A new approach for accurate quantitative determination using fluorine nuclear magnetic resonance spectroscopy

A new approach for accurate quantitative determination by fluorine nuclear magnetic resonance ( 19 F NMR) spectroscopy is presented and discussed. 19 F NMR spectroscopy has similar properties to 1 H NMR spectroscopy except for the wide chemical shift dispersion, which is the main difference between the two techniques. The off-resonance effect, which is caused by the chemical shift difference between the excitation pulse offset and the resonance signal position, is expected to be the most important parameter influencing the accuracy of the quantitative analysis by 19 F NMR spectroscopy. We propose a new method that reduces the influence of the off-resonance effect in 19 F NMR measurement. First, we discussed the areas of signals originating from different functional groups in a molecule. Then, we evaluated the areas of signals originating from two different reference materials (RMs). The accuracy of the ratios of two signal areas in the 19 F NMR spectrum of a molecule of Potassium perfluorooctanesulfonate was less than 1 %. We also evaluated the purity of flusulfamide and diflubenzuron as RMs, and found that the method could determine the purity to less than 1 % accuracy relative to the reference values.