Thin-layer Chromatography-flame Ionization Detection Research Articles

Laboratory Experiments and Field Tests of an Amphiphilic Metallic Chelate for Catalytic Aquathermolysis of Heavy Oil

An amphiphilic metallic chelate−aromatic sulfonic iron was synthesized for the first time, characterized by Fourier transform infrared (FT-IR) spectroscopy, and then used in catalytic aquathermolysis of heavy oil both in the laboratory and field. The laboratory results showed that this new catalyst was efficient, universal, and superior to other efficient catalysts we have synthesized before; in addition, for EX35 heavy oil, it led to a evident viscosity reduction by 90.66% at 200 °C with 14.66% in conversion of heavy contents to light contents. To evaluate the its performance, the structure and group composition of heavy oil was analyzed by FT-IR, thin-layer chromatography−flame ionization detection (TLC-FID), gas chromatography/mass spectrometry (GC/MS), 1H NMR, and elemental analysis (EL) before and after the aquathermolysis. It is found that the changes of the composition and structure of the heavy oil can lead to the viscosity reduction. In field tests of G61012 and G6606 wells in the Henan oilfield,...

Lipid class composition of bleached and recovering Porites compressa Dana, 1846 and Montipora capitata Dana, 1846 corals from Hawaii

Corals rely on stored reserves, especially lipids, to survive bleaching events. Lipid class composition reveals the lipid source, and provides evidence of metabolic changes (i.e., photoautotrophic or heterotrophic) during bleaching and recovery. Porites compressa Dana, 1846 and Montipora capitata Dana, 1846 corals were experimentally bleached in outdoor tanks with seawater temperature elevated to 30 °C (treatment corals). Additional control fragments were maintained in separate tanks at ambient temperatures (27 °C). After one month, all fragments were returned to the reef for 0, 1.5, 4, or 8 months. Lipid class composition was analyzed by Iatroscan (thin layer chromatography-flame ionization detection). In treatment P. compressa, triacylglycerol (TG) decreased at 0 and 1.5 months, phospholipid (PL) also decreased at 1.5 months, and both remained lower relative to controls along with wax esters (WE) after 8 months. Neither treatment nor control P. compressa had any detectable monoacylglycerol (MG) or diacylglycerol (DG). Overall, P. compressa first consumed available storage, then structural lipids, and all lipid classes remained low at the end of the study. In treatment M. capitata, TG and PL decreased, while MG increased relative to controls at 0 months. At 4 months, free fatty acid (FFA), sterol (ST), and PL in treatment M. capitata were two to ten times higher than controls. Treatment and control lipid class composition were not different from each other at 8 months. In contrast to P. compressa, M. capitata consumed some lipid classes and augmented others, probably due to sequential metabolism of storage lipids and increased heterotrophy. Overall, lipid class assimilation was more rapid in treatment M. capitata corals that switch between heterotrophy and photoautotrophy, than in treatment P. compressa corals that rely mostly on photoautotrophy.

Production of monoolein from oleic acid and glycerol in supercritical carbon dioxide media: A kinetic approach

Esterification of free fatty acids (FFA) with glycerol in supercritical carbon dioxide (SC-CO 2) media to produce designer monoacylglycerols (MAG) for food, cosmetic, and pharmaceutical industries, was conducted to elucidate the reaction kinetics and provide the reaction mechanism. Reactions were conducted in SC-CO 2 at 10–30 MPa, 170–250 °C in a batch stirred reactor using an anhydrous glycerol to oleic acid initial molar ratio (gly/oleic) of 10:1, 1:1 and 1:2 and in supercritical nitrogen at 10 MPa and 250 °C using 10:1 gly/oleic. Samples were collected as a function of time and MAG, diacylglycerol, triacylglycerol and FFA concentrations were determined using thin layer chromatography–flame ionization detection. The rate of MAG formation at 50% of equilibrium concentrations (Rate-50%) increased significantly ( p ≤ 0.05) with temperature but was not affected by pressure or supercritical media ( p > 0.05). Rate-50% values for 10:1 and 1:1 gly/oleic were similar ( p > 0.05) but higher ( p ≤ 0.05) than that for 1:2 gly/oleic. Equilibrium concentration of MAG significantly ( p ≤ 0.05) decreased with decreased initial glycerol concentration. The calculated rate constants provided a better understanding of the mechanism and are essential for optimal process design.

