Development and validation of a robust high-performance liquid chromatographic method for the analysis of monacolins in red yeast rice

A robust analytical method, using reversed phase high-performance liquid chromatography with diode array detection, was developed and validated for the quantification of monacolins in red yeast rice bulk products. Tests on the composition of the extraction solvent, extraction time and the number of repetitions of extraction were evaluated with the aim of complete extraction of the monacolins and minimal transitions between the monacolins during analysis. Monacolin K (acid form), monacolin K (lactone form) and minor monacolin peaks were separated on a C18 column (250×4.6mm, 5µm) using acetonitrile/0.1% trifluoroacetic acid as the mobile phase. For the calibration curve of monacolin K (lactone form), a linear correlation in the range 6-119µg/mL was found. The precision of the method for time and concentration gave a relative standard deviation of less than 5%, which was deemed acceptable. The recovery of the method was 98.75%.