Fully Automatic First-Order Multiplet Analysis (FAFOMA)

Nikolay G. Vassilev

Institute of Organic Chemistry BAS, 9, Akad G. Bonchev street, 1113 Sofia, Bulgaria.
Phone: +0359-2-9606-172
E-mail: niki@orgchm.bas.bg


Introduction

There are a lot of programs for online (on NMR spectrometer) or offline (on other computer) processing of 1H NMR spectra. All of them produce peak picking lists, which have to be analyzed in order to extract the necessary information: chemical shifts and coupling constants of nonequivalent protons. This analysis is very easy, but rather boring even for simple cases of 1st order spectra, rather time consuming for more complicated cases of 1st order spectra and/or for cases with overlapped multiplets.

With the increase of NMR spectrometers frequency most of the studied 1H NMR spectra become suitable for First-Order Multiplet Analysis of their peak picking files. The latest scientific work in this area are of T. R. Hoye, P. R. Hanson, J. R. Vyvyan and of S. Golotvin, E. Vodopianov, A. Williams. The latter group has implemented their algorithm in a program module J-coupler, which is part of the program suite ACD/NMR Manager.

The aim of program FAFOMA is to automate the procedure of analysis of peak picking lists utilizing different and more general algorithm. FAFOMA will help either the novice in analysis of NMR spectra or experienced user of NMR spectrometer in extraction of as much as possible information from the peak picking lists of 1st order 1H NMR spectra.

Features

The program FAFOMA is designed to find in peak picking list the presence of doublets (d), triplets (t), quartets (q), quintets, sextets, septets and any combination of them. FAFOMA can also find special cases of doublet of doublet of doublets (ddd) and doublet of doublet of doublet of doublets (dddd), where the number of peaks in multiplet is reduced due to special relation of coupling constants.

The algorithm of the program (patent pending) finds anywhere in peak picking list the above patterns in up to four steps. The program FAFOMA does primary analysis of peak picking list and generates a new peak picking list from chemical shifts of assigned multiplets, which list is subject to secondary analysis. The next generated peak picking list is subject to tertiary analysis and last generated peak picking list is subject to quaternary analysis.

The program FAFOMA was first implemented in an automatic au program for our BRUKER DRX 250 spectrometer with Aspect Station 1, running Xwinnmr 1.3 suite of programs. FAFOMA produces graphical output on screen in X-window and a text output.

Now we offer also a free web version of the program FAFOMA for testing the code from the broad NMR community. The features of web version of the program and the spectrometer version slightly differ:

Some results are available on experimental and simulated spectra.

Program limitations:

  1. The 2nd order multiplets are treated as 1st order and the corresponding results are therefore not correct. Please input only 1st order spectra or spectra slightly distorted by 2nd order effects in order to obtain correct results.
  2. If two multiplets are overlapped in the way that they have common peak or peaks with summed intensity, the program can not resolve these multiplets.
  3. The web version of the program is limited to 100 entries in peak picking list. It is recommended to input peak picking list with as litle as possible entries in order to obtain clearer graphics and more understandable text output file.

Known bugs:

  1. If two multiplets with equal total intensity of peaks and distance between their centers is less then 20 Hz (a predefined maximal coupling constant), the program reports in next step of analysis doublets of these multiplets.


Please fill free to use the web version of program FAFOMA. Any comments or suggestions through feedback are greatly appreciated.