Static Headspace GC-MS Research Articles

Application of static headspace GC–MS for detection of residual trichloroethylene and toluene solvents in β-cyclodextrin

Trichloroethylene (TCE) and toluene (TOL), which have been used for β-cyclodextrin (β-CD) synthesis, need to be properly inspected for quality assurance and safety of food additives. In this study, a combination of static headspace separation and gas chromatography-mass spectrometry (SH-GC–MS) was optimized for detecting those residual solvents in β-CD in the compatible safe and green chemistry. Sample injection amount for SH was determined to 100 μL with the minimum volume that provides the suitable accuracy. For the safety and accuracy of analysis, equilibrium conditions of solvents were considered and selected to 60 °C for 45 min. Also, we found that the addition of salt, like CaCl2, adversely affected recovery efficiency. Under the proposed condition, coefficients of determination (R2) of both TCE and TOL were more than 0.99 between 0.05–10 mg/L concentrations. Recovery rates and relative standard deviation (RSD) of tested solvents were between 91.7–106.0 % and 1.0–8.9 %, respectively. From validation with two commercial β-CDs, both TCE and TOL presented lower than regulatory limits for food additives (1 ppm) with satisfactory RSDs (<20 %). Collectively, the proposed analytical methods can contribute to safer, simpler, and greener inspection of residual chemicals present in foods for public health.

Metabolomics study on the main volatile components of Thai colored rice cultivars from different agricultural locations

This study investigated the main volatile components in ten Thai colored rice varieties cultivated in two agricultural locations of Thailand (Central and Northern region) using a static headspace GC–MS metabolomics approach. The results indicated that volatolomics could successfully differentiate between the geographical origins of the same rice variety grown in regions within the same country. The volatile profiles of the colored rice obtained from the two locations were clearly different, with three volatile compounds isolated as key aroma producers in each area. Primary volatile compounds upregulated in colored rice varieties grown in Northern Thailand included undecanoic acid, 10-methyl-methyl ester; methyl 8-methyl-nonanoate; and pyrimidine, 4-methyl. Hexadecanoic acid, methyl ester; methyl 9-cis,11-trans-octadecadienoate; and 10-octadecenoic acid methyl ester were upregulated in the rice samples grown in Central Thailand. The environmental factors that could affect colored rice aroma at the agricultural sites included temperature, downward surface shortwave radiation, and vapor pressure deficit.

Profiling of volatile and non-volatile compounds in Dianhong by a combined approach of static headspace GC-MS and UPLC-MS

ABSTRACT The systematic identification of volatile organic compounds (VOCs) and non-VOCs will facilitate understanding the characteristic aroma and bioactive constituents of Dianhong. This article reported for the first time the volatile and non-volatile composition profiles of Dianhong from four main producing areas. A combined total of 42 VOCs were identified from four Dianhong samples by static headspace GC-MS. Thirteen VOCs were found to be important common components contributing to the characteristic aroma of Dianhong. The non-VOCs of Dianhong were evaluated by UPLC-ESI-MS, and Dianhong samples from four producing areas shared almost the same component profiles. Thirty-four components including derivatives of quinic acid, gallic acid, and catechin, flavone C-glycosides, flavonol O-glycosides, and alkaloids were characterized. Finally, catechin, gallic acid, 5-O-galloylquininc acid, and theobromine were characterized as the main non-VOCs in Dianhong. Dianhong samples from four main producing areas showed similar VOCs and non-VOCs profiles under our optimized GC-MS and LC-MS conditions.

Evaluation of a GC-MS method for benzyl chloride content in processed food, meats, and marine products distributed in Korea.

