UNIVERSITYOENAPOLL"FEDERICOII"AGRICULTURALFEACULTYSoil ChemistryDepartmentMolecular characterization of soil humic acidafter recycled organic biomass additionDr. Spaccini Riccardo
UNIVERSITY OF NAPOLI “FEDERICO II” AGRICULTURAL FACULTY Soil Chemistry Department Dr. Spaccini Riccardo Molecular characterization of soil humic acid after recycled organic biomass addition
OBJECTIVEMolecular characterization of soil humic acids extracted after soiltreatments with recycled organic biomassbulkcharacterizationSpectroscopicanalysesCPMAS13CNMR (CrossPolarizationMagicAngleSpinning)molecularcharacterizationSequential extractionsGasCromatografyMassSpectrometryIREEA-NanjingAgricultural University/ April 2008
Molecular characterization of soil humic acids extracted after soil treatments with recycled organic biomass • IR-DRIFT (Diffuse Reflectance Infrared Fourier Transform) GasCromatografy MassSpectrometry • Sequential extractions • CPMAS13CNMR (CrossPolarizationMagicAngleSpinning) Spectroscopic analyses: off-line pyrolysis with TetraMethylAmmoniumHydroxide (TMAH termochemolysis) bulk characterization molecular characterization OBJECTIVE IREEA-Nanjing Agricultural University/ April 2008
NMR spectroscopya spinning nucleus, with magnetic properties, ('Hi3C, 31P, 15N) possess a magnetic momentuuonce immersed in external strong field (B.) the magnetic momentof nuclei with a spin quantum number I = /2 will be lined up to B.withagainstorBo0Z0thereby assuming a circular path around the main z axis called precessionwith an angolar frequency (larmor frequency) tipical of each nucleusIREEA-NanjingAgricultural University/ April 2008
a spinning nucleus, with magnetic properties, (1H, 13C, 31P, 15N) possess a magnetic moment μ or thereby assuming a circular path around the main z axis called precession with an angolar frequency ω (larmor frequency) tipical of each nucleus with z ω against z ω once immersed in external strong field (B0) the magnetic moment of nuclei with a spin quantum number I = ½ will be lined up to B0 B0 NMR spectroscopy μ IREEA-Nanjing Agricultural University/ April 2008
4the various nuclei (e.g.'H) will have a randomdistribution along z axis;xfollowing the Boltzman distribution theynuclei aligned with BO have lower energyand are in slight excessMZoperating a vectorial sum, thetrasversal (X and Y)Xcomponents will cancel outyleaving a resultant vector Mrepresenting the total magneticmoment of those nucleiIREEA-NanjingAgricultural University/April 2008
y x z y x z the various nuclei (e.g.1H) will have a random distribution along z axis; operating a vectorial sum, the trasversal (X and Y) components will cancel out, leaving a resultant vector M representing the total magnetic moment of those nuclei following the Boltzman distribution the nuclei aligned with B0 have lower energy and are in slight excess M IREEA-Nanjing Agricultural University/ April 2008
Izthe application of a radiofrequency B1on the X axis with a frequency = to theXLarmor (o) frequency of the nuclei(resonance)ywill equalize the nuclei distribution alongB1Z+ and Z- directions.2.changing at the same time the phase ofXof sigular spinning nucleus that will beygrasped towards the Y- direction(phase coherence)B111IREEA-NanjingAgricultural University/April 2008
y x z the application of a radiofrequency B1 on the X axis with a frequency = to the Larmor (ω) frequency of the nuclei (resonance) will equalize the nuclei distribution along Z+ and Z- directions. .changing at the same time the phase of of sigular spinning nucleus that will be grasped towards the Y- direction (phase coherence) B1 y x z B1 IREEA-Nanjing Agricultural University/ April 2008
ZZthe result will be a torqueof the magnetic moment-MzM from Z to Y with a 011angley1yB11MyB11111IZending the Bl application will result in arelaxationprocessXthe nuclei return to the equilibriumyrestoring the initial distributionthisrelaxationisdetectedandproduce theNMR signalIIREEA-NanjingAgricultural University/April 2008
