Simultaneous determination of 17 phthalate esters in edible vegetable oils by GC‐MS with silica/PSA‐mixed solid‐phase extraction

A quantified method for the determination of 17 phthalate esters (PAEs) in edible vegetable oil by GC‐MS with the pretreatment of acetonitrile extraction and silica/N‐(n‐Propyl)ethylenediamine‐mixed SPE column was established. By the quantification of internal standard of D₄‐di(2‐ethylhexyl) phthalate, a good linearity range of related 17 PAEs was observed. The correlation coefficient was ranged at 0.994～1.000, and the standard lowest quantified level was 0.05～0.15 mg/L. The spiking recoveries of 17 PAEs were 78.3～108.9% with the relative standard deviations of 4.3～12.1% (n = 6). The method detection limits were 0.1～0.2 mg/kg. Meanwhile, PAEs were determined in 30 plastic buckets of edible vegetable oil from supermarkets in Hangzhou city of China. The survey of 30 oil samples showed di(2‐ethylhexyl) phthalate (DEHP) had the 100% (30/30) detection rate. The levels of diisobutyl phthalate with 86.7% (26:30), di‐n‐butyl phthalate (DBP) with 70% (21:30) and diethyl phthalate with 10% (3:30) were detected. It was worth note that DBP with 16.7% (5:30) samples and DEHP with 10% (3:30) samples were beyond the regular migrating limit, which indicated that more attention should be paid to the PAEs in oil with plastic package.     

Determination of hydrate inhibitor in crude oil by nanoextraction-gas chromatography

This work focused on the quantitation of methanol as a hydrate inhibitor in crude oil. The novelty is nanoextraction of a polar compound from a complex non-polar matrix and selection of the proper fiber with maximum selectivity, loading percent, and lifetime. This approach not only does not require specific instrumentation, such as multiple columns and selective detectors, but also has eliminated the use of organic solvent and avoids the insertion of water inside the GC columns. The objective is optimization of extraction conditions, GC adjustments, and data processing. Experiments were conducted on the real sample of Iranian offshore crude oil by a carboxen/PDMS fiber via GC equipped with a cross-linked polyethylene glycol column and flame ionization detector. The results revealed that this fiber adsorbed the alcohols among other light non-polar compounds of crude oil. Moreover, the interference effects of ethanol were solved by proper selection of the thermal program. The LOD, LOQ, and linear range of this approach were determined to be 3.9, 12.9, and 14-229 ppm for methanol, respectively. Using the standard calibration and the standard addition methods, the relative errors of 1.6-7.2 and 5.3-14.0% were determined.     

稠油中饱和烃复杂混合物成分解析及其意义

利用两根极性不同的毛细柱,在全二维气相色谱上分析辽河油田遭受严重生物降解形成的稠油饱和烃组分,可以将传统色谱分析时形成的“基线鼓包”即不可分辨的复杂混合物（Unresolved Complex Mixtures）分开．根据饱和烃全二维气相色谱谱图的族分离特点和瓦片效应,结合飞行时间质谱提供的质谱信息初步解析不可分辨的复杂混合物主要成分．发现常规色谱分析时形成的所谓“基线鼓包”是由成千上万、含量相对较低的不同取代基的环状化合物组成,这些化合物在一维色谱上以分子量递增的顺序排列,在二维色谱上以极性的差异或者环的多少排列．C24之前的第一组不可分辨的复杂混合物主要由环己烷为基本单元的单环、双环和三环烷烃类化合物组成,信噪比在100以上的化合物数量约为饱和烃总数量的75％,质量分数是饱和烃总量的80％以上,是饱和烃的主要组成部分．C24之后出现的第二组不可分辨的复杂混合物主要由四个环或者五个环为基本单元的化合物组成,信噪比在100以上的化合物数量约为饱和烃总数量的17％,质量分数是饱和烃总量的0．5％．对稠油中这些不可分辨的复杂混合物的解析有助于对其成因机理的认识和高效开采方案的制定．     