Benzyl chloride is a harmful chemical that contaminates air, water, and food. A static headspace GC-MS method for determining benzyl chloride in food was developed and validated. Two food matrices (fat/oil and chicken) were used for method validation. Sample preparation involved ultrasonication extraction and purification (syringe filtration). Linearity (R 2) was > 0.99, accuracy ranged from 86.91% to 110%, the limit of detection was 0.04-0.17mg/kg, and the limit of quantification was 0.13-0.52mg/kg. Recovery varied from 88.19% to 111.77%, and precision ranged from 0.10% to 1.17% in intraday and interday analyses. Among 102 food items (oils, fats, meat, marine, and egg products) distributed in Korea, benzyl chloride was only detected in six of the marine products. The validated analytical method can be used for routine monitoring of benzyl chloride residues in food and thereby prevent the human health risks associated with the consumption of food contaminated with this chemical.

A Static Headspace GC–MS Method for the Determination of Ethanol in Solid or Semi-solid Consumer Goods

A Static Headspace GC–MS Method for the Determination of Ethanol in Solid or Semi-solid Consumer Goods

Deciphering the Supramolecular Organization of Multiple Guests Inside a Microporous MOF to Understand their Release Profile.

Metal-organic frameworks (MOFs) give the opportunity of confining guest molecules into their pores even by a post-synthetic protocol. PUM168 is a Zn-based MOF characterized by microporous cavities that allows the encapsulation of a significant number of guest molecules. The pores engineered with different binding sites show a remarkable guest affinity towards a series of natural essential oils components, such as eugenol, thymol and carvacrol, relevant for environmental applications. Exploiting single crystal X-ray diffraction, it was possible to step-wisely monitor the rather complex three-components guest exchange process involving dimethylformamide (DMF, the pristine solvent) and binary mixtures of the flavoring agents. A picture of the structural evolution of the DMF-to-guest replacement occurring inside the MOF crystal was reached by a detailed single-crystal-to-single-crystal monitoring. The relation of the supramolecular arrangement in the pores with selective guests release was then investigated as a function of time and temperature by static headspace GC-MS analysis.

Methylmercury determination in freshwater biota and sediments: Static headspace GC-MS compared to direct mercury analyzer

We developed and compared two analytical methods for determination of MeHg in freshwater biota and sediments, by: I) simplified static headspace GC-MS using internal standard (IS) isotope dilution quantification, after microwave acid digestion and aqueous phase NaBEt4 ethylation; II) Automated Mercury Analyzer, after double toluene extraction followed by back-extraction with L-cystein. The performance was evaluated by analysis of certified reference materials. For biota, mean recovery was 100 ± 2% and relative standard deviation (RSD) ≤ 6.8% for method I, and mean recovery was 98 ± 7% and RSD ≤13% for method II. For sediments, recovery of 94.5% and RSD of 8.8% were obtained with method I, and recovery of 90.3% and RSD of 9.4% with method II. Limits of detection (LOD) were 0.7 µg kg−1 and 6 µg kg−1, respectively. Both techniques were tested for MeHg analysis in freshwater invertebrates, fish and sediments, covering a large range of MeHg values (1.9–670 µg kg−1 d.w.).• Both protocols proved to be suitable for MeHg analysis in complex environmental matrices, even if, for method II, interferences in the extraction phase and limited sensitivity may hinder sediment analysis.• Passing-Bablock regression revealed a slight disproportion between methods, with line slope = 1.058 (95% CI ranging from 1.001 to 1.090).

Spatial distribution and sources of BTEX and TPH contamination in freshwater sediments from Lake Iznik, NW Turkey

Iznik Lake is an important water supply deteriorating gradually due to anthropogenic pollution. Concentration and distribution of monoaromatic hydrocarbons (benzene, toluene, ethylbenzene and three xylene isomers; BTEX) were detected in the lake sediments using a static headspace GC-MS. ∑BTEX concentrations varied between 10.6 and 272.3 µg kg-1 dry weight (dw), with an average of 88.3 µg kg-1 dw. The light aromatic fraction of m-,p-Xylene was the most abundant compound (50.0% in average), followed by toluene (31.2%), o-xylene (12.2%), ethylbenzene (5.3%) and benzene (1.3%). Multivariate statistical analyses indicated that the BTEX levels and their distributions were controlled mainly by morphological and textural features of the sediment; anthropogenic inputs transported by the surrounding rivers, mainly influenced by agricultural facilities; absorbance of BTEX compounds in sediment; and biodegradation processes. Due to lack of any national sediment quality guideline regarding BTEX, the results will establish a significant baseline that will shed light on the administrative authorities for formulating their rational environmental strategies.

