Headspace Sampling Gas Chromatography Research Articles

Rapid Discrimination of Aroma Components in Natural and Artificial Agarwood Incense by Static Headspace Sampling – Gas Chromatography – Mass Spectrometry (SHS-GC-MS) with Principal Component Analysis (PCA) and Partial Least Squares – Discrimination Analysis (PLS-DA)

Agarwood is a resinous, fragrant wood produced by tropical tree species of the genus Aquilaria, and is highly valued for its wide range of uses in medicine, incense, and perfume. In this study, the quality of agarwood and patterns of chemical constituents induced in natural and artificial agarwood by physical injury, chemical inducer, and chemical plus fungal infection were compared using static headspace sampling gas chromatography – mass spectrometry (SHS-GC-MS). The optimal agarwood heating temperature was determined to be 180 °C. The fingerprints of 40 batches of agarwood were established. Multivariate statistical analysis was utilized to identify 15 common and ten differentiating components, respectively. Agarwood induced by the physical method was more similar to natural agarwood. Exploration of the pyrolysis products of chromone derivatives and sesquiterpenes was undertaken to discover the causes of differences in chemical compositions between artificial and natural agarwood. Our findings revealed that benzylacetone, baimuxinal, and guaiol were significant for agarwood incense and these compounds may be used as markers for classification.

Development of a Headspace Sampling–Gas Chromatography–Mass Spectrometry Method for the Analysis of Fireground Contaminants on Firefighter Turnout Materials

Firefighting is classified as a 2B-possibly carcinogenic profession by the International Agency for Research on Cancer (IARC). Firefighters are exposed to a host of toxic fireground contaminants su...

Determination of Volatile Organic Compounds in Recycled Polyethylene Terephthalate Fibers by HS-GC-FID to Evaluate the Efficiency of Testing Conditions

A method to determine the volatile organic compounds (VOCs) in the recycled polyethylene terephthalate fiber was presented by using the headspace sampling-gas chromatography coupled to flame ionization detector (HS-GC-FID), in order to evaluate the level of VOC contamination. The extraction variables, such as the incubation temperature, the pre-incubation time and the size of the vial, were also studied. The effects on the determination of VOC were also compared using two type chromatographic columns. The optimal conditions were found using a headspace sampling for 20 min at 100 °C, where 120 mL vials and TM-1 column were prior to analysis of benzene compounds in PET(polyethylene terephthalate) fibers. The results can be used in analysis of VOC from recycled PET fibers.

Liquid/Gas and Liquid/Liquid Phase Equilibria of the System Water/Bovine Serum Albumin

The thermodynamic behavior of the system H2O/BSA was studied at 25 °C within the entire composition range: vapor pressure measurements via head space sampling gas chromatography demonstrate that the attainment of equilibria takes more than one week. A miscibility gap was detected via turbidity and the coexisting phases were analyzed. At 6 °C the two phase region extends from ca. 34 to 40 wt % BSA; it shrinks upon heating. The polymer rich phase is locally ordered, as can be seen under the optical microscope using crossed polarizers. The Flory-Huggins theory turns out to be inappropriate for the modeling of experimental results. A phenomenological expression is employed which uses three adjustable parameters and describes the vapor pressures quantitatively; it also forecasts the existence of a miscibility gap.

Analysis of volatile flavor compounds in top fermented wheat beer by headspace sampling-gas chromatography

Li Huimin, Li Hongjun*, Liu Xiuhua, Chen Bing (School of Agriculture and Food Engineering, Shandong University of Technology, Zibo 255049, China) Abstract: Headspace sampling-gas chromatography (HS-GC) coupled with an internal standard method (ISM) was developed to analyze the volatile flavor compounds in top fermented wheat beer in the laboratory. Eight compounds, i.e. acetaldehyde, N-propanol, ethyl acetate, isobutyl alcohol, isoamyl alcohol, isoamyl acetate, ethyl hexanoate and ethyl octanoate were separated and quantified. This method was validated to ensure the quality of the results: the precision was satisfactory with relative standard deviation (RSD) in the range of 1.51%-4.22%, recoveries for all the analytes ranged from 95.15% to 99.85%, and the limits of detection were in the range of 0.0002-0.024 mg/L. Results of real wheat beer samples analyzed using this method showed that the volatile compound concentrations were in the range of 0.08-99.91 mg/L. Results suggested that this method exhibited good reproducibility, selectivity and high precision, and it can be useful for the analysis of routine beer samples. Keywords: top fermentation, wheat beer, flavor detection, volatile flavor compounds, headspace sampling-gas chromatography, internal standard method DOI: 10.3965/j.ijabe.20120502.009 Citation: Li H M, Li H J, Liu X H, Chen B. Analysis of volatile flavor compounds in top fermented wheat beer by headspace sampling-gas chromatography. Int J Agric & Biol Eng, 2012; 5(2): 67

