Pioneering work for direct time-domain analysis of NMR data was begun by Dr. Krish Krishnamurthy and first published in 2013. . This work was extended to 2-dimensional NMR in 2016 . CRAFT provides a direct spectrum to spreadsheet by utilizing Bayesian analysis of the time domain spectrum thereby bypassing many issues brought about by the Fourier transform to a visual frequency dimension. Direct analysis of time-domain completely bypasses the issues of baseline and phase. In addition, the concept of spectral overlap is redefined. Two peaks which are too close to effectively quantify by traditional integration are completely resolved sinusoids in the time domain with separate information of frequency, amplitude, phase, and decay rate available as numbers in a table.
The Fourier transform has been traditionally used to transform time domain data into a 2-dimensional space which is comfortable to look at and easy to understand. Ironically the goal is often to then do lots of post transformation analysis on the frequency spectrum for the purpose of putting the information into a table which is easy for a computer to understand. CRAFT uses the visual frequency domain simply as guidance to make easy for a human to choose what they wish to analyze. The output of CRAFT is a spreadsheet arising purely from the time domain data neatly tabulated as frequency and amplitude with phase and decay rate also available if desired. Again, for the purpose of comfort factor the resulting table is used to simulate a complete spectrum and the simulated FID and actual experimental FID are subtracted to provide a quick visual means to evaluate the quality of the analysis.
Figure 1. Expansion showing complete craft analysis of santonin in the Delta CRAFT Tool.
Figure 2. Expansion of the craft simulation and experimental result for santonin. Note how even the details of the 13C satellites can be easily captured and quantified.