Complete characterisation of lanolin steryl esters by sub-ambient pressure gas chromatography-mass spectrometry in the electron impact and chemical ionisation modes

Steryl esters occurring in lanolin have been characterised by sub-ambient pressure gas chromatography coupled to mass spectrometry. Electron impact and chemical ionisation modes with different reagent gases have been evaluated in order to carry out unambiguous peak identification. Steryl esters with different sterol (i.e. cholesterol, lanosterol and dihydrolanosterol) and acid moieties either according to carbon number (i.e C₁₀–C₂₃) or isomeric forms (i.e. normal, iso and anteiso) have been identified. Identification of the sterol and acid moieties has been carried out by means of the mass spectral information obtained in the electron impact, chemical ionisation mode either in the positive or negative modes using methane, isobutane and ammonia as reagent gases. Isomeric identification has been achieved by chromatographic retention parameters (i.e. entire-chain length and fractional-chain length) and by the free fatty acid profile also present in lanolin.     

Isolation and Characterization of Wax Esters in Fennel and Caraway Seed Oils by SPE-GC

A rapid method for the isolation and quantitative determination of wax esters in vegetable oils was developed. For the first time wax esters in oils were separated from the triglyceride matrix by means of solid-phase extraction, which allows rapid sample preparation in parallel and therefore a high sample throughput. The thus obtained wax ester fractions of fennel and caraway seed oils were analyzed by high temperature gas chromatography. GC-MS analyses were carried out using electron impact ionization in order to characterize the wax ester fraction. With respect to the results of the GC-MS analyses different isomers of saturated wax esters with the same carbon number were observed. Additional monounsaturated wax esters with an unsaturated fatty acid moiety were identified.     

The effect of flame coal oxidation on the solid and soluble products of its extraction

Solid and soluble products of THF and CH₂Cl₂ extraction of flame coal oxidised by four different oxidising agents (peroxyacetic acid (PAA), 5% HNO₃, O₂/Na₂CO₃, air/125 °C) were studied by elemental analysis and FTIR. The extraction yield with THF was much higher than that with CH₂Cl₂ for all samples. The greatest changes in elemental composition were in the extracts from coal oxidised by nitric acid. The sulphur content was lowest in extracts from coal oxidised with 5% HNO₃ and PAA. FTIR confirmed that coal treatment with nitric acid incorporates nitrogen into the coal structure.     

Development and application of an analytical method for the determination of storage lipids, fatty acids and fatty alcohols in Calanus finmarchicus

A method was developed for the determination of the major storage lipids, wax ester and triglycerides, in the copepod Calanus finmarchicus. A variation of the Folch method was used to extract the lipid. The method was scaled down to enable the extraction of either pooled (-1 mg) or individual (approximately 200 microg) copepods. The major lipid classes were identified using TLC and quantified using HPLC coupled with evaporative light scattering detection. Analysis of laboratory reference materials indicated that this method underestimated the minor triglyceride component, but gave a good estimate of the major wax ester component. The fatty acid and fatty alcohol composition of the C. finmarchicus were determined following trans-esterification of the lipid extract in methanol. Fatty acids and fatty alcohols were initially identified by comparison with authentic standard and by mass spectroscopy. Using GC with flame ionisation detection the normalised area percentage of the fatty alcohols and fatty acid methyl esters was determined simultaneously in one run for either pooled or individual copepod samples. These methods were applied to C. finmarchicus collected from the Irminger Sea, North Atlantic in 2001 and 2002.     

Pre-Eutectic Densification of Calcium Carbonate Doped with Lithium Carbonate

Pressureless sintering of CaCO₃ was carried out, with Li₂CO₃ (from 0.5 to 8 wt%) as an additive, under different pressures of CO₂. Densification occurs between 600 and 700°C. Sintering above the eutectic temperature (T>662°C) leads to the decomposition of calcium carbonate and the materials become expanded. At 620° under 1 kPa of CO₂, a relative density of 96% is reached. Li₂CO₃ enhances the densification process and grain growth of calcium carbonate. CO₂ pressure slows down densification and grain growth kinetics. These results are explained by the influence of carbonate and calcium ion vacancies on the sintering mechanisms. This revised version was published online in August 2006 with corrections to the Cover Date.     

