Headspace Solid-phase Microextraction In Combination Research Articles

Characterization and geographical discrimination of saffron from Greece, Spain, Iran, and Morocco based on volatile and bioactivity markers, using chemometrics

In the present study saffron samples from Greece, Spain, Iran, and Morocco, collected during harvesting years 2005–2014, were characterized and classified according to geographical origin using volatile compounds and selected bioactivity parameters. The volatile compounds of saffron were semi-quantified using headspace solid-phase microextraction in combination with gas chromatography/mass spectrometry. Bioactivity parameters such as total phenolic content (TPC), radical scavenging activity (%RSA), and ferric reducing antioxidant power (FRAP) were determined using spectrophotometric assays. Results showed that significant variations (P < 0.05) in the volatile content, TPC, and antioxidant activity were observed according to geographical origin of saffron. Certain volatile compounds and bioactivity parameters were also affected by harvesting year (P < 0.05). Finally, strong positive Pearson’s correlations were obtained for TPC and %RSA (r = 0.90), TPC and FRAP (r = 0.90), highlighting that the methanolic fraction of saffron is rich in phytochemicals, contributing thus, to its overall antioxidant properties. The application of LDA to above combined parameters determined, enabled the correct geographical discrimination of saffron, resulting in a correct prediction rate of 95.5%. The use of a larger number of saffron samples will further validate present results.

Determination of Sesquiterpenes in Wines by HS-SPME Coupled with GC-MS

The sesquiterpene compounds present in red wines were characterized and quantified by Headspace Solid-Phase Microextraction in combination with Gas Chromatography–Mass Spectrometry (HS-SPME-GC-MS). Sixteen sesquiterpenes were identified, mainly hydrocarbons but also derived oxygenated compounds. Sesquiterpenes were acyclic, monocyclic, byciclic and tryciclic. Sesquiterpenes were detected in SIM (selected ion monitoring) mode using their characteristics ions. All the sesquiterpenes were identified by mass spectral data, linear retention indices (LRI), literature data and injection of standards where available. Quantitative results were obtained using the method of standard additions. The method showed an average LOD = 0.05 µg L−1 and LOQ = 0.15 µg L−1. The monocyclic sesquiterpene with the germacrene skeleton, Germacrene D and the bicyclic sesquiterpene with the muurolane skeleton, α-muurolene were present in all the wine samples analysed. Syrah wines were the samples richest in sesquiterpenes in agreement with their typical spicy and woody notes. The results evidenced the possibility to use sesquiterpenes for wine authenticity and traceability.

Volatile profile of Spanish Cistus plants as sources of antimicrobials for industrial applications

Cistus is a plant genus traditionally used in folk medicine as remedy for several microbial disorders and infections. The abundance of Cistus spp. in the Iberian Peninsula together with their ability to renew after wildfire contribute to their profitability as suppliers of functional ingredients. The aim of this study was to provide a comprehensive characterization of the volatile profile of different Cistus plants grown in Spain: Cistus ladanifer L., Cistus albidus L., Cistus salviifolius L., and Cistus clusii Dunal (the latter has not been studied before). A system combining headspace solid-phase microextraction and gas chromatography coupled to mass spectrometry (HS-SPME-GC–MS) was implemented; thereby, the volatile compounds were extracted and analyzed in a fast, reliable and environment-friendly way. A total of 111 volatile compounds were identified, 28 of which were reported in Cistus for the first time. The most abundant components of the samples (mono and sesquiterpenes) have been previously reported as potent antimicrobial agents. Therefore, this work reveals the potential use of the Cistus spp. studied as natural sources of antimicrobial compounds for industrial production of cosmeceuticals, among other applications.

