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The analysis and quantification of plant metabolites is a major challenge as medicinal and aromatic plant extracts are very complex and there is a lack of commercially pure standards that are important for both identification and quantification. The aim of this work is to compare the performance of different detectors (PDA and MS) used in high performance liquid chromatography and acquisition modes (Selected Ion Monitoring (SIM) and Selected Reaction Monitoring (SRM) in MS) for the quantification of specialized plant metabolites (i.e. phenolic and triterpenic compounds). All metabolites were quantified using the above detection methods with the reference standard and with a compound with similar UV and MS spectra (semi-quantification) to simulate the very common cases where the reference standard is not available or accessible. The precision of each quantification approach was evaluated by the percentage relative error based on the actual concentration of the quantified compound. The quantification precision was also tested in the presence of interferences and in two case studies, i.e. leaf extracts of Cynara cardunculus subsp. cardunculus L. and Punica granatum L.. The results show that quantification with the reference standard is certainly more precise. For semi-quantification, SIM and especially SRM are less suitable as they are more selective compared to PDA, but they allow detection and approximate quantification of the molecule of interest limiting interference, especially in complex matrices where coelution is sometimes unavoidable. A correction method is also proposed to overcome the over-underestimation that can occur with semi-quantification., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2025 Elsevier B.V. All rights reserved.)

The wide range of applications of hemp products, together with the environmental benefits that come from hemp cultivation are driving up the market demand for Cannabis sativa L. plant. One of the main restrictions for hemp cultivation and marketing concerns the content of delta-9-tetrahydrocannabidiol (Δ 9 -THC), which is known to have psychotomimetic effect. If the recent growing of hemp market is beneficial by an economic and environmental point of view, it is necessary to develop reliable analytical methods for the chemical characterization of hemp products, to guarantee the safety of use for the customers. This study aimed to develop a simple ultrasound-assisted dispersive solid-liquid microextraction (UA-DSLME) method for the extraction of cannabinoids in hemp products, using eutectic solvents (ESs) as extraction material. Two types of ESs were compared: one prepared with a [Ch + ][Br - ]-modified salts as hydrogen bond acceptor and one based on natural terpenoids. The ultrasound-assisted dispersive solid-liquid microextraction method was optimized to be applied for the analysis of aerial parts of hemp collected before flowering, hemp inflorescences and a commercial sample called CBD oil, and proved to be robust and versatile. Under optimal conditions, only 100 µL of ES and 2 mL of water as co-solvent were used in the US-assisted extraction, before the analysis in the UHPLC-PDA system. The developed approach allowed to obtain the same chemical profile of conventional methods, while improving the greenness of the method and the enrichment of the marker analytes. To overcome the strong matrix effect for cannabinoids, a matrix-matched calibration was used. Blank matrices of the samples under study were easily obtained by performing an exhaustive extraction of the marker analytes in the hemp samples. These matrices were successfully used for validation, achieving accuracy values between 82% and 118%., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Author(s). Published by Elsevier B.V. All rights reserved.)

Phosphonium-based ionic liquids (ILs) have proven to be successful stationary phases (SPs) for gas chromatography (GC) in several fields of application because of their unique selectivity and good chromatographic properties. This study focuses on the use of two ILs as GC SPs that are based on the phosphonium derivatives trihexyl(tetradecyl)phosphonium chloride ([P 66614 + ] [Cl - ]), and trihexyl(tetradecyl)phosphonium bis[(trifluoromethyl)sulfonyl]imide ([P 66614 + ][NTf 2 - ]), which have previously been shown to be complementary in terms of chromatographic selectivity and retention. Their application in routine analysis has been limited by their lower maximum allowable operating temperatures (MAOT) (200 °C for the [P 66614 + ][Cl - ] IL and 180 °C for [P 66614 + ][NTf 2 - ]), which restricts their use to samples that consist of analytes with relatively high volatility. A previous study carried out in the Authors' laboratory focused on extending the use of the [P 66614 + ][Cl - ] IL SP to the analysis of samples with analytes of medium-to-low volatility by optimizing column characteristics and operative conditions. This study addresses the immobilization of both the [P 66614 + ][Cl - ] and [P 66614 + ][NTf 2 - ] ILs to the inner wall of fused silica columns to increase their MAOT under soft and hard reaction conditions. The resulting MAOT depended on more or less drastic immobilization conditions, and reached 220 °C for soft immobilization (So-Im) and 240 °C for hard immobilization (Ha-Im) in the [P 66614 + ][Cl - ] IL columns, and 200 °C for So-Im and 220° for Ha-Im in columns coated with the [P 66614 + ] [NTf 2 - ] IL. The influence of immobilization on the separation power and performance of all the columns has been evaluated using i) the Grob test, ii) a model mixture of 41 compounds of different polarity, structure, and with different organic functional groups representative of the flavor and fragrance field, iii) a standard mixture of 37 fatty acid methyl esters, iv) the peppermint essential oil, v) two mixtures of sesquiterpenic alcohols (farnesols and santalols), and vi) a standard mixture of 16 pesticides. These test samples were also used to demonstrate the complementarity of the two phosphonium-based IL SPs in terms of selectivity and retention., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. The authors declare the following financial interests/personal relationships which may be considered as potential competing interests., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Accurate, reliable, and informative mapping of untargeted and targeted components across many samples is here performed by combining off-line GC-Olfactometry (GC-O) and comprehensive two-dimensional gas chromatography (GC×GC) coupled to time-of-flight mass spectrometry with variable ionization energy (TOF MS featuring Tandem Ionization™). In particular, untargeted and targeted (UT) features patterns are processed by chromatographic fingerprinting, giving differential priority to potent odorants' retention-times regions. Distinguishing peppermint essential oil (EO) from Piedmont (Italy - Mentha × piperita L. var. Italo-Mitcham - Menta di Pancalieri EO), with its unique sensory fingerprint (i.e., freshness and long-lasting sweetness), from high-quality peppermint EOs produced in other areas poses a great challenge. Chromatographic UT fingerprinting provided a great chemical dimensionality by mapping more than 350 peak-regions at 70 eV and 135 at 12 eV. From them, 95 components were identified and responses compared to available literature. Then, potent odorants, detected by GC-O using the aroma extraction dilution analysis (AEDA), were tracked over the chromatographic space and tentatively identified. With the highest flavor dilution (FD), 1,8-cineole (eucalyptus, fresh, camphoraceous); menthone (minty, herbaceous); and menthofuran (minty, musty, petroleum-like) were highlighted. Responsible for creamy and coumarinic notes were the diasteroisomers of (3,6)-dimethyl-4,5,6,7-tetrahydrobenzo[b]-furan-2(3H)-one (i.e., menthofurolactones), detected in higher relative abundance in Pancalieri EOs. By prioritizing the investigation of volatiles on higher LogFD retention regions, including 131 untargeted/targeted features, Pancalieri EOs were separately clustered from United States samples. Besides pre-targeted analytes, additional untargeted features were post-processed for identification within marker chemicals. Myrtenyl methyl ether, ethyl 3-methyl butanoate, propyl-2-methylbutanoate, and (E)-2-hexenal were putatively identified. Of the "unknown - knowns" with diagnostic roles, all metadata were collected including low energy spectra at 12 eV, which were found to be highly complementary to 70 eV spectra., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021. Published by Elsevier B.V.)

