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<front>
<journal-meta>
<journal-id journal-id-type="publisher">MRD</journal-id>
<journal-title-group>
<journal-title>Magnetic Resonance Discussions</journal-title>
<abbrev-journal-title abbrev-type="publisher">MRD</abbrev-journal-title>
<abbrev-journal-title abbrev-type="nlm-ta">Magn. Reson. Discuss.</abbrev-journal-title>
</journal-title-group>
<publisher><publisher-name></publisher-name>
<publisher-loc>Göttingen, Germany</publisher-loc>
</publisher>
</journal-meta>
<article-meta>
<article-id pub-id-type="doi">10.5194/mr-2026-11</article-id>
<title-group>
<article-title>Paramagnetic Relaxation Enhancement to Improve Sensitivity of 1,1-ADEQUATE NMR</article-title>
</title-group>
<contrib-group><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>DiCaprio</surname>
<given-names>Adam J.</given-names>
<ext-link>https://orcid.org/0000-0001-9880-4493</ext-link>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Cohen</surname>
<given-names>Ryan D.</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Reibarkh</surname>
<given-names>Mikhail</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
</contrib-group><aff id="aff1">
<label>1</label>
<addr-line>Pharmaceutical Analysis &amp; Digital Technologies, Merck &amp; Co. Inc., Rahway, NJ 07065 USA</addr-line>
</aff>
<pub-date pub-type="epub">
<day>26</day>
<month>10</month>
<year>2026</year>
</pub-date>
<volume>2026</volume>
<fpage>1</fpage>
<lpage>20</lpage>
<permissions>
<copyright-statement>Copyright: &#x000a9; 2026 Adam J. DiCaprio et al.</copyright-statement>
<copyright-year>2026</copyright-year>
<license license-type="open-access">
<license-p>This work is licensed under the Creative Commons Attribution 4.0 International License. To view a copy of this licence, visit <ext-link ext-link-type="uri"  xlink:href="https://creativecommons.org/licenses/by/4.0/">https://creativecommons.org/licenses/by/4.0/</ext-link></license-p>
</license>
</permissions>
<self-uri xlink:href="https://mr.copernicus.org/preprints/mr-2026-11/">This article is available from https://mr.copernicus.org/preprints/mr-2026-11/</self-uri>
<self-uri xlink:href="https://mr.copernicus.org/preprints/mr-2026-11/mr-2026-11.pdf">The full text article is available as a PDF file from https://mr.copernicus.org/preprints/mr-2026-11/mr-2026-11.pdf</self-uri>
<abstract>
<p>The 1,1-ADEQUATE NMR experiment provides easily interpretable spectra to identify two-bond proton-carbon correlations in the structural analysis of small molecules. Despite this, the low natural abundance of &lt;sup&gt;13&lt;/sup&gt;C drastically reduces the efficacy of this experiment due to its dependence on C-C magnetization transfers. A reduction of &lt;em&gt;T&lt;sub&gt;1&lt;/sub&gt;&lt;/em&gt; and &lt;em&gt;T&lt;sub&gt;2&lt;/sub&gt;&lt;/em&gt; relaxation times via paramagnetic relaxation enhancement (PRE) represents an opportunity to improve sensitivity and reduce experiment times by facilitating a reduction in recycle delays. In this work, we demonstrate Cr&lt;sup&gt;3+&lt;/sup&gt; at a concentration of 10 mM to be an excellent PRE agent. Paramagnetic relaxation enhancement was then applied in 1,1-ADEQUATE analysis of several compounds, limonene, camphor, amoxapine and quinidine, demonstrating signal-to-noise improvements up to 4.5-fold over diamagnetic conditions.</p>
</abstract>
<counts><page-count count="20"/></counts>
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