Detection of Adulterated Vegetable Oils Containing Waste Cooking Oils Based on the Contents and Ratios of Cholesterol, β-Sitosterol, and Campesterol by Gas Chromatography/Mass Spectrometry.

A simple and accurate authentication method for the detection of adulterated vegetable oils that contain waste cooking oil (WCO) was developed. This method is based on the determination of cholesterol, β-sitosterol, and campesterol in vegetable oils and WCO by GC/MS without any derivatization. A total of 148 samples involving 12 types of vegetable oil and WCO were analyzed.

[Identification of irradiated abalone by ESR spectroscopy].

Objective: To establish an analytical method for the detection and identification of irradiated abalone by electron spin resonance spectroscopy.

Methods: Electron spin resonance (ESR) was used to study the spectral characteristics of abalone and the characteristic peak for quantitation.

Results: There were obvious different ESR spectra between unirradiated and irradiated abalone.

[Rapid determination of 40 pesticide residues in fruits using gas chromatography-mass spectrometry coupled with analyte protectants to compensate for matrix effects].

A gas chromatography-mass spectrometry (GC-MS) method was developed for the determination of 40 pesticides in fruits. The effects of adding analyte protectants were evaluated for compensating matrix effects and the impacts on the quantitative results. A new combination of analyte protectants - Polyethylene Glycol 400 (PEG 400) and olive oil combination, which can be dissolved in acetone, was used for the quantitative analysis.

The behavior of tetracyclines and their degradation products during swine manure composting.

The purposes of this study were to investigate the behavior of three tetracyclines including chlortetracycline (CTC), oxytetracycline (OTC) and tetracycline (TC) and their degradation products in a pilot scale swine manure composting, and also to study the degradation kinetics of CTC, OTC and TC. During the pilot scale composting, CTC, OTC and TC were degraded by 74%, 92% and 70%, respectively. Several degradation products were found like 4-epitetracycline (ETC), 4-epioxytetracycline (EOTC), 4-epichlortetracycline (ECTC), demeclocycline (DMCTC) and anhydrotetracycline (ATC).

[Determination of dioxin like polychlorinated biphenyl residues in milk using isotope dilution gas chromatography-ion trap tandem mass spectrometry].

A method for the determination of dioxin like polychlorinated biphenyl (DL-PCB) residues in milk has been developed using high resolution gas chromatography coupled with ion trap mass spectrometry (GC-MS/MS-IT). Analytical procedure consisted of accelerate solvent extraction (ASE), lipid removal with acidic silica and clean-up using anthropogenic isolation column packed with multilayer silica. The analytes were separated on a DB-5 capillary column, detected with multiple reaction monitor mode (MRM) and quantified using internal standard calibration curve of isotope dilution technique.

[Rapid and simultaneous determination of thirteen organic phosphorous pesticide residues in spinach using gas chromatography-mass spectrometry coupled with stomach large volume injection and mini solid phase extraction].

A stomach large volume injection-gas chromatography-mass spectrometry (LVI-GC-MS) coupled with mini solid phase extraction (SPE) method for the rapid and simultaneous determination of 13 organic phosphorous pesticide residues in spinach samples is presented. The compounds were identified with their retention times and the abundance ratios of qualifier and target ions. Quantification was calculated based on the extraction of spiking standards in a blank sample.

Multiwalled carbon nanotubes as a solid-phase extraction adsorbent for the determination of three barbiturates in pork by ion trap gas chromatography-tandem mass spectrometry (GC/MS/MS) following microwave assisted derivatization.

A new method was developed for the rapid screening and confirmation analysis of barbital, amobarbital and phenobarbital residues in pork by gas chromatography-tandem mass spectrometry (GC/MS/MS) with ion trap MSD. The residual barbiturates in pork were extracted by ultrasonic extraction, cleaned up on a multiwalled carbon nanotubes (MWCNTs) packed solid phase extraction (SPE) cartridge and applied acetone-ethyl acetate (3:7, v/v) mixture as eluting solvent and derivatized with CH3I under microwave irradiation. The methylated barbiturates were separated on a TR-5MS capillary column and detected with an ion trap mass detector.

[Determination of polychlorinated dibenzo-p-dioxins and dibenzo-furans in sediment by accelerated solvent extraction, fluid management systems and high resolution gas chromatography/high resolution mass spectrometry].

