Analysis of frankincense in archaeological samples by gas chromatography-mass spectrometry

Four archaeological samples, unearthed from Qana in Yemen were analysed by analytical technique, currently applied in the field of petroleum geochemistry, and by gas chromatography coupled with a mass spectrometer (GC-MS). Sample no 1286 comes from a burned warehouse and samples no 964, 963 and 962 from the central sanctuary. These specimens were probably exposed to a heating source. In each case olibanum resin was identified according to the presence of their chemical markers corresponding to alpha- , beta-boswellic and lupeolic acids (3alpha-hydroxy-olean-12-en-24-oic, 3alpha-hydroxy-urs-12-en-24-oic and 3alpha-hydroxy-lup-20(29)en-24-oic acids) and their respective O-acetyled derivatives (3alpha- O-acetyl-olean-12-en-24-oic, 3alpha-O-acetyl-urs-12-en-24-oic and 3-O-acetyl-lup-20(29)-en-24-oic acids). Concerning the thermal degradation state of samples, the GC-MS results are in agreement with the geochemical ones. Sample no 1286 and 964 correspond to ageing incense which has not undergone any heating action and are consequently relatively well preserved. Lastly, samples no 963 and 962 are thermally degraded resins and their gross composition data permits to conclude that sample no 963 is only partially burnt while sample no 962 has been much more degraded.     

Parameter optimization in microwave-assisted distillation of frankincense essential oil

The essential oil of Boswellia species is extracted by the conventional method of hydrodistillation (HD). In this study, we aimed to compare this reference to microwave-assisted distillation (MAD) at different power densities. The results showed that microwave extraction can result in a substantial reduction (48 min against 180 min for reference) of the batch time when the power density of 2 W/g is applied. Also, the energy consumed by the new process is 2.7 times less than HD. The essential oil produced by MAD has a chemical composition different from that of reference treatment. Although microwave treatment increased the proportions of the main components (α-thujene and α-pinene), the opposite tendency was observed for o-cymene, estragole, methyl eugenol, and δ-guaiene. A 26.5% decrease in oil extracted by MAD at 1 W/g is required to achieve 50% inhibition of the DPPH radical compared to HD. In conclusion, MAD is a promising technology for producing olibanum oil with new qualitative attributes.     

Two New Triterpenoid Glycosides from the Roots of Rosa cymosa Tratt.

Two new triterpenoid glycosides, 3α,19α,23α‐trihydroxy‐2‐oxo‐12‐ursen‐28‐O‐β‐d ‐glucopyranoside ( 1 ) and 3α,19α,23α‐trihydroxy‐2‐oxoolean‐12‐en‐28‐O‐β‐d ‐glucopyranoside ( 2 ) as well as three known compounds, 2α,3α,19α‐trihydroxyolean‐12‐en‐28‐O‐β‐d ‐glucopyranoside ( 3 ), 2α,3α,19α,23‐tetrahydroxy‐12‐ursen‐28‐O‐β‐d ‐glucopyranoside ( 4 ), and 2α,3β,19α,23‐tetrahydroxyurs‐12‐en‐28‐oic acid ( 5 ) were isolated from 75% EtOH extract of Rosa cymosa. Their structures were elucidated by extensive spectroscopic methods. All the isolated compounds displayed moderate inhibitory activity against LPS‐induced NO production in macrophages.     

Investigating the history of prehistoric glues by gas chromatography-mass spectrometry

