HSQC-ADEQUATE: an investigation of data requirements

Utilizing (13)C-(13)C 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 ™.