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

•DSC, mass balance and qH NMR methods for purity assessment of FB1 were investigated.•No typical melting peak was observed for FB1.•HPLC-CAD method with isocratic elution was optimized for LC purity analysis of FB1.•Correction factor was necessary due to the nonlinear response of CAD detector.•Purity of in-house prepared FB1 was assessed by combining mass balance and qH NMR.