电感耦合等离子体发射光谱法测定植物油中的磷

用电感耦合等离子体发射光谱法(ICP-AES)测定了植物油中的磷.采用多谱线拟合技术(MSF)校正了铜对P213.617 nm和P214.914 nm光谱干扰.比较了活性炭炭化灰化法和微波消解法两种样品前处理方法对分析结果的影响.结果表明这两种前处理方法所得结果都能与国标磷钼蓝分光光度法的分析结果吻合,其中活性炭炭化灰化法的方法检出限(0.053 mg/kg)较微波消解法的方法检出限(0.42 mg/kg)更低,所以对低含量的磷的检测结果其相对误差及精密度更好.该法应用于植物油中磷的测定.     

常压火焰离子化质谱技术对食用植物油快速分析的初探

建立了常压火焰离子化质谱(Ambient flame ionization mass spectrometry,AFI-MS)快速分析食用植物油(橄榄油、芝麻油、花生油和葵花籽油)的方法。AFI-MS检出食用植物油(橄榄油、芝麻油、花生油和葵花籽油)中的26种甘油三酯和11种甘油二脂。AFI-MS分析显示,不同的食用植物油(橄榄油、芝麻油、花生油和葵花籽油)得到的质谱图轮廓信息不同。通过对不同食用植物油的甘油三酯相对峰强度进行分析,可初步归纳出食用植物油的类型。AFI-MS分析食用植物油的操作简单,普通的打火机就可以作为离子源用于食用植物油的分析。这种便捷的离子化技术可以用于食用植物油的快速分析。     

SPME/GC-MS鉴别地沟油新方法

采用固相微萃取(SPME)气相色谱-质谱联用(GC-MS)技术,研究了油脂内源及外源物质的微量化学成分。结果发现:纯正花生油和大豆油不含反式脂肪酸,地沟油含有反式脂肪酸trans-C18∶1、trans-C18∶2;纯正花生油和大豆油中含有正己醛、正壬醛和正癸醛等杂质,而地沟油中除了这几种醛类外还含有乙酸、3-丁烯腈、2,5-二甲基吡嗪等特征杂质成分。通过测定内源性物质和外源性物质的存在,两种检测结果互相印证,综合判断,最终可确定是否为地沟油,据此首次建立了SPME/GC-MS鉴别地沟油的新方法。该方法不但可用于地沟油的鉴别,还可用于掺假食用油的检测。     

Trace elemental characterization of edible oils by ICP-AES and GFAAS

A method for the determination of the inorganic profile in edible oils is proposed. The quantification of selected metals in various oils (olive, pumpkin seed, sunflower, sesame seed, hazelnut, grape, soya, rice oil) was carried out using microwave assisted digestion followed by ICP-AES and GFAAS. The detection power of the ICP-AES technique was sufficient for the determination of Ca, Fe, Mg, Na, and Zn. Since the samples contained very low amounts of Al, Cu, Co, Cr, K, Ni, Mn, and Pb, these elements were measured by GFAAS. Differences of metal concentrations for edible oils obtained in this preliminary study represent a starting basis for the development of an additional analytical procedure applicable for oil characterization.     

Capillary electromigration methods for fatty acids determination in vegetable and marine oils: A review

Fatty acids determination is of paramount importance for quality control and suitable labeling of edible oils, required by regulatory agencies in several countries, and fast methods for this determination are worldly desired. This review article aimed to explore the available analytical methods for vegetable and marine oils analyses employing CE, which can be a straightforward and faster alternative than GC methods for fatty acid determination, considering some purposes. CE usually offers the possibility of a rapid analysis with a simple preparation of the sample, without requiring specific columns, which are inherent advantages of the technique. Instrumental conditions and the key points about fatty acids determination employing the technique are highlighted, and the main challenges and perspectives are also approached. Potential use of CE for edible oil analyses has been demonstrated for research and routine, which can be of interest for industries, regulatory agencies, and edible oil researchers. Therefore, we have explored the analytical approaches described in the last decades, intending to spread the interest of CE methods for fatty acid monitoring, label accuracy assessment, and food authenticity evaluation of edible oils.     

傅里叶变换红外光谱结合模式识别法快速鉴别食用油的真伪

采用傅里叶变换红外光谱(FTIR)结合簇类独立软模式识别技术(SIMCA)建立了真伪食用油的快速鉴别方法. 该方法依据FTIR 的指纹特性, 收集并分析了53 个合格食用油和13 个伪造食用油的FTIR 谱图; 通过对谱图取二阶导数和标准化处理, 主成分分析(PCA)提取特征变量; 采用SIMCA 方法分别随机选取43 个合格食用油和9 个伪食用油样品的FTIR 谱图组成训练集, 构建得到真伪食用油的SIMCA 分类模型. 该模型经过剩余10 个合格食用油和4 个伪食用油的验证, 正确识别率达到了100%. 说明FTIR 结合SIMCA 可能成为快速鉴别食用油真伪的一种新方法.     