Kinetic modeling of glycerolysis–hydrolysis of canola oil in supercritical carbon dioxide media using equilibrium data

Glycerolysis–hydrolysis reactions to produce monoacylglycerol (MAG) and diacylglycerol (DAG) used in the production of functional foods and nutraceuticals were conducted in supercritical carbon dioxide (SC-CO 2) media to elucidate the reaction kinetics, provide the reaction mechanism and assess the potential catalytic agent involved. Reactions were conducted in an electrically heated, magnetically stirred autoclave at 250 °C, 10–30 MPa, anhydrous glycerol/canola oil molar ratio of 34:1 and initial water content of 0 to 8% (w/w). Reactions were also conducted in supercritical nitrogen at 250 °C, 10 MPa, and 8% (w/w) initial water. Samples were collected as a function of time and the concentrations of MAG, DAG, free fatty acids (FFA) and triacylglycerol (TAG) were obtained using thin layer chromatography–flame ionization detection. The maximum rate of MAG formation at 20 MPa was significantly higher ( p ≤ 0.05) than that at 30 MPa, but similar ( p > 0.05) to that at 10 MPa; a finding that has economical impact because a pressure of 10 MPa can be reached without the use of a high-pressure pump. Rates of MAG formation in SC-CO 2 and -N 2 media were similar ( p > 0.05) thereby demonstrating that SC-CO 2 does not contribute to catalysis. The maximum rate of MAG production at 10 MPa was significantly higher ( p ≤ 0.001) for reaction with 4% (w/w) initial water compared with anhydrous reactions and was significantly lower ( p ≤ 0.05) compared to that of reaction with 8% (w/w) initial water. Although this study was unable to identify the catalytic reagent, it did show that water played an important role. Reactions were carried out up to 14 h and equilibrium was reached at 9 h. The average equilibrium composition (mol%) obtained at 9–10 h for the reactions conducted at 10–30 MPa with 4–8% (w/w) water was 66–71% MAG, 13–15% DAG, 13–17% FFA and 0–1% TAG. A MAG concentration of >65% is higher than that obtained in conventional glycerolysis where the concentration of MAG generally does not exceed 58%. Such findings not only demonstrate improved yields but also lead to a better understanding of the complex mechanisms of simultaneous glycerolysis–hydrolysis reactions and are critical for optimal process design targeting the MAG and DAG products.

Lipid content and composition of dominant copepods in the Oyashio waters analyzed by the thin layer chromatography flame ionization detection method

Lipid content and composition of some dominant copepods inhabiting the Oyashio waters were analyzed by the thin layer chromatography flame ionization detection (TLC/FID) method. Copepod samples were collected dur- ing the RV Shoyo-maru cruise from September 18 to October 15 in 1988. A new three-step development: the first in hexane and diethyl ether (66 : 4, v/v), the second in hexane, diethyl ether and formic-acid (55 : 15 : 0.5) and the last in hexane and benzene (1 : 1), single scan method by TLC/FID was found to be useful for separation and analysis of lipids in boreal copepods. As a result, the eight species of calanoid copepods analyzed in this study could be divided into two groups according to their lipid class proportions. One group consisted of copepods containing many wax esters and in- cludes Neocalanus flemingeri, N. cristatus, Pseudocalanus minutus, Metridia pacifica and M. okhotensis. The other group containing many triglycerides includes Eucalanus bungii, Pleuromamma abdominalis and Acartia omorii. I have deduced that copepods storing wax esters could have long periods of dormancy in winter and consume lipids mainly for reproduction, while copepods storing triglycerides could overwinter without a period of dormancy and be opportunistic

Application of curve fitting in thin-layer chromatography-flame ionization detection analysis of the carbohydrate fraction in marine mucilage and marine snow samples from Italian seas.

This paper presents a thin-layer chromatographic-flame ionization detection (TLC-FID) procedure to characterize the carbohydrate fraction of marine mucilage and marine snow samples from the Italian Seas. The identification of the different carbohydrate subfractions is supported by the application of a deconvolution procedure based on a new mathematical function for describing chromatographic peaks and enhancing their resolution. The joint-approach TLC-FID analysis and deconvolution procedure allows for the characterization of the carbohydrate fraction of the marine samples in a single step without using the different derivatization procedures requested by the most common gas chromatography and high-performance liquid chromatographic methods for carbohydrate analysis. In fact, the results obtained by the TLC-FID procedure show that different neutral, uronic acid, and aminosugar subfractions can be present simultaneously in these samples. Moreover, the results support some hypotheses about the causes of the presence of mucilages in the Italian Seas.

