Gas Chromatography Fingerprinting Research Articles

Authentication of Shallots from Brebes using Gas Chromatography Fingerprinting Technique Combined with Chemometrics

Authentication of Shallots from Brebes using Gas Chromatography Fingerprinting Technique Combined with Chemometrics

Phase behavior and GOR evolution using a natural maturity series of lacustrine oil-prone shale: Implications from compositional modelling

For the exploration of shale oil, there is still an urgent need to relate hydrocarbon generation reactions and changing phase behavior to exact levels of thermal maturity. Six organic-rich shale samples from the Cretaceous Qingshankou Formation, Songliao Basin spanning the maturity range with vitrinite reflectance (Ro) 0.58%–1.16% were studied for petroleum generation characteristics using the PhaseKinetics, PhaseSnapshot, and GORFit approaches. All samples show very good petroleum potential and contain Type I kerogen with total organic carbon contents ranging between 1.5% and 5%. A full spectrum of light to heavy hydrocarbons, consistent with live oils, occurs in thermal extracts of all samples. Gas chromatography fingerprints of samples with Ro > 0.7% closely resemble waxy oils derived from lacustrine organic matter (OM); fingerprints of lower maturity samples are not yet as wax rich. The inferred petroleum type organofacies of all samples is paraffinic high wax with low organic sulfur levels. Hydrocarbon generation from the least mature sample is characterized by one dominant activation energy at 55 kcal/mol, accounting for 87% of the total bulk reaction. Assuming a simplified geological scenario, i.e., a 3 K/My linear heating rate, primary petroleum is generated (transformation ratio, i.e., TR: 10%–90%) over a narrow temperature interval of only 23 °C. Onset (10% TR), maximum (Tpeak), and completion (90% TR) temperatures and Ro values are 141 °C at Ro 0.85%, 155 °C at Ro 1.08%, and 164 °C at Ro 1.2%, respectively. Primary gas generation (148–172 °C) occurs 10 °C later (300 m deeper) than the generation of C6+ compounds (138–161 °C). Secondary gas formation from oil cracking begins at 182 °C, maximizes at 197 °C, and is completed well before 225 °C (beginning of late gas generation from the secondary cracking of thermally matured, macromolecular organic matter) at 206 °C. Thus, primary and secondary oil cracking processes do not overlap under geological conditions. In line with a paraffinic high-wax oil petroleum type organofacies, cumulative fluids generated from the least mature sample fall within the black oil class over most of the primary kerogen conversion range up to 90% TR as indicated by low saturation pressures (Psat) and gas-oil-ratios generally below 160 Sm3/Sm3. Maturation results in relatively heavy fluids with Psat values in the range 40–70 bar when the free hydrocarbons, i.e., already present prior to pyrolysis, are included, and in lighter fluids with Psat values in the range 70–90 bar, when the free, mostly waxy hydrocarbons, are excluded. Systematics of physical properties and fluid compositions evolution reproduce the general behavior of naturally occurring petroleum sourced from lacustrine OM very well and fit physical properties and compositions of produced shale oils in the Songliao Basin at comparable maturity levels.

Gas Chromatography Fingerprint of Martian Amino Acids before Analysis of Return Samples

Within the perspective of the current and future space missions, the detection and separation of building blocks such as amino acids are important subjects which are becoming fundamental in the search for the origin of life and traces of life in the solar system. In this work, we have developed and optimized a strategy adapted to space experimentation to detect the presence of amino acid-like compounds using gas chromatography coupled to mass spectrometry (GC-MS). Selected derivatization methods meet the instrument design constraints imposed on in situ extraterrestrial experiments. Coupled to a fast selective extraction, GC analysis would be highly efficient for the detection of organic materials. In the future, the corresponding GC-MS TIC could facilitate simple and fast selection of sediments/dust samples onboard GC-MS-equipped rovers for sample return-to-Earth missions.

Gas chromatography (GC) fingerprinting and immunomodulatory activity of polysaccharide from the rhizome of Menispermum dauricum DC.