Biogenic volatile organic compounds (BVOCs) are metabolites emitted by living plants that have a fundamental ecological role since they influence atmospheric chemistry, plant communication and pollinator/herbivore behaviour, and human activities. Over the years, several strategies have been developed to isolate and identify them, and to take advantage of their activity. The main techniques used for in-vivo analyses include dynamic headspace (D-HS), static headspace (S-HS) and, more recently, direct contact (DC) methods in association with gas chromatography (GC) and mass spectrometry (MS). The aim of this review is to provide insight into the in-vivo characterisation of plant volatile emissions with a focus on sampling, analysis and possible applications. This review first provides a critical discussion of the challenges associated with conventional approaches and their limitations and advantages. Then, it describes a series of applications of in-vivo volatilomic studies to enhance how the information they provide impact on our knowledge of plant behaviour, including the effects of abiotic (damage, flooding, climate) and biotic (insect feeding) stress factors in relation to the plants., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Room temperature ionic liquids (ILs) are well established stationary phases (SPs) for gas chromatography (GC) in several fields of applications because of their unique and tunable selectivity, low vapor pressure and volatility, high thermal stability (over 300 °C), and good chromatographic properties. This study is focused on an IL based on a phosphonium derivative (trihexyl(tetradecyl)phosphonium chloride, [P 66614 + ] [Cl - ]), previously shown to be suitable as a gas chromatographic SP because of its unique selectivity. In particular, it aims to establish the operative conditions to apply [P 66614 + ][Cl - ] to routine analysis of samples containing medium to high volatility analytes with different polarity, organic functional groups and chemical structure. In the first part, the study critically evaluates long term [P 66614 + ][Cl - ] column stability and maximum allowable operating temperatures (MAOT). The relatively low MAOT (210 °C) requires the adoption of a dedicated approach for analytes eluting above this temperature based on a suitable combination of efficiency and selectivity, and column characteristics (length, inner diameter and film thickness) and operative conditions. The performance of [P 66614 + ][Cl - ] as a GC SP have been validated through the Grob test, a model mixture of 41 compounds of different polarity, structure, and with different organic functional groups in the flavor and fragrance field, a standard mixture of 37 fatty acid methyl esters, some essential oils containing pairs or groups of compounds of different volatility critical to separate in particular peppermint, thyme, oregano, sandalwood and frankincense. The above approach has produced highly satisfactory separations with all of the samples investigated., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. The authors declare the following financial interests/personal relationships which may be considered as potential competing interests, (Copyright © 2020 Elsevier B.V. All rights reserved.)

The use of a thick sorbent coating in headspace sorptive extraction (HSSE) increases the amount of analytes extracted at equilibrium as well as the time needed to reach it. In this work we propose HSSE sampling under vacuum conditions to reduce equilibration times. A theoretical model is presented that describes the pressure dependence of the so-called vacuum-assisted HSSE (Vac-HSSE) method, and predicts the reduction in equilibration times when lowering the sampling pressure. We take advantage of the theoretical formulation to reach some general conclusions for HSSE on the relationship between the physical characteristics of the stir bar, uptake rates and equilibration times. The theoretical predictions were experimentally verified using water solutions spiked with naphthalene, acenaphthene and fluoranthene as model compounds. The effects of sampling temperature and extraction time under vacuum and regular pressure conditions were thoroughly investigated. The positive combined effect of heating the sample under low sampling pressure pointed that high humidity did not affect the performance of the extraction phase; an effect commonly recorded in headspace solid-phase microextraction. The extraction time profiles built at 25 and 55 °C visualized the substantial improvement in extraction kinetics with Vac-HSSE compared to the regular HSSE method. The results on naphthalene (assumed to evaporate relatively fast from the water sample) provided evidence that at 1 atm gas-sided resistance limited analyte uptake by the stir-bar and that this limitation could be effectively reduced by adopting the vacuum sampling approach. The accelerations of acenaphthene and fluoranthene suggested that gas-phase constraints limited both the evaporation and analyte uptake processes. Independent method optimization of HSSE under each pressure condition yielded a shorter sampling time for Vac-HSSE compared to the regular HSSE procedure (30 min vs. 60 min respectively). The analytical performances of the two optimized methods were evaluated and it was concluded that Vac-HSSE was performing similar (naphthalene and acenaphthene) or better (fluoranthene) than regular HSSE in half the sampling time needed., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Qualitative and quantitative determination of volatile markers in aqueous based fragrances assumes ever-increasing importance, because of both the need for quality control and the safety-regulatory limitations introduced for several compounds. This study reports and critically discusses the results of applying new water-compatible ionic-liquid (IL) GC stationary phases, based on phosphonium and imidazolium derivative cations combined with trifluoromethanesulphonate (Watercol™) to the direct quantitative analysis of aqueous samples in the perfume field with GC-MS. Narrow-bore columns of different lengths, especially prepared for this study, were adopted to minimize the amount of water reaching the MS detector after GC separation. All GC-MS analysis steps were investigated, to achieve results compatible with quality control requirements for the volatiles of interest in this field, in terms of LODs, LOQs, and repeatability. Reliability of the GC-MS results was demonstrated by determining volatile allergens in two commercial perfumes, as per EU regulations concerning no-declaration limits for leave-on (0.001%) and rinse-off (0.01%) cosmetic products., (Copyright © 2019 Elsevier B.V. All rights reserved.)