A liquid chromatography-tandem mass spectrometry method for fluazifop residue analysis in crops

An LC-MS-MS assay is described for fluazifop residue analysis in crops. The residues are extracted with acidified organic solvent, the esters and conjugates are hydrolysed with 6 M hydrochloric acid, then the extracts are cleaned-up by solid phase extraction using C₂(EC) and Si cartridges in tandem. Quantitative analysis is performed by gradient liquid chromatography coupled to triple quadrupole mass spectrometer using atmospheric pressure chemical ionisation. All fluazifop-P-butyl, free fluazifop-P and any conjugates are quantified as fluazifop-P. The limit of quantification is 0.01–0.05 mg/kg depending on crop matrices. The clean-up method is also suitable for LC-UV analysis with a compromise in higher limit of quantification 0.05–0.2 mg/kg.     

Sampling considerations in supercritical fluid chromatography

Summary Packed column supercritical fluid chromatography, like HPLC, utilizes a sample loop to introduce materials onto the column for analysis. Unlike HPLC the mobile phase in SFC cannot be used to dissolve the sample. In practice, this causes a solvent peak, which can create a problem in the chromatographic interpretation. This paper describes one approach to solving this problem. A valving scheme is used to extract materials with the supercritical CO₂ mobile phase and introduce them onto the column with no external handling. The viability of this method is demonstrated and separations of the CO₂ extracts for several materials are shown on various columns. Comparisons are made for coal and coffee extracts using this on-line method and conventional off-line CH₂Cl₂ extracts. Advantages of the on-line procedure as they apply to chromatography and high information detectors are also discussed.     

Thermal decomposition of Me3SnO2PCl2, Me2Sn(O2PCl2)2 and Ph3SnO2PCl2

TG and DTA studies on Me₃SnO₂PCl₂, Me₂Sn(O₂PCl₂)₂ and Ph₃SnO₂PCl₂ were carried out under dynamic argon atmosphere. The results show that the decomposition proceeds in different stages leading to the formation of Sn₃(PO₄)₂ as a stable product. This compound was characterized by IR spectroscopy. Decomposition schemes involving reductive elimination reactions were proposed.     

Characterization of lipids in complex samples using comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry

Most lipids are a complex mixture of classes of compounds such as fatty acids, fatty alcohols, diols, sterols and hydroxy acids. In this study, the suitability of comprehensive two-dimensional gas chromatography coupled to a time-of-light mass spectrometer is studied for lipid characterization in complex samples. With lanolin, a refined wool wax, as test sample, it is demonstrated that combined methylation plus silylation is the preferred derivatization procedure to achieve (i) high-quality GC x GC separation and (ii) easily recognizable ordered structures in lipid analysis. Optimization of the GC x GC column combination, the influence of the temperature programme on the quality of the separation, and the potential and limitations of automated TOF-MS-based identification are discussed. The combined power of a 2D separation, ordered structures and MS detection is illustrated by the identification of several minor sample constituents.     

A study on the liquid–liquid equilibria of 1-alkyl-3-methylimidazolium hexafluorophosphate with ethanol and alkanes

This work demonstrates the ability of the 1-alkyl-3-methylimidazolium hexafluorophosphate to act as an extraction solvent in petrochemical processes for the removal of alkanes from their azeotropic mixture with ethanol. LLE (liquid–liquid equilibrium) of the ternary systems hexane + ethanol + 1-hexyl-3-methylimidazolium hexafluorophosphate (HMIM PF₆) or 1-octyl-3-methylimidazolium hexafluorophosphate (OMIM PF₆) and heptane + ethanol + OMIM PF₆ are carried out at 298.15 K and atmospheric pressure. Experimental liquid–liquid data are correlated by using different equations. The solute distribution ratio and the selectivity, determined from tie-line data, suggest the efficiency of the ILs used as solvents. A comparison with other IL, in terms of solvent capacity, is included. The liquid–liquid extraction process is simulated by using conventional software and the obtained results are shown.     

