons in the molecular orbitals (note that electrons have a magnetic moment themselves). The electron distribution of the same type of nucleus (e.g. 1H,13C,15N) usually varies according to the local geometry (binding partners, bond lengths, angles between bonds, ...), and with it the local magnetic field at each nucleus. This is reflected in the spin energy levels (and resonance frequencies). The variations of nuclear magnetic resonance frequencies of the same kind of nucleus, due to variations in the electron distribution, is called the chemical shift. The size of the chemical shift is given with respect to a reference frequency or reference sample (see also chemical shift referencing), usually a molecule with a barely distorted electron distribution.
Conclusion
In conclusion, function of NMR and FTIR is same which is to detect the molecule present in the compound. Base on the result, unknown D have similar structure and position as aspirin, so we can conclude that compound D is aspirin.
Reference 1. Principle NMR, http://www.ch.ic.ac.uk/local/organic/nmr_principles.html, 2/6/2013, 11.31am. 2. Chemical shift NMR, http://en.wikipedia.org/wiki/Chemical_shift, 2/6/2013, 11.41am.
3. Nuclear Magnetic resonance,
http://en.wikipedia.org/wiki/Nuclear_magnetic_resonance,
2/6/2013, 11.45am.
4. Basic of NMR,
http://www.cis.rit.edu/htbooks/nmr/inside.htm,
2/6/2013, 11.55am.
5. Nuclear Magnetic resonance spectroscopy,
http://teaching.shu.ac.uk/hwb/chemistry/tutorials/molspec/nmr1.htm,
CHM 580
SPECTROCHEMICAL METHOD OF ANALYSIS
EXPERIMENT 2: ANALYSIS OF APC TABLET COMPONENT BY PROTON NMR
NAME : NORHIDAYU BT AZMI (2011214558)
GROUP MEMBER : NORHANIS HUSNA MD NADZARUDDIN (2011603436)
: KAIRUNISHA ABD RAJAN (2011729747)
: HANNISTHASIA JONNEY (2011983935)
INSTRUCTOR NAME : CIK SITI KARTIKA BT HAMDAN
LECTURER’S NAME : DR HALILA BT JASMANI
DATE OF EXPERIMENT : 29/4/2013
