Determination of 5-Hydroxymethyl-2-Furaldehyde in Cooked Japonica Rice Using a Modified QuEChERS Method Combined with Dispersive Liquid-Liquid Microextraction Followed by UPLC-ESI-MS/MS

Abstract

A modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) method combined with dispersive liquid-liquid microextraction (DLLME) pretreatment was developed for the determination of 5-hydroxymethyl-2-furaldehyde (HMF) in cooked japonica rice. Optimum conditions of the proposed method include MgSO4 (1 g), NaCl (0.5 g), C18 (60 mg), PSA (50 mg), the extraction solvent (CHCl3), dispersing solvent volume/extraction solvent volume (4:1), ultrapure water volume/the total volume of dispersing solvent volume and extraction solvent volume (1:1), and pH (7). HMF was concentrated by the clean-up method with the enrichment factor of 1.98. The separation of HMF was performed on an ACQUITY UPLC BEH-RP C18 column (2.1 mm × 100 mm, 1.7 μm) by the UPLC-ESI-MS/MS (ultraperformance liquid chromatography-electrospray ionization-tandem mass spectrometry). Acceptable values of HMF were achieved for the following parameters: recoveries between 82.87 and 110.48% with the relative standard deviation lower than 8.68%, accuracy in the range of 93.95–114.22%, precision (< 8.76%), limit of detection (LOD) (0.1 μg/L), and limit of quantification (LOQ) (0.3 μg/L). The concentrations of HMF were less than 1.13 μg/kg in rice samples, conspicuously increased with warming time. The color of rice samples, especially the b* value (in the range of 6.02–11.43), was well correlated with the content of HMF and the warming time.