GC Fingerprints Coupled to Pattern-Recognition Multivariate SIMCA Chemometric Analysis for Brazilian Gasoline Quality Studies

ASTM D6729 gas chromatographic fingerprinting coupled to pattern-recognition multivariate soft independent modeling of class analogy (SIMCA) chemometric analysis provides an original and alternative approach to screening Brazilian commercial gasoline quality. SIMCA, was performed on gas chromatographic fingerprints to classify the quality of representative commercial gasoline samples selected by hierarchical cluster analysis and collected over a 5 month period from gas stations in São Paulo State, Brazil. Following an optimized ASTM D6729 gas chromatographic-SIMCA algorithm, it was possible to correctly classify the majority of commercial gasoline samples. The method could be employed for rapid monitoring to discourage adulteration.     

Characterization of Gasoline by Raman Spectroscopy with Chemometric Analysis

A rapid Raman spectroscopy protocol is reported to classify gasoline according to its distributor and to identify and quantify common adulterants. Gasoline from three distributors was collected from 19 stations in São Paulo, Brazil. Principal component analysis (PCA) showed specific clusters for each distributor, and partial least squares discriminant analysis (PLS-DA) correctly identified the origin of the samples. To evaluate the technique for the identification and quantification of the adulterants, authentic samples from each distributor were fortified at levels from 2.5 up to 25.0% (v/v) using ethanol, methanol, toluene, and turpentine to obtain 120 altered samples. PCA showed clear separation among the samples with the adulterants and PLS-DA precisely identified the adulterants (478 in 480 predictions by cross-validation), irrespective of the distributor and the concentration. One classification model was used to characterize all distributors. To quantify the adulterants, 36 multivariate calibration models were constructed using partial least squares (PLS), interval PLS, and PLS genetic algorithm for each distributor and for each adulterant. Cross-validation errors of less than 5.0% were obtained for all adulterants regardless of the distributor. Raman spectroscopy and multivariate analysis were shown to be powerful for rapid and inexpensive for the characterization of gasoline origin and the identification and quantification of common adulterants.     

Screening Brazilian Automotive Gasoline Quality through Quantification of Saturated Hydrocarbons and Anhydrous Ethanol by Gas Chromatography and Exploratory Data Analysis

In this paper a set of Brazilian commercial gasoline representative samples from São Paulo State, selected by HCA, plus six samples obtained directly from refineries were analysed by a high-sensitive gas chromatographic (GC) method ASTM D6733. The levels of saturated hydrocarbons and anhydrous ethanol obtained by GC were correlated with the quality obtained from Brazilian Government Petroleum, Natural Gas and Biofuels Agency (ANP) specifications through exploratory analysis (HCA and PCA). This correlation showed that the GC method, together with HCA and PCA, could be employed as a screening technique to determine compliance with the prescribed legal standards of Brazilian gasoline.     

Quantification of Kerosene in Gasoline by Comprehensive Two-Dimensional Gas Chromatography and N-Way Multivariate Analysis

Abstract

In brazil, gasoline is usually adulterated by diesel oil, ethanol (in addition to the amount legally specified), petrochemical raffinates, and kerosene. This is an illegal action performed mainly in an attempt to raise profits. Therefore, methods for reliable identification of adulterated gasoline are very attractive. The aim of this work was to propose a method to quantify kerosene in gasoline through N-way multivariate analysis and a homemade Comprehensive Two-Dimensional Gas Chromatography with Flame Ionization Detection (GC × GC-FID). Models generated by Parallel Factor Analysis (PARAFAC), PARAFAC2, and Multi-way Partial Least Squares (N-PLS) allowed the quantification of kerosene in gasoline with Root Mean Square Error of Cross-Validation (RMSECV) values of 2.98%, 2.65%, and 2.08%, respectively.     

