水上溢油的气相色谱-质谱法鉴别

利用气相色谱－质谱法分析水上溢油样品和可凝溢油源样品，通过比较溢油样品和可疑溢油源样品的总离子流图的轮廓、m/z 191和m/z 217质量色谱图指纹和姥鲛烷（Pr)与峰面积比值APr/APh,建立了水上溢油的GC－MS鉴别方法。     

Comparison of solid phase extraction, saponification and gel permeation chromatography for the clean-up of microwave-assisted biological extracts in the analysis of polycyclic aromatic hydrocarbons

The feasibility of different clean-up procedures was studied for the determination of polycyclic aromatic hydrocarbons (PAHs) in biota samples such as oysters, mussels and fish liver. In this sense, once the samples were extracted--essentially with acetone and in a microwave system--and before they could be analysed by gas chromatography-mass spectrometry (GC-MS), three different approaches were studied for the clean-up step: solid phase extraction (SPE), microwave-assisted saponification (MAS) and gel permeation chromatography (GPC). The main aim of this work was to maximise the recoveries of PAHs and to minimise the presence of interfering compounds in the last extract. In the case of SPE, Florisil cartridges of 1, 2 and 5 g, and silica cartridges of 5 g were studied. In that case, and with oysters and mussels, microwave-assisted extraction and 5 g Florisil cartridges provided good results. In addition, the concentrations obtained for Standard Reference Material (SRM) NIST 2977 (mussel tissue) were in good agreement with the certified values. In the case of microwave-assisted saponification, the extracts were not as clean as those obtained with 5 g Florisil and this fact lead to overestimate the concentration of the heaviest PAHs. Finally, the cleanest extracts were obtained by GPC. The method was successfully applied to mussels, oysters and hake liver, and the results obtained for NIST 2977 (mussel tissue) were within the confidence interval of the certified reference material for most of the certified analytes.     

GEOCHEMISTY OF BICYCLIC ALKANES IN SEDIMENTS, COAL AND CRUDE OILS

By using GC-MS to analyze the extracts of source rocks, coal and crude oil samplesformed in different sedimentary environments in China, New Zealand and Australia, twenty-two compounds of five types of bicyclic alkanes have been dis covered in the samples. Thispaper makes an exposition of stereochemical structure, abundance and distributive features ofthese compounds and their relation to sedimentary environments and thermal evolution. Furt-thermore, it demonstrates how the abundance ratios of bicyclic alkanes to steranes and ter-panes, drimane to homodramane and the relative abundance of C_(15),C_(16),C_(12)-C_(14) series of bicyclic-alkane compounds can be used to judge and determine types of oil and gas forming environ-ments (the depositive environments of source rocks from which the oil and gas wereformed), characteristics of source rocks and degree of maturation.     

Optimization of matrix solid-phase dispersion conditions for UV filters determination in biota samples

A low solvent consumption method for the determination of eight ultraviolet (UV) filters, displaying low to medium polarities, in freeze-dried samples of marine bivalves and fish is proposed. Matrix solid-phase dispersion (MSPD) and gas chromatography with mass spectrometry (GC-MS) were used as sample preparation and determination techniques, respectively. This work describes the influence of several parameters (type and amount of dispersant and clean-up sorbents, as well as elution solvent) on the yield and the selectivity of the MSPD extraction. Under optimized conditions, samples (0.5?g) were ground with 2?g of Florisil in a mortar with a pestle and transferred into a polypropylene syringe, which contained 1?g of C18 as clean-up sorbent. Analytes were eluted with 5?mL of acetonitrile. This extract was concentrated to dryness, re-constituted with 1?mL of ethyl acetate and injected in the GC-MS system without any further clean-up. The global average recoveries, measured for three different biota samples, spiked at three different levels (between 50 and 1000?ng?g^?1), ranged from 80% to 101% with associated standard deviations below 10%. The inter-day precision of the method varied from 4% to 15% and the achieved LOQs (defined for a signal to noise ratio of 10) ranged from 4 to 28?ng?g^?1, referred to the freeze-dried matrix. Octocrylene (OCR) was found in some samples of fish and mussels at concentrations between 15 and 20?ng?g^?1, referred to dry mass.     