A correct botanical identification and analytical quality control of volatile key-markers responsible for aroma and biological activities is necessary to monitor volatile compounds transferred from a plant to the related herbal tea and human intake to guarantee their safe use. This is mainly true for markers limited by regulations or by a recommended maximum amount of consumption per day. GC-MS is the elective technique to analyze volatiles, provided that for aqueous samples (herbal teas) an appropriate sample preparation procedure, and/or a water-compatible GC stationary phases are applied. Solid Phase Micro Extraction (SPME) on-line coupled to GC-MS in a fully automatic approach is here applied to sample and quantify key markers in plant material (headspace) and in the corresponding herbal tea (direct immersion). In parallel, a new generation of GC columns coated with ionic liquid based stationary phases compatible with aqueous samples (Watercol ™ ) was applied to test direct injection of aqueous samples (DAI-GC-FID). The latter approach fully bypasses sample preparation thus speeding up quality control. This study deals with the quantitation of menthol, α- and β-thujone, estragole, and anethole contained in several plant species commonly used for herbal teas (i.e. peppermint, sage, wormwood, fennel, aniseed) and regulated by International Organizations. The two methods gave comparable results and are characterized by high repeatability, linearity and accuracy, although, as expected, their sensitivity was different because DAI-GC-FID implies injection of the sample as such without analyte concentration as for DI-SPME-GC-MS. For instance, LOD and LOQ of estragole were 0.03 and 0.1 mg L -1 with DI-SPME-GC-MS and 0.1 and 0.8 mg L -1 with DAI-GC-FID. The two methods are fully complementary and their adoption depends on the amount of marker(s) to be quantified., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Ptilostemon casabonae (L.) Greuter is a Mediterranean endemism traditionally used for its health-giving properties. Little is known about this species, therefore this study provides additional information about the phytochemical and biomolecular patterns of this plant, to have a combined fingerprint as a taxonomic tool. Several P. casabonae specimens were therefore collected from three different sites, two from Sardinia (Italy) and one from Corsica and the hydroalcoholic extracts of their aerial parts were investigated through HPLC-PDA-MS/MS analysis to study the phenolic composition. Quercetin, luteolin, kaempferol, apigenin and diosmetin O-glycosides, and caffeoylquinic acid derivatives were found as main components. Samples from the three sites showed similar phenolic profiles, although statistical analyses highlighted some quantitative differences for several compounds. The biomolecular analysis included amplification and sequencing of ITS, 5S-rRNA-NTS and psbA regions. No difference was found in the nucleotides among the P. casabonae samples from different geographical origins; however, a comparison with other Ptilostemon species sequences from Genbank, revealed an interspecific variability of ITS and psbA regions. The combination of the results of the phytochemical and biomolecular studies provide information on P. casabonae useful to depict this little-known plant, which can also be applied for future investigations and to obtain a fingerprint of it. Moreover, the stability of the phenolic profile within the species affords to identify a set of specialised metabolites useful for its chemotaxonomic characterization. At the same time, the stability of the biomolecular profile of P. casabonae, and the identification of sequences specific for this species, enables to identify useful biomolecular markers to distinguish it unequivocally., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

This paper focuses on several methodological aspects in the quantitation of volatiles in solid samples by headspace solid phase micro-extraction (HS-SPME) combined with gas chromatography and parallel detection by flame ionization detector and mass spectrometry (GC-FID/MS). Informative volatiles, including key odorants and process markers, from single-origin cocoa samples (Colombia, Ecuador, Mexico, Sao Tomè, and Venezuela) were captured at two processing stages along the chocolate production chain (nibs and cocoa mass). Accurate quantitation was achieved by multiple headspace extraction (MHE) in headspace linearity conditions and by external calibration. Quantitative results on selected analytes (3-hydroxy-2-butanone, 2-heptanol, 2,3,5-trimethylpyrazine, 2-ethyl-3,6-dimethylpyrazine, ethyl octanoate, benzaldehyde, 2-methylpropionic acid, 3-methylbutyric acid, ethyl phenylacetate, 2-phenylethyl acetate, guaiacol, 2-phenylethanol, and (E)-2-phenyl-2-butenal) provided reliable information about the key sensory notes of cocoa intermediates (odor activity values) and their origin specificities. Additional information about analytes release by the solid environment (cocoa nibs, mass, and powders) was achieved by modeling decay curves. Parallel detection by MS and FID enabled quantitative cross-validation, and FID-predicted relative response factors (RRFs) extended method quantitation capabilities to additional compounds that were not subjected to an external calibration procedure: 3-methylbutyl acetate (isoamyl acetate), 2-heptanone, heptanal, 2-nonanone, γ-butyrolactone, octanoic acid, 2-ethyl-5(6)-methylpyrazine, phenylacetic acid, phenol, 2-acetyl pyrrole, and 2,3-dihydro-3,5-dihydroxy-6-methyl(4H)-pyran-4-one. This procedure extends method capabilities and information potential with great consistency., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Room-temperature ionic liquids (ILs) have been shown to be successful as stationary phases (SPs) for gas chromatography in several fields of applications because of their unique and tunable selectivity, low vapor pressure and volatility, high thermal stability (over 300 °C), and good chromatographic properties. This study has been focused on two ILs based on a phosphonium cation (trihexyl(tetradecyl)phosphonium, P 66614 ) combined with different anions, previously shown to be suitable as gas chromatography (GC) SPs. In particular, trihexyl(tetradecyl)phosphonium bis[(trifluoromethyl)sulfonyl]imide ([P 66614 + ] [NTf 2 - ]) and trihexyl(tetradecyl)phosphonium chloride ([P 66614 + ] [Cl - ]) were investigated, as the Abraham linear solvation energy relationship has shown their ability to interact with the solute(s) when tested with a set of 26-34 probe analytes. The chromatographic performance were investigated on narrow bore and conventional test columns using the following: i) Grob test, ii) a group of model mixtures of compounds characteristic of the flavor, fragrance and essential oil fields (FFMix), iii) a standard mixture of 29 volatile allergens (AlMix), and iv) two essential oils of different complexity (sage and vetiver essential oils). The columns coated with the investigated IL SPs were characterized by similar polarity (Polarity Number (PN): 37 for [P 66614 + ] [Cl - ] and 33 for [P 66614 + ] [NTf 2 - ]), high efficiency and highly satisfactory inertness. The two IL SPs also exhibited a completely different separation performance, with [P 66614 + ] [Cl - ] test columns mainly characterized by high retention and selectivity based on the analyte functional groups, and [P 66614 + ] [NTf 2 - ] test columns featured by short retention and selectivity mainly related to the analyte volatility and polarity. These results were also confirmed with the analysis of sage and vetiver essential oils., (Copyright © 2018 Elsevier B.V. All rights reserved.)

