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Related Concept Videos

¹H NMR: Long-Range Coupling01:27

¹H NMR: Long-Range Coupling

The coupling interactions of nuclei across four or more bonds are usually weak, with J values less than 1 Hz. While these are usually not observed in spectra, the presence of multiple bonds along the coupling pathway can result in observable long-range coupling.
In alkenes, spin information is communicated via σ–π overlap, as seen in allylic (four-bond) and homoallylic (five-bond) couplings. These coupling interactions are stronger when the σ bond is parallel to the alkene π orbitals.
2D NMR: Overview of Heteronuclear Correlation Techniques01:18

2D NMR: Overview of Heteronuclear Correlation Techniques

Heteronuclear correlation spectroscopy is an analytical technique that investigates the coupling between different types of nuclei, often a proton and an X-nucleus, such as carbon-13 or nitrogen-15. This method is commonly used in nuclear magnetic resonance (NMR) spectroscopy to gain insights into complex chemical compounds' structural and compositional aspects. A typical heteronuclear correlation spectrum displays X-nucleus chemical shifts on one axis and a proton spectrum on the other axis.
¹³C NMR: ¹H–¹³C Decoupling01:04

¹³C NMR: ¹H–¹³C Decoupling

The probability of having two carbon-13 atoms next to each other is negligible because of the low natural abundance of carbon-13. Consequently, peak splitting due to carbon-carbon spin-spin coupling is not observed in spectra. However, protons up to three sigma bonds away split the carbon signal according to the n+1 rule, resulting in complicated spectra.
A broadband decoupling technique is used to simplify these complex, sometimes overlapping, signals. Broadband decoupling relies on a...
2D NMR: Heteronuclear Single-Quantum Correlation Spectroscopy (HSQC)01:19

2D NMR: Heteronuclear Single-Quantum Correlation Spectroscopy (HSQC)

Heteronuclear single-quantum correlation spectroscopy (HSQC) is a 2D NMR technique that reveals one-bond correlations between hydrogen and a heteronucleus. The HSQC experiment is similar to the heteronuclear correlation experiment (HETCOR) but is more sensitive. In the HSQC spectrum, the proton chemical shift is plotted on the horizontal F2 axis, while the 13C chemical shift is plotted on the vertical F1 axis. The corresponding proton and 13C spectra are also shown. The HSQC contour plot does...
NMR Spectroscopy: Spin–Spin Coupling01:08

NMR Spectroscopy: Spin–Spin Coupling

The spin state of an NMR-active nucleus can have a slight effect on its immediate electronic environment. This effect propagates through the intervening bonds and affects the electronic environments of NMR-active nuclei up to three bonds away; occasionally, even farther. This phenomenon is called spin–spin coupling or J-coupling. Coupling interactions are mutual and result in small changes in the absorption frequencies of both nuclei involved. While nuclei of the same element are involved in...
¹H NMR: Interpreting Distorted and Overlapping Signals01:02

¹H NMR: Interpreting Distorted and Overlapping Signals

Spin systems where the difference in chemical shifts of the coupled nuclei is greater than ten times J are called first-order spin systems. These nuclei are weakly coupled, and their chemical shifts and coupling constant can generally be estimated from the well-separated signals in the spectrum.
As Δν decreases and the signals move closer, the doublets appear increasingly distorted. The intensities of the inner lines increase at the cost of those of the outer lines as the signals are slanted or...

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Related Experiment Video

Updated: Jun 1, 2026

Metabolomic Analysis of Rat Brain by High Resolution Nuclear Magnetic Resonance Spectroscopy of Tissue Extracts
09:01

Metabolomic Analysis of Rat Brain by High Resolution Nuclear Magnetic Resonance Spectroscopy of Tissue Extracts

Published on: September 21, 2014

Capillary HPLC-NMR Coupling:  High-Resolution (1)H NMR Spectroscopy in the Nanoliter Scale.

B Behnke1, G Schlotterbeck, U Tallarek

  • 1Institut für Organische Chemie, Universität Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany, and Bruker Analytische Messtechnik, Silberstreifen, 76287 Rheinstetten, Germany.

Analytical Chemistry
|May 31, 2011
PubMed
Summary

This study introduces a novel method for coupling High-Performance Liquid Chromatography (HPLC) with Nuclear Magnetic Resonance (NMR) detection. This technique achieves high-resolution NMR spectra even with miniaturized systems, overcoming previous resolution loss issues.

Related Experiment Videos

Last Updated: Jun 1, 2026

Metabolomic Analysis of Rat Brain by High Resolution Nuclear Magnetic Resonance Spectroscopy of Tissue Extracts
09:01

Metabolomic Analysis of Rat Brain by High Resolution Nuclear Magnetic Resonance Spectroscopy of Tissue Extracts

Published on: September 21, 2014

Area of Science:

  • Analytical Chemistry
  • Spectroscopy
  • Chromatography

Background:

  • High-Performance Liquid Chromatography (HPLC) coupled with Nuclear Magnetic Resonance (NMR) is crucial for separating and identifying unknown compounds.
  • Miniaturization of separation techniques for HPLC-NMR coupling typically leads to significant loss in NMR spectral resolution.
  • Existing methods struggle to maintain NMR spectral quality when reducing detection volumes.

Purpose of the Study:

  • To develop and demonstrate a method for coupling gradient capillary HPLC with on-column, high-resolution NMR detection.
  • To overcome the resolution loss associated with miniaturized NMR detection volumes in HPLC coupling.
  • To enable simultaneous separation and structural elucidation of compounds using a miniaturized HPLC-NMR system.

Main Methods:

  • Coupling of gradient capillary HPLC with on-column, high-resolution NMR detection.
  • Acquisition of on-line stopped-flow and static proton (1H) NMR spectra using capillary columns (75–315 μm i.d.).
  • Utilized detection cells with volumes ranging from 50–900 nL over a 1.2 cm detection length.
  • Separation of dansylated amino acids using a C(18) stationary phase in a 315 μm i.d. capillary.

Main Results:

  • Achieved high-resolution NMR spectra (resolution ~3 Hz) with miniaturized detection volumes (50 nL).
  • Successfully measured 1.1 nmol of dansylated γ-aminobutyric acid under static conditions in a 75 μm i.d. capillary.
  • Demonstrated the economic feasibility of using fully deuterated solvents due to low solvent consumption.

Conclusions:

  • The developed HPLC-NMR coupling technique effectively combines miniaturized separation with high-resolution NMR detection.
  • This method overcomes the trade-off between detection volume and spectral resolution in hyphenated techniques.
  • The system is suitable for the structural elucidation of small amounts of unknown compounds in complex mixtures.