Efficacy of head space solid-phase microextraction coupled to gas chromatography-mass spectrometry method for determination of the trace extracellular hydrocarbons of cyanobacteria.

Hydrocarbons are widespread in cyanobacteria, and the biochemical synthetic pathways were recently identified. Intracellular fatty alka(e)nes of cyanobacteria have been detected by liquid-liquid extraction (LLE) coupled to gas chromatography-mass spectrometry (GC/MS). However, whether fatty alka(e)nes can be released to cyanobacterial culture media remains to be clarified.

GC-MS Analysis and Volatile Profile Comparison for the Characteristic Smell from Liang-wai Gan Cao (Glycyrrhiza uralensis) and Honey-Roasting Products.

The characteristic smell of Liang-wai Gan Cao (Glycyrrhiza uralensis) and honey-roasting products was comprehensively analyzed using gas chromatography-mass spectrometry (GC-MS). Steam distillation and headspace solid-phase microextraction (HS-SPME) were used to extract volatile organic compounds (VOCs). Multiple fibers of SPME may reflect the samples' comprehensive information to the greatest extent, depending on their chemical characters.

Hydrogen peroxide-independent production of α-alkenes by OleTJE P450 fatty acid decarboxylase.

Background: Cytochrome P450 OleTJE from Jeotgalicoccus sp. ATCC 8456, a new member of the CYP152 peroxygenase family, was recently found to catalyze the unusual decarboxylation of long-chain fatty acids to form α-alkenes using H2O2 as the sole electron and oxygen donor. Because aliphatic α-alkenes are important chemicals that can be used as biofuels to replace fossil fuels, or for making lubricants, polymers and detergents, studies on OleTJE fatty acid decarboxylase are significant and may lead to commercial production of biogenic α-alkenes in the future, which are renewable and more environmentally friendly than petroleum-derived equivalents.

Characterization of the bafilomycin biosynthetic gene cluster from Streptomyces lohii.

New hope for old bones: The plecomacrolide bafilomycin has been explored for decades as an anti-osteoporotic. However, its structural complexity has limited the synthesis of analogues. The cloning of the bafilomycin biosynthetic gene cluster from the environmental isolate Streptomyces lohii opens the door to the production of new analogues through bioengineering.

Quantitative analysis of fatty-acid-based biofuels produced by wild-type and genetically engineered cyanobacteria by gas chromatography-mass spectrometry.

Simple and rapid quantitative determination of fatty-acid-based biofuels is greatly important for the study of genetic engineering progress for biofuels production by microalgae. Ideal biofuels produced from biological systems should be chemically similar to petroleum, like fatty-acid-based molecules including free fatty acids, fatty acid methyl esters, fatty acid ethyl esters, fatty alcohols and fatty alkanes. This study founded a gas chromatography-mass spectrometry (GC-MS) method for simultaneous quantification of seven free fatty acids, nine fatty acid methyl esters, five fatty acid ethyl esters, five fatty alcohols and three fatty alkanes produced by wild-type Synechocystis PCC 6803 and its genetically engineered strain.

[Analysis of phenolic compounds in aqueous samples by gas chromatography coupled with headspace solid-phase microextraction using poly (phthalazine ether sulfone ketone) coated fiber].

The direct trace analysis of phenolic compounds in aqueous samples was performed by headspace solid-phase microextraction/gas chromatography (HS-SPME/GC). A laboratory made poly (phthalazine ether sulfone ketone) (PPESK, 30 microm) coated fiber was used to extract the phenols from aqueous samples. The parameters affecting the extraction efficiency, such as extraction temperature and time, pH value, and salt concentration, were optimized.

[Analysis of organochlorine pesticides in buckwheat using pressurized liquid extraction and gas chromatography].

Seven organochlorine pesticides (OCPs) in buckwheat were extracted by a homemade 24 cells auto-pressurized liquid extraction instrument (APLE) and then analyzed by gas chromatography with electronic capture detection. The optimal extraction condition was found to be 100 degrees C and 10 MPa for 5 min with acetone/n-hexane (1:1, v/v) as the extraction solvent. The extraction was performed twice for each sample to obtain complete extraction.

[Preparation of poly (trifluoropropyl) methylsiloxane coating for solid-phase microextraction and its application for the analysis of phenolic compounds in sea water].

The poly (trifluoropropyl) methylsiloxane (PTFPMS) coating was prepared as solid-phase microextraction (SPME) coating by sol-gel technique. The coating has a porous microstructure and the thickness was 10 microm. Since the PTFPMS phase contains the functional group of -C2H4CF3, it exhibits high affinity to compounds containing electron-attracting groups.

Poly(phthalazine ether sulfone ketone) as novel stationary phase for stir bar sorptive extraction of organochlorine compounds and organophosphorus pesticides.

A novel poly(phthalazine ether sulfone ketone) (PPESK) film prepared by immersion precipitation technique was coated on stir bars for sorptive extraction. Scanning electron micrographs showed that the coating has a denser porous surface (about 1 microm in thickness) with a sponge-like sublayer, and the thickness of the coating was 250 microm. The PPESK coated stir bar has high thermostability (290 degrees C) and long lifetime (50 times).

Fast temperature programming on a stainless-steel narrow-bore capillary column by direct resistive heating for fast gas chromatography.

A direct resistive-heating fast temperature programming device for fast gas chromatography was designed and evaluated. A stainless-steel (SS) capillary column acted both as a separation column and as a heating element. A fast temperature controller with the deviation derivative proportional-integral-derivative (DDPID) control algorithm, which was suitable for ramp control using ramp-to-setpoint function, was used to facilitate the fast pulse heating.

A new poly(phthalazine ether sulfone ketone)-coated fiber for solid-phase microextraction to determine nitroaromatic explosives in aqueous samples.

A novel polar solid-phase microextraction (SPME) fiber coated with poly(phthalazine ether sulfone ketone) (PPESK) was prepared by immersion precipitation technique. The microstructure of the coating exhibits a sponge-like sublayer supporting a dense cracking shaped top layer (about 1 microm in thickness). This coating shows long lifetime (up to 100 times) and is stable at desorption temperature up to 290 degrees C due to the rigid aromatic rings in chemical structure.

Study of conical columns with 10 degrees opening angle for preparative liquid chromatography.

The efficiency and sample capacity of conical liquid chromatographic columns with 10 degrees opening angle were studied at different ratio of cross section areas of inlet to outlet (A(in)/A(out)) and column dimension. As the A(in)/A(out) ratio changed from 4 to 2.25, the reduced plate height (h) was reduced and the h value decreased 12% when the column dimension was scaled up proportionally because of relatively smaller dead volume on both end of the column.