In the fields of essential oils and fragrances, samples often consist of mixtures of compounds with similar structural and physical characteristics (e.g. mono- and sesquiterpenoids), whose correct identification closely depends on the synergic combination of chromatographic and mass spectral data. This sample complexity means that new GC stationary phases with different selectivities are continually being investigated. Ionic liquids (ILs) are of great interest as GC stationary phases in this field because of their selectivity (significantly different than that of currently phases) and their high temperature stability. A first generation of IL GC columns was found to be competitive when applied to these field, in terms of selectivity and efficiency, compared to conventional columns (polydimethylsiloxane, (e.g. OV-1), methyl-polysiloxane 5%-phenyl (e.g. SE-52), 7%-cyanopropyl, 7%-phenyl polysiloxane (e.g. OV-1701), and polyethylen glycol (e.g. PEG-20M). However, these columns showed significant activity towards polar or active analytes, which primarily affected their quantitative performance. A new generation of highly-inactive columns coated with three of the most widely-used ionic liquid GC stationary phases has recently been introduced; these phases are SLB-IL60i (1,12-di(tripropylphosphonium) dodecane bis(trifluoromethylsulfonyl) imide [NTf 2 ], SLB-IL76i (tri-(tripropylphosphonium-hexanamido)-triethylamine [NTf 2 ]), and SLB-IL111i (1,5-di (2,3-dimethyllimidazolium) pentane [NTf 2 ]). This study carefully tested the new inert IL columns, in view of their routine application in the fragrance and essential oil fields. They were found to have unusually high selectivity, comparable to that of first-generation IL columns, while their inertness and efficiency were competitive with those of currently-used conventional columns. The IL column performance of first and second generations was compared, through the quali-quantitative analysis of components in a group of different complexity samples; these included the Grob test, a standard mixture of "suspected" skin allergens, and the essential oils of chamomile and sandalwood., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Recent technological advances in dynamic headspace sampling (D-HS) and the possibility to automate this sampling method have lead to a marked improvement in its the performance, a strong renewal of interest in it, and have extended its fields of application. The introduction of in-parallel and in-series automatic multi-sampling and of new trapping materials, plus the possibility to design an effective sampling process by correctly applying the breakthrough volume theory, have make profiling more representative, and have enhanced selectivity, and flexibility, also offering the possibility of fractionated enrichment in particular for high-volatility compounds. This study deals with fractionated D-HS ability to produce a sample representative of the volatile fraction of solid or liquid matrices. Experiments were carried out on a model equimolar (0.5mM) EtOH/water solution, comprising 16 compounds with different polarities and volatilities, structures ranging from C5 to C15 and vapor pressures from 4.15kPa (2,3-pentandione) to 0.004kPa (t-β-caryophyllene), and on an Arabica roasted coffee powder. Three trapping materials were considered: Tenax TA™ (TX), Polydimethylsiloxane foam (PDMS), and a three-carbon cartridge Carbopack B/Carbopack C/Carbosieve S-III™ (CBS). The influence of several parameters on the design of successful fractionated D-HS sampling. Including the physical and chemical characteristics of analytes and matrix, trapping material, analyte breakthrough, purge gas volumes, and sampling temperature, were investigated. The results show that, by appropriately choosing sampling conditions, fractionated D-HS sampling, based on component volatility, can produce a fast and representative profile of the matrix volatile fraction, with total recoveries comparable to those obtained by full evaporation D-HS for liquid samples, and very high concentration factors for solid samples., (Copyright © 2017 Elsevier B.V. All rights reserved.)