Mg-Zn-Al三金属类水滑石的合成及其复合氧化物的催化性能

水滑石（[Mg_６Al_２（OH）_(１６)[CO_３·４H_２O）是一种类似于水镁石结构的层状阴离子黏土，其骨架为阳离子，层间为阴离子。如改变骨架中的金属阳离子或在层间引入不同的阴离子，就可形成各种新组成的类水滑石。水滑石对有机分子反应具有较高的催化活性和选择性，且可以作为复合氧化物催化剂的前体，应用广泛。它作为碱催化剂，可用于醇醛缩合；作为氧化还原催化剂，用于水煤气转化、NO的还原、甲烷氧化反应等犤１，２犦。作为一种具有特殊结构的化合物，各种双金属组分的水滑石或类水滑石的合成、性质与应用已受到广泛的重视犤３…     

Water sorption of nails treated with wool keratin proteins and peptides

Water has a considerable effect on human keratin fibres, such as nails, and is therefore crucial for their cosmetic performance. Wool proteins are mild, natural, biodegradable and are sustainably produced with multiple functionalities. They have a potential for use in the cosmetic and detergent markets. The effectiveness of two wool keratin ingredients in restoring the water sorption characteristics of nails was determined. Acetone treatment modified nail water sorption, resulting in an increase in water sorption capacity and in nail permeability. The application of keratin peptides and proteins to healthy and damaged nails improved water sorption properties, reducing permeability, especially in the case of wool keratin protein treatment.     

Osmium catalyzed asymmetric dihydroxylation of methyl trans-cinnamate in ionic liquids, followed by supercritical CO2 product recovery

In this work, osmium-catalyzed asymmetric dihydroxylation (AD) of methyl trans-cinnamate was studied. Osmium and chiral ligand catalysts were immobilized in ionic liquid only, without any other reaction solvents, while the recovery of the product was performed by extraction with supercritical CO₂, and compared with results obtained by extractions with organic solvents such as hexane and diethyl ether. In supercritical CO₂ extraction experiments, optimal extraction pressure was found and ionic liquid chosen, so that the highest reaction yields coupled with lowest osmium content in the crude product can be achieved. Finally, recycle experiments of the same (ionic liquid + catalytic system) mixture were successfully conducted. Application of ionic liquids and supercritical CO₂ in osmium catalyzed AD allows for the isolation of the diol basically without contamination with osmium, in high yield and enantiomeric excess, and it makes possible the efficient reuse of ionic liquid solvent and the catalytic system.     

Development of a methodology for the simultaneous determination of inorganic and organolead compounds using supercritical fluid extraction followed by gas chromatography-mass spectrometry and its application to environmental matrices

A method for the extraction of triethyl lead (TEL⁺), trimethyl lead (TML⁺), and Pb²⁺ from sand was developed using supercritical modified CO₂-CH₃OH extraction and in situ complexation with sodium diethyldithiocarbamate (NaDDTC) using a 2⁵ factorial exploratory design is described. The screened variables were (i) pressure (69-193 bar), (ii) temperature (40-150 °C), (iii) ligand amount (0-100 mg), (iv) methanol volume (0.0-0.5 mL) and (v) static time (0-45 min). The optimum extraction conditions found were as follow: pressure, 193 bar; temperature, 40 °C; amount of NaDDTC, 100 mg; methanol volume, 0.5 mL; static time 45 min; and CO₂ flow rate, 1 mL min⁻¹. Under these conditions the following recoveries were obtained (TML⁺ 97 ± 2%, TEL⁺ 70 ± 5%, and Pb²⁺ 100 ± 4%). The presence of NaDDTC is not necessary for the extraction of TML⁺ and TEL⁺, but it is a very significative parameter for Pb²⁺. A second experimental design 2² + star for temperature and pressure was realized, but the results were not better than those of the first model. SFE extract derivatization was achieved with pentylmagnesium bromide, and target analyte determination was carried out by gas chromatography-mass spectrometry. Detection limits in the full-scan mode were 4, 10, and 39 pg as lead for TMPeL, TEPeL and PbPe₄, respectively. The method was validated with urban dust containing TML⁺ (CRM 605. Pb 7.9 ±1.2 μg kg⁻¹) and river sediment containing inorganic lead (GBW08301. Pb 79.0 ± 12.0 mg kg⁻¹) as reference materials. The proposed method was applied to lead analysis in sand collected from an oil-polluted beach in Chile.     