A powerful methodological approach combining headspace solid phase microextraction, mass spectrometry and multivariate analysis for profiling the volatile metabolomic pattern of beer starting raw materials

The volatile metabolomic patterns from different raw materials commonly used in beer production, namely barley, corn and hop-derived products – such as hop pellets, hop essential oil from Saaz variety and tetra-hydro isomerized hop extract (tetra hop), were established using a suitable analytical procedure based on dynamic headspace solid-phase microextraction (HS-SPME) followed by thermal desorption gas chromatography–quadrupole mass spectrometry detection (GC–qMS). Some SPME extraction parameters were optimized. The best results, in terms of maximum signal recorded and number of isolated metabolites, were obtained with a 50/30μm DVB/CAR/PDMS coating fiber at 40°C for 30min. A set of 152 volatile metabolites comprising ketones (27), sesquiterpenes (26), monoterpenes (19), aliphatic esters (19), higher alcohols (15), aldehydes (11), furan compounds (11), aliphatic fatty acids (9), aliphatic hydrocarbons (8), sulphur compounds (5) and nitrogen compounds (2) were positively identified. Each raw material showed a specific volatile metabolomic profile. Monoterpenes in hop essential oil and corn, sesquiterpenes in hop pellets, ketones in tetra hop and aldehydes and sulphur compounds in barley were the predominant chemical families in the targeted beer raw materials. β-Myrcene was the most dominant volatile metabolite in hop essential oil, hop pellets and corn samples while, in barley, the predominant volatile metabolites were dimethyl sulphide and 3-methylbutanal and, in tetra hop, 6-methyl-2-pentanone and 4-methyl-2-pentanone. Principal component analysis (PCA) showed natural sample grouping among beer raw materials.

Characterization of Novel Single-Variety Oxygenated Sesquiterpenoid Hop Oil Fractions via Headspace Solid-Phase Microextraction and Gas Chromatography–Mass Spectrometry/Olfactometry

The volatile composition of novel varietal oxygenated sesquiterpenoid hop oil fractions ("spicy essences") was characterized by headspace solid-phase microextraction in combination with gas chromatography-mass spectrometry. Oxygenated sesquiterpenes represent the major chemical compound class, accounting for at least 65% of the total volatile fraction. In addition to oxygenated sesquiterpenes, spicy hop essences consist of several ketones, sesquiterpene and monoterpene hydrocarbons, and a relatively high number of unidentified compounds. On the basis of their relative composition, spicy hop essences can be fully differentiated according to their varietal origin. Multidimensional gas chromatography in combination with time-of-flight mass spectrometry on spicy hop essence cv. Spalter Select further demonstrated the enormous complexity of this particular hop oil fraction. The aromagram obtained via gas chromatography-olfactometry comprised nine odor-active regions described in terms of "citrus", "green", "haylike", "earthy", "woody", and "spicy". 2-Undecanone, 2-tridecanone, γ-cadinene, α-calacorene, calarene, humuladienone, caryolan-1-ol, caryophyllene oxide enantiomers, and humulene epoxide II are tentatively identified in the odor-active zones.

Accurate Method for the Determination of Intramolecular 13C Isotope Composition of Ethanol from Aqueous Solutions

A new method, combining headspace solid phase microextraction (HS-SPME) with an online pyrolysis system coupled with isotope ratio mass spectrometry (IRMS), is developed for the determination of the intramolecular (13)C isotope composition of ethanol in aqueous solutions. The δ(13)C values of the pyrolytic fragments (CO, CH4, C2H4) are shown to be highly reproducible (sd <0.4‰). Furthermore, using 14 ethanol samples of known intramolecular isotope distribution, the CO and CH4 fragments are shown to arise solely from the methylene (CH2OH) and methyl (CH3) carbon atom positions of the original ethanol, respectively. Although the different steps (extraction and pyrolysis) fractionate between (12)C and (13)C, the isotopic fractionation is reproducible (sd <0.4‰), allowing correcting factors to be applied in order to back-calculate the original δ(13)CCH2OH and δ(13)CCH3 values of ethanol. The method thus allows the determination of the isotope composition of ethanol at the intramolecular and molecular levels, within a single run and a short experimental time (30 min), and with a very easy sample preparation. The method is then applied to alcoholic beverages to show its potential for authentication purposes.

