Supercritical fluid extraction and high-performance liquid chromatography–fluorescence detection method for polycyclic aromatic hydrocarbons investigation in vegetable oil

In spite of the fact that food processes, that involve drying and smoking, may cause polycyclic aromatic hydrocarbon contamination, an extraction clean/up procedure carried out by SFE was developed in order to isolate polycyclic aromatic hydrocarbons from oil vegetable samples for subsequent HPLC–FL determination. The detection and quantification limits obtained were <1.55 μg kg⁻¹ oil and <2.55 μg kg⁻¹ oil, respectively, allowed to check the presence of seven of the eight PAHs with legal limit in olive–pomace oil: benzo[a]anthracene, benzo[e]pyrene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, dibenzo[ah]anthracene and benzo[ghi]perilene. In brief, the method permits the evaluation of edible oil safety and, therefore, consumers protection.     

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

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。     

植物油基鱼罐头中矿物油污染物高灵敏检测方法的建立

本文建立了植物油基鱼罐头中矿物油（MOH）的高灵敏测定方法并调查了部分市售商品的MOH含量。方法采用皂化反应、环氧化反应进行提取和净化，以高效液相色谱-气相色谱联用法（HPLC-GC）分级、富集和定量检测。结果表明:所建立的植物油基鱼罐头中饱和烃矿物油（MOSH）和芳香烃矿物油（MOAH）测定方法的定量限（LOQ）为0.5 mg/kg，加标回收率为90.0%~106.0%，精密度（RSD）为1.6%~12.7%，满足欧洲联合研究中心（JRC）关于高油脂食品中矿物油的分析要求。应用该方法检测了北京地区10个市售鱼罐头产品，发现所有样品均含有MOSH，含量为2.6~53.7 mg/kg，其中5个检出MOAH，含量为0.7~5.5 mg/kg；谱图分析表明这些罐头的MOH污染与其植物油和鱼肉来源密切相关。     

吹扫捕集-气相色谱/质谱法测定不同饼干中挥发性成分

本研究将吹扫捕集进样技术与气相色谱/质谱法相结合应用于5种市售饼干样品中挥发性组分的分析,分离并鉴定39种挥发性化合物。所鉴定出的物质中,要包括醇类、醛类、酮类、烷烃类、酯类及杂环类等化合物。在5种饼干样品定性分析化合物中,TIC图峰面积比均较大的化合物主要为2-甲基丁醛、异戊醛、苯甲醛、己醛等芳香醛类物质。     

Determination of Mineral Oil-Saturated Hydrocarbons (MOSH) in Vegetable Oils by Large Scale Off-Line SPE Combined with GC-FID

A method based on an off-line large-scale solid phase extraction (SPE) approach combined with conventional gas chromatographic-flame ionization detection (GC-FID) was developed to determine the mineral oil-saturated hydrocarbons (MOSH) in vegetable oils. A large-scale SPE column loaded with 10 g of activated silica gel impregnated with 1% silver nitrate which was used to retain lipids and olefins in vegetable oils and the MOSH in the oil samples was eluted with hexane. Then 2 μL concentrated solution was splitlessly injected into a common GC-FID instrument. The quantification limit reached 2.5 mg/kg when the MOSH fraction was concentrated to 0.1 mL. The accuracy of this procedure, as assessed by measuring the recoveries from spiked oil samples, was higher than 80%. This procedure was applied to analyze the MOSH in 38 commercial vegetable oils from Chinese market, which was the first survey of mineral oil contaminant in Chinese edible oils. The oil samples contaminated with different levels of MOSH, among which, 15 samples contained no mineral oils and 3 samples were contaminated with more than 50 mg/kg of MOSH. The highest contamination level was found in one of rice oils, in which the concentration of MOSH was up to 713.36 mg/kg. Of the 9 types of oils analyzed, camellia oil contained MOSH ranging between 6.76 and 78.49 mg/kg, averaging 46.72 mg/kg, indicating a higher contamination level than other types of oils. The results suggested that it is necessary to routinely detect mineral oil contamination in vegetable oils for food safety.     

