A New Method for Olive Oil Screening Using Multivariate Analysis of Proton NMR Spectra

A new NMR-based method for the discrimination of olive oils of any grade from seed oils and mixtures thereof was developed with the aim of allowing the verification of olive oil authenticity. Ten seed oils and seven monovarietal and blended extra virgin olive oils were utilized to develop a principal component analysis (PCA) based analysis of ¹H NMR spectra to rapidly and accurately determine the authenticity of olive oils. Another twenty-eight olive oils were utilized to test the principal component analysis (PCA) based analysis. Detection of seed oil adulteration levels as low as 5% v/v has been shown using simple one-dimensional proton spectra obtained using a 400 MHz NMR spectrometer equipped with a room temperature inverse probe. The combination of simple sample preparation, rapid sample analysis, novel processing parameters, and easily interpreted results, makes this method an easily accessible tool for olive oil fraud detection by substitution or dilution compared to other methods already published.     

An empirical re-examination of natural resource scarcity and economic growth

This paper is concerned with the effect of natural resource scarcity on economic growth in the United States. After defining the notion of scarcity and introducing two measures of scarcity—unit costs and relative resource price—changes in resource scarcity trends for lead, zinc, nickel, aluminium, silver, iron and copper over the most recent three decades are investigated. Only for silver and iron is there any indication that such a change has occurred. For silver, the change is transitory. To the extent that change takes place, it has implications for future economic growth, i.e. natural resource scarcity and economic growth are interrelated. To see whether this is a relevant concern, subsequent to the examination of changing resource scarcity trends an objective effort is made to identify a long-run equilibrium relationship between natural resource scarcity and economic growth. Relying on cointegration techniques, only for the unit cost measure for lead and copper for one of the measures of cointegration is there a suggestion that natural resource scarcity has affected economic growth in the United States over the period 1889–1992.     

GC-MS headspace analysis of the volatile components of soya oil without heating the sample

The analysis of volatile compounds, and particularly of certain hydrocarbons, e.g. pentane, and some aldehydes, e.g. hexanal, has been used to estimate the degree of oxidation of vegetable oil. We have tested a dynamic headspace technique without heating the sample during the purge time of the analysis. Some tests have been performed after heating the sample at 180°C for a specified time before the analysis, to compare the results of analysis with and without heating. The best results were obtained at room temperature.     

On-line HPLC-HRGC coupling and simultaneous transfer of two different LC fractions: Determination of aliphatic alcohols and sterols in olive oil

A modified loop-type interface is decribed which uses two 6-way valves and concurrent eluent evaporation to perform an on-line transfer and simultaneous gas chromatographic analysis of two different fractions pre-separated by liquid chromatography. The interface is used to simultaneously analyze aliphatic alcohols and sterols present in olive oil. LC pre-separation is carried out using a normal phase column (20 cm × 0.21 cm i.d.) and hexane-isopropanol (99:1) as a mobile phase at a flow of 0.2 ml/min; for the GC analysis a 5 % phenyl, 95 % dimethyl siloxane (25 m × 0.32 mm i.d., 0.4 μm film thickness) column is used.     

An Edible Oil Enriched with Lycopene from Pink Guava (Psidium guajava L.) Using Different Mechanical Treatments

According to the regulations of the United States Food and Drug Administration (FDA), organic solvents should be limited in pharmaceutical and food products due to their inherent toxicity. For this reason, this short paper proposes different mechanical treatments to extract lycopene without organic solvents to produce an edible sunflower oil (SFO) enriched with lycopene from fresh pink guavas (Psidium guajava L.) (FPGs). The methodology involves the use of SFO and a combination of mechanical treatments: a waring blender (WB), WB+ high-shear mixing (HSM) and WB+ ultrafine friction grinding (UFFG). The solid:solvent (FPG:SFO) ratios used in all the techniques were 1:5, 1:10 and 1:20. The results from optical microscopy and UV–vis spectroscopy showed a correlation between the concentration of lycopene in SFO, vegetable tissue diameters and FPG:SFO ratio. The highest lycopene concentration, 18.215 ± 1.834 mg/g FPG, was achieved in WB + UFFG with an FPG:SFO ratio of 1:20. The yield of this treatment was 66% in comparison to the conventional extraction method. The maximal lycopene concentration achieved in this work was significantly higher than the values reported by other authors, using high-pressure homogenization for tomato peel and several solvents such as water, SFO, ethyl lactate and acetone.     

