Synchronous analysis method for detection of citrinin and the lactone and acid forms of monacolin K in red mold rice

The Monascus product known as red mold rice (RMR) has been found to contain the cholesterol-lowering agent monacolin K (MK), including the lactone form (MKL) and the acid form (MKA) and mycotoxin citrinin (CT). In current studies, CT and MK are usually detected by different analysis methods, which have a high level of error, and are inconvenient, expensive, and time-consuming. The goal of this study is to establish a rapid synchronous analysis method for the detection of CT, MKL, and MKA levels in RMR. In this study, CT, MKL, and MKA are extracted by the same extraction method and are then separated in a reversed-phase high-performance liquid chromatography (HPLC) C18 column. The elution from the C18 column is then passed through an ultraviolet detector and introduced directly into the fluorescence detector. The results show that higher recovery rates of CT, MKL, and MLK are yielded from RMR powder by extracting with 95% ethanol (10 mL) at 60°C for 30 min. Regarding the optimal conditions of HPLC, the peaks of CT, MKL, and MKA can be clearly separated from any noise peaks by isocratic elution with optimum mobile phase, acetonitrile-water-trifluoroacetate (55 + 45 + 0.05, v/v).