Although organic materials are very sensitive to biochemical alteration processes, they may be preserved for millennia in various archaeological contexts. Remains of adhesives made during prehistory were discovered at different sites, in the form of residues adhering to flint tools and ceramic vessels or as free lumps in sediment. To characterise the natural substances exploited for adhesive production during late prehistory, we undertook GC and GC/MS analysis of 90 samples from 8 sites dating from the Neolithic to Iron Age periods. This paper discusses our approach to the study of organic adhesives preserved in archaeological contexts, with a particular focus on the presentation of the various categories of organic adhesives that we analysed and the choice of chromatographic conditions adapted to the specificity of such samples. The results obtained show that birch bark tar, a triterpenoid adhesive made by destructive distillation of white birch bark, was predominantly used during the neolithic period even though other materials such as various barks or organic fossil substance were also used. During the Bronze and Iron ages, which follow the Neolithic period, adhesive production is evolving through the expansion of the range of the natural substances used (identification of diterpenoid pine resin) and the addition of beeswax as a plasticiser to birch bark tar. By combining chromatographic analysis and archaeological data, it was thus possible to follow the evolution of adhesive making at the end of prehistory, testifying to the inventiveness of the craftsmen whatever the period considered.     

Characterisation of beeswax in works of art by gas chromatography-mass spectrometry and pyrolysis-gas chromatography-mass spectrometry procedures

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.     

Aromatic resin characterisation by gas chromatography-mass spectrometry. Raw and archaeological materials

An analytical procedure based on alkaline hydrolysis, solvent extraction and trimethyl-silylation followed by gas chromatography-mass spectrometry (GC-MS) analysis was used to study the chemical composition of benzoe and storax resins, water-insoluble exudates of trees of the Styrax and Liquidambar genus. They are chemically characterised by having aromatic acids, alcohols and esters as their main components and are thus known as aromatic and/or balsamic resins. This analytical procedure allowed us to characterise the main components of the two resins and, even though cinnamic acid is the main component of both the resins, the presence of other characteristic aromatic compounds and triterpenes permitted us to distinguish between the two materials. All the compounds identified in benzoe resin were detected in an archaeological organic residue from an Egyptian ceramic censer (fifth to seventh centuries a.d.), thus proving that this resin was used as one of the components of the mixture of organic materials burned as incense. These results provide the first chemical evidence of the presence of benzoe resin in an archaeological material from Mediterranean area.     

Characterization and purification of polyunsaturated fatty acids from microalgae by gas chromatography-mass spectrometry and countercurrent chromatography

Summary The present study was undertaken in order to characterize then to purify fatty acids from marine phytoplankton. From a crude mixture of fatty acid methyl esters it was possible to isolate by countercurrent chromatography a mixture of four polyunsaturated fatty acid methyl ester identified as being hexadecatrienoic acid methyl ester, octadecatetraenoic acid methyl ester, eicosapentaenoic acid methyl ester and docosahexaenoic acid methyl ester by gas chromatography coupled with mass spectrometry in electron impact and in positive-ion chemical ionization mode. The four polyunsaturated fatty acids are in different ratios in mixtures from the two microorganisms:Skeletonema costatum andIsochrysis galbana.     

Characterization of bile acids and fatty acids from ox bile in oil paintings by gas chromatography-mass spectrometry

Characterization of ox bile, traditionally used in painting, is of interest in the fields of archaeometry and conservation and restoration of works of art. Bile acids, fatty acids (F), and cholesterol found in ox bile have been identified using a derivatization method that combines the formation of ethyl esters from the carboxylic groups and the trimethylsilyl ethers from hydroxyl groups. This method of analysis is consistent with these others proposed by the authors to analyze drying oils, proteins, and diterpenic resins usually used as binders and varnishes by the painters. Bile acids from binary samples such as animal glue/ox bile, casein/ox bile and Arabic gum/ox bile have been successfully analyzed using the proposed method. Finally, a method of analysis of mixtures of drying oil and ox bile has been also proposed attempting to quantitatively characterize samples in which ox bile was added to the drying oil for increasing the surfactant properties.     

Triterpenoids from the Leaves of Ilex hainanensis

Phytochemical investigation on the leaves of Ilex hainanensis Merr . led to the isolation of four new ursane‐ and oleanane‐based triterpenoids, ilexhainanins A–D ( 1 – 4 ), as well as two known compounds, 2α,3β,19α‐trihydroxyurs‐12‐ene‐23,28‐dioic acid and 2α,3β,19α‐trihydroxyolean‐12‐ene‐23,28‐dioic acid. Their structures were elucidated on the basis of chemical and spectroscopic evidence, and by comparison with literature data.     

