Electron Impact Mode Research Articles

Occurrence and distribution characteristics of polybrominated diphenyl ethers (PBDEs) from a closed deca-BDE manufacturing factory in Jiangsu province, China

Concentrations and distributions of polybrominated diphenyl ethers (PBDEs) were investigated in soils and plants from a closed deca-BDE manufacturing factory to evaluate and discuss their pollution level and distribution characteristics. Eight PBDEs were analyzed in this study. The eight native PBDEs and 13C12-PCB209 (internal standard) were bought from Accustandard Inc. The eight 13C12-labeled PBDEs (isotope internal standard) were obtained from the Cambridge Isotope Laboratories, Inc. Soxhlet was chosen as the sample extraction method. The majority of lipid and pigment were removed by adding concentrated H2SO4 to each extract. Then, the concentrated extracts were further cleaned by multilayer silica gel columns. Finally, the eluants were concentrated to 1 mL. An internal standard was added to the final extract prior to the instrumental analysis. Extracts were determined by gas chromatography coupled to mass spectrometry in electron impact mode with DB-1 column. Concentrations of PBDEs ranged from N.D. to 3.7 × 104 ng g−1 dry weight (dw) with the median concentrations from 0.60 to 1.17 × 104 ng g−1 dw. BDE-209 was the dominant congener in soils. The concentrations of PBDEs in different functional areas followed the order: manufacturing workshop (MW) → warehouse (WH) → administration area (AD). The levels of PBDEs were shown a decreasing tendency with the increase of the soil depth. However, different trends were observed between low-brominated BDE and high-brominated BDE. In plant samples, concentrations of ∑7 PBDEs (BDE-28, -47, -100, -99, -154, -153, -183) ranged from 7.89 to 1087.19 ng g−1 dw, and the concentrations of BDE-209 ranged from 2805.6 to 19,382.9 ng g−1 dw. The pollution level of PBDEs in the closed deca-BDE factory was lower than PBDEs of manufacturing factory, but higher than PBDEs of e-waste site and much higher than PBDEs of urban sites. The environmental risk caused by the residual of PBDE is of concern. This is the first research to study the pollution of PBDEs in soils and plants from a closed deca-BDE factory.

Volatile Profile Comparison of Raw and Dried Rizhome of Atractylodes japonica

Atractylodes japonica is a source of herbal medicinal material “Sab-Joo” for herbal medicine “Baekchul” in Korea. Volatile aroma compounds may play some valuable therapeutic activities. Volatiles in raw and dried Sab-Joo(the rhizome of A. japonica) were analyzed by GC-MS after a dynamic headspace method. The mashed samples were stabilized at 40°C for 30min and volatile compounds were captured by 100 □ polydimethylsiloxane coated SPME fiber just before DB-5MS column separation followed by mass spectrometric analysis (with electron impact mode). Among 58 detected peaks, the 15 major components were observed for their fate after drying of Sab-Joo. β-Elemene, β-maaliene, 2, 3, 4, 5-tetramethyltricyclo[3.2.1.02, 7] oct-3-ene, curcumene, 1-(3, 3-dimethyl-but-1-ynyl)-1, 2-dimethyl-3-methylene-cyclopropane, guaia-10, 11 diene, and furanodiene were diminished after drying. α-Selinene and valencene were almost disappeared in dried Sab-Joo. Among the eight volatiles relatively increased after drying, five components, such as β-patchoulene, valencene, α-selinene, 9, 10-dehydro-Isolongifolene, and (−)-aristolene were more than doubled up(percent change over 100%). β-Patchoulene, valencene increased about four times after drying. The major volatiles over 5%(NPA%) in the dried sample were all sesquiterpenes having molecular formula (MW=204). The relative quantitative volatile profiles were quite different before and after drying Sab-C15H24 Joo. Therefore the fate of the pharmaceutically/toxicallyimportant volatile components by the simple drying process should be carefully studied to maximize the efficacy and minimize the risk of the final product.

Simultaneous Determination of Coumarin and Its Derivatives in Tobacco Products by Liquid Chromatography-Tandem Mass Spectrometry.

