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Updated: Jul 18, 2026

Quantitative 31P NMR Analysis of Lignins and Tannins
Published on: August 2, 2021
Calibration by NMR for quantitative analysis: p-toluenesulfonic acid as a reference substance
Gang Shao1, Roger Kautz, Shiqi Peng
1Department of Pharmaceutical Sciences in the Bouve College of Health Sciences, Barnett Institute, Northeastern University, Boston, MA 02115, USA.
Abstract:
We have demonstrated the usefulness of p-toluenesulfonic acid (TsOH) as a reference substance to calibrate a water-soluble standard by NMR for quantitative analysis. In order to make TsOH convenient for this purpose, we first of all established its molar extinction coefficient under these conditions (epsilon = 351 at 262 nm). This was done by comparing it by quantitative NMR (qNMR) with a compound of known molar extinction coefficient, guanosine monophosphate. TsOH was then used as the standard in a second qNMR experiment to measure an aqueous solution of phosphoglycolate, a metabolite of interest in our laboratory. Perhaps due to its content of water, the purity of this compound was found to be 82%, lower than the value of 94% from the manufacturer.
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