Analysis of four pentacyclic triterpenoid acids in several bioactive botanicals with gas and liquid chromatography and mass spectrometry detection

Several pentacyclic triterpenoid acids including betulinic, oleanolic, and ursolic acids were reported to have health beneficial properties such as antiviral and anti‐inflammatory properties, as well as the capability to inhibit “in vitro” the development of various cancer cell types. For this reason betulinic, oleanolic, and ursolic acids are used as neutraceuticals. For the analysis of the pentacyclic triterpenoid acids in complex plant materials, an improved scheme was developed, involving a qualitative screening using silylation and gas chromatography with mass spectrometry analysis, followed by quantitation using a novel liquid chromatography with tandem mass spectrometry procedure. The use of the two methods provides more reliable information regarding the plant materials with unknown composition. Besides betulinic, oleanolic, and ursolic acids that were analyzed, by this procedure a fourth pentacyclic triterpenoid acid was identified and quantitated that was not previously reported to be present in plants. This acid has been identified as 3β‐3‐hydroxy‐lupa‐18,20(29)‐dien‐28‐oic acid. The newly identified acid has a structure as a derivative of lupane, although lupane with a double bond in the 18‐position was not previously reported as present in plants. The new liquid chromatography with tandem mass spectrometry procedure developed for this study offers a very low limit of quantitation, excellent precision, and robustness. Rosemary was found to contain the largest levels of pentacyclic triterpenoid acids among all the analyzed botanicals.     

Characterization of lubricity improver additive in diesel by gas chromatography-mass spectrometry

The characterization of lubricity improver additives by GC-MS-SIM is an important tool for the development and monitoring of new formulations as well as for quality control of additives in diesel. A simple method for the quantification of a linoleic oil additive derivative in diesel has been developed. Calibration is performed by analysis of standard solutions containing 2-hydroxy-ethyl linoleate with pentadecanoyl propanoate as the internal standard. The proposed method permitted the quantification of the linoleate ester at a concentration of 300 microg/mL in the additived diesel. The recovery of additive and the repeatability of the quantitative results are evaluated.     

Optimization of headspace solid phase microextraction for gas chromatography/mass spectrometry analysis of widely different volatility and polarity terpenoids in olibanum

The aim of this study was the optimization of headspace SPME conditions for trapping diterpenes present in frankincense (olibanum). Diterpenes like cembrenes or incensole and its derivatives are characteristic of olibanum. So in order to detect by SPME the occurrence of olibanum in archeological objects, it appears essential to have the best extraction conditions for these diterpenes that will be in very small quantities. Both sampling time and extraction temperature were studied and five fiber coatings were tested: polydimethylsiloxane (PDMS), polydimethylsiloxane/divinylbenzene (PDMS/DVB), carboxen/polydimethylsiloxane (CAR/PDMS), divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS) and carbowax/divinylbenzene (CW/DVB). The PDMS/DVB fiber was found to be the most efficient for trapping olibanum characteristic diterpenes, with a sampling time of 1 h and a sampling temperature of 80 degrees C.     

Characterization of prednisone, prednisolone and their metabolites by gas chromatography-mass spectrometry

Human urinary metabolites of the synthetic corticosteroids prednisone and prednisolone were detected in the course of gas chromatographic steroid profiling as methoxime-trimethylsilyl derivatives. Metabolites were provisionaly identified by combined gas chromatography-mass spectrometry. The major metabolites were 11-keto/11-hydroxy conversion products, 20-hydroxy and 4,5-dihydro analogues of the parent drugs. Cortisone, 6-hydroxy and fully saturated A-ring compounds were minor metabolites. Retention indices and mass spectral data are presented.     