Fast headspace-enantioselective GC–mass spectrometric-multivariate statistical method for routine authentication of flavoured fruit foods

This study describes a rapid total analysis system (TAS) to detect the authenticity of fruit-flavoured foods and beverages by on-line combining headspace solid phase microextraction (HS-SPME) with enantioselective GC–MS (Es-GC–MS) and statistical multivariate methods (PCA, HCA). Peach, coconut, apricot, raspberry, as fruits mainly characterised by γ- and δ-lactones as chiral markers, strawberry (α-ionone, linalool, nerolidol, ethyl 2-methylbutyrate, 2-methylbutyric acid and γ-lactones) and melon (ethyl 2-methylbutyrate and 2-methylbutanol) were investigated. The system was developed by (a) optimising non-equilibrium HS-SPME sample preparation, (b) speeding-up ES-GC using cyclodextrin derivatives as chiral selectors with conventional and narrow-bore columns and (c) elaborating data by multivariate methods. The resulting TAS affords a reduction of the time needed for the whole analytical process from about 150min to 20–50min (67–87% of the current routine method) depending on matrix, sampling and analysis conditions and Es-GC columns.

The Evaluation of Human Hand Odor Volatiles on Various Textiles: A Comparison Between Contact and Noncontact Sampling Methods*,†

The focus of this study is to compare contact and noncontact human scent collection procedures across an array of textiles (cotton, rayon, polyester, and wool) to determine an optimized collection method for human scent evidence. Six subjects were sampled in triplicate for each textile and collection mode, and the samples were then analyzed through headspace solid-phase micro-extraction in combination with gas chromatography/mass spectrometry (SPME-GC/MS). Contact sampling with cotton material has been shown to be the collection method that yielded the greatest number of volatile compounds and the highest scent mass amounts. Through Spearman rank correlations, it was shown that an individual's scent profile is more reproducible within samples collected on the same textile type than between different materials. Furthermore, contact sampling with cotton fabric demonstrated the greatest reproducibility producing the lowest amount of type I and type II errors with 90.85% of the samples distinguished at the 0.9 match/no match threshold.

Determination of volatile monophenols in beer using acetylation and headspace solid-phase microextraction in combination with gas chromatography and mass spectrometry

Monophenols are widely spread compounds contributing to the flavour of many foods and beverages. They are most likely present in beer, but so far, little is known about their influence on beer flavour. To quantify these monophenols in beer, we optimised a headspace solid-phase microextraction method coupled to gas chromatography–mass spectrometry. To improve their isolation from the beer matrix and their chromatographic properties, the monophenols were acetylated using acetic anhydride and KHCO 3 as derivatising agent and base catalyst, respectively. Derivatisation conditions were optimised with attention for the pH of the reaction medium. Additionally, different parameters affecting extraction efficiency were optimised, including fibre coating, extraction time and temperature and salt addition. Afterwards, we calibrated and validated the method successfully and applied it for the analysis of monophenols in beer samples.

Determination of different recreational drugs in hair by HS-SPME and GC/MS

A simple procedure combining headspace solid-phase microextraction (HS-SPME) and gas chromatography-mass spectrometry (GC/MS) to detect and quantify amphetamines, ketamine, methadone, cocaine, cocaethylene and Delta(9)-tetrahydrocannabinol (THC) in hair is described. This procedure allows, in a single sample, even scant, analysis of drugs requiring different analytical conditions. A hair sample (10 mg) is washed and subjected to acidic hydrolysis. Then the HS-SPME is carried out (10 min at 90 degrees C) for amphetamines, ketamine, methadone, cocaine and cocaethylene. For derivatization of analytes, the fibre is introduced into the headspace of another closed vial containing acetic anhydride. After a chromatographic run, an alkaline hydrolysis for THC analysis is carried out in the same vial containing the hair sample previously used. For adsorption, the solid-phase microextraction needle is inserted into the headspace of the vial and the fibre is exposed for 30 min at 150 degrees C. For derivatization of analytes, the fibre is introduced into the headspace of another closed vial containing N-methyl-N-(trimethylsilyl)trifluoroacetamide. The GC/MS parameters were the same for both chromatographic runs. The linearity was proved to be between 0.01 and 10.00 ng/mg. The repeatability (intra- and interday precision) was below 10% as the coefficient of variation for all compounds. The accuracy, as the relative recovery, was 96.2-103.5% (spiked samples) and 88.6-101.7% (quality control sample). The limit of detection ranged from 0.01 to 0.12 ng/mg, and the limit of quantification ranged from 0.02 to 0.37 ng/mg. Application of the procedure to real hair samples is described. To the best of our knowledge, the proposed procedure combining HS-SPME and GC/MS is the first one be to successfully applied to the simultaneous determination of most of the common recreational drugs, including THC, in a single hair sample.

