High-throughput microcoil NMR of compound libraries using zero-dispersion segmented flow analysis.
An automated system for loading samples into a microcoil NMR probe has been developed using segmented flow analysis. This approach enhanced 2-fold the throughput of the published direct injection and flow injection methods, improved sample utilization 3-fold, and was applicable to high-field NMR facilities with long transfer lines between the sample handler and NMR magnet. Sample volumes of 2 microL (10-30 mM, approximately 10 microg) were drawn from a 96-well microtiter plate by a sample handler, then pumped to a 0.5-microL microcoil NMR probe as a queue of closely spaced "plugs" separated by an immiscible fluorocarbon fluid. Individual sample plugs were detected by their NMR signal and automatically positioned for stopped-flow data acquisition. The sample in the NMR coil could be changed within 35 s by advancing the queue. The fluorocarbon liquid wetted the wall of the Teflon transfer line, preventing the DMSO samples from contacting the capillary wall and thus reducing sample losses to below 5% after passage through the 3-m transfer line. With a wash plug of solvent between samples, sample-to-sample carryover was <1%. Significantly, the samples did not disperse into the carrier liquid during loading or during acquisitions of several days for trace analysis. For automated high-throughput analysis using a 16-second acquisition time, spectra were recorded at a rate of 1.5 min/sample and total deuterated solvent consumption was <0.5 mL (1 US dollar) per 96-well plate.
Kautz
Roger A
RA
The Barnett Institute of Chemical and Biological Analysis, Northeastern University, 360 Huntington Avenue, Boston, Massachusetts 02115, USA. rkautz@lynx.neu.edu
Goetzinger
Wolfgang K
WK
Karger
Barry L
BL
D020650:Combinatorial Chemistry Techniques; D017022:Flow Injection Analysis; D009682:Magnetic Resonance Spectroscopy / Q000295:instrumentation / Q000379:methods*; D015394:Molecular Structure; D012822:Silicon Dioxide / Q000737:chemistry; D012997:Solvents
D012997:Solvents; D012822:Silicon Dioxide