7/28/2019 Presentazione CERM 19-04-2007
1/53
SOLID STATE NMR SPECTROSCOPY APPLIED TONATURAL ORGANIC MATTER AND
ENVIRONMENTAL SAMPLES
Pellegrino Conte
Dipartimento di Ingegneria e Tecnologie Agro-Forestali,Universit degli Studi di Palermo
Contact: [email protected]
7/28/2019 Presentazione CERM 19-04-2007
2/53
Definition of Natural Organic Matter (NOM)
The decomposition of plant, animaland microbial material in soil andwater produces a variety of complex
organic molecules, collectively callednatural organic matter. Thesecompounds play many importantroles in the environment.
7/28/2019 Presentazione CERM 19-04-2007
3/53
Roles of Natural Organic Matter (NOM)
NOM is ubiquitous in soils, watersand sediments.
In agriculture, NOM is importantbecause of its positive effects onthe structure, water retentionand nutrient properties of soils.
7/28/2019 Presentazione CERM 19-04-2007
4/53
Roles of Natural Organic Matter (NOM)
NOM also interacts with metal ionsand minerals to form complexes ofwidely differing chemical andbiological nature.
Solubility, mobility and toxicity ofmany trace metals are stronglycorrelated with the concentration of
natural organic matter in soil andwater.
7/28/2019 Presentazione CERM 19-04-2007
5/53
Roles of Natural Organic Matter (NOM)
NOM interacts with organicpollutants (i.e. polycyclic aromatic
hydrocarbons, PAH) to reduce theirenvironmental availability and toxicity
7/28/2019 Presentazione CERM 19-04-2007
6/53
Roles of Natural Organic Matter (NOM)
Natural organic matter createsproblems for the water supplyindustry. It is required its removal inorder to minimize water color andeliminate formation of potentiallyharmful chemical byproducts as aresult of chlorination.
Through a process called "bio-fouling," natural organic matter is
also a major culprit in degrading theperformance of membrane filtrationsystems used for water purificationand desalination.
7/28/2019 Presentazione CERM 19-04-2007
7/53
Models for studying NOM complexity
7/28/2019 Presentazione CERM 19-04-2007
8/53
Nature of Natural Organic Matter (NOM)
Persistent and universal naturalorganic matter molecules are in theenvironment, they are littleunderstood.
Natural organic matter has no uniquestructure or composition, cannot becrystallized and is extremely difficultto characterize.
Structure proposed by Flaig (1960)
Structure proposed by Stevenson (1982)
Structureproposed byStein (1997)
Structure proposed bySchulten (1993)
7/28/2019 Presentazione CERM 19-04-2007
9/53
Nature of Natural Organic Matter (NOM)
Natural Organic Matter is a complexmixture of several different self-
aggregatingcompounds formingsupramolecular aggregates.
The size of each molecular systemwithin NOM does not exceed 2000Da.
The new view (by Piccolo, 2001)
Weak dispersive forcesare mainlyinvolved in the conformationalstabilization of NOM
Saccharides
Peptides
Alkyl chains
Aromatic systems
Cations
7/28/2019 Presentazione CERM 19-04-2007
10/53
Importance of NMR in characterizing NOM
Solid state NMR(CPMAS 13C-NMR)
Liquid state NMR(13C-NMR)
7/28/2019 Presentazione CERM 19-04-2007
11/53
Liquid state 13C-NMR vs Solid state 13C-NMR spectroscopy
7/28/2019 Presentazione CERM 19-04-2007
12/53
7/28/2019 Presentazione CERM 19-04-2007
13/53
7/28/2019 Presentazione CERM 19-04-2007
14/53
Hydrophobic core
Hydrophilic moiety
Water
7/28/2019 Presentazione CERM 19-04-2007
15/53
Conformational analysis of NOM fractions
7/28/2019 Presentazione CERM 19-04-2007
16/53
High performance size exclusion profile
7/28/2019 Presentazione CERM 19-04-2007
17/53
7/28/2019 Presentazione CERM 19-04-2007
18/53
7/28/2019 Presentazione CERM 19-04-2007
19/53
ppm (t2)
-200-1000100200300400
=
CH
CH
CH
T
CTHT
T
HT
CT
HT
TItI
)(1
exp1)(
exp)(
1)(1
1
1
1
0
7/28/2019 Presentazione CERM 19-04-2007
20/53
TCH: 1. fast local motionshigh TCH
values;2. high amount of protonslow TCHvalues
T1(H):proton spin lattice in therotating frame; fast local motionsshorterT1(H) values. High protonconcentrationfaster spin diffusionwith shorter T
1(H) values.