Discriminating olive and non-olive oils using HPLC-CAD and chemometrics

This work presents a method for an efficient differentiation of olive oil and several types of vegetable oils using chemometric tools. Triacylglycerides (TAGs) profiles of 126 samples of different categories and varieties of olive oils, and types of edible oils, including corn, sunflower, peanut, soybean, rapeseed, canola, seed, sesame, grape seed, and some mixed oils, have been analyzed. High-performance liquid chromatography coupled to a charged aerosol detector was used to characterize TAGs. The complete chromatograms were evaluated by PCA, PLS-DA, and MCR in combination with suitable preprocessing. The chromatographic data show two clusters; one for olive oil samples and another for the non-olive oils. Commercial oil blends are located between the groups, depending on the concentration of olive oil in the sample. As a result, a good classification among olive oils and non-olive oils and a chemical justification of such classification was achieved.     

Rapid characterization of edible oils by direct matrix-assisted laser desorption/ionization time-of-flight mass spectrometry analysis using triacylglycerols

Direct matrix-assisted laser desorption/ionization time-of-flight mass spectrometric (MALDI-TOFMS) analysis of solutions of edible fats/oils yielded spectra useful for their rapid differentiation and classification. Results also reflected the individual fatty acid components and their degree of unsaturation. After dissolution in hexane, MALDI-MS analysis revealed spectra showing characteristic triacylglycerols (TAGs), the main fat/oil components, as sodium adduct ions. The Euclidean distances calculated using the mass and intensity values for 20 TAGs were used to evaluate and compare spectra. With cluster analysis, animal fats grouped together differently than vegetable oils and the individual oils grouped together by type. The ion abundances for the individual TAGs and their presumed compositions were used to approximate the overall fatty acid composition of canola, soybean, corn, olive and peanut oil, as well as lard. Using this approach the calculated fatty acid compositions and degree of unsaturation generally fell within about 4% of literature values. When the degree of saturation was compared with values calculated from the package labeling the differences were about 7%.     

Ultrasound velocity and density studies in some refined and unrefined edible oils

Density and ultrasonic velocity at a frequency of 3?MHz and in the temperature range 298–333?K are measured in some of the refined and unrefined edible oils, namely coconut oil, castor oil, sunflower oil, kardi (safflower oil) and groundnut oil, which are predominantly used in south India. Velocity has been observed to be decreasing with temperature nonlinearly in some oils in the temperature range studied. This is in agreement with others' observations made in different oils and fats. Velocity change with temperature is attributed to change in intermolecular distance with temperature and the nature of variation depends on the internal molecular dynamics. Density of all the oils has been found to be decreasing with temperature. Various physical parameters such as specific volume, molar sound velocity, adiabatic compressibility, molar compressibility and intermolecular free length have been estimated using measured data on velocity and density.     

Effort to improve the quantitative determination of oxidation and hydrolysis compound classes in edible vegetable oils.

This paper proposes an analytical method to evaluate the classes of products of polymerization, oxidation and hydrolysis as well as the polar compounds present in refined edible oils in a more reliable fashion. The polar compounds of a marketed refined peanut oil were analyzed by preparative gel permeation chromatography and the classes of substances corresponding to single chromatogram peaks were collected by means of a fraction collector, purified and used as standards for high-performance size-exclusion chromatographic analysis. The linearity of detector response, the precision and accuracy of the method for each class of compounds and for polar compounds were assessed. Another aim was to verify whether this method may be applied to other refined peanut oils and to edible vegetable oils in general, even of different botanical origin, using the standards that had already been prepared for that particular peanut oil. The results obtained showed that this was possible and the analytical method developed can be extended to the most common edible vegetable oils.     