Retained ethanol in fried batters prepared with alcoholic beverages

Ethanol concentration in batters prepared with alcoholic beverages was measured upon deep frying, using static headspace GC-MS. The concentration decreased dramatically during the first two minutes of frying resulting in a concentration of maximum 0.28 ± 0.03 g/100 g. Frying for another two minutes had an insignificant effect on the concentrations. The measured concentrations resulted in 0.14 g ethanol per serving, which is considered very low and not problematic for human consumption. When the batter was fried as a coating for fish, the concentrations were slightly higher than when fried alone, namely 0.69 ± 0.21 g/100 g after two minutes of frying.

Volatiles of Tanacetum macrophyllum Obtained by Different Extraction Methods

Terpene compounds of Tanacetum macrophyllum as 1) essential oils, obtained by hydrodistillation (HD), 2) essential oil extracts, obtained by simultaneous hydrodistillation and extraction (SDE) and 3) volatiles, obtained by Static Headspace GC-MS analysis (HS) were processed. Monoterpenes were the most dominant (49.2%, 49.5% and 90.4%, respectively). Profiles of essential oils obtained by HD and SD were quite similar, with oxygenated monoterpenes (39.3% and 39.4%) being the most abundant. In HS volatiles oxygenated monoterpenes also dominated (57.4%). Total sesquiterpenes were abundant in HD and SDE volatiles (38.2% and 39.2%, resp.), where sesquiterpene hydrocarbons were prevalent (27.3% and 28.7%, resp.). Germacrene D was dominant in HD and SDE oils (22.0% and 23.3%, resp.) and 1,8-cineole in HS volatiles (34.3%). To our knowledge, this is the first use of Headspace technique on T. macrophyllum. Furthermore, this is the first comparison of different techniques of volatile extraction in T. macrophyllum.

Interactive effects of aphid feeding and virus infection on host gene expression and volatile compounds in salt-stressed soybean, Glycine max (L.) Merr.

Saline soils are becoming an important limiting factor in production agriculture. Soybean cultivars [Glycine max (L.) Merr.] differ in their ability to tolerate salt stress with those that cannot limit ion uptake into leaves being salt sensitive. Those that can partially limit ion uptake into leaves are generally more salt tolerant. Soybean mosaic virus (SMV) is an important viral pathogen of soybean worldwide and is commonly transmitted by the soybean aphid, Aphis glycines Matsumura. In this study, we investigate the interaction of salt stress in soybean with SMV infection and infestation by the soybean aphid by measuring aphid populations in a no-choice assay, gene expression levels, and the induction of volatile organic compounds using static headspace GC–MS analysis. Salt stress and SMV infection both reduced total aphid populations, though SMV did not reduce the total number of aphids per gram of fresh weight. Aphid suppression of a calcium EF hand gene and OPR1 was lost when salt-sensitive soybean plants were salt stressed and when salt-tolerant plants were subjected to all three stressors. The relative levels of SMV in aphid-infested soybeans were increased by salt stress in the salt-sensitive cultivar, whereas SMV levels decreased in the salt-tolerant cultivar. Static headspace collection of volatile organic compounds revealed that salt stress and SMV infection had suppressive activities on aphid-induced terpenes. These results suggest that although salt stress has a negative impact on aphid population size, the changes in volatiles and SMV levels could alter the incidence of SMV in salt-stressed fields.