Multivariate Analysis for the Classification Differentiation of Brazilian Sugarcane Spirits by Analysis of Organic and Inorganic Compounds

Abstract

Brazilian sugarcane spirits were analyzed to elucidate similarities and dissimilarities by principal component analysis. Nine aldehydes, six alcohols, and six metal cations were identified and quantified. Isobutanol (LD 202.9 µg L^?1), butiraldehyde (0.08–0.5 µg L^?1), ethanol (39–47% v/v), and copper (371–6068 µg L^?1) showed marked similarities, but the concentration levels of n-butanol (1.6–7.3 µg L^?1), sec-butanol (LD 89 µg L^?1), formaldehyde (0.1–0.74 µg L^?1), valeraldehyde (0.04–0.31 µg L^?1), iron (8.6–139.1 µg L^?1), and magnesium (LD 1149 µg L^?1) exhibited differences from samples.     

专用测定汽油中含氧化合物气相色谱仪的研制和开发

采用气相色谱分析技术,可快速、准确地测定清洁汽油中的含氧化合物含量.参照ASTM D4815及SH/T0663的要求,在上海市计算技术研究所自主研制生产的气相色谱仪上开发此专用分析方法,分析汽油中C1～C4醇、甲基叔丁基醚(MTBE)、乙基叔丁基醚(ETBE)、叔戊基甲基醚(TAME)等组分,测试范围:醇,0.1%(M/M)～12.0%(M/M);醚,0.1%(M/M)～20.0%(M/M).再结合开发的专用色谱分析软件,力求给用户提供性价比更高、操作更加便捷的分析系统.     

Automotive Gasoline Quality Analysis by Gas Chromatography: Study of Adulteration

Summary The addition of organic solvents (light aliphatic, heavy aliphatic and aromatic hydrocarbons) in Brazilian gasoline is unfortunately very frequent, and this illicit practice impares gasoline quality. Gas chromatography (GC) and gas chromatography coupled to mass spectrometry (GC-MS) analyses can be used as a procedure to improve the detection of adulterated gasoline. The results showed that adulterated samples and also the type of organic solvent used in adulteration can be detected by comparison of chromatographic profiles (standard samples versus adulterated samples). However, a single GC analysis can detect an adulterated gasoline, and so decrease the number of adulterated samples approved as presenting good quality.     

气相色谱-质谱法和主成分投影分析法用于烟用香精的分析和质量控制

采用同时蒸馏萃取法及气相色谱-质谱法对 AB6 香精中挥发性成分进行了提取分离与测定.定性了 15 种成分,占总成分的 80.5%(截除溶剂峰),其中 4 种主要组分在10个不同批次样品中含量的相对标准偏差分别为 3.9%,6.1%,5.7%和 2.2%,由此构成合格样品库,并采用主成分投影分析法有效地区分了掺有溶剂的 AB6 香精与 AB6 香精的合格样品,随着溶剂量的增加它们之间的距离越远,同时,不同品种的香精样品之间也具有显著的差异.气相色谱-质谱法分析和主成分投影分析法可用于香精的质量控制.     

气相色谱和气相色谱/质谱法分析高级脂肪伯醇混合物的化学组分

多廿醇是从制糖滤泥中分离得到的一种高级脂肪伯醇天然混合物,其化学组成分析未见报道。本文采用气相色谱法（GC）和气相色谱／质谱法（GC／MS）,对其组分和结构进行了分析和鉴定。     

Essential Oils of New Lippia alba Genotypes Analyzed by Flow-Modulated Comprehensive Two-Dimensional Gas Chromatography (GC×GC) and Chemometric Analysis