This study arises from both the today's trend towards exploiting plant resources exhaustively, and the wide quantitative discrepancy between the amounts of commercially-valuable markers in aromatic plants and those recovered from the related essential oil. The study addresses the determination of both the qualitative composition and the exhaustive distribution of free and glucosidically-bound L-menthol in peppermint aerial parts (Mentha x piperita L., Lamiaceae) and of eugenol in dried cloves (Syzygium aromaticum (L.) Merr. & L.M.Perry, Myrtaceae), two plants known to provide widely ranging essential oil yields. The two markers were investigated in essential oils and residual hydrodistillation waters, before and after enzymatic hydrolysis. Their amounts were related to those in the headspace taken as reference. The results showed that the difference between marker compound in headspace and in essential oil amounted to 22.8% for L-menthol in peppermint, and 16.5% for eugenol in cloves. The aglycones solubilised in the residual hydrodistillation waters were 7.2% of the headspace reference amount for L-menthol, and 13.3% for eugenol, respectively representing 9.3% and 15.9% of their amounts in the essential oil. The amount of L-menthol from its glucoside in residual hydrodistillation waters was 20.6% of that in the related essential oil, while eugenol from its glucoside accounted for 7.7% of the amount in clove essential oil. The yield of L-menthol, after submitting the plant material to enzymatic hydrolysis before hydrodistillation, increased by 23.1%, and for eugenol the increase was 8.1%, compared to the amount in the respective conventional essential oils. This study also aimed to evaluate the reliability of recently-introduced techniques that are little applied, if at all, in this field. The simultaneous use of high-concentration-capacity sample preparation techniques (SBSE, and HS-SPME and in-solution SPME) to run quali-quantitative analysis without sample manipulation, and direct LC-MS glucoside analysis, provided cross-validation of the results., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Herbs and spices are used worldwide as food flavoring, thus determination of their identity, origin, and quality is mandatory for safe human consumption. An analysis strategy based on separative (HS-SPME-GC-MS) and non-separative (HS-SPME-MS) approaches is proposed for the volatile fraction of herbs and spices, for quality control and to quantify the aromatic markers with a single analysis directly on the plant material as such. Eight-to-ten lots of each of the following herbs/spices were considered: cloves (Syzygium aromaticum (L.) Merr. & Perry), American peppertree (Schinus molle L.), black pepper and white pepper (Piper nigrum L.), rosemary (Rosmarinus officinalis L.), sage (Salvia officinalis L.) and thyme (Thymus vulgaris L.). Homogeneity, origin, and chemotypes of the investigated lots of each herb/spice were defined by fingerprinting, through statistical elaboration with principal component analysis (PCA). Characterizing aromatic markers were directly quantified on the solid matrix through multiple headspace extraction-HS-SPME (MHS-SPME). Reliable results were obtained with both separative and non-separative methods (where the latter were applicable); the two were in full agreement, RSD% ranging from 1.8 to 7.7% for eugenol in cloves, 2.2-18.4% for carvacrol+thymol in thyme, and 3.1-16.8% for thujones in sage., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Comprehensive two-dimensional gas chromatography (GC×GC) coupled with Mass Spectrometry (MS) is one of today's most powerful analytical platforms for detailed analysis of medium-to-high complexity samples. The column set usually consists of a long, conventional-inner-diameter first dimension ((1)D) (typically 15-30m long, 0.32-0.25mm dc), and a short, narrow-bore second dimension ((2)D) column (typically 0.5-2m, 0.1mm dc) where separation is run in a few seconds. However, when thermal modulation is used, since the columns of a set are coupled in series, a flow mismatch occurs between the two dimensions, making it impossible to operate simultaneously at optimized flow conditions. Further, short narrow-bore capillaries can easily be overloaded, because of their lower loadability, limiting the effectiveness of (2)D separation. In this study, improved gas linear velocities in both chromatographic dimensions were achieved by coupling the (1)D column with two parallel (2)D columns, having identical inner diameter, stationary phase chemistry, and film thickness. In turn, these were connected to two detectors: a fast quadrupole Mass Spectrometer (MS) and a Flame Ionization Detector (FID). Different configurations were tested and performances compared to a conventional set-up; experimental results on two model mixtures (n-alkanes and fourteen medium-to-high polarity volatiles of interest in the flavor and fragrance field) and on the essential oil of Artemisia umbelliformis Lam., show the system provides consistent results, in terms of analyte identification (reliability of spectra and MS matching) and quantitation, also affording an internal cross-validation of quantitation accuracy., (Copyright © 2014 Elsevier B.V. All rights reserved.)

This study reports and critically discusses the results of a systematic investigation on the effectiveness of different and complementary sampling approaches, based on either sorption and adsorption, treated as a further dimension of a two-dimensional comprehensive gas chromatography-mass spectrometry analytical platform for sensomics. The focus is on the potentials of a group of high concentration capacity (HCC) sample preparation (Solid Phase Microextraction, SPME, Stir Bar Sorptive Extraction, SBSE and Headspace Sorptive Extraction, HSSE) and Dynamic Headspace (D-HS) techniques investigated to provide information useful for fingerprinting and profiling studies of food aroma. Volatiles and semi-volatiles contributing to define whole and nonfat dry milk aroma have been successfully characterized thanks to the combination of effective and selective sampling by HCC and D-HS techniques, high separation and detection power of GC×GC-MS and suitable data elaboration (i.e., Comprehensive Template Matching Fingerprinting - CTMF). Out of the sample preparation techniques investigated, HSSE and SBSE have shown to be really effective for sensomics studies because of their high concentration factors, providing highly representative profiles as well as analyte recovery suitable for GC-Olfactometry even with high odor threshold (OT) markers or potent odorants in sub-trace amounts., (Copyright © 2013 Elsevier B.V. All rights reserved.)

The study proposes an investigation strategy that simultaneously provides detailed profiling and quantitative fingerprinting of food volatiles, through a "comprehensive" analytical platform that includes sample preparation by Headspace Solid Phase Microextraction (HS-SPME), separation by two-dimensional comprehensive gas chromatography coupled with mass spectrometry detection (GC×GC-MS) and data processing using advanced fingerprinting approaches. Experiments were carried out on roasted hazelnuts and on Gianduja pastes (sugar, vegetable oil, hazelnuts, cocoa, nonfat dried milk, vanilla flavorings) and demonstrated that the information potential of each analysis can better be exploited if suitable quantitation methods are applied. Quantitation approaches through Multiple Headspace Extraction and Standard Addition were compared in terms of performance parameters (linearity, precision, accuracy, Limit of Detection and Limit of Quantitation) under headspace linearity conditions. The results on 19 key analytes, potent odorants, and technological markers, and more than 300 fingerprint components, were used for further processing to obtain information concerning the effect of the matrix on volatile release, and to produce an informative chemical blueprint for use in sensomics and flavoromics. The importance of quantitation approaches in headspace analysis of solid matrices of complex composition, and the advantages of MHE, are also critically discussed., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Ionic liquids (ILs) are of great interest as moderately polar to polar stationary phases for GC, because their selectivity differs markedly from that of conventionally used phases. In the flavor, fragrance and essential oil fields, analysts often deal with complex mixtures of compounds having similar structural and physical characteristics (e.g., mono- and sesquiterpenoids), therefore requiring an interactive combination between chromatographic and mass spectral data for correct identification. New GC stationary phases with different selectivity must therefore be continually tested. Performance and evolution over time of commercially available IL columns versus those commonly used in these fields are here evaluated, mainly in view of their routine use. Chromatographic and separative properties (efficiency, separation capability, inertness and/or activity) of commercially available IL columns were compared to those of columns coated with 5% phenyl-95% methylpolysiloxane, 14% cyanopropyl-86% polysiloxane, and polyethylene glycol, on different complexity samples, including standard mixtures of volatile suspected allergens and pesticides, and cornmint and vetiver essential oils. The results show that IL columns can successfully be used for a wide range of applications characteristic of these fields, mainly because of their unusual selectivity, in particular when separations based on functional groups are required. Moreover, the latest generation of IL columns (IL61 and IL60) presents chromatographic performance comparable to or only slightly lower than that of the conventional columns routinely used in these fields., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Stir Bar Sorptive Extraction (SBSE) is a solventless sampling technique first introduced to extract organic analytes from aqueous samples, in the following applied to headspace sampling (HeadSpace Sorptive Extraction - HSSE). In SBSE and HSSE, analytes are sorbed onto a thick film of polydimethylsiloxane (PDMS) coating a glass-coated magnet. However, PDMS is apolar and not highly effective in recovering polar analytes (i.e. with logK(o/w) below 2), making difficult their sampling in complex matrices. A new generation of medium-to-high polarity polymeric coatings for twisters i.e. polyethyleneglycol-modified silicone (EG) and polyacrylate/polyethyleneglycol (PA) has recently been introduced to overcome this limit. In this study, EG and PA twisters have been applied to SBSE and HSSE of a number of dedicated standard mixtures and real-world samples of vegetable origin to evaluate their capability to increase recovery of medium to highly polar analytes. The results obtained, expressed as percent concentration factor (CF%) versus PDMS twisters taken as reference, showed that analyte logK(o/w) is a key-factor driving the choice of the most effective coating. The new twisters showed to be successful for both SBSE and HSSE, although to a different extent. EG twisters gave high recoveries with analytes over a wide range of polarities and in particular with logK(o/w) below 2 and/or containing hydroxyl or carboxylic functional groups independently on their logK(o/w). On the other hand, PA twisters were selectively effective for highly polar compounds with logK(o/w) below 1., (Copyright © 2012 Elsevier B.V. All rights reserved.)