Optimisation of specialty malt volatile analysis by headspace solid-phase microextraction in combination with gas chromatography and mass spectrometry

The objective of this study was to develop a technique for analysing 14 flavour components, relevant for specialty malts. Therefore, a method was developed for the analysis of these components in dry ground malt using headspace solid-phase microextraction coupled with gas chromatography and mass spectrometry. A procedure was optimised for the optimal amount of sample, fibre selection, extraction temperature and extraction time. Afterwards, the method was calibrated and validated by the quantification of the specialty malt flavour components in a colour, a caramel and a roasted malt.

Determination of carbonyl compounds in beer by derivatisation and headspace solid-phase microextraction in combination with gas chromatography and mass spectrometry

Headspace solid-phase microextraction (SPME) followed by gas chromatography and mass spectrometry was applied for quantification of 41 chemically diverse carbonyl compounds in beer. Therefore, in-solution derivatisation with o-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine (PFBHA) combined with SPME was optimised for fibre selection, PFBHA concentration, extraction temperature and time and ionic strength. Afterwards, the method was calibrated and validated successfully and extraction efficiency was compared to sampling with on-fibre derivatisation. In-solution derivatisation enabled the detection of several compounds that were poorly extracted with on-fibre derivatisation such as 5-hydroxymethylfurfural, acrolein, hydroxyacetone, acetoin, glyoxal and methylglyoxal. Others, especially (E)-2-nonenal, were extracted better with on-fibre derivatisation.

Simultaneous Determination of Some Phenothiazine Derivatives in Human Blood by Headspace Solid-Phase Microextraction and Gas Chromatography with Nitrogen-Phosphorus Detection

Chlorpromazine, levomepromazine, promazine, triflupromazine, and trimeprazine were simultaneously determined in human whole blood and plasma by combining headspace solid-phase microextraction and gas chromatography with nitrogen-phosphorus detection. Extraction efficiency for the phenothiazine derivatives was 0.013-0.117% for both sample types. Regression equations were linear [correlation coefficient (r) = 0.9951-0.9999] within the range 2.5-200 ng/0.5 mL for triflupromazine and trimeprazine, and 6.3-200 ng/0.5 mL for chlorpromazine, levomepromazine, and promazine. The limit of detection for each compound was 0.2-3.9 ng/0.5 mL whole blood and plasma. Intraday and interday coefficients of variation for all phenothiazines in both human samples were commonly < 15 and 20%, respectively. We also report the determination of levomepromazine in human plasma after oral administration.

Optimisation of wort volatile analysis by headspace solid-phase microextraction in combination with gas chromatography and mass spectrometry

The aim of this study was to create a simple, solventless technique without derivatisation in order to analyze a broad range of volatiles in beer wort. A method was developed using headspace solid-phase microextraction coupled with gas chromatography and mass spectrometry. The procedure was optimised by selection of the appropriate fibre and optimisation of extraction temperature, extraction time, and salting-out. The detection limits were well below the actual wort concentrations of the selected volatiles, ranging from 12 ng/l for linalool to 0.53 μg/l for furfural. Moreover, the procedure showed a good linearity and was applied to the analysis of wort samples taken from a wort boiling process in an industrial brewery.

A direct quantitative analysis method for monitoring biogenic volatile organic compounds released from leaves of Pelargonium hortorum in situ

A direct quantitative method is presented that is based upon the use of multiple headspace solid phase microextraction (HS-SPME) to monitor biogenic volatile organic compounds (BVOCs) released from a living leaf of Pelargonium hortorum in situ. Seventeen BVOCs were detected by GC-MS after a single SPME extraction using a CAR/DVB/PDMS fibre. An internal standard was employed to determine the absolute amounts of seven terpenoid compounds released from a P. hortorum leaf. The quantitative analysis was performed over two days, with extraction preformed for 20 min every 3 h. The amount of volatiles extracted varied with the time of day, with two maxima recorded at 14:00 (day 1) and 17:00 (day 2), corresponding to 236 and 277 ng of the seven terpenoids recorded, respectively. These results indicate that multiple HS-SPME in combination with an internal standard is a simple, quick, and quantitative technique for analysising BVOC emissions from a live plant sample.