Lippia alba (Mill.) N. E. Br. (Verbenaceae) is an aromatic shrub whose essential oils have stood out as a promising source for application in several industrial fields. In this study, the essential oils chemical characterization of eight new L. alba genotypes was performed. The selected materials were collected from the Active Germplasm Bank of the Agronomic Institute and the essential oils were extracted by hydrodistillation. Flow-modulated comprehensive two-dimensional gas chromatography coupled to mass spectrometry (GC×GC-MS) was employed for chemical characterization and evaluation of possible co-eluted compounds. In addition, the chemical analyses were submitted to multivariate statistical analyses. From this investigation, 73 metabolites were identified in the essential oils of the genotypes, from which α-pinene, β-myrcene, 1,8-cineole, linalool, neral, geranial, and caryophyllene oxide were the most abundant compounds among the accessions. This is the first report disclosing α-pinene in higher amounts in L. alba (19.69%). In addition, sabinene, trans-verbenol, myrtenol, (E)-caryophyllene, α-guaiene, germacrene D, and α-bulnesene were also found in relevant quantities in some of the genotypes, and myrtenal and myrtenol could be well separated through the second dimension. Such results contributed to the understanding of the chemical composition of those new genotypes, being important to drive a future industrial applicability and studies in genetic breeding.     

纹党参与白条党参红外光谱的SIMCA聚类鉴别方法研究

以纹党参和白条党参的红外光谱为聚类分析的对象,研究了红外光谱结合SIMCA聚类分析法对纹党参和白条党参进行识别与分类的可行性.选取400 ～2 000 cm~(-1)范围内的光谱,通过基线补偿(Offset)和散射校正(MSC)等预处理后,采用SIMCA聚类分析法建立识别模型.结果表明,所建模型对纹党参和白条党参的识别率分别达92%和96%,拒绝率均为100%.用盲样对所建模型进行了测试,测试结果全部正确.该法可实现对纹党参和白条党参的快速鉴别.     

Fatty Acids Profiling and Biomarker Identification in Snow Alga Chlamydomonas Nivalis by NaCl Stress Using GC/MS and Multivariate Statistical Analysis

The snow alga Chlamydomonas nivalis is a model species of microalgae for the investigation of cell response mechanism and adaptation ability in natural habitats in polar regions and similar extreme environments. The alteration of fatty acids in cellular lipids is known to play a vital role for cell survival and reproduction under various stress conditions. In the present work, an integrated approach of gas chromatography/mass spectrometry (GC/MS) coupled with multivariate statistical analysis was developed to investigate the fatty acid profiles and identify the biomarkers in response to NaCl stress. The data of fatty acid profiles between the control and NaCl-stress group was classified by orthogonal projection on latent structure discriminant analysis (OPLS-DA) and hierarchical cluster analysis (HCA); six of fatty acids (C16:0, C16:3, C18:0, C18:1, C18:2, and C18:3) were identified as biomarkers. These biomarkers showed a regulatory role by decreasing the degree of lipid unsaturation (DLU), providing an expected function in reducing membrane fluidity and permeability for enhancing the tolerance to higher salinity. This is the first report to demonstrate the fatty acid biomarkers in microalgae as the physiological regulators corresponding to the response and adaptation to NaCl stress based on an integrated approach at the lipidomic level.     

气相色谱/质谱/质谱法分析石油基引燃物

应用Ｖａｒｉａｎ ３８００ ＧＣ／Ｓａｔｕｒｎ ２０００ ＭＳ 气相色谱／质谱联用分析仪（简称ＧＣ／ＭＳ／ＭＳ）对以汽油、煤渍和紫油为引燃物，燃烧聚丙稀化纤地毯和土壤时的模拟现场物品进行了引燃物的检出。发现采用ＧＣ／ＭＳ／ＭＳ方法比用ＧＣ／ＭＳ方法可以较彻底地排队由于柱注失、地毯燃物分解产物、土壤背景产物和地毯增塑剂等引起的干扰，而且可以提高检测灵敏度。详细考察了以不同质荷比的离子作母离子时对ＧＣ     

Quality control of PET labeled agents by TLC, GC and HPLC

Radioactive nuclides emitting b⁺-radiation are used for labeling in PET diagnostic. Before the radioactive labeled agent can be used, the radiochemical purity has to be determined by means of two separate radio-chromatography methods. For HPLC, TLC, GC and CE special radioactivity detectors sensitive for b⁺-radiation are required, which fulfil the regulations of various international and national authorities. All conventional chromatography detectors in applications of HPLC, TLC, GC and CE like UV-absorption, fluorescence, reflective index, conductivity, amperometry etc. have an analog signal output 0-1 V. Therefore all signal recording and peak integration systems for chromatography have analog inputs of 0-1 V.     

