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1.
Pyrolysis (Py) with in situ derivatisation with hexamethyldisilazane-gas chroma-break tography-mass spectrometry (GC-MS) and a gas chromatography-mass spectrometry procedure based on microwave-assisted saponification were used to identify the organic components in small sized beeswax samples. With the latter procedure quantitative recoveries can be made and hydrocarbons, alcohols and omega-1-diols in the neutral fraction, and fatty acids and omega-1-hydroxy acids in the acidic fraction can be efficiently separated and detected. Both procedures were used to characterise a wax anatomic sculpture "The Plague" (1691-1694) by Gaetano Zumbo, resulting in the identification of beeswax and a Pinaceae resin. The GC-MS analysis brought to light some essential differences in beeswax composition between the raw material and the old modelled wax thus giving some clear indications about the recipe used by the sculptor. 相似文献
2.
Logvinenko V. A. Gavrilova G. V. Morozova N. B. 《Journal of Thermal Analysis and Calorimetry》1998,52(2):341-344
Quasi-equilibrium thermogravimetry (with sample holders specially calibrated for the vapour pressure) was used for thermoanalytical
screening of volatile compounds. ‘p-T’ relationships (in the range 0.0006 to 0.11 at) were obtained for acetylacetonates and
fluoroacetylacetonates of Al, Cr and Zr. The incorporation of the trifluoromethyl group into the acetylacetone ligand noticeably
increases the volatility: the enthalpy of evaporation remains practically constant, but the evaporation entropy changes distinctly.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
3.
Jiménez JJ Bernal JL Aumente S Toribio L Bernal J 《Journal of chromatography. A》2003,1007(1-2):101-116
Gas chromatography with mass spectrometric detection was used to find the fraction of alcohols and acids present in pure beeswax from Apis mellifera. Some new compounds not described till now were found, such as a family of unsaturated linear fatty acids, several hydroxyacids and 1,2,3-propanetriol monoesters. The chromatographic profiles obtained from pure beeswax and bee-rejected foundation beeswax can be used to discriminate them; they mainly differ in the amount of some acids and alcohols. 相似文献
4.
Gas chromatography-mass spectrometry has been used to determine the nature of organic materials used in mummification balms. A comparative analysis of samples taken from Egyptian mummies is developed. The results are given in two parts. First, it is shown that the chemical composition of the balm is practically independent of the part of the mummy from which it is taken. This study was done on a Ptolemaic mummy (circa 100 BC from the Guimet Museum in Lyon). Fats, beeswax, and diterpenic resins were the main components: they were found everywhere. Castor oil was also very often detected (in half of the samples). This particular fat is present in the balm inside the thorax but not in the skull. Moreover it is shown that a vegetable tannin was employed. Components indicative of vegetable tannin input (gallic acid and inositols) were found in seven samples out of eighteen, particularly close to the body and on the canopic pack of the heart. Secondly, some conclusions from a comparative study of the composition of balms from mummies of various social levels as well as of different Egyptian periods are reported. It is shown that beeswax was used as from very early times (XVIIIth dynasty). The mixture of beeswax, fats, and diterpenoid resins would appear to be more recent. The balms of three mummies dating from more recent Egyptian periods (XIXth to XXVth dynasty) were analysed. No evidence of a resin, gum-resin, or plant gum could be found. Some mummies would appear to have been embalmed with fats or beeswax. Finally, the entrails canopic pack said to belong to Ramses II undoubtedly shows an embalming process with a triterpenic resin of the mastic type. The adopted analytical methodology enabled us to achieve simultaneous detection of four components of the balm of the Ptolemaic mummy. Analysis of the other five mummies revealed far less complex chemical compositions for the balms. This may be an indication of different embalming processes, although we should bear in mind the question of organic matter preservation through the ages. 相似文献
5.