水蒸气诱导自组装制备介-微孔ZSM-5分子筛的研究

软模板剂方法可以合成介-微孔分子筛,但有些模板剂与硅铝酸盐之间弱的化学结合力导致晶化过程模板剂与合成体系的相分离,结果形成了无定型的介孔材料和微孔分子筛的混合物。采用新的技术路线:通过使用四丙基氢氧化铵(TPAOH)作模板剂,以三嵌段共聚物P123原位植入介孔结构,采用水蒸气诱导干凝胶自组装晶化的方法制备介-微孔ZSM-5分子筛。优点是:大大减少了模板剂的使用量,省去了产品与母液分离的繁琐步骤,无大量废液产生,对环境友好。采用X射线衍射 (XRD)、傅立叶变换红外光谱(FT-IR)、N₂吸附-脱附比表面分析(BET)、扫描电镜(SEM)、高倍透射电镜(TEM)系列表征方法对介-微孔ZSM-5分子筛进行表征,可知样品具有典型的ZSM-5分子筛的骨架结构和明显地介孔孔道。在800 ℃,100%水蒸气条件下经15 h水热老化后,分子筛的比表面积保留率73.44%,孔容保留率74.35%,表明分子筛的水热稳定性良好。     

纸质食品包装材料的矿物油迁移研究进展

食品中的矿物油污染物是指石油来源的C10~C50烃类化合物, 包括烷烃矿物油(mineral oil saturated hydrocarbons, MOSH)和芳烃矿物油(mineral oil aromatic hydrocarbons, MOAH)2大类。近年来的研究表明, 食品中的矿物油污染物主要来源于食品的回收纸包装材料迁移。本文综述了国外近十年来纸质包装材料的矿物油迁移研究情况, 包括纸质包装材料迁移的矿物油分析方法——液相色谱-气相色谱联用法; 矿物油迁移至食品的2种方式: 气态扩散迁移和包装材料接触迁移; 降低矿物油迁移的技术方法, 即食品包装纸质材料的回收工艺, 向包装纸质中添加活性炭等吸附剂以及增加阻隔层以阻挡矿物油的迁移。旨在为相关企业和机构提供数据与技术参考。     

离线SPE-LVI-GC-FID法分析婴儿配方奶粉中的饱和烃类矿物油

建立婴儿配方奶粉中饱和烃类矿物油(mineral oil saturated hydrocarbons,MOSH)的离线固相萃取(solid phase extraction,SPE)结合大体积进样-气相色谱-氢火焰离子化检测器(large volume injection-gas chromatographyflame ionization detection,LVI-GC-FID)的分析方法。该方法以正己烷为提取溶剂,提取液经硝酸银渍硅胶SPE柱净化;通过比较不同长径比SPE柱的净化效果,确定以5 mL玻璃注射器作为分离MOSH的SPE柱,收集洗脱液5 mL,浓缩后注入LVI-GC-FID测定。GC的进样口升温程序为:初始温度45℃,保持1 min(分流比200∶1),以250℃/min升温至360℃(分流阀关闭2 min),并保持27 min(分流比为100∶1);柱温箱升温程序为:35℃保持3 min,以25℃/min升温至350℃,再以5℃/min升温至370℃,保持10 min;FID温度380℃;进样量40μL。结果表明:MOSH的标准品液体石蜡在2~500 mg/kg范围内呈良好线性关系,相关系数为0.999,方法的定量限为0.05 mg/kg,加标回收率在92.62%~102.86%之间,相对标准偏差在0.85%~2.57%之间,适用于婴儿配方奶粉中MOSH的定量分析。应用该方法检测市售10种婴儿配方奶粉中的MOSH含量,其结果在0.24~1.30 mg/kg之间,其中MOSH(C16~C35)含量在0.12~0.85 mg/kg之间,表明有必要对婴儿配方奶粉中的矿物油污染进行监管。     

基于液相色谱-气相色谱联用测定巧克力中的饱和烃与芳香烃矿物油

建立基于液相色谱-气相色谱（on-line liquid chromatography-gas chromatography,LC-GC）联用测定巧克力中饱和烃（mineral oil saturated hydrocarbons,MOSH）和芳香烃矿物油（mineral oil aromatic hydrocarbons,MOAH）的方法。该方法以正己烷于60 ℃超声提取20 min,取上清液以硅胶除去脂肪,以间氯过氧苯甲酸与烯烃进行环氧化反应,最后以LC-GC联用技术分离测定,其中LC用于保留油脂和烯烃环氧化物,同时分离得到MOSH和MOAH,通过由阀切换、保留间隙与溶剂排空阀组成的LC-GC接口分别将MOSH和MOAH导入2 个平行的GC通道并以氢火焰离子化检测器测定。该方法的定量限为0.5 mg/kg,矿物油在0.5～85.5 mg/L内线性关系良好（R2=0.998）,加标回收率为80.3%～93.8%,相对标准偏差为1.58%～8.22%。测定了28 个巧克力产品中的矿物油含量,其中有20 个产品检出MOSH,含量为1.83～22.23 mg/kg,1 个检出1.57 mg/kg MOAH。谱图分析表明,一些产品中含有塑料迁移出的聚烯烃低聚饱和烃（polyolefin oligomeric saturated hydrocarbons,POSH）,LC-GC无法分离POSH与MOSH,因此测得结果实际上是MOSH和POSH的总量。