This research aimed to establish the gas chromatography (GC) fingerprints and examine the immunomodulatory activity of the rhizome of Menispermum dauricum polysaccharides. In this study, the preparation conditions were optimized by the response surface method (RSM). GC is an effective and sensitive technique employed to measure the composition of monosaccharides; the GC fingerprints of total polysaccharides from 10 batches of the rhizome of M. dauricum (tMDP) were established, and chemometrics methods were adopted to examine the differences and similarities of tMDP from distinct regions. The similarity evaluation illustrated that the polysaccharides derived from the rhizome of M. dauricum from different origins were highly similar. The results of principal components analysis (PCA) illustrated that all the tMDPs may be integrated into one group within the 95% confidence interval, but the rhizome of M. dauricum from different origins could also be distinguished in the plot of PCA scores. Then, the major bioactive fraction MDP was purified and obtained by column chromatography. Our previous study showed that MDP exhibited significant immunomodulatory activity, but the mechanism of the in vitro immunomodulatory activity of MDP is unclear. The macrophage activation induced by MDP was abolished when Toll-like receptor 4 (TLR4) signaling was knocked down by the TLR4 inhibitor. Furthermore, western blot analysis illustrated that MDP activated RAW264.7 cells through MAPKs and NFκB pathways induced by TLR4. This research offers a theoretical foundation for quality control and additional study as a potential immunomodulator of MDP.

Comprehensive evaluation of Loblolly fruit by high performance liquid chromatography four wavelength fusion fingerprint combined with gas chromatography fingerprinting and antioxidant activity analysis

Loblolly fruit (LBF) is mainly used as raw material for beverage, but there are few researches on its quality evaluation or control. The aim of this study was to develop comprehensive evaluation methods for the quality control of Loblolly fruit. firstly, double wavelength coefficient ratio spectrum was used to identify the purity of chromatographic fingerprint peak. It is very important to identify the purity of fingerprint peaks because only the quantitative determination of pure chromatographic peaks is meaningful for its efficient quality control. Then, multi-wavelength fusion fingerprint was established to avoid one-sidedness of a single wavelength for further evaluation by systematically quantified fingerprint method (SQFM). According to the outcome of Pm, 25 batches of LBF were classified into two classifications by hierarchical cluster analysis, which was consistent with the SQFM evaluation results. Two active components, gallic acid (GAC) and ethyl gallate (EGA) in LBF, were quantitatively determined by quantitative analysis of multi-components by single marker (QAMS). In addition, the fingerprint efficacy relationship was established using an off-line antioxidant system and partial least-squares model to explore the connection between chemical components and antioxidant activities. Finally, the evaluation results of high-performance liquid chromatography and gas chromatography were integrated by the mean algorithm, which could reduce the error caused by single method. The results showed that the proposed strategy could provide a method for quality evaluation of LBF and even other traditional Chinese medicines (TCMs).

Oil-Source Rock Correlation Of Oil Seepage And Rock Samples Collected From The Cibulakan Formation At Palimanan Area, West Java

This paper presents the results and discussion of a petroleum geochemistry study performed on two oil seepage and seven outcrop samples collected from the Cibulakan Formation at Palimanan area, West Java. The presence of two oil seepages in Palimanan area indicates that there is an effective source rock which has produces hydrocarbon. The objectives of the study were to determine the hydrocarbon source potential of outcrops, and to characterise selected rock extracts and oil seepage samples, and determine the progenitor source facies at time generation/expulsion. The method used in this research is field study and laboratory analysis. Field studies were conducted on oil and rock sampling, while the geochemical laboratory analysis includes Total Organic Carbon, Rock-Eval Pyrolysis, Vitrinite Reflectance, Kerogen Typing, Bitumen Extraction, Liquid Chromatography, Gas Chromatography fingerprint and GC-MS biomarker. The oil-source rock correlation to its oil based on GC fingerprint (n-alkane distributions) and GC-MS biomarker (triterpanes and sterane distributions) has been done. The oil seepage is correlated with possible source rocks from the Cibulakan Formation. Based on the n-alkane distribution the oil seepage showed biodegradation, but based on the biomarker distributions, it is interpreted that the oil seepage have been generated from a source rock facies containing mainly non-marine algal debris (Type II Kerogen) mixed with some input from terrestrial higher plant organic matter (Type III Kerogen). The oil seepage shows a moderately good correlation with the rock extracts based on GC-MS biomarker data. These biomarker parameters has been successfully used to determine the origin of oil with its precursor source rock by correlating the rock extracts to possible source rocks in the oil and gas exploration.

