Citrinin Determination in Red Fermented Rice Products by Optimized Extraction Method Coupled to Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS)

A rapid and sensitive method was developed and validated for citrinin determination in red fermented rice products by liquid chromatography tandem mass spectrometry (LC-MS/MS) under the selected reaction monitoring mode. Sample preparation was especially focused, and the quantitative methods of LC-MS/MS and high-performance liquid chromatography with fluorescence detection (HPLC-FLD) were compared. In red fermented rice samples, the limit of detection was 1.0 g/kg for LC-MS/MS compared to 250 g/kg for HPLC-FLD, the limit of quantification was 3.0 g/kg for LC-MS/MS compared to 825 g/kg for HPLC-FLD. High correlation coefficient was obtained (R-2 = 0.999) within the linear range (0.1 to 100 g/L) in the MS method. The recoveries ranging from 80.9% to 106.5% were obtained in different spiking concentrations. The average intra- and inter-day accuracy ranged from 75.4% to 103.1%, and the intra- and inter-day precisions were from 3.3% to 7.9%. The developed method was applied to 12 commercial red fermented rice products, and citrinin was found in 10 samples ranging from 0.14 to 44.24 mg/kg. Compared to traditional qualitative and quantitative methods, the newly developed LC-MS/MS method for citrinin determination includes the merits of using a small amount of extraction solvent, simple preparation steps, and high sensitivity.