Comparative analysis of the volatile composition of honeys from Brazilian stingless bees by static headspace GC–MS

The volatile composition of honeys produced by eight species of stingless bees collected in three municipalities in the state of Paraná (Brazil) was compared by combining static headspace GC–MS and chemometrics methods. Forty-four compounds were identified using NIST library and linear retention index relative to n-alkanes (C8–C40). Linalool derivatives were the most abundant peaks in most honeys regardless geographical or entomological origin. However, Principal Component Analysis discriminated honeys from different geographical origins considering their distinctive minor volatile components. Honey samples from Guaraqueçaba were characterized by the presence of hotrienol while those from Cambará showed epoxylinalol, benzaldehyde and TDN as minor discriminating compounds. Punctual species such as Borá showed similar fingerprints regardless geographical origin, with ethyl octanoate and ethyl decanoate as characteristic intense chromatographic peaks, which may suggest a specialized behavior for nectar collection. Discriminant Analysis allowed correct geographic discrimination of most honeys produced in the three spots tested. We concluded that volatile profile of stingless bee honeys can be used to attest authenticity related to regional origin of honeys.

Simultaneous determination of 14 disinfection by-products in meat products using microwave-assisted extraction and static headspace coupled to gas chromatography–mass spectrometry

This paper described the first analytical method to simultaneously determine 14 disinfection by-products (DBPs) in meat products using microwave-assisted extraction (MAE) and static headspace (SHS) followed by gas chromatography–mass spectrometry (GC–MS). The DBPs included were 4 trihalomethanes, 7 haloacetic acids, 2 haloacetonitriles and trichloronitromethane, which are commonly formed as a consequence of the disinfection process of water. The combination of the MAE and SHS techniques allows meat samples to be analysed in two sequential steps into the same HS vial in spite of the sample’s complexity. Detection limits were obtained within the range of 0.06–0.70ng/g, and the average relative standard deviation was 7.4%. Recoveries throughout the whole process were between 86 and 95%. The SHS–GC–MS method was applied to determine DBPs in meat products with different industrial processing which could be contaminated through contact with disinfectants and/or treated water employed in the factory either for washing or for the cooking of meat. Up to 5 DBPs were found at ng/g levels in about 36% of the samples analysed, cooked ham being the most contaminated meat product because of the brine solutions employed in its manufacturing process.

Gas chromatography-mass spectrometry strategies for the accurate and sensitive speciation of sulfur dioxide in wine

Understanding the chemistry of wine oxidation requires the accurate and sensitive quantitative determination of the most important molecular species which SO2 can form. An analytical strategy based in three independent static headspace GC–MS determinations is proposed in order to obtain information about the total, nominally free and truly free levels of SO2. Nominally free forms are directly determined after sample acidulation, total forms require the previous incubation at 100°C, and truly free forms are determined after preconcentration of the headspace of the undisturbed sample in an alkaline solution. The two first determinations provide results equivalent to those reported by the aeration-oxidation (A-O) method, with lower limits of detection (1mgL−1) and better repeatabilities (<4.0%). Results from the analysis of different wines revealed that levels of nominally free are systematically in excess than those of truly free SO2, which suggests that free SO2 determined by any method using previous acidulation includes at least two different species of SO2, which may have different antioxidant behavior.

Volatile compounds in hilsa (Tenualosa ilisha , Hamilton) as detected by static headspace gas chromatography and mass spectrometry