Determination of fat content in fish feed by supercritical fluid extraction and subsequent lipid classification of extract by thin layer chromatography-flame ionization detection

A supercritical fluid extraction (SFE) method employing carbon dioxide with an alcohol modifier was developed to determine fat content in fish feed. Fat content was determined for 14 dry extruded salmon or trout grower feeds with advertised fat contents ranging from 14% to 33% (w/w). Results with the new method were significantly higher than those obtained from Soxhlet extractions (AOCS Method Ba 3–38) with a difference in mean fat content of 1.9% ( P<0.001) and were similar but significantly higher than total fat determinations by acid hydrolysis followed by organic extraction (AOAC Method 922.06) with a difference in mean fat content of 0.3% ( P<0.001). Lipid extracts from the Soxhlet and the SFE methods were classified by thin layer chromatography-flame ionization detection into five lipid classes. Extracts from the SFE method contained a significantly greater amount of phospholipids (15–85%) than extracts from the Soxhlet method ( P<0.001). Advantages of the SFE method over conventional fat determination methods include an increased yield of lipid, shorter analysis times and the absence of hazardous chemicals. The SFE method has the additional advantage over acid hydrolysis methods of estimating total fat content with minimal chemical damage to the lipid extract.

Ultrasound extraction and thin layer chromatography–flame ionization detection analysis of the lipid fraction in marine mucilage samples

This paper reports an analytical procedure based on ultrasound to extract lipids in marine mucilage samples. The experimental conditions of the ultrasound procedure (solvent and time) were identified by a FT-IR study performed on different standard samples of lipids and of a standard humic sample, before and after the sonication treatment. This study showed that diethyl ether was a more suitable solvent than methanol for the ultrasonic extraction of lipids from environmental samples because it allowed to minimize the possible oxidative modifications of lipids due to the acoustic cavitation phenomena. The optimized conditions were applied to the extraction of total lipid amount in marine mucilage samples and TLC–flame ionization detection analysis was used to identify the relevant lipid sub-fractions present in samples.

Dynamics of Bitumen Fractions by Thin-Layer Chromatography/Flame Ionization Detection

Thin-layer chromatography/flame ionization detection (TLC/FID) allows for the fractionation of bitumen into four fractions, namely, the saturates, the aromatics, the resins A and the resins B (SARAB). The technique is rapid and economical, but it lacks reproducibility. The effect of chromarod aging on reproducibility was investigated along with that of the time between bitumen dissolution and its analysis (time lapse effects). It is found that chromarod aging causes a 2−5% variation in SARAB content, and that time lapse causes a 50−75% variation in the aromatics and resins A content. The effect of time lapse stems from the aging of bitumen in solution. A mechanism for this aging is provided. It is demonstrated to be a physical rather than a chemical transformation of bitumen that reveals itself as a conversion of aromatics into resins. The physical nature of aging is shown by the absence of oxidation and aromatization in solution and by the successful modeling of aging after a reversible process. The conversion of aromatics into resins is explained by the grouping of alkyl-aromatics into micelles. Micelles mimic resins during chromatography and cause an apparent increase in resins concentration.

Quality-assurance study of marine lipid-class determination using chromarod/iatroscan® thin-layer chromatography-flame ionization detector

An Iatroscan® thin-layer chromatography–flame ionization detector has been utilized to quantify lipid classes in marine samples. This method was evaluated relative to established quality-assurance (QA) procedures used for the gas chromatographic analysis of PCBs. A method for extracting and analyzing eight major lipid classes in the ribbed mussel (Guekensia demissus) was developed. The analytical method met the QA criteria prescribed for consistent external calibrations, low blanks, complete extraction of all lipid classes, and precise replicate analysis. Matrix and blank spikes were satisfactorily recovered (50-130%), provided that the samples contained a large enough mass (>4% dry weight) of total lipids to overcome the absorption of polar lipids on glassware. The use of frozen mussel homogenate as a standard reference material was not possible because of lipid degradation, particularly of triacylglycerols and phospholipids. Also, total lipids measured gravimetrically significantly decreased in frozen samples, which could influence bioaccumulation predictions. A laboratory intercalibration was performed using a mussel homogenate and chloroform extract, which verified the accuracy of the method and the lipid-class identification. Characterizing the structure of one class of polar lipids, the acetone mobile polar lipid (AMPL), showed that it contained no ester linkages or free/sterically unhindered -OH groups; however, the AMPL did contain an ether linkage.

