title: "Ask Ernö": a self-learning tool for assignment and prediction of nuclear magnetic resonance spectra.
abstract: BACKGROUND
  We present "Ask Ernö", a self-learning system for the automatic analysis of NMR spectra, consisting of integrated chemical shift assignment and prediction tools. The output of the automatic assignment component initializes and improves a database of assigned protons that is used by the chemical shift predictor. In turn, the predictions provided by the latter facilitate improvement of the assignment process. Iteration on these steps allows Ask Ernö to improve its ability to assign and predict spectra without any prior knowledge or assistance from human experts.
  
  
  RESULTS
  This concept was tested by training such a system with a dataset of 2341 molecules and their (1)H-NMR spectra, and evaluating the accuracy of chemical shift predictions on a test set of 298 partially assigned molecules (2007 assigned protons). After 10 iterations, Ask Ernö was able to decrease its prediction error by 17 %, reaching an average error of 0.265 ppm. Over 60 % of the test chemical shifts were predicted within 0.2 ppm, while only 5 % still presented a prediction error of more than 1 ppm.
  
  
  CONCLUSIONS
  Ask Ernö introduces an innovative approach to automatic NMR analysis that constantly learns and improves when provided with new data. Furthermore, it completely avoids the need for manually assigned spectra. This system has the potential to be turned into a fully autonomous tool able to compete with the best alternatives currently available.Graphical abstractSelf-learning loop. Any progress in the prediction (forward problem) will improve the assignment ability (reverse problem) and vice versa.
authors.affiliation: Facultad de Ingeniería, Universidad Nacional de Colombia, Bogotá D.C., Colombia ; Chemistry Department, Universidad del Valle, Cali, Colombia.
authors.forename: Andrés M
authors.initials: AM
authors.lastname: Castillo
authors.affiliation: Chemistry Department, Universidad del Valle, Cali, Colombia.
authors.forename: Andrés
authors.initials: A
authors.lastname: Bernal
authors.affiliation: Analytical Research Center, R&T - Flavors Division EAME, Symrise, Holzminden, Germany.
authors.forename: Reiner
authors.initials: R
authors.lastname: Dieden
authors.affiliation: Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland.
authors.forename: Luc
authors.initials: L
authors.lastname: Patiny
authors.affiliation: Chemistry Department, Universidad del Valle, Cali, Colombia.
authors.forename: Julien
authors.initials: J
authors.lastname: Wist
keywords: Automatic assignment; Chemical shift prediction; HOSE codes; Machine learning; Nuclear magnetic resonance; Peak-picking