Tenualosa ilisha (Hilsa) is a commercially important food fish in countries around the Bay of Bengal and enjoys high consumer preference for its unique flavor and culinary properties. Fish flavors, an important factor for consumer acceptance are largely characterized by the volatile compounds. Static headspace gas chromatography mass spectrometry was used to investigate the volatiles in hilsa. A total of 41 compounds were identified: 12 alcohols, 1 ketone, 2 aldehydes, 4 furans, 3 acids, 7 esters, 5 alkadienes, 3 alkynes, 3 aromatic compounds, and 1 epoxide derivative. Principal component analysis showed gradual changes in the volatile composition with increasing storage time. The volatile substances present in hilsa which could be contributing to its flavor were identified. 2,4-Pentadiene-1-ol, 3-ethyl-(2Z), and 2,4-hexadienal were identified as possible freshness indicators and 7-Heptadecyne-17-chloro and 2-methyl-1, 5 hexadiene as possible spoilage indicators which could be useful in assessing the quality of the fish. Practical applications Hilsa is a commercially important food fish and is known for its unique flavor and culinary properties; the flavor is perhaps attributed to the volatile compounds present. Hilsa is transported for import/export purpose in large scale in ice packaging, especially in South East Asian countries; therefore, there is a need to access the quality of frozen fish during ice storage, both freshness and spoilage. In this context, the volatile compounds in hilsa could be useful in characterizing its unique flavor as well as freshness and spoilage status during transport/storage. Static headspace GC-MS combined with a statistical multivariate approach could be a useful method to identify volatile compounds and characterize fish freshness and spoilage. As the consumers are now more conscious about food safety and quality issues; freshness and spoilage markers would be useful in quality management in fish trade.

Volatile profiling of two pear genotypes with different potential for white pear aroma improvement

Abstract. Chinese white pear (Pyrus bretschneideri) is sweet, juicy and crispy, but not fragrant. The two pears ‘Xiang-Mian Li’ (‘XML’) and ‘Mu-Tou Su’ (‘MTS’) with fragrant and large fruits were noted recently from pear germplasm screening. Their volatile profiles were compared with those of typical white pear ‘Dang-Shan Suli’ (‘DSS’) (P. bretschneideri) and fragrant pear ‘Nan-Guo Li’ (‘NGL’) (P. ussuriensis) in this study for a better understanding the chemistry of the differences among the tested cultivars. Headspace solid phase microextraction (HS-SPME) coupled to gas chromatography–mass spectrum (GC–MS) was used for sensitive intact fruit volatile profiling while a static headspace GC–MS system was employed for accurate volatile quantification. The rank of the tested intact fruits based on detected volatile numbers and total odor active values was ‘NGL’ > ‘XML’ > ‘MTS’ > ‘DSS’. Among many detected volatiles, ethyl 2-methylbutyrate and ethyl hexanoate were the most potent and pleasant odorants from the intact fruit and fruit pulp of ‘XML’ and ‘NGL’, but not from ‘MTS’ pulp. They were identified as the most important contributors to the volatile profile variance among the tested pear fruits. Our study indicated that compared to ‘MTS’, ‘XML’ had much more intense aroma and this genotype had potential for Chinese white pear aroma improvement.

Analysis of flavor volatiles of some Iranian rice cultivars by optimized static headspace gas chromatography–mass spectrometry

Static headspace coupled to gas chromatography–mass spectrometry (SHS-GC–MS) was applied to the extraction and analysis of volatiles in some Iranian rice varieties. Optimization of static headspace sampling was investigated by full factorial design and a face-centered central composite design procedure. According to the results of full factorial design, the effective parameters of static headspace sampling were extraction temperature (T) and extraction time (t). Then a central composite design was applied to find the optimum level of these factors. The results of three replications of experiments under optimal conditions (T = 100 °C, t = 900 s) indicated that, there is a good agreement between the predicted (5.28) and experimental (5.20) responses (98.48 %). Then developed method was used for analysis of volatile chemicals in three Iranian rice cultivars. According to the results of GC–MS analysis 26, 21, and 19 chemicals were assigned to Domsiah, Deylamani, and Tarom rice samples, respectively. The major compounds identified in these samples were the alkyl aldehydes. The results obtained are promising for future isolation and identification of the flavor volatiles of other rice cultivars by SHS-GC–MS analysis. The method of static headspace GC–MS has been developed and has proven to provide an effective means for simple and rapid quantitative analysis of the aroma compound of rice. A central composite design was applied to found the optimal conditions. The results of three replications of experiments under optimal conditions (T = 100 °C, t = 900 s) indicated that, there is a good agreement between the predicted (5.28) and experimental (5.20) responses (98.48 %). Then, developed method was used to analyze the volatile chemicals in the rice samples. A total of 26, 21, and 19 chemicals were assigned to Domsiah, Deylamani, and Tarom rice samples, respectively.