The study compares standard addition (SA), stable isotope dilution assay (SIDA) and multiple headspace extraction (MHE) as methods to quantify furan and 2-methyl-furan in roasted coffee with HS-SPME-GC-MS, using CAR-PDMS as fibre coating, d(4)-furan as internal standard and in-fibre internal standardization with n-undecane to check the fibre reliability. The results on about 150 samples calculated with the three quantitation approaches were all very satisfactory, with coefficient of variation (CV) versus the U.S. Food and Drug Administration (FDA) method, taken as reference, almost always below the arbitrarily-fixed limit of 15%. Furan was detected in the 1-5 ppm range, 2-methyl-furan in the 4-20 ppm range. Moreover, experimental exponential slopes (Q) and linearity (r) of both furan and 2-methyl-furan MHE regression equation on 50 samples were very similar thus making possible to use the same average Q value for all samples of the investigated set and their quantitation with a single determination. This makes this approach very rapid and competitive in-time with SA and SIDA. A non-separative method (HS-SPME-MS) was also developed in view of possible application on-line monitoring of furan and 2-methyl-furan in a pilot-plant with the aim of optimizing the roasting process to reduce these compounds to a minimum. Sampling times of 20 and 5 min were tested, the latter enabling total analysis time to be reduced to about 9 min. The results on 105 samples with both SIDA and MHE approaches were again highly satisfactory most of the samples giving a CV% versus the conventional methods below 20%. In this case too average Q values for both furan and 2-methyl-furan were used for MHE. The separative method presented very good repeatability (RSD% always below 10%) and intermediate precision over three months (RSD% always below 15%); performance were similar for the non-separative method, with repeatability (RSD%) always below 12% and intermediate precision over three months (RSD%) always below 15%. The sensitivity of both separative and non-separative methods was also very good, LOD and LOQ being in the ppb range for both furan and 2-methyl-furan, i.e. well below the amounts present in the roasted coffee samples., (© 2010 Elsevier B.V. All rights reserved.)

Asymmetrically substituted 6(I-VII)-O-t-butyldimethylsilyl(TBDMS)-3(I-VII)-O-ethyl-2(I-VII)-O-methyl-beta-cyclodextrin (MeEt-CD) and 6(I-VII)-O-TBDMS-2(I-VII)-O-ethyl-3(I-VII)-O-methyl-beta-cyclodextrin (EtMe-CD) were synthesised to evaluate the role of the substitution pattern in positions 2 and 3 on the enantioselectivity, in particular in view of their application to routine analysis in fast enantioselective gas chromatography (Es-GC). The chromatographic properties and enantioselectivities of the new derivatives were tested by separating the enantiomers of a series of medium-to-high volatility racemates in the flavour and fragrance field, and compared to those of the corresponding symmetrically substituted 6(I-VII)-O-TBDMS-2(I-VII),3(I-VII)-O-methyl-beta-CD (MeMe-CD) and 6(I-VII)-O-TBDMS-2(I-VII),3(I-VII)-O-ethyl-beta-CD (EtEt-CD), and were then applied to analysis of real-world essential oil (e.o.) samples. A new synthetic process including the sonochemical approach to obtain synthetic reproducibility and significant yields of the per-substituted derivatives with acceptable reaction times was developed. The results show that asymmetrically substituted methyl/ethyl CDs compared to the methyl or ethyl symmetrical derivatives in general provide better enantioselectivity in terms of both enantiomer resolution and number of separated chiral compounds, and show how the substitution pattern in positions 2 and 3 of the CD ring can influence the separation. Moreover, these new CD derivatives with better enantioselectivity are also shown to be very useful in routine analysis for the exhaustive control of samples containing several chiral characterizing markers in a single run., (Copyright 2009 Elsevier B.V. All rights reserved.)