SPME/GC-MS鉴别地沟油新方法(Ⅱ)

采用固相微萃取/气相色谱-质谱(SPME/GC-MS)方法测定地沟油中的微量杂质成分,通过对各种纯正植物油中的内源性微量成分与不同地区地沟油中的外源性杂质成分的对比分析,以及对地沟油中杂质成分来源的分析,确定了广州、贵州、深圳、北京等地区地沟油的特征成分,并作为鉴别指示成分。该方法灵敏度高、特征性强,在卫生部组织的地沟油检测盲样考核中,对阳性样品判断的准确率高达95.5%。     

Comprehensive Review on Application of FTIR Spectroscopy Coupled with Chemometrics for Authentication Analysis of Fats and Oils in the Food Products

Currently, the authentication analysis of edible fats and oils is an emerging issue not only by producers but also by food industries, regulators, and consumers. The adulteration of high quality and expensive edible fats and oils as well as food products containing fats and oils with lower ones are typically motivated by economic reasons. Some analytical methods have been used for authentication analysis of food products, but some of them are complex in sampling preparation and involving sophisticated instruments. Therefore, simple and reliable methods are proposed and developed for these authentication purposes. This review highlighted the comprehensive reports on the application of infrared spectroscopy combined with chemometrics for authentication of fats and oils. New findings of this review included (1) FTIR spectroscopy combined with chemometrics, which has been used to authenticate fats and oils; (2) due to as fingerprint analytical tools, FTIR spectra have emerged as the most reported analytical techniques applied for authentication analysis of fats and oils; (3) the use of chemometrics as analytical data treatment is a must to extract the information from FTIR spectra to be understandable data. Next, the combination of FTIR spectroscopy with chemometrics must be proposed, developed, and standardized for authentication and assuring the quality of fats and oils.     

高效液相色谱-荧光衍生法快速测定地沟油中的长链脂肪醛

本研究利用地沟油精炼过程中会产生醛类化合物的特点, 以O-(3-(9H-咔唑-9-基)丙基)羟胺为荧光衍生化试剂, 采用高效液相色谱法测定己醛、庚醛、辛醛、壬醛、癸醛5种长链脂肪醛来鉴别地沟油及食用油中是否掺杂地沟油. 10 μL待测油样品溶于200 μL异丙醇, 在最佳条件下与O-(3-(9H-咔唑-9-基)丙基)羟胺反应生成稳定的衍生物, 乙腈萃取后进样分析.以乙腈-水(90∶10, V/V)为流动相, 在λex /λem=292 nm/348 nm下荧光检测, 衍生物在C18柱上15 min内可完全分离.检测5种脂肪醛的线性范围均为0.01~1.00 μmol/L, 检出限为0.05~0.10 nmol/L, 加样回收率为95.6%~101.4%.待测油样品的测定结果表明, 食用油基本不含上述5种脂肪醛, 而精炼地沟油中5种脂肪醛含量显著增加, 因此5种脂肪醛含量可作为检测地沟油的指标.本方法专属性强、灵敏度高、准确性好,方便,快捷, 可用于快速检测地沟油.     

Analysis of wax esters in edible oils by automated on-line coupling liquid chromatography-gas chromatography using the through oven transfer adsorption desorption (TOTAD) interface

An automated method for the direct analysis of wax esters in edible oils is presented. The proposed method uses the TOTAD (through oven transfer adsorption desorption) interface for the on-line coupling of normal phase liquid chromatography and gas chromatography. In this fully automated system, the oil with C32 wax ester as internal standard and diluted with heptane is injected directly with no sample pre-treatment step other than filtration. The proposed method allows analysis of different wax esters, and is simpler and faster than the European Union Official Method, which is tedious and time-consuming. The obtained results closely match the certified values obtained from the median of the analytical results of the inter-labs certification study. Relative standard deviations of the concentrations are less than 5%. The method is appropriate for routine analysis as it is totally automated.     

植物油中邻苯二甲酸酯类化合物的一步萃取方法

为实现植物油中邻苯二甲酸酯（PAEs）的现场快速检测,建立了气液微萃取（GLME）技术并与GC-MS检测技术联用实现了植物油中PAEs的一步萃取检测。GLME方法在气流吹扫-微注射器萃取技术的基础上建立而成。此方法定量取0.1 g植物油样品,利用GLME在5 min内完成PAEs的萃取、净化和浓缩,结合内标法确保了结果的准确性。在大豆油、调和油、橄榄油、香油等4种样品中添加200 μg/kg的15种PAEs,基质加标回收率为60.0%~112.3%,相对标准偏差（RSD）为0.9%~28.4%。该法操作简单、方便,准确度高,重现性好,基质干扰少,适用于现场检测和快速检测,对于保障我国食品安全、构建完整的食品安全检测体系具有重大意义。     

Infrared study of aging of edible oils by oxidative spectroscopic index and MCR-ALS chemometric method

One of the most suitable analytical techniques used for edible oil quality control is Fourier transform mid infrared spectroscopy (FT-MIR). FT-MIR spectroscopy was used to continuously characterize the aging of various edible oils thanks to a specific aging cell. There were differences in the spectra of fresh and aged oils from different vegetable sources, which provide the basis of a method to classify them according to the oxidative spectroscopic index value. The use of chemometric treatment such as multivariate curve resolution-alternative least square (MCR-ALS) made it possible to extract the spectra of main formed and degraded species. The concentration profiles gave interesting information about the ability of the various oils to support the oxidative treatment and showed that all oils present the same aging process. Both methods led to concordant results in terms of induction times determined by the oxidative spectroscopic index and the appearance of oxidation products revealed by MCR-ALS.     