Biological treatment of oil-contaminated sand: comparison of oil degradation based on thin-layer chromatography/flame ionization detector and respirometric analysis

Oil biodegradation in oil-contaminated sand was simultaneously measured by respirometric and thin-layer chromatography/flame ionization detector (TLC/FID) methods. Degradation rate of 10–32 mg-C kg sand−1 day was achieved by amending the sand with inorganic nutrients and an oil-degrading yeast. The amendment also increased the initial CO2 production rate by 5–15 folds, which was not detected by the TLC/FID analysis. However, it was possible to monitor the accumulation of resin/asphaltene fraction up to 130% by the TLC/FID analysis during the oil degradation.

Geochemical Characteristics and Origin of Tar mats from the Yaha Field in Tarim Basin, China

Tar mats were firstly discovered and determined accurately in terrestrial oil and gas reservoirs associated with Lower Tertiary sandstone reservoirs in the Yaha field of the Tarim Basin, China, by thin-layer chromatography-flame ionization detector (TLC-FID) and Rock-Eval analysis. The relative content of asphaltene in gross composition of tar mat extracts accounts for more than 30 %, that in the corresponding oil leg less than 20 %. In the geochemical description profile of oil and gas reservoirs, drastic changes in asphaltene contents between tar mats and oil legs could be discovered. This is an important marker to determine tar mats. Distribution characteristics of saturated and aromatic hydrocarbons from reservoir core extracts and crude oils in the Yaha oil and gas reservoirs in the Tarim Basin are described systematically in this paper, and the results show there are similarities among n-alkane distribution characteristics, biomarker distribution characteristics and their combined characteristics of saturated hydrocarbons, and the geochemical characteristics of aromatic hydrocarbons for tar mats, oil leg, asphaltic sand and crude oil. These characteristics suggest the hydrocarbons in these samples were originated from the common source rocks. However, the geochemical characteristics of tar mats revealed that the mechanism of formation of tar mats is the precipitation of asphaltene from crude oils in petroleum reservoirs caused by increased dissolved gas in oil legs (gas injection).

99/02866 Suitability of thin-layer chromatography—flame ionization detection with regard to quantitative charactarization of different fossil fuel products. II. Calibration methods concerning quantitative hydrocarbon-group type analysis

99/02866 Suitability of thin-layer chromatography—flame ionization detection with regard to quantitative charactarization of different fossil fuel products. II. Calibration methods concerning quantitative hydrocarbon-group type analysis

99/02867 Suitability of thin-layer chromatography—flame ionization detection with regard to quantitative characterization of different fossil fuel products. I. FID performances and response of pure compounds related to fossil fuel products

99/02867 Suitability of thin-layer chromatography—flame ionization detection with regard to quantitative characterization of different fossil fuel products. I. FID performances and response of pure compounds related to fossil fuel products

Synthesis of Poly(ethylene adipate) with a Stable Nitroxyl Radical at Both Chain Ends, and Applications to a Counter Radical for Living Radical Polymerization

Synthesis of poly(ethylene adipate) (PEA) with 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) at both chain ends was attained by reaction of 4-hydroxy-TEMPO and PEA with isocyanate groups at the terminals. PEA obtained was found to have the living nitroxyl radical, because the electron spin resonance (ESR) spectrum of the polymer manifested a typical three sharp signals based on TEMPO. TEMPO-supported PEA served as a polymeric counter radical for the radical polymerization of styrene, to quantitatively give the block copolymer of ethylene adipate and styrene. Polymerization proceeded in accordance with a living mechanism, because the molecular weight of the copolymer was proportional to conversion of styrene and reciprocal of initial concentration of TEMPO attached to PEA. Analysis of the copolymer using a thin layer chromatography/flame ionization detection (TLC/FID) clarified that the copolymer contained no homopolystyrene. This absence of homopolystyrene implies that no diblock copolymer is formed during polymerization. 1H NMR analysis demonstrated the structure of copolymer obtained to be A-B-A triblock.

Suitability of Thin-Layer Chromatography-Flame Ionization Detection with Regard to Quantitative Characterization of Different Fossil Fuel Products. I. FID Performances and Response of Pure Compounds Related to Fossil Fuel Products

Controversy exists concerning quantitation using thin-layer chromatography-flame ionization detection (TLC-FID). Inadequate sample selections and detector designs and the non-uniformity of chromarods have been blamed for some confusing results. In this paper, performances of a modern TLC-FID system (which includes the newest detector configuration) are tested on polycyclic aromatic compound standards and related compounds as a preliminary step to evaluate its suitability for quantitative hydrocarbon group type analysis of different coal and petroleum products. Thus, evaluation of performances of the most modern FID configuration is carried out. FID linearity is evaluated as a function of sample load and scan speed for high-molecular-weight and semi-volatile standards. TLC-FID response factors for compounds of several homologous series are studied in order to differentiate effects of volatility from those exclusively due to chemical nature concerning FID response. Therefore, criteria are developed for the accurate application of TLC-FID to fossil fuel samples. Measurements of chromarod temperatures are carried out in order to evaluate whether an evaporation of compounds outside the H2 flame might take place.