Oil-spill identification by gas chromatography-mass spectrometry

Two approaches are proposed for the identification of a contaminant caused by the spilling of oil or oil products in water. A capillary gas chromatography (CGC)-mass spectrometry (MS) method for oil spill identification is applied. The presented approaches describe the use of MS data of 18 selective ions of spilled product and the probable pollutant. The spill identification is accomplished on the bases of a quantitative comparison between the ion chromatograms of the samples taken from the probable pollutant and from the spill itself. The other approach is made by chemometric treatment of complete CGC-MS data.     

气相色谱-质谱法测定富硒酵母中的硒蛋氨酸

建立了气相色谱-质谱（GC-MS）测定富硒酵母中硒蛋氨酸含量的方法。比较了3种从样品中提取硒蛋氨酸方法的效果。样品在三羟甲基氨基甲烷（Tris）缓冲液中酶解24 h后,以丁醇及三氟乙酸酐为衍生化试剂对硒蛋氨酸进行衍生化,采用选择离子模式对衍生物进行GC-MS测定。硒蛋氨酸的回收率为98.5%~103.7%,相对标准偏差为0.9%~2.4%,检出限为0.5 mg/L（S/N=3）。对实际样品进行测定,得到样品中硒蛋氨酸的含量结果。该法简便快速,准确可靠,灵敏度高。     

Pyrolysis of asphaltenes and biomarkers for the fingerprinting of the Amoco-Cadiz oil spill after 23 years

The geochemical technique of asphaltenes pyrolysis was successfully applied to the long-term monitoring of the Amoco-Cadiz oil spill 23 years after the wreck in the salt marshes of Île Grande, Northern Brittany, France. This method allows the reconstitution of the saturated fraction of the original oil from the asphaltenes fraction of severely degraded oil residues. The results showed that the oil reached a degradation rate of 60% relatively to the initial oil. The asphaltenes pyrolysis generated a gas chromatographic profile very similar to the original Amoco-Cadiz oil. In the biomarkers fraction, gas chromatographic/mass spectrometric (GC-MS) analyses demonstrated that terpanes were conserved whereas steranes were partly degraded. We also showed that the class of seco-hopanes biomarkers are conserved and can be used in the long-term monitoring of oil pollutions.     

Spectrochemical study for the in situ detection of oil spill residues using laser-induced breakdown spectroscopy

Laser-induced breakdown spectroscopy (LIBS) has been used to identify the differences or similarities between crude oil and fuel residues. Firstly, a man portable LIBS analyzer was used for the on-site environmental control and analysis of the oil spill from The Prestige. An exhaustive analysis of crude oil and oil spill residues (collected during the field campaign in the Galician Coast) was performed in the laboratory. Characteristics elements in petroleum such as C, H, N, O, Mg, Na, Fe and V were detected. In addition, contributions from Ca, Si and Al in the composition of residues have been found. The use of intensity ratios of line and band emissions in the original fuel (crude oil) and in the aged residues allowed a better characterization of the samples than the simple use of peak intensities. The chemical composition between the crude oil and the fuel residues was found completely different. As well, a statistical method was employed in order to discriminate residues. Although significant differences were observed, no conclusions in terms of age and provenance could be reached due to the unknowledgment in the origin of the samples.     