Determination of benzo[a]pyrene in edible oils using phase‐transfer‐catalyst‐assisted saponification and supramolecular solvent microextraction coupled to HPLC with fluorescence detection

For the analysis of edible oils, saponification is well known as a useful method for eliminating oil matrices. The conventional approach is conducted with alcoholic alkali; it consumes a large volume of organic solvents and impedes the retrieval of analytes by microextraction. In this study, a low‐organic‐solvent‐consuming method has been developed for the analysis of benzo[a]pyrene in edible oils by high‐performance liquid chromatography with fluorescence detection. Sample treatment involves aqueous alkaline saponification, assisted by a phase‐transfer catalyst, and selective in situ extraction of the analyte with a supramolecular solvent. Comparison of the chromatograms of the oil extracts obtained by different microextraction methods showed that the supramolecular solvent has a better clean‐up effect for the unsaponifiable matter from oil matrices. The method offered excellent linearity over a range of 0.03– 5.0 ng mL⁻¹ (r > 0.999). Recovery rates varied from 94 to 102% (RSDs <5.0%). The detection limit and quantification limit were 0.06 and 0.19 μg kg⁻¹, respectively. The proposed method was applied for the analysis of 52 edible oils collected online in China; the analyte contents of 23 tested oil samples exceeded the maximum limit of 2 μg kg⁻¹ for benzo[a]pyrene set by the Commission Regulation of the European Union.     

Determination of triazole pesticide residues in edible oils using air‐assisted liquid–liquid microextraction followed by gas chromatography with flame ionization detection

In the present study, a rapid, simple, and highly efficient sample preparation method based on air‐assisted liquid–liquid microextraction followed by gas chromatography with flame ionization detection was developed for the extraction, preconcentration, and determination of five triazole pesticides (penconazole, hexaconazole, diniconazole, tebuconazole, and triticonazole) in edible oils. Initially, the oil samples were diluted with hexane and a few microliter of a less soluble organic solvent (extraction solvent) in hexane was added. To form fine and dispersed extraction solvent droplets, the mixture of oil sample solution and extraction solvent is repeatedly aspirated and dispersed with a syringe. Under the optimum extraction conditions, the method showed low limits of detection and quantification between 2.2–6.1 and 7.3–20 μg/L, respectively. Enrichment factors and extraction recoveries were in the ranges of 71–96 and 71–96%, respectively. The relative standard deviations for the extraction of 100 and 250 μg/L of each pesticide were less than 5% for intraday (n = 6) and interday (n = 3) precisions. Finally edible oil samples were successfully analyzed using the proposed method, and hexaconazole was found in grape seed oil.     

Analysis of tinuvin 1577 polymer additive in edible oils using on-line coupled HPLC-GC

An application of automated on-line HPLC-HRGC is described for direct analysis of edible oils for migrated polymer additives. The sample preparation, separating the additive from the oil triglycerides, is carried out using normal phase HPLC. The fraction of the eluent containing the additive is automatically transferred to a HRGC where a second and final separation of the additive from minor oil components takes place. The method compares well with off-line separation methods. Migration data for Tinuvin 1577 from PET and PC polymers as well as an unspecified experimental polymer is given. The advantages and disadvantages of using different edible oils as food simulants are discussed.     

Evaluation of antioxidant activity of hydrophilic and lipophilic compounds in edible oils by a novel fluorimetric method

A novel fluorimetric method is described for the evaluation of the antioxidant activity of hydrophilic and lipophilic compounds and complex natural products such as edible oils. The method is based on the measurement of fluorescence emission intensity of N-methylacridone produced during the reaction of lucigenin with hydrogen peroxide. The presence of antioxidants in the sample inhibits the concentration of N-methylacridone and reduces the fluorescence intensity. The method was fully validated and applied to a variety of hydrophilic and lipophilic compounds as well as to various types of edible oils and their corresponding hydrophilic and lipophilic extracts. Results were compared to those derived from a lucigenin based chemiluminescent method and the Folin-Ciocalteau method for total phenols. The differences in total antioxidant activity of edible oils of various origins and the effect of heating on total antioxidant activity was further studied and discussed.