For real sample analysis, a conventional external standard method was firstly employed to get the rough values of BAs content in rice wine.
Then rice wine samples were labeled with d0-MASC and BAs standards at appropriate concentration were labeled with
d3-MASC.
Light-labeled samples and heavy-labeled standards solution were mixed and injected to HPLC–MS/MS for acquiring light and heavy signal ratios.
The contents of BAs in rice wine samples were calculated according to the isotope-based relative quantification method.