Gas chromatographic fingerprint analysis of secondary metabolites of Stachys lanata (Stachys byzantine C. Koch) combined with antioxidant activity modelling using multivariate chemometric methods

S. lanata has been traditionally used as a medicinal plant due to its various biological activities such as antioxidant activity. Therefore, identification and quality control studies of this plant are of great importance. To this end, gas chromatography (GC) combined with chemometrics was proposed for fingerprint analysis of S. lanata samples. This study sought to classify GC fingerprints of twenty-eight S. lanata samples from eight different regions of Iran and more importantly, to correlate fingerprints to the antioxidant activity to select S. lanata volatile antioxidant markers. S. lanata samples were classified into five and three classes using partial least squares-discriminant analysis (PLS-DA) according to their GC fingerprints and antioxidant peaks, respectively. The results of PLS regression (PLS-R) and variable importance in projection (VIP) showed that phenol, 2,4-bis (1,1-dimethylethyl)-, hexadecanoic acid- ethyl ester, vitamin E, Beta- sitosterol, and 1- monolinoleoylglycerol trimethylsily ether are volatile antioxidant markers of S. lanata samples.

Optimization of experimental conditions for whole oil gas-chromatography—An example of tight oil in Jimsar sag, Junggar Basin

A series of optimization experiments were conducted on programed temperature rates, injection mode and the inlet temperature to explore an optimum whole oil gas-chromatography experimental method for the tight oil in Jimsar sag, Junggar Basin. The results showed that the quality and quantity of the gas-chromatography fingerprint peaks were significantly improved by setting the programed temperature rate at 3–5 °C/min; splitting injection at a certain split ratio; setting the inlet temperature at 350 °C; increasing the oven temperature to 370 °C.

Geochemical assessment of the Colombian oils based on bulk petroleum properties and biomarker parameters

This geochemical survey defines the typical features of representative oils from the major Colombian basins, and proposes a classification scheme useful for hydrocarbon exploration. This work is based on properties of whole oils such as API gravity, sulfur, vanadium and nickel concentrations, and gas chromatography fingerprints. The framework is completed by inclusion of biomarker parameters derived from GCMS and GCMSMS analysis.Oils from the basins of the Middle Magdalena Valley, Upper Magdalena Valley, Sinú - San Jacinto, Putumayo-Caguan, Lower Magdalena Valley and Catatumbo were assessed. Conclusions were drawn regarding possible sources of origin, oil families, degree of thermal evolution, biodegradation, mixing and refreshing, and inferences regarding exploration implications.The oils from the Middle Magdalena Valley and Upper Magdalena Valley (intermontane basins) and Putumayo (foreland basin), except those from the Caguan area, are oils with similar characteristics. In these three cases the oils are probably coming from source rocks intervals deposited in a marine Cretaceous platform, with variable carbonate/siliciclastic features. In these basins there are no oils derived from Tertiary source rocks.In Sinú-San Jacinto and Lower Magdalena Valley basins the main proportions of oils comes from very proximal environments, probably deltaic type, of Tertiary age with a minor proportion of oils coming from Cretaceous source rocks of marine anoxic environment (the only marine Cretaceous oils discovered so far in the Sinú-San Jacinto and Lower Magdalena Valley basins).The oils from Eastern Foothills of the Eastern Cordillera, look to be derived mainly from proximal Cretaceous source rocks with some mixing of oils derived from Tertiary strata. In the Catatumbo basin there are oils derived mainly from Cretaceous source rocks and some from Tertiary source rocks.Regarding the processes after entrapment, in all of the basins, the biodegradation effects were observed in varying degrees. These processes are dominant toward more quiescent regions, beyond the areas with more tectonic activity, far from the foothills of the Eastern Cordillera. Instead, close to the Eastern Cordillera are more common the paleobiodegradation processes due to reburial of younger molasses. The effects of mixing or refreshing are remarkable close to the Eastern Cordillera foothills in Llanos, Middle Magdalena Valley, and Upper Magdalena Valley basins.

