HSQC-ADEQUATE: an investigation of data requirements

• Published in: Magnetic resonance in chemistry 2011-06, Vol.49 (6), p.350-357
• Main Authors: Martin, Gary E., Hilton, Bruce D., Willcott III, M. Robert, Blinov, Kirill A.
• Format: Article
• Language: English
• Subjects: 1,1‐ADEQUATE; 1-ADEQUATE; Assembly; Carbon; Carbon Isotopes; Computation; Correlation; Databases, Factual; HSQC-ADEQUATE; Magnetic resonance; Magnetic Resonance Spectroscopy - methods; Magnetic Resonance Spectroscopy - standards; Mathematical analysis; Micro CryoProbe; Molecular Structure; multiplicity-edited GHSQC; Reference Standards; Signal to noise ratio; Spectra; strychnine; Strychnine - chemistry; unsymmetrical indirect covariance
• ISSN: 0749-1581; 1097-458X; 1097-458X
• DOI: 10.1002/mrc.2757

Utilizing 13C‐13C connectivity networks for the assembly of carbon skeletons from HSQC‐ADEQUATE spectra was recently reported. HSQC‐ADEQUATE data retain the resonance multiplicity information of the multiplicity‐edited GHSQC spectrum and afford a significant improvement in the signal‐to‐noise (s/n) ratio relative to the 1,1‐ADEQUATE data used in the calculation of the HSQC‐ADEQUATE spectrum by unsymmetrical indirect covariance (UIC) processing methods. The initial investigation into the computation of HSQC‐ADEQUATE correlation plots utilized overnight acquisition of the 1,1‐ADEQUATE data used for the calculation. In this communication, we report the results of an investigation of the reduction in acquisition time for the 1,1‐ADEQUATE data to take advantage of the s/n gain during the UIC processing to afford the final HSQC‐ADEQUATE correlation plot. Data acquisition times for the 1,1‐ADEQUATE spectrum can be reduced to as little as a few hours, while retaining excellent s/n ratios and all responses contained in spectra computed from overnight data acquisitions. Concatenation of multiplicity‐edited GHSQC and 1,1‐ADEQUATE data also allows the interrogation of submilligram samples with 1,1‐ADEQUATE data when using spectrometers equipped with 1.7‐mm Micro CryoProbes ™. Copyright © 2011 John Wiley & Sons, Ltd. Unsymmetrical or generalized indirect covariance processing of multiplicity‐edited GHSQC and 1,1‐ADEQUATE spectra affords an HSQC‐ADEQUATE spectrum from which carbon–carbon connectivity networks can be readily extracted. The s/n gain from the covariance processing allows the reduction of the acquisition time for the 1,1‐ADEQUATE data and/or the size of the sample required. HSQC‐ADEQUATE spectra for samples < 2 µmoles of strychnine were calculated.