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The James and Faith Waters The Barnett Institute NMR Facility offers access to 500 MHz NMR, Microcoil NMR, and LC-NMR instrumentation to the university and local community. Limited analytical service is also available. --- INSTRUMENTATION
--- Microcoil NMR: Microcoils are about 20 times more sensitive than a conventional 5 mm tube, for samples soluble at 1 mM or more. The principle is that smaller NMR coils have lower noise, and therefore are more sensitive. Additionally, solenoidal coils are 3x more sensitive than the open saddle coils, required to accept NMR tubes. The Barnett Institute invented microplugNMR, its use in LC-MS-NMR, and capillary ITP-NMR, and is working in collaboration with Magnetic Resonance Microsensors (MRM) and their parent company Protasis Corp on new applications of microcoil NMR. With the MRM Microflow probe, 2 uL samples are injected using a flow system similar to LC-NMR. Injection may be either manual for single samples, or automated from 96-well plates using our gilson 215 sample handler and Varian VAST software. Sensitivity is 0.1 ug for 1D 1H NMR, 1 ug for 2D 1H, or 50 ug for heteronuclear 2D (HSQC, HMBC). Additionally, several smaller microcoil probes (30 nL to 1 µL) have been constructed in collaboration with JV Sweedler for capillary ITP and other custom applications. For more information on microcoil NMR, visit Protasis Corp; click "MicroFlow NMR". Magnetic Resonance Microsensors (MRM) presented posters at ENC 2003 on : Sample Handling and Mass-Limited Applications
--- LC-NMR The Barnett Institute is proud to host one of the first LC-NMR systems placed in an American university, as part of a collaborative agreement between Varian instruments and the Barnett Institute to develop LC-NMR and capillary NMR applications and hardware. ( Varian LC-NMR brochure ) For LC-NMR, the flow probe is connected to an HPLC system controlled by a PC wired to the NMR console, with software supporting mutual control of NMR acquisition and chromatographic events from either keyboard. A high-pressure capillary loop fraction collector is available for off-line analysis of multiple LC fractions. Capabilities Complex samples may be injected into HPLC analysis and NMR spectra recorded continuously and correlated with the UV chromatogram. Greater sensitivity can be achieved by stopping the LC pump to trap a peak of interest in the NMR probe (stopped flow LC-NMR). Good 1D NMR spectra can typically be obtained with 3 µg of the analyte of interest in a 100 µL LC peak volume. 2D spectroscopy is possible with 10 µg of analyte. Considerations --- RATES Routine NMR (5 mm tubes). Analysis of samples supplied prepared in tubes typically costs about $50 for the first sample and $35 for subsequent samples, with printed or faxed output giving expansions with integrals and exact chemical shift of peaks and multiplets. The time required for 2D depends on sample concentration and the information required: COSY varies from 5 min at 10 mg/ml to overnight for 1 microgram in the microcoil. HMBC varies from 20 min at 100 mg/ml in the 5 mm probe, to overnight at 50 ug in the microcoil
LC-NMR A typical analysis requires materials, set-up, trial HPLC in D2O mobile phase, several 1D spectra,
and a predicted spectrum of a chemical structure (if provided) and
starts around $1500. Long acquisitions to obtain 2D spectra, or overnight
1D spectra of trace components, may add $300-$600. Additional interpretation,
resonance assignments, or translating data (e.g. into PowerPoint
slides) are also available. Microcoil NMR. Typical analysis requires 3-5
hours to set up for an overnight acquisition, for $700- $1200.
Analysis may be of a single sample, or multiple samples
automatically loaded from a 96-well plate, and changed at 1-5 hr
intervals. Weekend acquisition is possible for many
samples.
Instrumentation and Facilities |
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