B. Bartl L. Kobera K. Drábková M. Ďurovič J. Brus 《Magnetic resonance in chemistry : MRC》2015,53(7):509-513
The term ‘wax bloom’ is used to describe a thin whitish crystalline layer that develops on the surface of beeswax objects under specific conditions. This phenomenon is undesirable, especially in the cases of objects with aesthetic or informational value, such as wax sculptures or historical seals. A combination of solid‐state NMR and FTIR measurements allowed to obtain fairly detailed insight into the problem and to suggest a probable mechanism of its development. Secondary crystallization of unsaturated hydrocarbons from beeswax was determined as a primary cause. After the macroscopic solidification of beeswax from the melt, these molecules remain for months in a highly mobile, liquid‐like state. This facilitates their diffusion to the surface, where they eventually crystallize, forming the ‘wax bloom’ effect. Although these results are of particular interest with respect to the conservation of beeswax artifacts, they are relevant to this material in general and help with understanding its unique properties. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
6.
7.
M. N. Radhakrishnan Nair M. R. Gopinathan Nair 《Journal of Thermal Analysis and Calorimetry》2011,103(3):863-872
Thermal stability of solution-cast blends of poly(vinylchloride) and NR-b-PU block copolymers of three different chain extender
diols was studied by thermogravimetry. Thermal degradation of individual components and their blends were investigated with
special reference to blend ratio. As the block copolymer content in the blends increased their thermal stability was also
found to increase. Enhanced thermal stability of PVC is believed due to the favorable interaction with PVC and the PU hard
segments of the block copolymer. DTG curves were used for the determination of different stages involved in the degradation.
Activation energy for degradation was determined from Coats–Redfern plot. 相似文献
8.
Yufeng Shen Hongxin Huang Xueliang Liu Qinghai Wang Liangmo Zhou 《Journal of separation science》1994,17(2):74-76
A home-made supercritical fluid chromatograph fitted with a capillary micropacked column and equipped with FID detection has been used to separate the components of silicone DC-200, beeswax, tea oil, cod-liver oil, rancid butter, and several traditional Chinese medicines such as Honghua oil, Jiuxin oil, and Wanhua oil. 相似文献
9.
John Rojas Sergio Cabrera Julie Benavides Yasmín Lopera Cristhian J. Yarce 《Molecules (Basel, Switzerland)》2021,26(9)
Clove essential oil (CEO) is known for having excellent antioxidant and antimicrobial properties, but the poor stability of its components to light and temperature compromise this activity. The aim of this study is to evaluate the textural, antioxidant, antimicrobial and microstructural properties of matrixes produced with representative natural waxes and CEO. Thus, waxy emulsifiers, such as beeswax, candelilla wax, carnauba wax, and ozokerite wax, were employed to create such matrixes. The thermal, microstructural, textural, wetting, antioxidant, antimicrobial and infrared characteristics of the matrixes were then studied. The diverse chemical composition (long-chain wax esters in carnauba wax and short-chain fatty acids and hydrocarbons in beeswax and ozokerite wax, respectively) explained the differences in wetting, texture, melting, and crystallization characteristics. Crystal forms of these matrix systems varied from grainy, oval, to needle-like shape, but keeping an orthorhombic allomorph. The alignment and reorganization of beeswax and ozokerite wax into needle-like crystals increased the matrix strength and adhesion force compared to those of carnauba and candelilla matrixes, which showed weak strength and grainy morphology. The former two waxes and their matrixes also showed the largest plasticity. These lipidic matrixes show potential use for topical applications having acceptable antioxidant and textural properties. 相似文献
10.