Determination of migration rates of contaminants in a hydrocarbon-polluted site using non-reactive tracer test in the Niger Delta, Nigeria

A natural gradient tracer test with sodium chloride as the injectate was conducted using one injection well and eleven observation wells in an oil-contaminated site in the study area. The aim was to characterize the site and to determine migration rates of the contaminants to provide information on their fate in groundwater resources in the area. The migration of the tracer was constantly monitored by sampling all the observation wells spaced 5 m from each other at 15–30 min intervals for a period of 6 days. The test soil layer is a clayey silty sand consisting of 50 % sand, 30 % silt and 20 % clay. The average static water level at the site is about 2.5 m. Gas chromatography fingerprinting showed that kerosene and diesel are the dominant fractions within the soil matrix. The arrival times of the breakthrough moments of the migrating tracer plume from two observation piezometers situated 2.0 and 7.22 m away from the injection well showed that the mean velocity in the longitudinal direction in the aquifer is 1.403 × 10−3 ms−1 (121 m/day). The longitudinal and transverse dispersion coefficients of 2.45 × 10−3 m2s−1 and 2.3 × 10−3 m2s−1 were used to obtain longitudinal and transverse dispersivities of 1.78 and 1.64 m, respectively. High hydraulic conductivity denoted by the high migration rate of the tracer implies that contaminant at the site will migrate through the aquifer with relative ease. However, the significant clay fraction within the soil provides the medium for adsorption and partitioning of contaminants to the soil.

The Application of Semi-quantitative Total Hydrocarbon Chromatography Technology in Determining Production Allocation of Individual Sand Layer in a Commingled Production Well

The authors present a case study of using semi-quantitative oil fingerprinting technology to correctly back allocate production of individual sand layer in commingled well. A large number of oil samples were collected over time and analyzed by gas chromatography (GC) for their oil fingerprints. The results showed that the production allocation of single layer in two-layer commingled well and the hydrocarbon concentrations of commingled oil were in a liner relationship. However, the production allocation of single layer and oil GC fingerprint parameters were in curvilinear relationship. The semi-quantitative oil fingerprinting technology was suitable for the case of two-layer commingled well, and three-layer commingled well with larger gas chromatography differences among oil of each layer.

Evaluation of reservoir connectivity using whole-oil gas chromatographic fingerprint technology: A case study from the Es33 reservoir in the Nanpu Sag, China

In this study, whole-oil gas chromatographic fingerprint analyses were performed on oils from the Es33 reservoir in the Liubei area of the Nanpu Sag. The gas chromatographic peaks of cyclic and branched alkanes with relatively high resolution from nC10 to nC25 were selected to establish a database of whole-oil gas chromatographic peak height ratio fingerprints. Reservoir fluid connectivity was identified by using clustering analysis. This method can reflect the gas chromatography fingerprint information accurately and entirely, and avoid the one-sidedness of the star diagram method which only selects several fixed gas chromatographic peaks.

Development, Optimization and Validation of Gas Chromatographic Fingerprinting of Brazilian Commercial Diesel Fuel for Quality Control

A three-step development, optimization and validation strategy is described for gas chromatography (GC) fingerprints of Brazilian commercial diesel fuel. A suitable GC-flame ionization detection (FID) system was selected to assay a complex matrix such as diesel. The next step was to improve acceptable chromatographic resolution with reduced analysis time, which is recommended for routine applications. Full three-level factorial designs were performed to improve flow rate, oven ramps, injection volume and split ratio in the GC system. Finally, several validation parameters were performed. The GC fingerprinting can be coupled with pattern recognition and multivariate regressions analyses to determine fuel quality and fuel physicochemical parameters. This strategy can also be applied to develop fingerprints for quality control of other fuel types.

