Kautz Roger A, Goetzinger Wolfgang K, Karger Barry L
The Barnett Institute of Chemical and Biological Analysis, Northeastern University, 360 Huntington Avenue, Boston, Massachusetts 02115, USA.
J Comb Chem. 2005 Jan-Feb;7(1):14-20. doi: 10.1021/cc0498940.
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.
利用分段流动分析技术开发了一种将样品加载到微线圈核磁共振（NMR）探头中的自动化系统。这种方法使已发表的直接注射法和流动注射法的通量提高了2倍，样品利用率提高了3倍，并且适用于样品处理装置与NMR磁体之间具有长传输线的高场NMR设备。样品处理装置从96孔微量滴定板中吸取2微升（10 - 30毫摩尔，约10微克）的样品体积，然后作为由不混溶的氟碳流体隔开的紧密排列的“塞子”队列泵入0.5微升的微线圈NMR探头。通过其NMR信号检测各个样品塞，并自动定位以进行停流数据采集。通过推进队列，可在35秒内更换NMR线圈中的样品。氟碳液体润湿了聚四氟乙烯传输线的壁，防止二甲基亚砜（DMSO）样品与毛细管壁接触，从而使样品在通过3米长的传输线后的损失降低到5%以下。在样品之间使用溶剂清洗塞，样品间的残留率<1%。值得注意的是，在加载过程中或在进行几天的痕量分析采集过程中，样品不会分散到载液中。对于使用16秒采集时间的自动化高通量分析，光谱记录速率为1.5分钟/样品，每96孔板的全氘代溶剂消耗量<0.5毫升（1美元）。