The analysis of complex real-world samples of vegetable origin requires rapid and accurate routine methods, enabling laboratories to increase sample throughput and productivity while reducing analysis costs. This study examines shortening enantioselective-GC (ES-GC) analysis time following the approaches used in fast GC. ES-GC separations are due to a weak enantiomer-CD host-guest interaction and the separation is thermodynamically driven and strongly influenced by temperature. As a consequence, fast temperature rates can interfere with enantiomeric discrimination; thus the use of short and/or narrow bore columns is a possible approach to speeding-up ES-GC analyses. The performance of ES-GC with a conventional inner diameter (I.D.) column (25 m length x 0.25 mm I.D., 0.15 microm and 0.25 microm d(f)) coated with 30% of 2,3-di-O-ethyl-6-O-tert-butyldimethylsilyl-beta-cyclodextrin in PS-086 is compared to those of conventional I.D. short column (5m length x 0.25 mm I.D., 0.15 microm d(f)) and of different length narrow bore columns (1, 2, 5 and 10 m long x 0.10 mm I.D., 0.10 microm d(f)) in analysing racemate standards of pesticides and in the flavour and fragrance field and real-world-samples. Short conventional I.D. columns gave shorter analysis time and comparable or lower resolutions with the racemate standards, depending mainly on analyte volatility. Narrow-bore columns were tested under different analysis conditions; they provided shorter analysis time and resolutions comparable to those of conventional I.D. ES columns. The narrow-bore columns offering the most effective compromise between separation efficiency and analysis time are the 5 and 2m columns; in combination with mass spectrometry as detector, applied to lavender and bergamot essential oil analyses, these reduced analysis time by a factor of at least three while separation of chiral markers remained unaltered.

This study describes the development of a gas chromatography-mass spectrometry (GC-MS) library to identify optically active compounds in the flavour and fragrance field using enantioselective GC with cyclodextrin derivatives (CDs) as chiral selectors in combination with MS. The library operates on the "interactive" combination of linear retention indices (I(T) values) in parallel to MS spectra, so as to identify enantiomers reliably and to measure EE and/or ER unequivocally. Since MS is not a selective probe to discriminate optical isomers, mass spectra (or diagnostic ions in SIM mode) are used to locate the enantiomer(s) in the chromatogram, and I(T) values to identify it(them) safely and reliably in particular in complex mixtures. The library has been built up through the following steps: Some applications of the library are also reported. (a) Selection of CD derivatives able to cover a wide range of racemate separations. Four cyclodextrin derivatives were used: 2,6-di-O-methyl-3-O-pentyl-beta-CD, 2,3-di-O-methyl-6-O-tert-butyldimethylsilyl-beta-CD, 2,3-di-O-ethyl-6-AO-tert-butyldimethylsilyl-beta-CD, and 2,3-di-O-acetyl-6-O-tert-butyldimethylsilyl-beta-CD. (b) Determination of the analytes' I(T) values and evaluation of their stability and reliability at both intra- and inter-laboratory level. (c) Determination of the range within which the I(T) of an enantiomer has to be correctly identified, i.e. determination of a common retention index allowance (RIA). (d) Construction of the library, at the moment comprising the enantiomers of 134 racemates. A record has been attributed to each enantiomer including I(T) values determined on the four CD coated columns, mass spectrum, IUPAC chemical names, CAS numbers, molecular weight, and, when separated, racemate enantiomer resolution on the CD investigated. Some applications of the library are also reported.

The evolution of vapour phase sampling of the volatile fraction of vegetable matrices, or of products directly related to them, over the period 1996-2007 is reviewed. High concentration capacity headspace (HCC-HS) and dynamic headspace (D-HS) techniques, that is headspace sampling approaches where the analytes in the vapour phase are concentrated into a sorbent, an adsorbent or a solvent, are considered. Advantages, disadvantages and applications to the vegetable field of several successful techniques based on these approaches are critically presented, including in-tube sorptive extraction (INCAT, HS-SPDE), headspace sorptive extraction (HSSE), solid-phase aroma concentrate extraction (SPACE), large surface area HCC-HS sampling (MESI, MME, HS-STE), headspace liquid-phase microextraction (HS-LPME) and dynamic headspace samplings (D-HS). The developments necessary to overcome some of the limits of the above approaches and techniques are also discussed in view of their application to new fields.

Dual phase twisters (DP twisters), consisting of a polydimethylsiloxane (PDMS) outer coating and a second complementary (ad)sorbent as inner packing, have recently been shown to extend the applicability of headspace sorptive extraction (HSSE). In comparison to HSSE using PDMS only, the recovery of analytes from the headspace of a solid or liquid matrix is increased by combining the concentration capabilities of two sampling materials operating on different mechanisms (sorption and adsorption). This study compares the performance of DP twisters consisting of different PDMS outer coatings and different packing materials, including Tenax GC, a bisphenol-PDMS copolymer, Carbopack coated with 5% of Carbowax and beta-cyclodextrin, for the analysis of the headspace of roasted Arabica coffee, dried sage leaves and an aqueous test mixture containing compounds with different water solubility, acidity, polarity and volatility as test samples. In general, DP twisters showed a higher concentration capability than the corresponding conventional PDMS twisters for the analytes considered. The highest recoveries were obtained with DP twisters consisting of 0.2mm thick PDMS coating combined with Tenax GC, a bisphenol-PDMS copolymer and Carbopack coated with 5% of Carbowax as inner adsorption phase.

This article evaluates the HS-SPME recovery repeatability, intermediate precision and their performance over time when applied to HS-SPME sampling for quality control of medicinal and aromatic plants. Experiments were carried out on two sets of fibres coated with two different coatings and belonging to different lots (i.e 100 microm polydimethylsyloxane (PDMS) and Carboxen/divinylbenzene/PDMS 50/30 microm, l: 1 cm (CAR/DVB/PDMS)) and on chamomile (Matricaria chamomilla L.), sage (Salvia lavandulifolia Vahl.) and a standard solution containing 3-hexanol, isoamyl acetate, 1,8-cineole and menthol in diisobutyl phthalate. The performance of each set of fibres was evaluated by determining a group of complementary statistical parameters including: (i) repeatability of the absolute areas of each marker from each matrix with each fibre; (ii) intra-fibre repeatability of the total absolute areas of the markers of each matrix obtained with each fibre of each set; (iii) inter-fibre intermediate precision of the total absolute areas of the markers of each matrix obtained with all fibres of each set; and (iv) analysis of variance by one-way ANOVA with Fisher and Tukey tests. The influence of the number of analyses on fibre effectiveness (fibre life-time) was studied by linear regression analysis (LRA). The results proved that HS-SPME can successfully be used for routine control analysis of aromatic ad medicinal plants since both types of fibres showed good repeatability and intermediate precision of analytes recovery and consistency over time. Unlike data previously reported by other authors, CAR/DVB/PDMS coated fibres gave better results than those coated with PDMS. The fibre-life seemed mainly to be influenced by the number and conditions of samplings and nature of the matrix investigated.

