Abstract: A method based on on-line high performance liquid chromatography-gas chromatography (HPLC-GC) was proposed for the determination of mineral oil-saturated hydrocarbons (MOSH) in paddy and rice. Firstly, the MOSH in samples were extracted with n-hexane. The extract was then purified using activated aluminum oxide to remove alkanes from it, concentrated and injected into the HPLC system. The MOSH fraction separated was transferred into the GC system by “heart-cut” technique and detected by a hydrogen flame ionization detector (FID). Under optimized analysis conditions, the calibration curve established using paraffin oil as reference standard displayed a good linearity within the range of 0.5–100 mg/L with a correlation coefficient of 0.999. The quantification limit (LOQ) of the method was 0.05 mg/kg. The recoveries for spiked samples ranged between 89.1% and 91.4% with relative standard deviation (RSD) of 4.6%–5.5%. The MOSH contents of 24 real samples ranged from 0.30 to 2.30 mg/kg as determined by this method.

Key words: paddy, rice, mineral oil saturated hydrocarbons, aluminum oxide, high performance liquid chromatography-gas chromatography