Zinc Ion Doped Solid-Phase Extraction of Eicosapentaenoic Acid and Docosahexaenoic Acid from Antarctic Krill

Antarctic krill crude extracts contain high levels of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Accordingly, the solid phase extraction of EPA and DHA from Antarctic krill crude extracts has attracted significant research interest. This study compared the extraction of EPA and DHA from Antarctic krill crude extracts using an aminopropyl, zinc ion-doped silica, and C₁₈ and zinc ion-doped C₁₈ solid-phase column. The best extraction effect was obtained using the zinc ion-doped C₁₈ SPE with water containing methanol as the eluant. The efficiency increased gradually with increasing methanol concentration from 12.5 to 25% in the washing stage, and when pure methanol (5.0 mL) or acetonitrile (3.0 mL) was used as the eluant. To detect EPA and DHA, the acids were first converted to their methyl esters and detected by gas chromatography with flame ionization detection (GC–FID). In the zinc ion-doped C₁₈ elution fractions, EPA and DHA were isolated from the crude extracts in high yield (85–91% (r² = 4.8–6.3%)).     

Supercritical carbon dioxide extraction and gas chromatography–mass spectrometry analysis of Gymnema sylvestre R.Br. roots

Supercritical fluid extraction (SFE) achieves a wide range of applications since the past decade as a sustainable green technology. The present study investigates the process for producing high yield by supercritical carbon dioxide (Sc-CO₂) extraction form Gymnema sylvestre R.Br. roots. The effect of temperature and pressure on the percentage of accumulative yield is demonstrated. It is found that the highest yield is obtained at the temperature of 60°C and the pressure of 10?MPa. A proper review showed that there is a lack in the study of Sc-CO₂ extraction of this plant especially for optimization of SFE process which makes this study useful and valuable. For more benefit, the extract which achieves highest percentage is subjected to gas chromatography–mass spectrometry to study its chemical composition and detect the active principle compounds which present with high concentration and expected to be responsible of the pharmaceutical properties of the extract.     

Systematic characterisation of long-chain aliphatic esters of wool wax by gas chromatography-electron impact ionisation mass spectrometry

A detailed structural characterisation of the aliphatic high-molecular-mass esters extracted from raw wool based on high-temperature gas chromatography-electron impact ionisation mass spectrometry is described. The raw wool esters extracted are in the range of C37 to C54 (i.e., molecular mass 550-788). The selected ion chromatogram exhibited four isomers for the esters with an odd number of carbon atoms (i:a, i:n, a:n and n:n) and five for those with an even number of carbon atoms (i:i, a:a, i:n, a:n and n:n). Isomeric structural elucidation is discussed with respect to the long-chain fatty acid and long-chain fatty alcohol structures, on the basis of chromatographic retention behaviour and mass spectral information.     

Identification of natural dyes in archeological Coptic textiles by liquid chromatography with diode array detection

Reversed-phase HPLC with diode-array UV-Vis spectrophotometric detection has been used for identification of natural dyes in extracts from wool and silk fibres from archeological textiles. The examined objects originate from 4th to 12th Century Egypt and belong to the collection of Early Christian Art of the National Museum in Warsaw. Extraction from fibres was carried out with HCl solution containing ethanol or with warm pyridine. As the main individual chemical components of natural dyes, anthraquinone, indigoid and flavonoid dyes including alizarin, purpurin, luteolin, apigenin, carminic acid, ellagic acid, gallic acid, laccaic acids A and B and indigotin were found. For pyridine extracts another mobile phase with an optimized gradient of organic modifier concentration was used. With such an eluent the appearance of double peaks for indigotin and indirubin was eliminated. For acidic extraction of dyes from fibres, ethanol was used. Due to its higher boiling point than methanol it evaporates slower from the extraction solution enabling a more efficient extraction of dyes.     

Influence of water in the lamellar rearrangement of internal wool lipids

Small angle X-ray scattering (SAXS) was applied to a new lipid model arrangement, which was achieved by concentrating or diluting internal wool lipid liposome suspensions in varying water concentrations. The influence of the water content in the lamellar structure of the internal wool lipids is compared with the lamellar structure of phosphatidylcholine bilayers present in the membranes of the living cells. The high increase in the lamellar distances with the water content indicates that large amounts of water can be retained in the lipid wool membrane in contrast to the case of phosphatidylcholine liposomes. A transition temperature between 40 and 50 degrees C tends to eliminate the ordered lamellar structure when more than 60% of water is present in the bilayer structure. This could account for the increase in the permeability of the wool fibres when these are soaked in water at temperatures exceeding 40 degrees C.