K. Medina-Dzul S. Medina-Peralta C. Carrera-Figueiras M. Sánchez 《International journal of environmental analytical chemistry》2017,97(9):831-840
Beeswax is a complex mixture of lipophilic compounds and other components such as aliphatic alcohols and carotenoids. Then, extraction and clean-up for pesticide analysis in beeswax is a challenge. In this work, a multiresidue method for the analysis of dichlorvos (DCV), diazinon, malathion, methyl parathion and coumaphos (CMF) in beeswax was developed. The proposed approach is based on matrix solid-phase dispersion extraction. The adsorbent for sample clean-up was studied and a simplex-centroid cubic statistical design was applied to evaluate pure solvents and their binary and ternary mixtures to elute the analytes. Finally, Florisil and ethyl acetate were chosen as solid support and eluting solvent, respectively. After extraction, pesticides were separated and detected by gas chromatography/mass spectrometry. The method achieved acceptable recoveries (70–85%; except for DCV, 24–38%) with relative standard deviations below 5%. The repeatability of the method was lower than 8% and interday variability was below 12%. The limit of detection (LOD) for the analytes varies between 0.2 and 2.6 µg?kg?1 and limit of quantification from 0.93 to 8.8 µg?kg?1. LOD reached for CMF was below the maximum residue limit allowed by the legislation of the United States and Canada. 相似文献
11.
Gas chromatographic and mass spectrometric investigations of organic residues from Roman glass unguentaria 总被引:1,自引:0,他引:1
A combination of gas chromatographic (GC) and mass spectrometric (MS) techniques, including direct exposure-MS (DE-MS), high-temperature GC-MS (HTGC-MS) and GC-MS of neutral and acid fractions, was employed to study the composition and recognise origin of the organic materials used to manufacture balm residues surviving in a series of glass unguentaria recovered from excavations of a Roman villa (Villa B) in the ancient town of Oplontis (Naples, Italy). DE-MS provided comprehensive 'fingerprint' information on the solvent soluble components of the contents of the unguentaria, while GC-MS analyses provided detailed molecular compositions, highlighting the presence of a wide range of compound classes including mid- and long-chain fatty acids, long-chain hydroxy-acids, n-alkanols, alkandiols, n-alkanes, long-chain monoesters, phytosterols and diterpenoid acids. Characteristic biomarkers and their distributions indicate the presence of beeswax, Pinaceae resin and another wax, as the main organic constituents of all of the preparations examined. In particular, the occurrence of phytosterols and long-chain monoesters, in which the acyl moiety was not exclusively palmitic acid, suggested the presence of a second waxy-lipid constituent of plant origin. The results are consistent with beeswax being used in the preparation of the cosmetics preserved in the unguentaria, while the other lipids are most likely the residue of some as yet unidentified plant extract(s), possibly deriving from the cuticular waxes of flowers and/or leaves. The composition of the extracts are consistent with the ancient practices of maceration and/or "enfleurage", in which lipid-based materials, such as beeswax, animal fat or vegetables oils, were used to extract aromatic and fragrant substances from resin, flowers, spices and scented wood, in order to produce unguents and balms. 相似文献
12.
Thermogravimetric Study of Volatile Precursors For Chemical Thin Film Deposition. Estimation of vapor pressures and source temperatures 总被引:1,自引:0,他引:1
Niskanen A. Hatanpää T. Ritala M. Leskelä M. 《Journal of Thermal Analysis and Calorimetry》2001,65(3):955-964
Normal pressure thermogravimetry (TG) measurements were used to study the sublimation behavior of several volatile metal compounds,
used as metal precursors in thin film fabrication by chemical vapor phase methods, like atomic layer deposition (ALD) and
chemical vapor deposition (CVD). The results indicated that dynamic TG measurements may be used to find correct source temperatures
to be used in an ALD reactor: a good correlation between the source temperatures used in ALD and temperatures corresponding
to mass losses of 10 and 50% in TG was verified. It was also found that isothermal TG measurements offer a simple way for
the vapor pressure measurements which otherwise are not trivial for solids with only moderate volatility.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
13.
T. A. Kuchmenko Zh. Yu. Kochetova Ya. I. Korenman 《Journal of Analytical Chemistry》2001,56(11):986-990
The sorption–desorption of acetone and phenol on thin-film coatings of electrodes of bulk acoustic wave piezoelectric resonators was studied. Natural materials (bee-glue and beeswax) were used as natural coatings. The sorption activity of the coatings was determined along with their sorption selectivity and stability for the analytical application of modified bulk acoustic wave piezoelectric sensors in the detection of acetone and phenol in the air. 相似文献
14.