y x z Mz the result will be a torque of the magnetic moment M from Z to Y with a θ angle ending the B1 application will result in a relaxation process the nuclei return to the equilibrium restoring the initial distribution y x z B1 y x z My θ B1 this relaxation is detected this relaxation is detected and produce the NMR produce the NMR signal IREEA-Nanjing Agricultural University/ April 2008
the relaxation is characterized by energy emission and a loss of phasecoherenceboth processes are detected and produce the NMR signaleach nucleus will relax with a circular pathZthereby producing a sinuoisodal FID (freeinductiondecay)XthisissignalInt.bycharacterizedIntensityversusTime domain-Timethemathematical FourierTransformation will convertthe FID in a classical NMRsignalIntensityversusfrequenciesFrequency domainIREEA-NanjingAgriculturalUniversity/April2008
the relaxation is characterized by energy emission and a loss of phase coherence both processes are detected and produce the NMR signal y x z each nucleus will relax with a circular path thereby producing a sinuoisodal FID (freeinductiondecay) this signal is characterized by Intensity versus Time domain Int. Time the mathematical Fourier Transformation will convert the FID in a classical NMR signal Intensity versus Frequency domain IREEA-Nanjing Agricultural University/ April 2008 frequencies
the intensity of radiofrequency Bl (MHz) is related to the intensity ofBO field (Tesla)B0=9.4 Tesla B1= 400 MHzB0=14.1 Tesla B1= 600 MHzthis affects the amplitude of resonance frequencies that willchange in different instrumentsB1=300Mhz signal=450HzB1=60Mhz2 signal=90Hzin order to compare the response of different instruments thefrequency resonances are divided for the applied B1 fieldHz/MHzthereby expressing the resonances of the nuclei inPpm (part per million)90Hz/60MHz x 106 1.5 ppm450Hz/300MHzx1061.5ppmIREEA-Nanjing Agricultural University/ April 2008
the intensity of radiofrequency B1 (MHz) is related to the intensity of B0 field (Tesla) this affects the amplitude of resonance frequencies that will change in different instruments B0=9.4 Tesla B1= 400 MHz B0=14.1 Tesla B1= 600 MHz in order to compare the response of different instruments the frequency resonances are divided for the applied B1 field Hz/MHz thereby expressing the resonances of the nuclei in Ppm (part per million) B1=60Mhz signal= 90Hz B1=300Mhz signal= 450Hz 90Hz/60MHz x 106 1.5 ppm 450Hz/300MHz x 106 1.5 ppm IREEA-Nanjing Agricultural University/ April 2008
?the electronic environment of each atom (for instance chemicalbond) will affects its magnetic properties (shielding effect) therebymodifying the frequency resonance of different atoms (chemicalshift)·this property allows to distinguish the different nuclei in theorganic molecule (aromatic. phenolic, aliphatic etc.)FID of 2-hydroxy-butyric acidOHO=C-CH-CH2-CH3OHIREEA-NanjingAgriculturalUniversity/April2008
•the electronic environment of each atom (for instance chemical bond) will affects its magnetic properties (shielding effect) thereby modifying the frequency resonance of different atoms (chemical shift) •this property allows to distinguish the different nuclei in the organic molecule (aromatic, phenolic, aliphatic etc.) FID of 2-hydroxy-butyric acid OH O=C-CH-CH2-CH3 OH IREEA-Nanjing Agricultural University/ April 2008
The NMR in solid state is characterized by the following drawbacksChemical Shift Anysotropy (CSA):depends on the orientation of the chemical bond respect to externalmagnetic field BO that will increase the range of chemical shift effectin liquid state the molecules are free to move (tumbling)each chemical bond will assume each possibleB0orientation respect to BO thereby averaging toBzero the CSA effectSignal Amplitude 100 HzR
each chemical bond will assume each possible orientation respect to B0 thereby averaging to zero the CSA effect Signal Amplitude 100 Hz in liquid state the molecules are free to move (tumbling)