Headspace Solid Phase Microextraction for Terpenes and Volatile Compounds Determination in Mastic Gum Extracts, Mastic Oil and Human Urine by GC– MS

Advances in the characterisation and identification of mastic (Pistacia sp.) resin in archaeological samples by GC-QToF-MS

The optimisation and application of an analytical method based on gas chromatography coupled to quadrupole time-of-flight mass spectrometry (GC-QToF-MS) is proposed for the first time for the characterisation and identification of mastic (Pistacia sp.) resin in archaeological samples. The GC-QToF-MS method demonstrated higher sensitivity compared to single quadrupole GC-MS and enabled enhanced structural elucidation power to be exploited, particularly due to the high mass resolution and accuracy, the possibility to use standard and low ionisation energies as well as its tandem MS capabilities. The heat-induced degradation of the resin was also studied in open air conditions, showing that 28-norolean-17-en-3-one forms upon heating, but then progressively degrades. This makes it a reliable marker for heating of Pistacia resin; however, the lack of detection does not imply that the resin was not heated. These observations were used to interpret the results of a large number of archaeological samples containing Pistacia resin in different formulations, from various archaeological contexts and exposed to different environmental conditions. Lumps of relatively pure resin found in marine waterlogged conditions (Uluburun shipwreck, Turkey), residues on ceramics from Sai Island (Nubia, Sudan) as well as varnish and coating layers on Egyptian coffins from the collections of the British Museum (London, UK) and Fitzwilliam Museum (Cambridge, UK) were analysed to understand what the molecular profiles reveal about the use of the resin. The results showed that the resin was often mixed with a drying or semi-drying oil in ancient varnish formulations, thus suggesting that oil was used as a medium to dissolve the resin, which would have been impossible to apply as a layer using simple heat. These new observations significantly add to our understanding of ancient Egyptian technology and provide museum scientists and conservators with key information to accurately identify Pistacia resin and preserve objects containing it.

Focusing on Volatile Organic Compounds of Natural Resins by Selected-Ion Flow Tube-Mass Spectrometry

The analysis of archeological artifacts, due to the high value of antique objects, is preferably performed by nondestructive, noninvasive, and in situ techniques. At present, the most common in situ protocols used for the analysis of organic materials are spectroscopic approaches. In this work, we tested selected-ion flow tube-mass spectrometry (SIFT-MS), a transportable mass spectrometry system for the characterization and discrimination of natural resins by the analysis of their volatile organic compounds profiles. We chose diterpenoid, triterpenoid, and aromatic resins as reference materials, focusing on the most identified in archeological artifacts. This work aims to create a SIFT-MS database of mass spectra suitable for characterizing archeological samples. The spectral data obtained by SIFT-MS were interpreted with the aid of chromatograms and mass spectra obtained by head space-gas chromatography/mass spectrometry (HS-GC/MS). Finally, principal components analysis (PCA) was used to further underline the differences among the different materials and to investigate the possibility of discriminating different classes of resins based on their SIFT spectra.

Myrcene-What Are the Potential Health Benefits of This Flavouring and Aroma Agent?

Myrcene (β-myrcene) is an abundant monoterpene which occurs as a major constituent in many plant species, including hops and cannabis. It is a popular flavouring and aroma agent (food additive) used in the manufacture of food and beverages. This review aims to report on the occurrence, biological and toxicological profile of β-myrcene. The main reported biological properties of β-myrcene-anxiolytic, antioxidant, anti-ageing, anti-inflammatory, analgesic properties-are discussed, with the mechanisms of activity. Here we also discuss recent data regarding the safety of β-myrcene. Overall, β-myrcene has shown promising health benefits in many animal studies. However, studies conducted in humans is lacking. In the future, there is potential for the formulation and production of non-alcoholic beers, functional foods and drinks, and cannabis extracts (low in THC) rich in β-myrcene.