Suitability of Thin-Layer Chromatography-Flame Ionization Detection with Regard to Quantitative Characterization of Different Fossil Fuel Products. II. Calibration Methods Concerning Quantitative Hydrocarbon-Group Type Analysis

Time-consuming external standard-based calibration methods are usually performed for hydrocarbon group type analysis (HGTA) of fossil fuels, regardless of the instrumental chromatographic technique. In this work, HGTA of a broad variety of coal and petroleum products is performed using a modern thin-layer chromatography-flame ionization detection (TLC-FID) system and a rapid method based on internal normalization. Repeatability, linear intervals, and sample load ranges for quantitative application of this method are detailed for different products that cover a broad range of boiling points and chemical functionalities in the field of fossil fuels: a heavy oil and its derived hydrocracked products, raw and chemically-modified petroleum asphaltenes, a coal-tar pitch, several coal extracts, and coal hydroliquefaction products. Results from external standard calibration and a normalization method (both obtained by TLC-FID) are in agreement, and they are validated using TLC-ultraviolet scanning. The use of the latter demonstrates that TLC-FID can also be applied to products such as coal extracts and hydroliquefaction products, despite these products being more volatile than petroleum asphaltenes or heavy oils. For preparative purposes when external calibration is necessary, preparative TLC and SPE are less time-consuming alternatives to MPLC fractionation, providing similar results.

Studies on tissues associated to hydroxybenzoquinone secretion in Myrsine laetevirens (Myrsinaceae)

Structural and complementary chemical studies were performed on specialized secretory structures which produce benzoquinones in Myrsine laetevirens (Myrsinaceae). These structures include: schizogenous secretory cavities, idioblasts or groups of idioblasts in root cortex and xylem rays and groups of cells in the placental epidermis, which produce crystals embedded in indentations of the seed surface. By means of high performance thin layer chromatography (HP‐TLC), gas‐liquid chromatography (GLC), thin layer chromatography flame ionization detector (TLC‐FID), and infrared and ultraviolet spectroscopy, the contents of secretory cavities were identified as neutral lipids (triacylglycerols and free fatty acids) and rapanone (2,5‐dihydroxy‐3‐tridecyl‐2,5‐cyclohexadiene‐l,4‐dione). Analysis of seed crystals and idioblast contents revealed rapanone as the main constituent. Ultrastructural observations of secretory cells show that plastids, endoplasmic reticulum and vacuoles are probably related to rapanone synthesis. The possible function and the systematic significance of these compounds are discussed.

Applications of chromatographic techniques to evaluate enzymatic hydrolysis of oxidized and polymeric triglycerides by pancreatic lipase in vitro

AbstractWith the aim of studying the susceptibility to enzymatic hydrolysis of oxidized and polymeric triglycerides (TG) that are formed during frying, various chromatographic techniques were applied in combination, i.e., adsorption chromatography, high‐performance size‐exclusion chromatography (HPSEC), and thin‐layer chromatography‐flame ionization detection (TLC‐FID). Polar fractions, isolated by adsorption chromatography from thermoxidized trilinolein as model system, and real used frying fats and oils, were analyzed by HPSEC before and after incubation with pancreatic lipase in vitro. Also, the influence of degradation level of used frying oils on hydrolysis of intact TG was investigated with the additional aid of TLC‐FID. Results showed the high hydrolysis rate of oxidized TG monomers in contrast to the significant discrimination of pancreatic lipase against TG dimers and, particularly, TG polymers. On the other hand, hydrolysis of intact TG can be affected by the presence of dimers and polymers in abused frying oils.

Discovery of tar mats in terrestrial gas-condensate reservoirs and its geological significance

TAR mat is reservoir zone containing petroleum rich in asphaltene, and is situated in gascondensate reservoirs and light oil reservoirs. Tar mat is an organic barrier for oil and gas reservoirs. Recently, determination of tar mat has become reality as thin layer chromatography-flame ionization detection (TLC-FID) technique is applied to organic geochemical de-...