Analytical Liquid-State Applications
Analytical liquid-state NMR experiments are performed on our
two Varian Mercury-300 superconducting NMR spectrometer operating at 7.2 Tesla.
These systems are equipped with multiple probes and are capable of
performing most modern NMR experiments.
Table 1 and Table 2 show the 1H and 13C functional group chemical shifts that can be utilized to derive detailed molecular information on samples of interest in the petroleum and petrochemical industries. Detailed molecular information can be obtained from petroleum related samples such as crude oils, base oils, diesels, bitumen, asphaltenes, naphthas. Based on these particular chemical types that can be identified it is possible to generate average molecular parameters that allow the effects of various processes to be observed when the NMR parameters are compared for samples taken before, during and after the desired processing.
We describe below typical liquid-state NMR applications that are routinely performed at PNA.
Crude oil (including heavy oil) analysis - detailed chemical breakdown obtained that allows effects of various thermal and hydrothermal upgrading processes as well as desulfurization to be followed by their effects on a series of detailed average molecule parameters. Table 3 and Table 4 shows the detailed analysis parameters that can be obtained on crude oil samples as well as all other petroleum products.
Petroleum Product Analysis - this includes a large number of NMR interpretations on samples such as used motor oils, lubricant oils, gasolines, diesel fuels, greases, waxes, gas oils, recycled oils, fatty oils, vegetable oils, edible oils, etc. Detailed chemical information as well as the quantity and type of contaminants can be determined.
For example, in used motor oils 31P NMR can be used to determine the
degradation of the Zinc dithiophosphate anti-wear agents, as well as the presence of contaminants originating in gasoline (polyether, and PIB based additives) and diesel fuel (heavy aromatics).
Lubricant oil physical properties can be determined from the detailed chemistry observed in the 13C and 1H NMR spectra.
Polymer Characterization - 1H and 13C NMR can be used effectively to determine the monomer ratio of various mixed copolymers, the number average molecular weight, effectiveness of hydrogenation, olefin analysis, molecular conformation, etc. Typical polymers analyzed are PIB, PE, PP, mixed butene-ethylene, PVC, polystyrene, styrene copolymers, EP copolymers, methacrylates, synthetic rubbers, polybutenes, PTFE, nylons, etc.
Multinuclear experiments - various NMR active nuclei can be studied to determine the chemical make-up of catalysts, polymers, and modified materials. Nuclei commonly observed are 29Si, 31P, 19F, 27Al, 11B. Table 5 shows the typical 29Si chemical shifts observed for siloxanes and silicates. The structure and molecular weight of these materials can be readily obtained by NMR.
Multidimensional NMR Experiments - Various specialized NMR experiments can be used to determine the basic chemical functionality of a sample (DEPT), the structural detail and connectivity (COSY, HETCOR), as well as the conformation of a molecule (2D-3D NOE experiments). For example, COSY experiments can be used to determine the conjugated diolefin content of gasolines and naphthas.
Unknown Compound Structural Elucidation - Detailed NMR analysis can be used in conjunction with sample isolation techniques to allow identification of unknown compounds that are of interest in competitive analysis reverse engineering, product marketing and field issues, customer satisfaction issues, and environmental studies.
Further Examples of NMR Analysis:
- Mannuronate (M) and alpha-L-Guluronate (G)
Vinegar Analysis - Authentification and Ageing by 1H NMRASTM Methods of Hydrocarbon Testing Correlated to Data From Laboratory-Based 1H and 13C NMR SystemsMultidimensional NMR Spectroscopy - COSY, HETCOR, HMQC, HMBCMultinuclear NMR Studies - 29Si, 2H, 11B, 31P, 15N, 27Al, 23Na ..... in Liquid and Solid-State Systems.
1H NMR in
Permanent Magnet 60 MHz NMR systems
Whole Leaf Marker
and Maltodextrin - Dry Weight Quantification in Aloe Vera Raw Materials -
Extended 1H NMR Method
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