Chemometric analysis of gas chromatographic data-investigation of enological parameters of a bag-in-box white wine as affected by storage time and temperature

In this study, a bag-in-box white wine was stored at 22, 35, and 45 °C for up to 48 days to produce a series of samples that exhibited different enological parameters (absorbance at 420 nm, free SO2, total SO2, total phenol, and total aldehyde). Wine samples were extracted with dichloromethane and analyzed using gas chromatography (GC) to generate volatile fingerprints. Principal component analysis (PCA) score plots of the first three principal components showed grouping trends that were influenced by storage time and temperature. PCA loading plots revealed that changes in chemical profiles were different for wines held at different storage temperatures. Storage time could be predicted accurately by partial least squares (PLS) regression of the GC data. Coefficients of determination (R2) were >0.99, and the standard error of prediction values were 0.4, 0.5, and 1.9 days over the test period of 15, 30, and 48 days, respectively. Using the same GC data with PLS analyses, the enological parameters could be accurately predicted from GC fingerprints, except for the predictions of SO2 in a wine stored at 22 °C and total phenol in a wine stored at 45 °C. Copyright © 2011 John Wiley & Sons, Ltd.

Determination of Polyunsaturated Fatty Esters (PUFA) in Biodiesel by GC/GC–MS and 1H‐NMR Techniques

AbstractIn the present work, methods based on Gas Chromatography (GC), Gas Chromatography–Mass Spectrometry (GC–MS) and 1H‐NMR techniques was developed for the characterization and estimation of Polyunsaturated Fatty Esters (PUFA) in biodiesel. The GC method enables the separation, identification and estimation of these polyunsaturated fatty acid methyl esters to be carried out using a highly polar capillary column (100% cyanopropyl silicon). GC–MS was utilized for unambiguous identification and estimation of esters and isomers present in biodiesel. The estimation of PUFA content is important because PUFA content is a part of the EN 14214 specifications of biodiesel. There is no existing standard method for the estimation of total PUFA content in biodiesel. The developed GC method also quantifies EPA and DHA (C20:5 and C22:6) fatty acid methyl esters which can be used as markers for the estimation of fish oil biodiesel. The presence of EPA and DHA indicates the contamination of fish oil in biodiesel. Further, the 1H‐NMR technique has also been employed to identify and estimate PUFA containing ≥3 double bonds. The PUFA content was estimated from the integral intensities of the chemical shift region corresponding to all type of double bonds in the 1H‐NMR spectra. Based on the developed method, GC fingerprinting of various biodiesel samples was carried out to estimate a PUFA content as low as 1,000 ppm.

Development of the chromatographic fingerprint of Scutellaria barbata D. Don by GC–MS combined with Chemometrics methods

Gas chromatography fingerprint of Scutellaria barbata D. Don (SB) from different origins was studied by gas chromatography–mass spectrometry (GC–MS) and related Chemometrics methods. The constituents of essential oil of Scutellaria barbata D. Don (SB) and its two adulterants Oldenlandia diffusa (OD) and Lobelia chinensis Lour (LCL) were analyzed and compared, 50, 36 and 38 components were identified from SB, OD and LCL, respectively, there were 16 and 18 common components between SB and OD, SB and LCL. Nine different samples collected from different producing areas of SB were studied. The relative standard deviations (RSDs) of retention time and peak area of each component were less than 0.2% and 6%, respectively. The number of common peaks was up to 52 and the un-common peak area was less than 10%. The similarity and difference among SB and its adulterants were also evaluated by correlation coefficient similarity analysis and principal component analysis, the result showed that developed fingerprint characterize the SB from different producing areas and it is useful and feasible for the discrimination of its adulterants.