气相色谱与气相色谱-质谱联用法对七氟醚降解产物的测定

七氟醚是一种新型临床麻醉剂,由于具有稳定性好,刺激性小,诱导麻醉迅速,恢复快,代谢能力强等优点,成功研制出后很快被推广应用.但有学者指出,七氟醚的降解产物氟甲基五氟丙烯醚(Compound A)对小鼠的肝肾功能具有损害作用[1],在人体内的毒性作用目前还没有明确的结论.为了观察Compound A降解量对人体肝肾功能的影响,本文建立了一种快速测定Compound A的气相色谱和气相色谱一质谱联用法.     

用气相色谱/质谱法分析醚化后催化裂化轻汽油中的醚及相关烯烃

用气相色谱／质谱联用仪对醚化工艺过程中醚化前后的催化裂化轻汽油组成进行了定性定量分析。由定性结果分析汽油中的活泼烯烃和生成醚的类型,由定量结果分析活泼烯烃转化成醚后的量的变化情况及生成醚的多少。最终鉴定出６种烯烃参与了醚化过程,生成了４种醚。经查证,这些醚对提高汽油辛烷值均有贡献。     

Multivariate Screening Analysis of Water-in-Oil Emulsions in High External Electric Fields as Studied by Means of Dielectric Time Domain Spectroscopy

The effect of crude oil resins with various polar characters on the stability of w/o model emulsions containing asphaltenes is investigated using a mixture design. The resins were extracted using an adsorption-desorption technique. One asphaltene fraction and four different resin fractions from one European crude oil were used. The stabilities are measured using time-domain dielectric spectroscopy in high external electric field. It is found that resins with different polar character have different effects on the emulsion stability. At asphaltene/resin ratios of 1 and 5 : 3 the resins in some cases lead to an emulsion stability higher than that of a similar emulsion stabilized by asphaltenes only, while at low asphaltene/resin ratios ( approximately 1 : 3) the emulsion stability is reduced by the resins. The effect on emulsion stability of combining two different resin fractions depended on the resin types combined as well as the relative amount of resins and asphaltenes. Also, an increase in the stability of some of the emulsions containing resins and asphaltenes for a period of 50-300 min after the emulsification was observed. This time-dependence of emulsion stability is attributed to the mobility of resins at the oil-water interface and the slow buildup of a stabilizing interfacial film consisting of resins and asphaltenes. Copyright 2000 Academic Press.     

GC-MS对刑事案件中汽油残留物的检验

近年来,刑事案件中的纵火案件呈上升趋势,助燃剂的使用屡见不鲜.准确认定助燃剂的种类,既能为确定案件性质提供重要依据,又能为诉讼提供强有力的证据.汽油由于最容易得到,因此成为刑事案件中最常见的助燃剂.     

气相色谱/质谱-化学计量学法分析测定药对桃仁-红花挥发油

药对是中药配伍中最基本、最常用的形式,具有中药配伍的基本特点。药对化学是复方化学的核心内容。联用色谱和化学计量学方法是分析中药复方复杂体系的有效工具。采用GC/MS法分离测定了药对桃仁-红花、单味药桃仁和红花的挥发油成分,并对其重叠色谱峰采用化学计量学解析法进行了分辨,得到药对和各单味药的纯色谱曲线和质谱。药对桃仁-红花、单味药桃仁和红花分辨出的色谱峰,通过质谱库对其进行定性,分别得到84、27和52个定性结果,占总含量的92.06%、89.43%和94%。实验结果表明:桃仁-红花挥发油成分与单味药桃仁和红花的存在较大差别,也不是两者挥发油成分之加和。