Trace Analysis by Low-Field NMR: Breaking the Sensitivity Limit
Trace Analysis by Low-Field NMR: Breaking the Sensitivity Limit
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DOI：
10.1021/ac101738f
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发表时间：
2010-09-01
影响因子：
7.4
通讯作者：
Appelt, Stephan
中科院分区：
文献类型：
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作者：
Gong, Qingxia;Gordji-Nejad, Ali;Appelt, Stephan
灵敏度对核磁共振波谱和磁共振成像（MRI）提出了持续的挑战。非氢化对氢诱导极化（NH-PHIP）是近年来提高高场核磁共振灵敏度的一种有效方法。本文报道了在低场核磁共振中应用NH-PHIP的可行性。在0.4 mL核磁共振样品(浓度为31 μ M或10（16)/cm(3)）中，仅几纳升（类似于12纳摩尔）的痕量吡啶可以通过NH-PHIP在一次扫描中测量到。热预极化与NH-PHIP的信噪比（SNR）有显著差异：预极化H-1核磁共振信号的信噪比随着H-1浓度（[H-1]）的降低而线性降低，而NH-PHIP实验中的信噪比首先随着[H-1]的降低而增加，然后保持在2个数量级以上不变，最后随着PM的降低而线性降低。这为生物、化学和材料科学中的低场核磁共振微量分析开辟了迄今为止未知的潜力。
Sensitivity poses a persistent challenge to NMR spectroscopy and magnetic resonance imaging (MRI). Nonhydrogenative para-hydrogen induced polarization (NH-PHIP) has recently emerged as an efficient method to substantially increase the sensitivity of high-field NMR. Here, we report the feasibility of applying NH-PHIP in the low-field NMR. A trace amount of pyridine of just a few nanoliters (similar to 12 nmol) in a 0.4 mL NMR sample (a concentration of 31 mu M or 10(16)/cm(3)) could be measured in a single scan by NH-PHIP. There is a striking difference in the signal-to-noise ratio (SNR) between thermal prepolarization and NH-PHIP: The SNR of the prepolarized H-1 NMR signal decreases linearly with decreasing H-1 concentration ([H-1]) while the SNR in NH-PHIP experiments first increases with decreasing [H-1] then remains constant over 2 orders of magnitude, and finally decreases linearly with decreasing PM A hitherto unknown potential opens up for trace analysis by low-field NMR in the bio-, chemical, and material sciences.