Headspace solid-phase microextraction in combination with gas chromatography–mass spectrometry for the rapid screening of organophosphorus insecticide residues in strawberries and cherries

A headspace solid-phase microextraction (HS-SPME) method in combination with GC–MS was used for the extraction and quantification of diazinon, fenitrothion, fenthion, parathion ethyl, bromophos methyl, bromophos ethyl and ethion. The method was developed using a 100-μm poly(dimethylsiloxane) fiber. The obtained results showed higher responses of the insecticides after addition of aliquots of water and solvent to the fruit samples. Calibration curves that were constructed for the analytes spiked into strawberry and cherry samples followed linear relationships with good correlation coefficients ( R 2>0.986). Linearity range was between 50 and 500 μg/kg and the precision was found to be lower than 15% when applying the optimized HS-SPME procedure to fruit samples. Limits of detection in both strawberry and cherry samples using GC–MS (selected ion monitoring mode) were below 13 μg/kg. Moreover, the HS-SPME method was applied to the analysis of fruit samples and compared with liquid–liquid extraction. Results obtained in this study were in good agreement with those obtained using liquid–liquid extraction demonstrating that the recommended procedure was a fast, accurate and stable sample pretreatment method obtaining good efficiency for the extraction of organophosporus insecticides from strawberries and cherries.

Rapid differentiation of new apple cultivars by headspace solid-phase microextraction in combination with chemometrical data processing.

The aim of this study was to test a combination of automated headspace solid phase-microextraction gas chromatography (GC) with chemometrical data treatment for the rapid differentiation of enzyme-inactivated homogenates of new apple cultivars. The four cultivars Pinova, Piflora, Renora and Florina are characterized by different volatile patterns. Differences in the contents of volatiles were especially found for butyl acetate, ethyl butanoate, 2-methyl butanol, ethyl acetate and 6-methyl-5-hepten-2-ol. The used sample preparation method for GC coupled with pattern recognition of chromatograms is a useful tool for rapid and reliable determination of large numbers of samples.

Headspace solid-phase microextraction in combination with gas chromatography and tandem mass spectrometry for the determination of organochlorine and organophosphorus pesticides in whole human blood

A method for the determination of several organochlorine and organophosphorus pesticides in human whole blood samples was developed. The combination of solid-phase microextraction in headspace mode with gas chromatography with tandem mass spectrometry allowed the determination of 11 selected pesticides at ppb levels, minimizing the sample treatment. Quantitation was carried out by means of calibration curves prepared in blood using labelled surrogate/internal standards. The method showed good linearity between 1 and 50 ng ml −1 (0.5–25 ng ml −1 for HCB) using second-order calibration curves. Precision was found to be better than 20% at the three concentration levels assayed in the range of ng ml −1. The detection limits obtained were in the range 0.02–0.7 ng ml −1, except for p,p′-DDT (3 ng ml −1). The developed procedure was applied to blood and serum samples obtained from agricultural workers. HCB, β-HCH and p,p′-DDE were most frequently detected in the samples analyzed.

Static headspace, solid-phase microextraction and headspace solid-phase microextraction for BTEX determination in aqueous samples by gas chromatography

The determination of benzene, toluene, ethylbenzene and xylenes (BTEX) in aqueous samples by gas chromatography with flame ionization detection (GC–FID) with three sampling techniques, viz. static headspace (HS), solid-phase microextraction (SPME) and combined HS–SPME by using a polydimethylsiloxane fiber has been investigated. Experimental parameters optimisation of the BTEX determinations using the three techniques are given. At their optimum conditions of operation, detection limits, times required for analysis and precision observed for the three techniques used are established. A detailed comparison of the analytical performance characteristics of HS, SPME and HS–SPME as sampling techniques for final GC–FID determination of BTEX in waters is given. Although all three techniques turned out to be sufficiently accurate, offering detection limits on the ≤ng ml −1 range, the most sensitive, selective and least time consuming technique was HS–SPME, which seems to be particularly appropriate for routine analysis of BTEX in waters by GC.