A random forest of combined features in the classification of cut tobacco based on gas chromatography fingerprinting

We applied the random forest method to discriminate among different kinds of cut tobacco. To overcome the influence of the descending resolution caused by column pollution and the subsequent deterioration of column efficacy at different testing times, we constructed combined peaks by summing the peaks over a specific elution time interval Δ t. On constructing tree classifiers, both the original peaks and the combined peaks were considered. A data set of 75 samples from three grades of the same tobacco brand was used to evaluate our method. Two parameters of the random forest were optimized using out-of-bag error, and the relationship between Δ t and classification rate was investigated. Experiments show that partial least squares discriminant analysis was not suitable because of the overfitting, and the random forest with the combined features performed more accurately than Naïve Bayes, support vector machines, bootstrap aggregating and the random forest using only its original features.

Hydrocarbon Speciation by Fingerprinting Technique and Diagnostic Vanadium/Nickel Ratio of Mgbede-20 Oil-Impacted Site in the Niger Delta Basin of Nigeria

This article describes the speciation and recognition of the hydrocarbon distribution pattern and the diagnostic ratios of source-specific pristane and phytane for the characterization of the chemical composition and source identification of spilled oil at Mgbede-20 in the Niger Delta Basin of southern Nigeria. Gas chromatography fingerprinting and data interpretation of analyses of oil residues from the site indicated that the released oil was a partially degraded paraffin-base crude oil with fairly well resolved peaks in the n−C11 to n−C23 range. The chromatograms also contained the acyclic isoprenoids pristane and phytane, at mean concentrations of 8,100 ± 1,700 mg/kg and 24,000 ± 7,300 mg/kg, respectively (without overlap in standard errors at 95% confidence level). The loss of the light end n-alkanes of carbon numbers lower than n−C11 indicated that the spilled oil was only slightly weathered after the spill incident and that the chemical composition of the aliphatic components had not undergone significant alteration, suggesting that the on-site spilled oil was relatively fresh. A mean pristane-to-phytane (Pr/Ph) ratio of 0.39 was obtained for replicate spill samples; these Pr/Ph ratios were suggestive of an anoxic-derived source crude oil, with some likely non-waxy, marine-derived organic matter content. The V-to-N; ratios and the distribution of polycyclic aromatic hydrocarbons may serve as a corrective profile for future characterization of the Mgbede-20 oil.

Chemical Fingerprinting of Gardenia jasminoides Fruit Using Direct Sample Introduction and Gas Chromatography with Mass Spectrometry Detection

A rapid, rugged, and inexpensive approach is described to develop chemical fingerprints of volatile and semivolatile fractions in herbal medicine. The method is based on the combination of direct sample introduction and gas chromatography (GC) analysis with mass spectrometry detection. In comparison with routine methods, the proposed approach provides the most informative fingerprint and does not demand time-consuming extraction, pretreatment, and cleanup procedures. The approach was applied to establish the GC fingerprint of gardenia fruit (Gardenia jasminoides Ellis), in which 39 components were identified. With the help of principal components analysis, the obtained fingerprint could reveal the variation in and within different herb samples as affected by season and developmental state (wild or cultivated). The results indicated that the proposed approach could serve as a rapid, simple, and effective technique for the quality control of herbal medicines.

The application of gas chromatography fingerprint technique to calculating oil production allocation of single layer in the commingled well

Gas chromatography fingerprint technique has the advantages of fast performance and low cost. It can be used to conduct analysis without interruption either in the field or at laboratory. This technique has been used successfully in such cases that conventional production logging techniques are powerless. Taking low-concentration anthracene as internal standard, we calculated the absolute concentrations of fingerprints, initially made some experiments directly on biodegradation of crude oils, and calculated production allocation in the Gudong Oil field. Compared with the production logging, this method has made up for the deficiencies of the former GC fingerprint technique. It will find wide applications in monitoring the trend of production in various oil-fields.