Monday, May 04, 2009

Streamlining automated solubility measurements with NMR JCAMP-DX files

Two months ago I reported on a protocol for measuring solubility using NMR JCAMP-DX files and a web service set up by Andrew Lang called from within a Google Spreadsheet. Things were going well until David at ORU was a little too productive and crashed the server from too many requests.

Andy had to change the way the script worked and used this as an opportunity to make the service more broadly usable. It turns out that the compressed JCAMP-DX files produced by different NMR instruments are not created with exactly the same standards. A way to address that issue is to convert the files to an uncompressed XY format. Unfortunately, there was a glitch in JSpecView which created XY formatted spectra displaying in Hz instead of the standard ppm.

Now all of these issues have been resolved and the process is simpler than ever. Robert Lancashire fixed the glitch in the April 26, 2009 release of JSpecView. And Andy not only made his integration web service work for the new release but also created another service to display JCAMP-DX spectra directly from the the DX file (see here for an example). In the past students had to create an associated HTML file to display JCAMP-DX files and this was just another point in the process to introduce errors and slow things down.

The new process for the semi-automated measurement of solubility (SAMS) using NMR is as follows:

1) Make a saturated solution in a given solvent (sonicate for at least 30 mins - more on this in a separate post)
2) Transfer about 0.1 mL to an NMR tube with some compatible deuterated solvent (for locking)
3) Take the NMR spectrum and export the JCAMP-DX file (on our machines these are in a compressed format)
4) Open the initial JCAMP-DX files in JSpecView and save as JCAMP-DX XY format
5) Upload the converted file to the ONSC server in the spectra folder
6) Fill out the requested information in the SAMS spreadsheet and you have the solubility calculation (first open the SAMStemplate and save as a copy with a new name)

We can now easily finish processing the backlog of measurements that the ONSchallenge participants have been obtaining and record them in the SolubilitySum spreadsheet for querying.

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