Establishment of SI-traceable purity assessment of Fumonisin B1 using a combination of quantitative 1H NMR and mass balance

Abstract

The accurate purity assessment of Fumonisin B1 (FB1) is of great challenge due to the lack of inherent chromophore, which is important for the development of FB1 certified reference material. In this study, differential scanning calorimetry (DSC), mass balance and quantitative 1H nuclear magnetic resonance (qH NMR) methods were developed and validated for international system of unit (SI) traceable purity assessment of in-house prepared FB1. The thermodynamic analysis showed no typical melting peak was observed for FB1, indicating DSC was not applicable for purity assessment of FB1. A high-performance liquid chromatography coupled with corona charged aerosol detector (HPLC-CAD) method was developed and an isocratic elution procedure was optimized for the chromatographic purity analysis of FB1. The linear range of optimized HPLC-CAD method could not cover the concentration range of FB1 and the structure-related impurity in the raw material, which was identified to be partial hydrolyzed FB1 (pHFB1). The correction factor used to correct the chromatographic purity obtained by area normalization method was approximately 0.2 %. Moisture (0.30 %) and pHFB1 (0.48 %) were the main impurities according to the mass balance analysis. A mixture of dimethyl sulfoxide-d6 and trifluoroacetic acid-d was confirmed to be a suitable deuterated solvent for accurate qH NMR analysis of FB1. The purity obtained by mass balance (99.13 % with uncertainty of 0.06 %) and qH NMR (99.12 % with uncertainty of 0.28 %) showed good consistency and equivalent precision. These methods are expected to be applicable to development of FB1 certified reference material with metrological traceability to the SI unit to ensure comparable and reliable detection results.