The study evaluates the influence of selectivity tuning of the stationary phase of the second dimension on the orthogonality of a comprehensive two-dimensional gas chromatography (GC x GC) system. Two different sets of columns, providing independent and semi-independent separation mechanisms were used. The first consisted of a first dimension separating analytes on a volatility basis (i.e. a non-polar polydimethylsiloxane (OV1) column) combined with a second dimension separating by polarity, using columns coated with 100% polyethylene glycol (CW20M), CW20M/OV1 mixtures in ratios of 25-75%, and polydimethylsiloxane, 7% phenyl, 7% cyanopropyl (OV1701). The second set consisted of a first dimension separating analytes on a polarity basis (100% CW20M column) combined with a second dimension separating by volatility, consisting of columns coated with 100% OV1, OV1/CW20M mixtures in ratios of 25-75%, and 100% OV1701. Medium-complexity mixtures of natural origin (i.e. peppermint essential oil and a standard mixture of suspected allergens) consisting of components in a relatively limited range of molecular weights (MW) and volatilities, but belonging to different classes of compounds in a wide range of polarity (mono- and sesquiterpenoids, hydrocarbons and oxygenated compounds) were analysed with the above sets of columns. Different approaches were used to evaluate peak spreading on the GC x GC separation plane and degree of orthogonality of the column sets, namely: (1) a Factor Analysis (FA) approach, estimating the correlation coefficients and spreading angles of the sample components in the two-dimensional chromatographic plane; (2) an Informational Theory (IT) approach, based on determining a group of parameters including: informational entropy, % synentropy and similarity (H); and (3) an approach based on estimating the amount of separation space used, i.e. a practical parameter that directly refers to the experimental separation plane of the GC x GC chromatogram. Results showed that peak spreading in the chromatographic plane, when CW20M and OV1 are combined in different ratios, can be predicted from retention mechanisms, and that the degree of orthogonality measured with different approaches, is consistent with the divergent nature, in terms of polarity of the stationary phases combined in the GC x GC system.

The fields of applicability of headspace sorptive extraction (HSSE) and stir bar sorptive extraction (SBSE) using polydimethylsiloxane (PDMS) as sorbent have been intensively discussed and widely described. One of the limits of sorptive extraction is that PDMS (i.e. an apolar phase) is the only polymer currently in use making it difficult to recover polar analytes from complex or multi-ingredient matrices and those with very volatile components (C1-C4 analytes). Dual-phase twisters are here introduced as new tools for HSSE and SBSE to overcome the above limits. Dual-phase twisters combine the concentration capabilities of two or more sampling materials operating in different ways (in this case sorption and adsorption). The new twisters consist of a short PDMS tube the ends of which are closed with two magnetic stoppers, thus creating an inner cavity that can be packed with different types of adsorbents like activated carbons. The concentration capability of dual-phase twisters was evaluated by using them for the HSSE and SBSE sampling of a number of matrices in the vegetable, food and environmental fields. The contributions made by different carbons to recovery, repeatability and intermediate precision were also investigated.

This study evaluates concentration capability of headspace sorptive extraction (HSSE) and the influence of sampling conditions on HSSE recovery of an analyte. A standard mixture in water of six high-to-medium volatility analytes (isobutyl methyl ketone, 3-hexanol, isoamyl acetate, 1,8-cineole, linalool and carvone) was used to sample the headspace by HSSE with stir bars coated with different polydimethylsiloxane (PDMS) volumes (20, 40, 55 and 110 microL, respectively), headspace vial volumes (8, 21.2, 40, 250 and 1000 mL), sampling temperatures (25, 50 and 75 degrees C) and sampling times (30, 60 and 120 min, and 4, 8 and 16 h). The concentration factors (CFs) of HSSE versus static headspace (S-HS) were also determined. Analytes sampled by the PDMS stir bars were recovered by thermal desorption (TDS) and analysed by capillary GC-MS. This study demonstrates how analyte recovery depends on its physico-chemical characteristics and affinity for PDMS (octanol-water partition coefficients), sampling temperatures (50 degrees C) and times (60 min), the volumes of headspace (40 mL) and of PDMS (in particular, for high volatility analytes). HSSE is also shown to be very effective for trace analysis. The HSSE CFs calculated versus S-HS with a 1000 mL headspace volumes at 25 degrees C during 4 h sampling ranged between 10(3) and 10(4) times for all analytes investigated while the limits of quantitation determined under the same conditions were in the nmol/L range.

High concentration capacity headspace techniques (headspace solid-phase microextraction (HS-SPME) and headspace sorptive extraction (HSSE)) are a bridge between static and dynamic headspace, since they give high concentration factors as does dynamic headspace (D-HS), and are as easy to apply and as reproducible as static headspace (S-HS). In 2000, Chromtech (Idstein, Germany) introduced an inside-needle technique for vapour and liquid sampling, solid-phase dynamic extraction (SPDE), also known as "the magic needle". In SPDE, analytes are concentrated on a 50 microm film of polydimethylsiloxane (PDMS) and activated carbon (10%) coated onto the inside wall of the stainless steel needle (5 cm) of a 2.5 ml gas tight syringe. When SPDE is used for headspace sampling (HS-SPDE), a fixed volume of the headspace of the sample under investigation is sucked up an appropriate number of times with the gas tight syringe and an analyte amount suitable for a reliable GC or GC-MS analysis accumulates in the polymer coating the needle wall. This article describes the preliminary results of both a study on the optimisation of sampling parameters conditioning HS-SPDE recovery, through the analysis of a standard mixture of highly volatile compounds (beta-pinene, isoamyl acetate and linalool) and of the HS-SPDE-GC-MS analyses of aromatic plants and food matrices. This study shows that HS-SPDE is a successful technique for HS-sampling with high concentration capability, good repeatability and intermediate precision, also when it is compared to HS-SPME.