Multivariate statistical methods for evaluating biodegradation of mineral oil

Two methods were developed for evaluating natural attenuation and bioremediation of mineral oil after environmental spills and during in vitro experiments. Gas chromatography-mass spectrometry (GC-MS) in selected ion monitoring (SIM) mode was used to obtain compound-specific data. The chromatographic data were then preprocessed either by calculating the first derivative, retention time alignment and normalization or by peak identification, quantification and calculation of diagnostic ratios within homologue series of polycyclic aromatic compounds (PACs). Finally, principal component analysis (PCA) was applied to the preprocessed chromatograms or diagnostic ratios to study the fate of the oil. The methods were applied to data from an in vitro biodegradation experiment with a North Sea crude oil exposed to three mixtures of bacterial strains: R (alkane degraders and surfactant producers), U (PAC degraders) and M (mixture of R- and U-strains) over a 1-year-period with five sampling times. Assessment of variation in degradability within isomer groups of methylfluorenes (m/z 180), methylphenanthrenes (m/z 192) and methyldibenzothiophenes (m/z 198) was used to evaluate the effects of microbial degradation on the composition of the oil. The two evaluation methods gave comparable results. In the objective pattern matching approach, principal component 1 (PC1) described the general changes in the isomer abundances, whereas M samples were separated from U and R samples along PC2. Furthermore, in the diagnostic ratio approach, a third component (PC3) could be extracted; although minor, it separated R samples from U and M samples. These results demonstrated that the two methods were able to differentiate between the effects due to the different bacterial activities, and that bacterial strain mixtures affected the PAC isomer patterns in different ways in accordance with their different metabolic capabilities.     

Objective chemical fingerprinting of oil spills by partial least-squares discriminant analysis

An objective method based on partial least-squares discriminant analysis (PLS-DA) was used to assign an oil lump collected on the coastline to a suspected source. The approach is an add-on to current US and European oil fingerprinting standard procedures that are based on lengthy and rather subjective visual comparison of chromatograms. The procedure required an initial variable selection step using the selectivity ratio index (SRI) followed by a PLS-DA model. From the model, a "matching decision diagram" was established that yielded the four possible decisions that may arise from standard procedures (i.e., match, non-match, probable match, and inconclusive). The decision diagram included two limits, one derived from the Q-residuals of the samples of the target class and the other derived from the predicted y of the PLS model. The method was used classify 45 oil lumps collected on the Galician coast after the Prestige wreckage. The results compared satisfactorily with those from the standard methods.     

固相萃取-气相色谱-质谱联用检测地沟油中胆固醇

建立了固相萃取-气相色谱-质谱联用(SPE-GC-MS)检测地沟油样品中胆固醇的分析方法。样品用硅胶固相萃取小柱前处理净化,先用20 mL含0.6%乙醚的正己烷溶液淋洗,再用10 mL含15%乙醚的正己烷溶液洗脱,胆固醇萃取率达97%。净化后的样品用配备电子轰击离子源的气相色谱-质谱联用仪进行测定,以保留时间和特征碎片离子定性,在选择离子监测模式下用外标法定量,选择离子为m/z 213、275、301、368、386,目标离子为m/z 386,参考离子为m/z 213和275。不同加标水平下的加标回收率为91.7%～101%,相对标准偏差(RSD)小于6%,检出限为0.01 mg/L。胆固醇质量浓度在0.24~6.0 mg/L范围内有良好的线性关系(相关系数为0.9996)。该法可精确检测油脂中胆固醇的含量,检测结果可作为判断其中是否掺有地沟油的依据之一。     

Fast solid-phase extraction-gas chromatography-mass spectrometry procedure for oil fingerprinting. Application to the Prestige oil spill

A rapid and simple fractionation procedure using solid-phase extraction (SPE) cartridges was developed for an accurate determination of aliphatic and polycyclic aromatic hydrocarbons in petroleum residues and further application in chemical fingerprinting of oil spills by gas chromatography-mass spectrometry (GC-MS). Among the adsorbents evaluated, SiO2/C3-CN exhibited the best selectivity, providing, by elution with n-hexane (4 ml) and n-hexane-CH2Cl2 (1:1) (5 ml), two well-resolved aliphatic and aromatic hydrocarbon fractions, with recoveries of 97 +/- 7.2 and 99.7 +/- 13.9%, respectively. The SPE fractionation procedure was compared with the conventional silica-alumina adsorption chromatography showing similar results but practical advantages in terms of reproducibility, analysis time, solvent reduction and cost. Moreover, is particularly suitable for routine analysis with a high sample throughput. The developed methodology was tested in the characterization of fuel-oil samples collected along the Spanish north-west coast, after the Prestige oil spill accident.     

