Analytical liquid-state NMR experiments are performed on our Varian VXR-300S superconducting NMR spectrometer operating at 7.2 Tesla. A 200 MHz Varian UnityPlus200 Spectrometer and a JEOL Eclipse 300 are also available for liquid-state experiments. We also have two Qualion process NMR units available for process NMR application development, and two low field NMR spectrometers (2.5 and 20 MHz Oxford Instruments spectrometers, for time-domain NMR experiments.
Here is a listing of past NMR projects that Process NMR Associates has been involved with.
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.
The following describe several 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. Example data for crude oils can be found here.
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 the 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, specialty acrylates and polyurethanes, 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 experiments 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.
Product Quality and Natural Product Purity - Liquid-state NMR is routinely used to determine the quality and purity of dietary supplements. Typical examples may be purity of synthesized body building food supplements, or quality of aloe vera juices and freeze dried powder. An example of pass and fail Aloe Vera quality test is given here. This Aloe Vera test is now required by the International Aloe Science Council. See this short write-up of the official test method.
Database Development - Process NMR Associates is currently developing several databases - Examples: Heavy Hydrocarbon NMR Database and Essential Oils Database.
Here are some simple NMR experiments demonstrating the methodology that can lead to full chemical characterization.
Process NMR Associates is interested in developing NMR quality control databases in conjunction with various industries. We are also not limited to NMR database development. We currently have stable stored sample sets that can be utilized to develop IR, Raman or other spectroscopy databases.
For more information on this topic please contact:
John Edwards
Manager, Process and Analytical NMR Services
Process NMR Associates LLC,
87A Sand Pit Rd
Danbury, CT 06810, USA
Tel: (203) 744-5905
