高效液相色谱-气相色谱联用法测定稻谷和大米中的饱和烃矿物油

Determination of Mineral Oil-Saturated Hydrocarbons in Paddy and Rice by On-Line High Performance Liquid Chromatography-Gas Chromatography

建立高效液相色谱-气相色谱(high performance liquid chromatography-gas chromatography,HPLC-GC)联用测定稻谷和大米中饱和烃矿物油(mineral oil saturated hydrocarbons,MOSH)的方法。首先,采用正己烷提取大米(或稻谷)中的MOSH;稻谷中含有大量天然烷烃,需要用氧化铝净化除去。然后,提取液浓缩后注入HPLC分析。目标物MOSH通过中心切割技术精准分离并转移至GC,以氢火焰离子化检测器测定。方法学考察表明:液体石蜡(MOSH的标准物质)在0.5~100 mg/L范围呈良好线性关系(相关系数为0.999),方法定量限为0.05 mg/kg,加标回收率为89.1%~91.4%(相对标准偏差为4.6%~5.5%)。应用本方法测定24个稻谷和大米样品中的MOSH,其含量为0.30~2.30 mg/kg。

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 of0.5–100 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.