Campanella L Chicco F Colapietro M Gatta T Gregori E Panfili M Russo MV 《Annali di chimica》2005,95(3-4):167-176
Purpose of this scientific research is the physic and chemical characterization of two historical wax manufactures, made at the end of XIX century by Francesco Bianchi, a papal engraver. The chemical and analytical investigation was necessary to complete and to confirm the restorer's work. The IR Spectroscopy, X-Ray and GC-MS, the best technique to characterise wax, allowed us to obtain the following results. The two manufactures were made with commercial beeswax: in fact, the relative chromatograms showed unchanged peaks about esters of palmitic acid with C24 to C32 alcohol molecules; using standard beeswax we determined the same amount of hydrocarbons present in the wax manufactures. We found several hydrocarbons in these beeswax materials so that it is reasonable to think about successive modifications. ZnO (white zinc), a pigment, was added, probably due to its colour and covering capacity. Sb2S3, Anthimoniun vermilion, a red-orange pigment, was added to these manufactures to give them a soft pink-orange colour. By all used techniques we determined some modifications in the original beeswax; surely they were made to get a more malleable, mouldable, and then more able to be modelled wax. 相似文献
15.
《Journal of separation science》2017,40(5):1158-1166
In this study, a new method for the determination of 12 nitroimidazoles and their hydroxymetabolites (metronidazole, hydroxymetronidazole, dimetridazole, ronidazole, hydroxydimetridazole, ipronidazole, hydroxyipronidazole, carnidazole, ornidazole, secnidazole, ternidazole, tinidazole) in beeswax has been developed and validated. The optimized sample preparation procedure included melting and dilution of beeswax in a mixture of n‐hexane and isopropanol followed by extraction with 2% acetic acid. The extracts were purified on strong cation exchange based solid‐phase extraction cartridges and evaporated in a vacuum system with vortex motion. The separation and detection of the nitroimidazoles in the beeswax extracts were achieved within 12 min by liquid chromatography tandem mass spectrometry using a pentafluorophenyl analytical column and applying a gradient elution with acetonitrile and 0.01% acetic acid as mobile phases. The method performance characteristics were evaluated at three concentration levels (1, 2, and 5 μg/kg) and the method was found to be suitable for determination of all tested nitroimidazoles. The limits of detection and quantification were 0.2–0.5 and 0.5–1 μg/kg, respectively. The recoveries varied from 71.2 to 104.9% while the relative standard deviations were less than 13.8% under the intermediate precision conditions. 相似文献
16.
Stacey RJ 《Analytical and bioanalytical chemistry》2011,401(6):1749-1759
Residues from medicine containers in the collections of the British Museum have been investigated as part of a wider programme
of scientific work on Roman surgical instruments. The cylindrical bronze containers are often described as instrument cases,
but some contain materia medica, ranging from extensive extant remains of ancient preparations to possible minor deposits on the interior surfaces of the
containers. Samples from seven residues have been analysed by gas chromatography–mass spectrometry (GC-MS) to identify lipid,
resin and carbohydrate components and by X-ray fluorescence and Raman spectroscopy to characterise inorganic materials. The
results have provided evidence for ointments and powders or pills consistent with a medical purpose. The ingredients identified
include beeswax, fat, conifer resin and gum-derived sugars, plus elemental carbon and lead and zinc salts. Particularly significant
were the varied compositions of residues from four sections of a multi-compartment container. In one of these compartments,
the beeswax seems to have been prepared as the ‘Punic wax’ described by Pliny. Experimental preparation of Punic wax following
Pliny’s method was undertaken in the laboratory and the product analysed to compare with the ointment residues. This paper
discusses the GC-MS results of both the experimental material and the archaeological residues and their significance for the
interpretation of the past intended applications of the medicines and the use of the containers. 相似文献
17.