气相色谱-质谱法测定乳制品中光引发剂异丙基硫杂蒽酮的残留量

建立了采用气相色谱（GC）-质谱(MS)检测由包装材料迁移到乳制品中的光引发剂异丙基硫杂蒽酮残留量的方法。使用氘代蒽为内标,样品经Carrez试剂除蛋白质后用丙酮-正己烷(体积比为1∶1)提取,上层提取液用氟罗里硅土固相萃取小柱净化。采用单四极杆质谱进行样品筛选和定量,选取的监测离子为m/z 184,m/z 224,m/z 239,m/z 254(异丙基硫杂蒽酮)和m/z 80,m/z 94,m/z 188,m/z 160(氘代蒽)。疑似样品采用离子阱串联质谱法进行确证,选取的母离子和子离子分别为m/z 254,m/z 239(异丙基硫杂蒽酮)和m/z 188,m/z 160(氘代蒽)。本方法的测定低限(LOQ)分别为7.0 μg/L(GC-MS)和5.0 μg/L(GC-MS/MS),回收率为74.9%~89.6%。采用该方法对11种不同类型的乳制品进行了检测,发现了两例阳性样品。     

Inner chromatogram projection (ICP) for resolution of GC-MS data with embedded chromatographic peaks

The chromatographic peak located inside another peak in the time direction is called an embedded or inner peak in contradistinction with the embedding peak, which is called an outer peak. The chemical components corresponding to inner and outer peaks are called inner and outer components, respectively. This special case of co-eluting chromatograms was investigated using chemometric approaches taking GC-MS as an example. A novel method, named inner chromatogram projection (ICP), for resolution of GC-MS data with embedded chromatographic peaks is derived. Orthogonal projection resolution is first utilized to obtain the chromatographic profile of the inner component. Projection of the two-way data matrix columnwise-normalized along the time direction to the normalized profile of the inner component found is subsequently performed to find the selective m/z points, if they exist, which represent the chromatogram of the outer component by itself. With the profiles obtained, the mass spectra can easily be found by means of a least-squares procedure. The results for both simulated data and real samples demonstrate that the proposed method is capable of achieving satisfactory resolution performance not affected by the shapes of chromatograms and the relative positions of the components involved.     

Practical aspects of chemometrics for oil spill fingerprinting

Tiered approaches for oil spill fingerprinting have evolved rapidly since the 1990s. Chemometrics provides a large number of tools for pattern recognition, calibration and classification that can increase the speed and the objectivity of the analysis and allow for more extensive use of the available data in this field. However, although the chemometric literature is extensive, it does not focus on practical issues that are relevant to oil spill fingerprinting. The aim of this review is to provide a framework for the use of chemometric approaches in tiered oil spill fingerprinting and to provide clear-cut practical details and experiences that can be used by the forensic chemist. The framework is based on methods for initial screening, which include classification of samples into oil type, detection of non matches and of weathering state, and detailed oil spill fingerprinting, in which a more rigorous matching of an oil spill sample to suspected source oils is obtained. This review is intended as a tutorial, and is based on two examples of initial screening using respectively gas chromatography with flame ionization detection and fluorescence spectroscopy; and two of detailed oil spill fingerprinting where gas chromatography-mass spectrometry data are analyzed according to two approaches: The first relying on sections of processed chromatograms and the second on diagnostic ratios.     