假蒟挥发油化学成分气质联用分析研究

采用常规水蒸气蒸馏法提取出假岛精油,经气相色谱-质谱联机分析,分出60多个峰,鉴定出67种化合物,它们主要是2,4,5-三甲氧基-1-丙烯基苯3．20％）,顺-石竹烯（13．33％）,1,2-二甲氧基-4-（1-丙烯基）苯（12．63％）,细辛（9．94％）,4-甲氧基-6-（2-丙烯基）-1,3-苯并二恶茂（5．71％）,δ-杜松烯（3．03％）etc,占总峰面积的67．84％。     

柴油中正构烷烃的高温气相色谱分析

利用高温气相色谱法对柴油中正构烷烃的碳数分布及含量进行了分析。同时根据所得数据计算出正构烷烃的平均相对分子质量及平均碳原子数。试验表明,气相色谱的最佳测定条件为：柱初温60℃,柱终温330℃,升温速率6℃／min,汽化室温度350℃。分析出吐哈两种柴油中C11～C19的正构烷烃均占分析总量的75％以上,吐哈0^#与-10^#柴油正构烷烃的平均相对分子质量、平均碳原子数分别为214．57、15．18和203．34、14．38。所得数据为设计研究针对吐哈原油有效降凝剂提供了参考数据。     

基于不同光谱技术的原油样品的荧光分析

应用同步扫描、三维发射以及目前石油荧光仪所采用的二维发射荧光分析技术对胜利油田15个井区25种原油样品在10-4 g·L-1～10 g·L-1浓度范围内进行了光谱采集,对比分析了不同光谱技术所获取的光谱信息与浓度之间的相应关系。结果表明,对于原油这种多组分样品,二维发射光谱难以满足分析要求;三维光谱信息丰富但数据采集与提取困难。同步扫描光谱具有简单快捷、光谱特征丰富明显、干扰小等特点,选择Δλ为40 nm获得的原油同步扫描光谱可反映三维光谱的主要信息。与二维发射光谱和三维光谱相比,同步荧光法在原油样品分析中显现出较大优势和发展空间,可望发展成为石油录井中对岩屑岩芯样品含油量的定量分析的新方法。     

聚酯废弃物改性植物油沥青粘结剂的红外研究

采用蒸馏厂的下脚料——各种植物油沥青(棉油沥青、豆油沥青、混合油沥青)为主要原料,用聚酯废弃物为改性剂,经裂解、酯化等工艺制备成三种铸造用植物油沥青粘结剂(MB)。同时采用红外光谱和热重分析等手段对该三种粘结剂的基团结构,性能与固化机理进行探索,并与合脂粘结剂比较。 结果表明：改性粘结剂的主要成分与合脂粘结剂大致相同,且具有更高的干拉强度、更慢的发气速度等优异性能,达到甚至超过合脂粘结剂的性能,可用于Ⅰ级型芯砂的粘结,而且成本低廉。     

周期性管柱信道的声波通信技术研究综述

井下声波通信技术利用周期性管柱信道实时传输声波数据,相比于其他通信方式,具有适应性好、复杂度低、传输效率高等优点,在随钻地质导向、油水井监测等方面有广阔的应用前景,是发展智能油田的关键技术之一。本文主要综述上世纪90年代以来关于信道物理模型、信道容量、声信号调制与接收方法等关键问题的研究历程,并对通信系统的设计要点与国内外相关产品的现场应用进行梳理,为后续的技术改进提供依据。