• ACA provides a safe assessment of the consistency between a given structure and its 1H NMR spectrum with the optional use of HSQC information.
  • ACA performs a complete NMR spectral analysis in a fully automated fashion by predicting NMR parameters (chemical shifts; J-couplings) and optimizing them to match the experimental data using quantum mechanical spectral analysis.
  • ACA returns the completely assigned spectrum and accurate spectral parameters extracted from the data even for overlapping signals and higher order effects.
  • ACA evaluates the consistency between structure and spectral data upon the quality of the fit and the similarity between predicted and actual spectral parameters.
  • ACA also gives a good estimate of the sample's purity.


  • PERCH's NMR prediction providing precise NMR-parameters with realistic error estimates based on a conformational analysis of the expected structure (MOL-file) and a sophisticated semi-empiric data-model built from high quality NMR-data.
  • PERCH's spectrum post-processing identifying spectral regions, solvent signals including broad lines to retrieve accurate intensity and line-shape information.
  • PERCH's pre-assignment using the information from the NMR prediction and post-processing to generate a probability ranking of all reasonable shift-assignments.
  • PERCH's spectrum iteration using quantum mechanical calculations of the spin-system finding the most likely assignments by optimizing the pre-assigned NMR-parameters and maximizing their match with the experimental spectrum.
  • PERCH's spectrum simulation outputting a Bruker spectrum calculated from the best matching NMR-parameters to be compared with the experimental one.



  • Safe Assessment of the consistency between structures with MW up to 500 and their good quality spectral data with no major spectral artefacts is given for cases an NMR-experienced user is able to completely assign manually as well.
  • Extremely High Specificity is guaranteed because the complete spectral analysis assures that all NMR-parameters are self-consistent while the quantum mechanical calculation also deals with spectral overlap and higher order effects. Thus the "false positive rate" is remarkably small (well below 3% even for very similar structures).
  • High Throughput with respect to the extracted information and the NMR data acquisition with report generation within an average of 5 min per analysis can be accomplished on standard computer equipment.
  • High Verification Rates of up to 80% depending on the complexity and ambiguity of the data are achievable. In general, cases an NMR-experienced user can completely and unambiguously assign manually also ACA is able to assign to such high degree.
  • Supported Solvents are DMSO, CDCl3, CH3OD, D2O and Acetone fully included in the iterative spectral analysis as separate spin-particles. Thus exclusions or "dark regions", which could adversely affect the complete analysis, are avoided and also signals overlapping with solvent signals can be assigned.
  • A Purity Estimate is given by the percentage the compound and the solvent signals contribute to the total spectral intensity.