酯交换生物柴油的柱层析分离纯化与分析

以文冠果油通过酯交换法制备的粗生物柴油为原料,采用柱层析进行精制纯化,然后利用气相色谱、GC-MS、红外光谱和1 H核磁共振等分析产物的成分。粗油经柱层析分离出两个馏分:石油醚洗脱馏分(A1),主要是由文冠果油经酯交换反应得到的生物柴油,包括亚油酸甲酯、油酸甲酯等;甲醇洗脱馏分(A2)主要是甘油馏分,是油脂酯交换反应的副产物。结果表明:由柱层析进行分离纯化后,生物柴油的纯度由原来的77.51%提高到93.87%,生物柴油的回收率也高达91.04%;红外光谱和1 H核磁共振的分析结果进一步表明柱层析能够有效地提高生物柴油的纯度,为工业化纯化生物柴油提供了依据。     

基于RBF神经网络的较低浓度下同步荧光光谱的溢油鉴别

针对海面溢油样品的含量难以确定,同时考虑到海水掺杂及风化等问题的影响,提出了在较低非线性浓度范围内采集溢油嫌疑样品的同步荧光光谱,获取其训练样本集,利用主成分分析法(Principal com-ponent analysis,PCA)提取其特征光谱,结合径向基函数(Radial basis function,RBF)神经网络对肇事样本和嫌疑样本进行模式识别的方法。通过对相近油源原油样品分类识别研究表明:该方法仅需单次对肇事样本同步光谱测量,再借助数据分析,就可以很好区分相近油源溢油样品,外扰对识别率影响也不大。RBF神经网络算法识别率在92%左右。该结论对海洋环境中溢油的实时检测及油指纹数据信息库的建立有重要意义。     

Recent developments in polymeric superoleophobic surfaces

The construction and application of superoleophobic surfaces have aroused worldwide interest during the past few years. These surfaces are of great significance not only for fundamental research but also for various practical applications in self‐cleaning, oil‐repellent coatings, and antibioadhesion. The unique properties of polymers have made them one of the most important materials for constructing superoleophobic materials. This article reviews recent developments in the design, fabrication, and application of polymeric superoleophobic surfaces. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012     

Kinetics of ultrasound-assisted lipase-catalyzed glycerolysis of olive oil in solvent-free system

This work reports experimental kinetic data of solvent-free glycerolysis of olive oil using a commercial immobilized lipase (Novozym 435) under the influence of ultrasound irradiation. The experiments were performed in a mechanically stirred reactor under ultrasound irradiation, evaluating the effects of temperature (50-70 °C), enzyme concentration (2.5-10 wt%) and glycerol to oil molar ratio (0.8:1-3:1). Results show that ultrasound-assisted lipase-catalyzed glycerolysis might be a potential alternative route to conventional methods, as high contents of reaction products, especially monoglycerides, were achieved at mild irradiation power supply (∼130 W) and temperature, in a relatively short reaction time (2 h) and low enzyme content (7.5 wt%). To completeness, two simplified kinetic modeling approaches, based on the ordered-sequential bi bi mechanism and reaction stoichiometry, were employed to represent the experimental data, thus allowing a better understanding of the reaction kinetics.     

Thermodynamic interactions and characterisation of naphthenic oil by inverse gas chromatography

The thermodynamic properties of naphthenic oil, a plasticiser, were investigated by means of inverse gas chromatography (IGC) using 10 different kinds of solvents as probes. Some thermodynamic parameters, such as specific retention volume, weight fraction activity coefficient, Flory–Huggins interaction parameter, partial molar heats of mixing and solubility parameter were obtained to judge the interactions between oil and solvents and the solubility of oil in these solvents. The results indicated that n-heptane, n-hexane, cyclohexane, chloroform, benzene and diethyl ether are good solvents for oil at experimental temperatures. The solubility parameters of oil varied from 13.94 to 13.21?(J?cm^?3)^1/2 at temperature range 323–353?K. The solubility parameter of oil was calculated to be 14.38?(J?cm^?3)^1/2 at room temperature, which is consistent with that obtained using surface tension–solubility parameter relation method.     

Determination of Olive Oil Acidity Using an Enzymatic Method

In this work, a new method for determination of olive oil acidity is proposed. The method is based on the measurement of polyunsaturated free fatty acids reacting with lipoxygenase. Hydroperoxy-fatty acids enzymatically formed were easily determined by UV spectrophotometry at 234 nm. The proposed method is successfully applied to the determination of acidity in olive oil samples and good agreement between the proposed enzymatic method and the classical official one was obtained. This method is accurate, simple, sensitive, inexpensive, and reliable for olive oil acidity determination with a high sample throughput.