7/28/2019 Presentazione CERM 19-04-2007
21/53
7/28/2019 Presentazione CERM 19-04-2007
22/53
7/28/2019 Presentazione CERM 19-04-2007
23/53
7/28/2019 Presentazione CERM 19-04-2007
24/53
Quantitative assessment of CPMAS 13C-NMR spectroscopy
7/28/2019 Presentazione CERM 19-04-2007
25/53
What does it mean?
(ppm)
-40-20020406080100120140160180200220240
Content of a chemical groupI
i/I
ix 100
7/28/2019 Presentazione CERM 19-04-2007
26/53
1H 90 pulse
Hartman-Hahn condition
Contact time
Spin diffusion
7/28/2019 Presentazione CERM 19-04-2007
27/53
Measurement of1
H90 pulse
via CP
via1
H
7/28/2019 Presentazione CERM 19-04-2007
28/53
Precise measurement of1H 90 pulse by application of a 4 x 90 CP pulse sequence
7/28/2019 Presentazione CERM 19-04-2007
29/53
Spectra acquired with:
1H 90 pulse calibrated on Gly
1
H 90 pulse calibrated on Glyand 4 x 90 CP sequence1H 90 pulse calibrated with 4 x90 CP sequence
7/28/2019 Presentazione CERM 19-04-2007
30/53
Samples 1H 90 pulse (s) by
DD (Inversion
Recoverymeasurement)
4 x 90 CP sequence
SDS 3.12 2.83
CMC 3.02 2.83
HMB 3.06 2.83
pepsin 3.11 2.80
HA1 3.17 2.90
FA1 3.12 2.88
UM1 3.04 2.80
HA2 2.96 2.80
HA3 2.98 2.84HA4 3.05 2.84
Between 2 and 6% of signalrecovery is obtained when aquantitative evaluation of CPMAS 13C-NMR spectra isdone after application of thecorrect 1H 90 pulse.
7/28/2019 Presentazione CERM 19-04-2007
31/53
The Hartmann-Hahn Condition
SSIIBB 11 =
SI=
7/28/2019 Presentazione CERM 19-04-2007
32/53
The rotor spin rate is directly related to thestrength of the dipolar interactions
7/28/2019 Presentazione CERM 19-04-2007
33/53
Rotor spinning rate: 5kHz
7/28/2019 Presentazione CERM 19-04-2007
34/53
Cross polarization
Cross polarization
with RAMP on 1H
Cross polarizationwith RAMP on 13C
7/28/2019 Presentazione CERM 19-04-2007
35/53
7/28/2019 Presentazione CERM 19-04-2007
36/53
Effect of spin diffusion (Standard molecules)
SO4-
12
34
56
78
910
1112
OH
O
OHO
CH3
12
34
5
6
78
9
10
CH3
CH3
CH3
CH3
CH3
CH3
Hexamethylbenzene (HMB)
Sodium dodecylsulphonate (SDS)
Ferulic Acid
12
3
4
5
O
OH
O
6
OH
O
CH27 O
O
O
*
*
n
Carboxymethylcellulose sodium salt (CMC)
7/28/2019 Presentazione CERM 19-04-2007
37/53
7/28/2019 Presentazione CERM 19-04-2007
38/53
7/28/2019 Presentazione CERM 19-04-2007
39/53
7/28/2019 Presentazione CERM 19-04-2007
40/53
7/28/2019 Presentazione CERM 19-04-2007
41/53
7/28/2019 Presentazione CERM 19-04-2007
42/53
7/28/2019 Presentazione CERM 19-04-2007
43/53
7/28/2019 Presentazione CERM 19-04-2007
44/53
7/28/2019 Presentazione CERM 19-04-2007
45/53
Standards Humic substances
7/28/2019 Presentazione CERM 19-04-2007
46/53
Solid state NMR in the differentiation of NOM of different origin
7/28/2019 Presentazione CERM 19-04-2007
47/53
7/28/2019 Presentazione CERM 19-04-2007
48/53
7/28/2019 Presentazione CERM 19-04-2007
49/53
Solid state NMR in the analyses of bulk soils
7/28/2019 Presentazione CERM 19-04-2007
50/53
A Chinese soil
An Italian soil
An Australian soil
7/28/2019 Presentazione CERM 19-04-2007
51/53
7/28/2019 Presentazione CERM 19-04-2007
52/53
7/28/2019 Presentazione CERM 19-04-2007
53/53
CONCLUSIONS
1. Solid state NMR spectroscopy is a very powerful tool to analyzehardly soluble natural organic matter
2. It is the only way to obtain quantitative information on the chemicalnature of NOM
3. It provides information on the chemical nature of organic matterdirectly in bulk soils
4. It can be used to study the interactions between NOM and theinorganic moieties of soils as well as the interactions withenvironmental pollutants
5. Further applications are still possible such as solid state 31P-NMR(for the analyses of phosphorous cycle in the environment), 27Al-and29Si-NMR (for the understanding of amorphous clay minerals)