Characterization of thermally assisted hydrolysis and methylation products of polyphenols from modern and archaeological vine derivatives using gas chromatography-mass spectrometry

If some ceramics, such as vinary amphorae attest the consumption and trade of wine in the Roman world, the first wine productions in Occident often stay undocumented. Chemical analysis of organic materials preserved in archaeological vessels is the only way to bring new lights about the elaboration and the consumption of this fermented beverage. To determine the preservation state of wine and other grape derivatives residues, we proceeded to in situ tetramethylammonium hydroxide (TMAH) treatment followed by thermally assisted hydrolysis and methylation—gas chromatography—mass spectrometry (THM-GC-MS). The objectives of the study were (i) the understanding of the pyrolytic mechanisms of proanthocyanidins and (ii) the assessment of the usefulness of thermochemolysis for the identification of phenolic markers from polymeric solid deposit in modern wine bottle and Roman amphorae. THM-GC-MS was revealed to be an efficient method for the characterization of fruit derivatives even if mixed with another organic material, such as pitch used to ensure the watertightness of the ceramic container. The preservation of tannins during millennia in archaeological context is here enlightened for the first time by using analytical pyrolysis. The proposed identification of vinary residues is now based on the detection of the association of more than 30 pyrolytic markers derived from di- and trimethoxylated benzenoid compounds. THM-GC-MS represents a new method for the rapid detection of wine traces in ancient ceramics, adapted to tiny samples (<0.1 mg), allowing to precise the role and function of pottery during antiquity.     

A study for the characterization of binding media from medieval polychrome sculptures by gas chromatography-mass spectrometry

Summary Binding media in samples taken from XIIth–XIIIth century polychrome sculptures in the Baptistery of Parma (Italy) were characterized by gas chromatography-mass spectrometry, after hydrolysis and derivatization procedures. The use of SE-52 capillary columns and the application of selected ion monitoring (SIM) allowed an increasing in the sensitivity and the ability to differentiate between animal glues, casein, egg and drying oils as components of the binders of paint and ground layers. Small amounts of material were enough for a satisfactory characterization.     

Characterization of Spanish unifloral honeys by solid phase microextraction and gas chromatography-mass spectrometry

Volatile compounds have been investigated in unifloral honeys of the most popular types in Spain. A total of 21 eucalyptus samples, 35 rosemary samples, 33 heather samples, and 15 citrus samples were collected in the course of 3 years in different Spanish regions. Samples were analyzed by SPME followed by GC-MS. About 83 compounds were identified; the concentrations of 33 of them were selected to be processed by multivariate analysis. Discriminant analysis allowed correct assignment of most samples: 94% citrus, 92% eucalyptus, 84% heather, and 84% rosemary. As pure reference honeys are not available, a two step data analysis is proposed, selecting the samples most clearly classified in discriminant analysis as "reference samples" to be used in multiple regression to estimate the most representative compounds for each honey type and considering the rest of the samples as of mixed origin.     

气相色谱-质谱联用法检测母乳脂肪中反式脂肪酸

建立了母乳中反式脂肪酸(TFAs)的气相色谱-质谱(GC-MS)检测方法,并应用于母乳脂肪中TFAs的检测。母乳用氨水水解,乙醚和石油醚提取脂肪,提取的脂肪加入C21: 0内标,用三氟化硼甲醇溶液在80℃水浴中冷凝回流15 min进行甲酯化,正己烷提取,上清液用GC-MS分析,内标法定量。在低、中、高加标水平上验证方法的准确度与精密度,结果显示该方法可用于母乳中18种TFAs及其同分异构体的检测,其中12种TFAs在母乳脂肪中的方法检出限为4.0~47.1 mg/kg,回收率为80%~113%, RSD为2.9%~14.5%(n=6)。TFAs在部分母乳脂样品中检出,含量为9.54~6.9 mg/kg。该方法定性、定量准确,可有效用于母乳中TFAs的检测,但仍存在脂肪酸本底干扰等问题,可结合银离子固相萃取柱预分离技术进一步完善。