Trace Analysis by Low-Field NMR: Breaking the Sensitivity Limit
2010; American Chemical Society; Volume: 82; Issue: 17 Linguagem: Inglês
10.1021/ac101738f
ISSN1520-6882
AutoresQingxia Gong, Ali Gordji-Nejad, Bernhard Blümich, Stephan Appelt,
Tópico(s)NMR spectroscopy and applications
ResumoSensitivity 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 ( approximately 12 nmol) in a 0.4 mL NMR sample (a concentration of 31 microM 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 (1)H NMR signal decreases linearly with decreasing (1)H concentration ([(1)H]) while the SNR in NH-PHIP experiments first increases with decreasing [(1)H], then remains constant over 2 orders of magnitude, and finally decreases linearly with decreasing [(1)H]. A hitherto unknown potential opens up for trace analysis by low-field NMR in the bio-, chemical, and material sciences.
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