H. A. Schneider 《Journal of Thermal Analysis and Calorimetry》1993,40(2):677-687
Due to the complex character of the thermal degradation of polymers as a solid-gas chain reaction, an unequivocal kinetic
characteirzation is possible only for stationary states of both radical concentration and reaction mechanism. These conditions
are hardly realizable in non-isothermal thermogravimetry. Additional the weight losses are depedent on the volatility of the
reaction products. That is not always certain in polymer degradation. As a consequence the deduced ‘kinetic parameters’ are
not unequivocal. They are conversion and heating rate dependent and may be influenced by sample shape and size. Thus the ‘kinetic
parameters’ are in fact from the point of view of mathematics the fitting parameters of a ‘rate equation’ like relation, specific
for the used reaction conditions only. From the point of view of chemical kinetics they are neither attributable to a determined
reaction mechanism nor can they be used for predictions.
Dedicated to the 70th Anniversary of Dr. Jo Flynn 相似文献
18.
AbstractThis preliminary study has mainly focused on the wax identification by nuclear magnetic resonance (NMR) and removal. Wax is used for many purposes in the field of art as protective coatings on wooden, stone or metal objects. From the comparison of the spectra H NMR and in particular with the correspondence of the resonance peaks of the samples taken from the statue and beeswax and paraffin, we can conclude that the wax applied on the statue surface is beeswax. From our data, it can be concluded that, to remove the beeswax, from any stone support, the more effective solvent is the mixture of cyclohexane/ethyl acetate. The removal percentages ranged from 19 to 99%. Lower percentages of removal have been observed in the case of yellow marble, probably because of its high porosity. We can affirm that, this solvent mixture can be employed in real art objects using cotton swabs to remove protective wax. 相似文献
19.
Sturgeon RE Lam JW Windust A Grinberg P Zeisler R Oflaz R Paul RL Lang BE Fagan JA Simard B Kingston CT 《Analytical and bioanalytical chemistry》2012,402(1):429-438
Several techniques were evaluated for the establishment of reliable water/moisture content of single-wall carbon nanotubes. Karl Fischer titration (KF) provides a direct measure of the water content and was used for benchmarking against results obtained by conventional oven drying, desiccation over anhydrous magnesium perchlorate as well as by thermogravimetry and prompt gamma-ray activation analysis. Agreement amongst results was satisfactory with the exception of thermogravimetry, although care must be taken with oven drying as it is possible to register mass gain after an initial moisture loss if prolonged drying time or elevated temperatures (120 °C) are used. Thermogravimetric data were precise but a bias was evident that could be accounted for by considering the non-selective loss of mass as volatile carbonaceous components. Simple drying over anhydrous magnesium perchlorate for a minimum period of 8-10 days is recommended if KF is not available for this measurement. 相似文献
20.
János Madarász Viola Nagygyörgy Elias Stathatos György Pokol 《Journal of Thermal Analysis and Calorimetry》2013,113(3):1055-1062
Loss of volatile components from two types of quasi-solid gel electrolytes to be used in Grätzel (or dye-sensitized, DSSC)-type alternative solar cells are checked time to time by thermogravimetry (TG) to follow the stability or changes of composites during storage at ambient. One of the gel samples, labeled as P2000 and based on UreaSil 2000, a 3D-cage precursor compound, has been found quite stable, while the related P230 sample based on UreaSil 230 seems to have a bit higher deviation in heterogeneity and some tendencies losing gradually from its volatile content, time to time. In addition, two online coupled evolved gas analytical tools (TG–EGA–FTIR and TG/DTA–EGA–MS) are applied to check the gel electrolytes for thermal vaporization, degradation, and decomposition processes as a function of temperature during dynamic heating in air. Initial minor elimination of ethyl acetate has been detected by both in situ coupled mass spectroscopy and FTIR spectroscopic gas cell. According to both evolved gas analytical systems, the other liquid ingredients, acetic acid (AcOH) and sulfolane are also released in the order of their volatility. Above 300 °C, an oxidative thermal degradation of UreaSil-type host matrices is indicated by the occurrence of, among others, formaldehyde or ammonia for electrolyte samples P2000 and P230, respectively. Evolution of various alkyl iodides with short chain length has only been detected by the mass spectroscopic evolved gas analysis method only. 相似文献