Characterization of the volatile fraction of mastic oil and mastic gum

GC-MS of ethyl acetate solutions and HS-SPME-GC-MS of mastic oil and mastic gum showed the presence of α-pinene and β-myrcene as main components of the mixture. In the GC-MS analysis of mastic oil 19 compounds were detected, while mastic gum allowed to detect only twelve compounds. Mastic gum showed the presence of compounds with a higher molecular weight. In HS-SPME analysis the amount of β-myrcene increased in comparison to the results obtained in the analyses performed in solution. The relative ratio between α-pinene and β-myrcene showed that SPME analysis induces a preferential detection for β-myrcene (α-pinene/β-myrcene in the mastic oil 16.18 in GC-MS analysis, and 5.06 in SPME analysis; α-pinene/β-myrcene in mastic gum 10.64 in GC-MS analysis, and 2.25 in SPME analysis). These results can be explained considering a different absorption selectivity of these compounds on the SPME fiber.

Validation Study of Selected Ion Flow Tube-Mass Spectrometry (SIFT-MS) in Heritage Science: Characterization of Natural and Synthetic Paint Varnishes by Portable Mass Spectrometry

The identification at molecular level of organic materials in heritage objects as paintings requires in most cases the collection of micro-samples followed by micro-destructive analysis. In this study, we explore the possibility to characterize natural and synthetic resins used as paint varnishes by mean of non-invasive analysis of released volatile organic compounds (VOCs) through selected ion flow tube-mass spectrometry (SIFT-MS). SIFT-MS is a portable direct mass spectrometric technique that achieves the analysis of VOCs at trace levels in real time, by controlled ultra-soft chemical ionization using eight different chemical ionization agents. We tested the portable instrumentation on different reference resins used as paint varnishes, both natural (mastic, dammar, and colophony) and synthetic (Paraloid B67, MS2A, Regalrez 1094, and polyvinyl acetate), to evaluate the possibility to acquire qualitative data for the identification of these materials in heritage objects avoiding any sampling. This new analytical approach was validated by comparison with the traditional approach for VOCs analysis based on solid phase micro extraction-gas chromatography/mass spectrometry (SPME-GC/MS) analysis. The results demonstrate the use of SIFT-MS as an in situ non-invasive and non-destructive mass spectrometric technique to identify organic materials, such as paint varnishes.

Determination of Volatile Compounds in Nut-Based Milk Alternative Beverages by HS-SPME Prior to GC-MS Analysis

A reliable Headspace-Solid Phase Microextraction (HS-SPME) method was developed for the determination of polar volatile components of commercial nut-based milk alternative drinks prior to Gas Chromatography–Mass Spectrometry (GC-MS) analysis. Under the optimum extraction conditions, a divinylbenzene (DVB)/Carboxen™ CAR)/polydimethylsiloxane (PDMS) fiber was used and 2 mL of sample was heated at 60 °C for 40 min under stirring, without salt addition. Ten compounds from different chemical classes (heptane, a-pinene, toluene, 2-methylpyrazine, 3-heptanone, heptanal, 2-octanone, 1-heptanol, benzaldehyde and 1-octanol) were chosen as model analytes for quantification. Limits of detection and limits of quantification were found to be 0.33–1.67 ng g⁻¹ and 1–5 ng g⁻¹, accordingly. Good linearity, precision and accuracy were obtained as well as a wide linear range. The proposed method was successfully applied to various beverages including almond milk, walnut milk, peanut milk and almond chocolate milk. More than 70 volatile compounds were detected in the different samples. Most of the detected volatiles were aldehydes, ketones and alcohols. This technique can be used for the determination of volatile compounds in nut-based beverages, to detect compositional changes during storage and technological treatment used for their production.

Microextraction in urine samples for gas chromatography: a review

Since the complexity origin of biological samples, the research trends have been directed to the development of new miniaturized sample preparation techniques. This review provides a comprehensive survey of past and present microextraction methods followed by GC analysis for preconcentration and determination of various analytes in urine samples. These techniques have been classified in three general groups, including liquid-, solid- and membrane-based techniques. The principal of different microextraction methods that are located in each general group as well as their various extraction modes and the recent developments introduced for them has been presented. Subsequently, a comparison survey has been carried out among different microextraction techniques and finally a future perspective has been predicted based on the existing literature.