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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 ]), 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 + ][NTf 2 ] IL and 180 °C for [P - ]), 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 - ] 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 + ] IL columns, and 200 °C for So-Im and 220° for Ha-Im in columns coated with the [P - ] 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.)

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 - ] 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 - ] 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.)

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.)

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.)

A simple and rapid ionic liquid (IL)-based in situ dispersive liquid-liquid microextraction (DLLME) method was developed and coupled to headspace gas chromatography (HS-GC) employing electron capture (ECD) and mass spectrometry (MS) detection for the analysis of polychlorinated biphenyls (PCBs) and acrylamide at trace levels from milk and coffee samples. The chemical structures of the halide-based ILs were tailored by introducing various functional groups to the cations to evaluate the effect of different structural features on the extraction efficiency of the target analytes. Extraction parameters including the molar ratio of IL to metathesis reagent and IL mass were optimized. The effects of HS oven temperature and the HS sample vial volume on the analyte response were also evaluated. The optimized in situ DLLME method exhibited good analytical precision, good linearity, and provided detection limits down to the low ppt level for PCBs and the low ppb level for acrylamide in aqueous samples. The matrix-compatibility of the developed method was also established by quantifying acrylamide in brewed coffee samples. This method is much simpler and faster compared to previously reported GC-MS methods using solid-phase microextraction (SPME) for the extraction/preconcentration of PCBs and acrylamide from complex food samples., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Nine crosslinked polymeric ionic liquid (PIL)-based SPME sorbent coatings were designed and screened in this study for the trace level determination of acrylamide in brewed coffee and coffee powder using gas chromatography-mass spectrometry (GC-MS). The structure of the ionic liquid (IL) monomer was tailored by introducing different functional groups to the cation and the nature of the IL crosslinker was designed by altering both the structure of the cation as well as counteranions. The extraction efficiency of the new PIL coatings towards acrylamide was investigated and compared to a previously reported PIL sorbent coating. All PIL fibers exhibited excellent analytical precision and linearity. The PIL fiber coating consisting of 50% 1,12-di(3-vinylbenzylbenzimidazolium)dodecane dibis[(trifluoromethyl)sulfonyl]imide as IL crosslinker in 1-vinyl-3-(10-hydroxydecyl)imidazolium bis[(trifluoromethyl)sulfonyl]imide IL monomer resulted in a limit of quantitation of 0.5μgL(-1) with in-solution SPME sampling. The hydroxyl moiety appended to the IL cation was observed to significantly increase the sensitivity of the PIL coating toward acrylamide. The quantitation of acrylamide in brewed coffee and coffee powder was performed using the different PIL-based fibers by the method of standard addition after a quenching reaction using ninhydrin to inhibit the formation of interfering acrylamide in the GC inlet, mainly by asparagine thermal degradation. Excellent repeatability with relative standard deviations below 10% were obtained on the real coffee samples and the structure of the coatings appeared intact by scanning electron microscopy after coffee sampling proving the matrix-compatibility of the PIL sorbent coatings., (Copyright © 2016 Elsevier B.V. All rights reserved.)

