Correction of <i>Q</i> Factor Effects for Simultaneous Collection of Elemental Analysis and Relaxation Times by Nuclear Magnetic Resonance

Paisner, Scarlett Widgeon; Janicke, Michael T.; Kaseman, Derrick C.; Frankle, Rachel K.; Yoder, Jacob; Alvarez, Marc A.; Espy, Michelle A.; Williams, Robert F.

doi:10.1021/acs.analchem.9b05603

Cited by 1 publication

(2 citation statements)

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“…The remaining variation between the peaks defines the local receptivity as which provides the normalization factor between the different peaks in the JCS that is necessary for quantitation. In contrast to the constant field Ξ employed in the high-field qNMR literature Ξ local depends on H local . , At high magnetic fields, H eff ≈ H 0 and eqs and produce equivalent results. Ξ local becomes increasingly important as | J /(ν I – ν S )| → 1.…”

Section: Theorymentioning

confidence: 93%

“…This study investigates the previously unexplored and unexplained aspects of qNMR at Earth’s magnetic field. A general equation for the constant field receptivity (Ξ) is developed as an extension to work performed by Widgeon Paisner et al that is valid for the determination of pseudoempirical formulas at nearly all magnetic fields . The validity of the equation is tested using a variety of samples, which contain all three heteronuclear coupling scenarios (uncoupled, weak, and strong) encountered at Earth’s magnetic field.…”

Section: Introductionmentioning

confidence: 99%

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Quantitation of Nuclear Magnetic Resonance Spectra at Earth’s Magnetic Field

Kaseman

Malone

Tondreau³

et al. 2021

Anal. Chem.

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The inherently quantitative nature of nuclear magnetic resonance (NMR) spectroscopy is one of the most attractive aspects of this analytical technique. Quantitative NMR analyses have typically been limited to high-field (>1 T) applications. The aspects for quantitation at low magnetic fields (<1 mT) have not been thoroughly investigated and are shown to be impacted by the complex signatures that arise at these fields from strong heteronuclear Jcouplings. This study investigates quantitation at Earth's magnetic field (∼50 μT) for a variety of samples in strongly, weakly, and uncoupled spin systems. To achieve accurate results in this regime, the instrumentation, experimental acquisition, processing, and theoretical aspects must be considered and reconciled. Of particular note is the constant field nuclear receptivity equation, which has been re-derived in this study to account for strong coupling and quality factor effects. The results demonstrate that the quantitation of homonuclear molecular groups, determination of heteronuclear pseudoempirical formulas, and mixture analysis are all feasible at Earth's magnetic field in a greatly simplified experimental system.

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