Chemometric analysis of volatiles of propolis from different regions using static headspace GC-MS

Abstract Six samples of propolis were analyzed in the paper: a sample from Brazil, Estonia, China and three samples from different locations of Uruguay. Static headspace technique coupled with gas chromatography-mass spectrometry analysis has been applied for the determination of the characteristic volatile profile with the aim to differentiate the propolis from different regions. Monoterpenes (α- and β-pinenes) were predominant in all samples, except the sample from China. This sample separated itself by the alcohols 3-methyl-3-buten-1-ol and 3-methyl-2-buten-1-ol, (40.33% and 11.57%, respectively) and ester 4-penten-1-yl acetate (9.04%). α-Pinene and β-pinene composed 64.59–77.56% of volatiles in Brazilian and Uruguayan propolis, and 29.43% in Estonian propolis. Brazilian propolis was distinguished by a high amount of β-methyl crotonaldehyde (10.11%), one of Uruguayan samples 3- by limonene (15.58%), and the Estonian sample — by eucalyptol (25.95%). Statistical investigation of the samples was made applying principal component, hierarchical cluster and K-Means cluster analyses. Various data pre-processing techniques were proposed and used to study and obtain the important volatile compounds contributed to the differentiation of the propolis samples from different regions to separate clusters.

Influence of storage conditions on aroma compounds in coffee pads using static headspace GC–MS

Static headspace gas chromatography coupled to mass spectrometry (SHGC–MS) was used to identify aroma compounds in coffee pad powder. Based on the peak areas of these aroma compounds, the influence of the type of original package on the time of evolution was studied. Statistical ANOVA indicated that coffee pads which were individually packed and hermetically sealed lost less aroma compounds than did pads which were enclosed together in an open package. In addition, coffee pads from an open package were stored in closed plastic bottles at two different temperatures. Storing the pads at 4 °C instead of keeping them at room temperature had a positive influence on the evolution of aroma compounds with time.

Identification and Quantification of a Marker Compound for ‘Pepper' Aroma and Flavor in Shiraz Grape Berries by Combination of Chemometrics and Gas Chromatography−Mass Spectrometry

'Black pepper' aroma and flavor is important to some Australian Shiraz red wine styles but the aroma compounds involved have yet to be identified, and no objective analytical method to assess 'pepper' grape aromas is available to date. Samples of potentially 'spicy'/'peppery' grapes were obtained from vineyards in South Australia and Victoria over two vintages. The important sensory attributes of the grapes, including the aroma descriptor 'pepper', were rated by a sensory panel. The sensory study revealed a strong correlation between the intensity of 'pepper' aroma and the intensity of 'pepper' flavor perceived on the palate. The grape homogenates were analyzed by static headspace GC-MS using a cool inlet system. Vectors obtained by analysis of over 13 000 individual mass spectra per grape sample were then subjected to multivariate analyses. Both principal component analysis and partial least-squares regression were used to develop multivariate models based on mass spectra and aroma descriptors to explain the intensity of the rating of the 'pepper' character. Corresponding differences in mass spectra and aroma were observed among vineyards and from the same vineyards in different years. Additional optimization of the methodology enabled selection of a single region of the GC-MS chromatogram that allowed prediction of 'pepper' aroma intensity with a correlation coefficient >0.98 and led to the identification of alpha-ylangene, a tricyclic sesquiterpene. To assess the potential of alpha-ylangene as a marker for this sensory characteristic, a method for alpha-ylangene analysis of grapes and wine using HS-SPME-GC-MS was developed. Although not a significant aroma compound by itself, alpha-ylangene was a satisfactory marker for the 'pepper' aroma in grapes and wine, and its concentration showed similar discrimination between 'peppery' vineyards and vintages as that obtained using the multivariate models. Despite its presence in grapes, we could not detect alpha-ylangene in wine.