A rapid, sensitive and accurate method has been developed for the determination of seventeen 2, 3, 7, 8-substituted congeners of polychlorinated dibenzo-p-dioxins and dibenzo-furans (PCDD/Fs) in sediment using isotope dilution high resolution gas chromatography/high resolution mass spectrometry (HRGC/HRMS). Dibenzo-p-dioxins and dibenzo-furans were extracted from samples by accelerated solvent extraction (ASE) and then purified by fluid management systems (FMS) with silica column, alumina column and carbon column. Confirmation and quantitative analysis at pg/g level of PCDD/Fs were performed by HRGC/HRMS using voltage selective ion record (VSIR) mode.

Simultaneous determination of three residual barbiturates in pork using accelerated solvent extraction and gas chromatography-mass spectrometry.

A new method was developed for the rapid extraction and unequivocal determination of barbital, amobarbital and phenobarbital residues in pork. The isolation of the analytes from pork samples was accomplished by utilizing an accelerated solvent extractor ASE 300. The procedure was automatically carried out in series for fat removing and extraction, respectively with n-hexane and acetonitrile pressurized constantly at 10.

[Determination of acrylamide in fried starchy foods by gas chromatography-mass spectrometry].

A method was developed for the determination of acrylamide in fried starchy foods using isotope dilution gas chromatograpy-selected mass spectrometry (GC-MS). The acrylamide was extracted from samples by water, then centrifuged and cleaned up by a column of graphitized carbon black. Acrylamide was derivatized through bromination at low pH and low temperature and determined by GC-MS.

[Simultaneous determination of 25 persistent organic pollutants in rice by gas chromatography-mass spectrometry with selected ion monitoring mode].

A multi-residue analytical method for the simultaneous determination of persistent organic pollutants (POPs) in rice samples was developed. POPs were extracted from rice with ethyl acetate/n-hexane (80:20, v/v) by sonication, and determined by gas chromatography with electron impact mass spectrometric detection in the selected ion monitoring mode. A fused silica capillary column DB-35MS (30 m x 0.

[Simultaneous determination of the residues of pyrethriods, organochlorines and polychlorinated biphenyl congeners in unpolished rice by gas chromatography with gel permeation chromatography purification].

The separation behaviors of organochlorine pesticides, pyrethriod pesticides, polychlorinated biphenyl congeners (PCBs) and unpolished rice matrixes were systematically investigated with gel permeation chromatography (GPC) because of its outstanding capability in removing lipid and pigments from sample solutions. A separation method was proposed for the quantitative determination of 35 pesticides and PCBs in unpolished rice by GPC and gas chromatography simultaneously. Samples were extracted with ethyl acetate, purified by GPC, and then determined by gas chromatography and electron capture detection (GC-ECD).

Regional distribution of organochlorinated pesticides in pine needles and its indication for socioeconomic development.

The regional distribution of 10 potentially harmful organochlorinated pesticides (OCPs) was investigated in pine needles from 18 sites in six Chinese regions. The OCPs concentrations in six regions were as follows: sigmaHCH (sigmaHCH=alpha-+beta-+gamma-+delta-HCH), 4.7-51.

Nitrate and nitrite in vegetables from north China: content and intake.

The contents of nitrate and nitrite in potato, cabbage, Chinese cabbage, scallion (shallot), celery, cucumber, tomato, eggplant and wax gourd taken from the north China market from 1998 to 1999 were determined. These vegetables provide the major contribution to the nitrate intake from the diet. The highest content of nitrate was found in celery followed by Chinese cabbage, cabbage, scallion, wax gourd and eggplant.

2001 survey of organochlorine pesticides in retail milk from Beijing, P R China.

A monitoring study was conducted in 2001 to determine the organochlorine pesticides and their metabolite residues in milk taken from supermarkets in Beijing, P. R. China.

Levels of extractable organohalogens in pine needles in China.

Pine needles can accumulate organohalogens from the ambient air, which are, hence, able to serve as a biomonitor to evaluate the levels of organochlorinated contaminants in the atmospheric environment. Extractable organochlorine (EOCl), the most abundant of the extractable organohalogens (EOX) in environmental samples, has received much attention as a parameter for evaluation of total contamination levels of organochlorinated compounds (OCs). However, few data concerning EOCl in vegetation are available.

Some polycyclic aromatic hydrocarbons in vegetables from northern China.

Nine important vegetables were collected from northern Chinese wholesale markets and analyzed for polycyclic aromatic hydrocarbon (PAH) contents. Anthracene, flupranthene, benzo(a)anthracene and benzo(a)pyrene were determined. The contents of the four PAH congeners were at the same level with the mean concentrations 6.