Determination of several flavours in beer with headspace sampling–gas chromatography

In order to determine flavours (diacetyl, pentanedione, acetoin and acetaldehyde) in beer, gas chromatography coupled with headspace sampling technique was developed in our laboratory. The calibrations were accomplished by six level standard addition methods, and relative coefficients were ⩾0.999. Repeatability experiments were accomplished by detecting 20 successive same standard samples, which showed that detection precision was <2% relative standard deviation (RSD) for three flavours (diacetyl, pentanedione and acetaldehyde), and detection precision of acetoin was <2.5% (RSD). Four flavours gradually increased and then decreased during the process of fermentation, and they leveled off when the fermentation was over. The ratio (diacetyl/pentanedione) reflected the degree of contamination: normal beer had a ratio of approximate 1; the ratio (diacetyl/pentanedione) was higher than 1, displaying that beer was contaminated by microbes. Our data suggested that gas chromatography coupled with headspace sampling technique could be used successfully to determine flavours (diacetyl, pentanedione, acetoin and acetaldehyde) in beer.

Characterisation of different clones of Picea abies (L.) Karst using head-space sampling of cortical tissues combined with enantioselective capillary gas chromatography for the separation of chiral and non-chiral monoterpenes

Head-space sampling (HS) has been combined with enantioselective gas chromatography (GC) for the analysis of chiral and non-chiral monoterpenes present in the cortical tissues of five different Norway spruce clones. (1 S)-(−)-α-Pinene, (1 S,5 S)-(−)sabinene, (1 S)-(−)-β-pinene, and (4 S)-(−)limonene dominated over (1 R)-(+)-α-pinene, (1 R,5 R)-(+)-sabinene, (1 R)-(+)-β-pinene, and (4 R)-(+)-limonene. Results showed a large variation in the enantiomeric composition of cortical tissues between different clones. The development of HS–GC greatly increased the speed of precise analyses of chiral monoterpenes in small samples and therefore offer excellent opportunities in studies on the ecophysiological and chemotaxomic roles of these chiral components.

Volatile compounds of Baltic herring analysed by dynamic headspace sampling–gas chromatography–mass spectrometry

The effect of storage time at 6 °C on the volatile compounds of Baltic herring was studied using the dynamic headspace–gas chromatography–mass spectrometry method. The fish were baked just before analysis. In the headspace of baked, fresh herring (1 day storage) the most abundant volatiles were 3–methylbutanal, 2–methylbutanal and hexanal comprising 18, 16 and 13% of all volatiles, respectively. When the fish were stored for 3 days the proportions of 4–heptenal, 2–heptanone and octatriene increased significantly. After further storage the peak areas of hexanal, heptanal, 1–penten–3–ol and octadienes also increased many-fold, which indicated the oxidation of long chain unsaturated fatty acids. After 8 days storage several volatile compounds were detected in the baked fish which were not found in freshly baked herring. Some compounds related to microbial spoilage (3–methyl–1–butanol, cresol) were identified.

Analysis of dissolved gases by headspace sampling gas chromatography with column and detector switching. Preliminary results

This preliminary study presents a new method for the determination of dissolved gases in sea-water. After headspace extraction, gaseous compounds are separated by GC on a dual column adsorption system. The individual species are thereafter eluted to three different detectors (thermal conductivity, flame ionization and FPD) using a second switching valve. The analysis is quantitative for methane and carbon dioxide with limits of determination of 0.1 and 50 µmol l–1, respectively, and corresponding standard deviations of 4 and 7%, and has been applied to deep sea hydrothermal samples. Further optimization is necessary to allow the quantitative determination of hydrogen sulfide, nitrogen, oxygen and carbon monoxide.

Investigation of the thermal oxidation of a polybutadiene by headspace sampling—gas chromatography

A novel method was developed, utilizing headspace sampling in conjunction with gas chromatography, to quantitatively follow the thermal oxidation in air of a low molecular weight, hydroxy-terminated polybutadiene. This method was found to offer an efficient and simple technique by which to analyze both the rate and the extent of oxidation of the polymer. Rate studies of the oxidation revealed an induction period followed by self-catalyzed oxidation, the rate of which quickly becomes controlled by diffusion of oxygen into the polymer. By determining the rate of oxygen consumption at various temperatures, an Arrhenius-type plot was derived and an activation energy value of 13 kcal/mol was calculated. The relative effects on oxidation of a number of common antioxidants and organometallic cure catalysts were also determined by this technique.