The Barnett Institute

Faculty Biosketches

   Karger
   Hancock
   Jones
   Vouros
   Giese
   Engen
   Zhou

The James and Faith Waters
Barnett Institute NMR Facility
The Barnett Institute of Chemical and Biological Analysis
Northeastern University, Boston, MA.

Roger Kautz

The Barnett Institute NMR Facility offers access to 500 MHz NMR, Microcoil NMR, and LC-NMR instrumentation, to the university and local community. Analytical service is also available.

--- INSTRUMENTATION

CONSOLE: Varian Unity-INOVA 500 MHz spectrometer: 2 synthesizer channels, pulse-shaping, Z-gradients.

PROBES:
Proton detected 5mm dual resonance (inverse) ¹H {¹⁵N, ¹³C, ³¹P} with Pulsed Field Gradients (PFG);
Broadband 5 mm (48 - 202 MHz) direct detection;
LC-NMR 60 uL (3 mm) flow probe, PFG triple-resonance {¹H, ¹³C, ¹⁵N};.
Microcoil NMR: 2 uL MRM ¹H {¹³C } capLC probe with field gradients

--- 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. Sensitivity is 0.1 ug for 1D ¹H NMR overnight; 1 ug for 2D ¹H, or 50 ug for heteronuclear 2D (HSQC, HMBC).

Additionally, several smaller and larger custom microcoil probes (30 nL to 1 µL) have been constructed for capillary ITP and other 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 support for NMR acquisition and LC events to trigger each other. 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 (on-flow LC-NMR). 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
LC separation conditions should be worked out by the client in advance. The mobile phases water/acetonitrile, water/chloroform, or water/methanol give good results, because these solvents each have only 1 peak. Solvent resonances may be suppressed, but suppression obscures analyte resonances of similar chemical shift (e.g. 1.9 - 2.2 ppm for acetonitrile). Other solvents with more than one NMR resonance can also be suppressed, but will obscure more of the NMR spectrum. Typically D2O replaces water in the LC-NMR mobile phase, and standard (not deuterated) organic solvents are used. Fully deuterated mobile phase can be used at a cost of about $100/run.

--- RATES

Service Costs are based on an hourly rate.

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.

Hourly Rates

Operator-assisted NMR	$150/hr
Unattended acquisition	$80/hr
Overnight maximum	$300/night
Bench Time, Reports	$80/hr

Instrumentation and Facilities

Last Updated 7/30/10