催化加氢热解/气相色谱-质谱研究沉积物中生物标志物

针对地质体中高演化沉积有机质,应用催化加氢热解/气相色谱-质谱方法测定了干酪根中以共价键结合的生物标志物。结果表明,实验样品的催化加氢热解产物收率明显高于二氯甲烷（DCM）索氏抽提,产物色谱图中饱和烃的峰形、保留时间和质谱特征与索氏抽提峰形基本一致;对比两种方法产物中饱和烃主要指标甾烷m/z 217和藿烷m/z 191表明,经过加氢还原,干酪根分子网络中共价键结合着两种生物标志物分子骨架得到印证,为催化加氢热解提取沉积物中生物标志物的方法可靠性提供了依据。催化加氢热解/气相色谱-质谱技术是一种对研究高演化沉积有机质中生物标志化合物有独特作用的有效分析手段。     

Endocrine-disrupting nonylphenols - ultra-trace analysis and time-dependent trend in mussels from the German bight

A very sensitive and efficient analytical procedure is presented for the determination of 4-nonylphenols (NP) in blue mussels by use of off-line coupling of high-performance liquid chromatography (HPLC) and gas chromatography with mass spectrometric detection (GC-MS). Combined steam distillation and solvent extraction were used to extract the analytes from the mussel samples. Before quantification by GC-MS the raw extracts were purified by normal-phase HPLC. 4-n-Nonylphenol was used as internal standard. The detection limit was 15 ng NP absolute, calculated from the blank value. The method was applied to the determination of NP in blue mussel samples from the German North Sea sampled over a period of 10 years. Collection, homogenization, and storage of the mussels were performed according to the Standard Operating Procedures of the German Environmental Specimen Bank since 1985. The total NP concentrations in the mussels decreased significantly from 1985 (4 microgram kg (-1)) to 1995 (1.1 microgram kg (-1)).     

Analysis of triallate residues in cereals and soil by gas chromatography with ion-trap detection.

Triallate residues in barley seedlings and soil samples were determined by gas chromatography with ion-trap detection. Soil was extracted with methanol on a mechanical shaker, and plants were extracted with acetonitrile in a Sorvall homogenizer. After evaporation of the organic solvents, the residue was dissolved in hexane, and plants extracts were cleaned-up on an alumina column. Gas chromatographic analysis was carried out using a BP-1 fused-silica capillary column with helium as carrier gas. To quantitate residues the total-ion chromatogram was obtained and then the selected-ion monitoring chromatograms were displayed at m/z 86 for triallate and at m/z 154 for the internal standard, methyl-(4-amino-2-chloro)-benzoate. The average recovery through the method from barley and soil samples was always higher than 80%. The limit of detection in the selected-ion mode was 0.01 mg/kg. Barley and soil samples treated with triallate were also analysed. A good agreement was observed between results obtained by this method and by gas chromatography with nitrogen-phosphorus detection.     

Simplified pesticide multiresidue analysis in virgin olive oil by gas chromatography with thermoionic specific, electron-capture and mass spectrometric detection

In the present work, an analytical multiresidue method has been developed for the analysis of 32 organochlorine, organophosphorus and organonitrogen pesticides at microg kg(-1) levels in virgin olive oil. The method consists of the extraction of the pesticides with acetonitrile saturated in n-hexane followed by a clean-up process based on gel permeation chromatography (GPC) with ethyl acetate-ciclohexane (1:1) as mobile phase to separate the low-molecular mass pesticides from the high-molecular mass fat constituents of the oil. The target compounds were determined in the final extract by gas chromatography (GC) using thermoionic specific (TSD) and electron-capture (ECD) detection. In the case of positive samples, the amounts found were confirmed by GC-MS/MS, being the results in good agreement. Recoveries and RSDs (n = 10) values were 91-124% and 1-8% (GC-ECD), 82-100% and 9-20% (GC-TSD), and 89-105% and 4-14% (GC-MS/MS), respectively. The three proposed methods were applied to samples collected directly in two olive mills located in the Jaén province (Spain). Specifically, 24 samples of virgin olive oil were collected. The most frequently pesticide residues found were the herbicides terbuthylazine and diuron and endosulfan sulfate, a degradation product of the insecticide endosulfan. The herbicide concentration was higher in those oil samples obtained from olives which were collected from the ground after they had fallen down than in those oil samples from olives harvested directly from the tree. The GC-MS/MS developed method was also applied to the analysis of an olive oil sample from a proficiency test spiked with organochlorine pesticides and all the values obtained were within the specified "satisfactory" range.