This study describes a simple and rapid sampling method employing a polymeric ionic liquid (PIL) sorbent coating in direct immersion solid-phase microextraction (SPME) for the trace-level analysis of acrylamide in brewed coffee and coffee powder. The crosslinked PIL sorbent coating demonstrated superior sensitivity in the extraction of acrylamide compared to all commercially available SPME coatings. A spin coating method was developed to evenly distribute the PIL coating on the SPME support and reproducibly produce fibers with a large film thickness. Ninhydrin was employed as a quenching reagent during extraction to inhibit the production of interfering acrylamide. The PIL fiber produced a limit of quantitation for acrylamide of 10μgL(-1) and achieved comparable results to the ISO method in the analysis of six coffee powder samples., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Within a project exploring the application of lab-on-chip GC to in-field analysis of the plant volatile fraction, this study evaluated the performance of a set of planar columns (also known as microchannels, MEMS columns, or microfabricated columns) of different dimensions installed in a conventional GC unit. Circular double-spiral-shaped-channel planar columns with different square/rectangular sections up to 2m long were applied to the analysis of both essential oils and headspace samples of a group of medicinal and aromatic plants (chamomile, peppermint, sage, rosemary, lavender and bergamot) and of standard mixtures of related compounds; the results were compared to those obtained with reference narrow-bore columns (l:5m, dc:0.1mm, df:0.1 μm). The above essential oils and headspaces were first analyzed quali-and quantitatively with planar columns statically coated with conventional stationary phases (5%-phenyl-polymethylsiloxane and auto-bondable nitroterephthalic-acid-modified polyethylene glycol), and then submitted to chiral recognition of their diagnostic markers, by enantioselective GC with a planar columns coated with a cyclodextrin derivative (30% 6(I-VII)-O-TBDMS-3(I-VII)-O-ethyl-2(I-VII)-O-ethyl-β-cyclodextrin in PS-086). Column characteristics and analysis conditions were first optimized to obtain suitable retention and efficiency for the samples investigated. The planar columns tested showed performances close to the reference conventional narrow-bore columns, with theoretical plate numbers per meter (N/m) ranging from 6100 to 7200 for those coated with the conventional stationary phases, and above 5600 for those with the chiral selector., (Copyright © 2015 Elsevier B.V. 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.)

Two thermodynamic parameters - entropy (ΔS) and enthalpy (ΔH) - ideally describe the thermodynamics of how the retention of an analyte in a stationary phase depends on the temperature. The paper examines the conversion of an analyte's entropy and enthalpy into chromatographically more meaningful equivalents: its characteristic temperature and thermal constant. Thermodynamic and characteristic parameters of 29 enantiomer pairs of chiral analytes, analysed with four cyclodextrin stationary phases, were measured, tabulated, and investigated. The distribution of all newly-measured characteristic parameters was found to be similar to the known distribution of these parameters for some 12,000 pairs of analytes, analysed with several stationary phases. This similarity suggests that the peak widths of the investigated analytes in temperature-programmed analyses should be generally the same as the peak widths of other similarly retained analytes. It also suggests that the previously-known optimum general heating rate (about 10 ºC/tM, i.e. 10°C per hold-up time) is also the general optimum for temperature-programmed enantioselective GC analyses with cyclodextrins as stationary phases. The optimum general heating rate corresponds to the shortest analysis time for a predetermined peak capacity. It can substantially differ from specific optima corresponding to the best separation of particular peak pairs. Theoretical prediction of these specific optima requires more complex non-ideal thermodynamic models, and more accurate measurement of the parameters involved-these topics that are outside the scope of this report., (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.)

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.)

The study aimed to find the best trade-off between separation of the most critical peak pair and analysis time, in enantioselective GC-FID and GC-MS analysis of lavender essential oil, using the GC method-translation approach. Analysis conditions were first optimized for conventional 25 m x 0.25 mm inner diameter (dc) column coated with 6(I-VII)-O-tert-butyldimethylsilyl-2(I-VII)-3(I-VII)-O-ethyl-beta-cyclodextrin (CD) as chiral stationary phase (CSP) diluted at 30% in PS086 (polymethylphenylpolysiloxane, 15% phenyl), starting from routine analysis. The optimal multi-rate temperature program for a pre-set column pressure was determined and then used to find the pressures producing the efficiency-optimized flow (EOF) and speed-optimized flow (SOF). This method was transferred to a shorter narrow-bore (NB) column (11 m x 0.10 mm) using method-translation software, keeping peak elution order and separation. Optimization of the enantioselective GC method with the translation approach markedly reduced the analysis time of the lavender essential oil, from about 87 min with the routine method to 40 min with an optimal multi-rate temperature program and initial flow with a conventional inner diameter column, and to 15 min with FID as detector or 13.5 min with MS with a corresponding narrow-bore column, while keeping enantiomer separation and efficiency., (Copyright 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.