Thermal study, identification of intermediate solid products and evolved gas analysis (EGA) during pyrolysis and oxidative decomposition of sodium complex of quercetin-5′-sulfonic acid (Na-5′-QSA)

•The thermal analysis for Na-5′-QSA was performed in air and helium.•Previously unreported data on thermal behavior of flavonoid-sulfonate of Na(I) were obtained.•The crystalline anhydrous quercetin was identified as one of intermediate solid products.•Na2SO4 or a mixture of Na2C2 and soot were identified as solid degradation products.•H2O, CO2, SO2, COS and CO were mainly identified by the TG–FITR–MS analysis.