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JCAMP "standard" file format

JCAMP Standard NMR Data Format

The push toward a standard, portable data format is motivated by users’ desire to share data irrespective of the spectrometer on which it was acquired and the need for long-term data archival, well past the expected lifetime of current hardware and software. One big obstacle is the question of whether or not regulatory agencies will accept archived data which is not in its original format, despite the logical arguments that such a format is much more likely to be readable in the future than obsolete, proprietary formats.

JCAMP stands for Joint Committee on Atomic and Molecular Physical Data the original organization that defined a standard data format for IR, which has since been extended to accommodate NMR, Mass spec and other data. Further development/refinement of standards is now under the auspices of IUPAC. See the URLs below for specifics and references:

IUPAC Working Party on Spectroscopic Data Standards (JCAMP-DX)


Robert Lancashire’s site at University of the West Indies, Jamaica


http://members.aol.com/rmcdjcamp/index.htm contains lots of details of the JCAMP-DX specifications

Because the format was designed for IR, it is somewhat awkward when adapted to NMR data. Modification of the format to make it more sensible for NMR data is complicated by the need to maintain consistency with the original published guidelines. Those guidelines are about 10 years old, and the world of computers has changed substantially in that time.

There is a browser plugin (Chime) and a Java applet (DXYPlot) for the display of NMR data in JCAMP-DX format available on the Internet. A link to a JCAMP file can be placed on a web page, and anyone with the Chime plugin can not only display the spectrum, but can also read off chemical shifts and expand the spectrum to view details. It is possible to correlate a spectrum and a structure, so that clicking on a peak will highlight the corresponding atom in the structure. This requires inserting some additional lines in the JCAMP header. See example, (1H spectrum of codeine).

The documented JCAMP-DX format has some parameters and a string of data points in an ASCII format. JCAMP-DX defines multiple formats for outputting the data points, including compressed formats which reduce the final file size. The size reduction comes at the cost of the data no longer being readable by a human being without a translation program.

In September, 1990, the “Industrial NMR User’s Meeting” (INUM) was held at the Lago Maggiore in Italy. One subject discussed at this meeting, attended by representatives from all NMR vendors, was the JCAMP-DX standard data format. All vendors agreed to implement JCAMP import and export routines as soon as possible. There has been some support for these operations by the NMR vendors, but the import and export of NMR data in the JCAMP-DX format is not yet universally supported by all NMR data processing programs.

NUTS imports JCAMP files of all types, as verified by the available Test Data. Nuts also exports both XYDATA and NTUPLES JCAMP-DX5 standard formats (using AFFN Packed format rather than any of the compressed formats). We have done our best to interpret the instructions and extend the format to accommodate export of 2D data, but have not seen any other examples of JCAMP 2D data. There is a Task Group working on defining a format for 2D data.

Examples of files exported by NUTS:

XYDATA of the real part of a spectrum of ethyl benzene

NTUPLES spectrum of ethyl benzene (real and imaginary)

NTUPLES 2D of a frequency-domain HETCOR spectrum of sucrose

Last updated: 06/07/14