In this paper an analytical method based on high performance liquid chromatography coupled to tandem mass spectrometry (HPLC-MS/MS) for the determination of coumarin and its derivatives in tobacco products was developed. The MS/MS fragmentation pathways of the eight coumarins were elucidated. The new analytical method was defined based on two main axes, an extraction procedure with acetonitrile and analyte detection performed by HPLC-MS/MS in electron impact mode. The excellent selectivity and sensitivity achieved in multiple reaction monitoring (MRM) mode allowed satisfactory confirmation and quantitation for the coumarin flavor additives. Under the optimized gradient elution conditions, it took only 4.5 min to separate all eight coumarins. Good linearity for all the analytes were confirmed by the correlation coefficient r2, ranging from 0.9987 to 0.9996. The limits of detection (LODs) and limits of quantitation (LOQs) of these compounds were in the range of 0.5–1.7 μg/kg and 1.7–5.2 μg/kg, respectively. The average recoveries at three spiked levels (LOQ, 1.5LOQ, 2LOQ) were all in the range of 69.6%–95.1% with RSDs (n = 6) lower than 5.3%. The method of HPLC-MS/MS developed in this study was initially applied to the research of coumarin flavor additives in tobacco products collected from the located market in Beijing from China and proved to be accurate, sensitive, convenient and practical.

Optimization of a microwave-assisted extraction procedure for the determination of selected alkyl, aryl, and halogenated phenols in sewage sludge and biosolids

A microwave-assisted extraction method for the determination of 15 alkyl, aryl, and halogenated phenols in sewage sludge and biosolids samples was developed and optimized. The effects of solvent, temperature, time, moisture content, acid, and number of extractions on the recovery of phenols were evaluated. Results indicated that extraction solvent had the greatest impact on the recovery of all phenols while pH had the largest effect on recovery of hexachlorophene and pentachlorophenol. Wet sludge samples were extracted with acetone-hexane mixture in the presence of glacial acetic acid. The extract was evaporated, acetylated by acetic anhydride and cleaned up by silica gel. For dry sludge samples, an optional procedure for the simultaneous extraction and acetylation of phenols was also proposed. Triclosan (TCS) and the alkyl and aryl phenols in sludge extracts were analyzed by gas chromatography-mass spectrometry (GC-MS) in electron-impact mode while polyhalogenated phenols were analyzed by GC-MS in negative ion chemical ionization mode. Method detection limits were ca. 200 ng/g for nonylphenol, <25 ng/g for TCS and other alkyl and aryl phenols, and <5 ng/g for other halogenated phenols. This method has been applied to the determination of phenolic compounds in over 150 sludge and biosolids samples since 2009.

Determination of Dihydrobenzoacridinone Structures by NMR, IR, and UV Spectroscopy and Mass Spectrometry

Introduction. Synthetic benzoacridinone derivatives are critical because of their applications as luminescent materials [1], antitumor drugs [2], and antibiotics [3]. The activity of such compounds was found to depend on the location of the carbonyl in the cyclic system [4]. Therefore, the location of the carbonyl in the fi nal product from three-component condensation of 2-naphthylamine, aromatic aldehydes, and dimedone is important because 9,9-dimethylor 10,10-dimethyl dihydrobenzoacridinones can be produced. The goal of the present work was to elucidate the structures of synthesized dihydrobenzoacridinone derivatives IVa–IVf. Experimental. 2-Naphthylamine (I, 1.43g, 0.01 mol), the appropriate aromatic aldehyde (IIa–IIf, 0.01 mol), and dimedone (III, 1.4 g, 0.01 mol) were refl uxed in EtOH until crystals of IVa–IVf began to precipitate (30–60 min) and then cooled. The resulting precipitate was fi ltered off, rinsed with Et2O, and recrystallized from EtOH:C6H6 (1:1). PMR and 13C NMR spectra were recorded from DMSO-d6 solutions (2–5%) on an Avance-500 spectrometer (BrukerBiospin, operating frequency 500.13 and 125.77 MHz for 1H and 13C). Chemical shifts were determined relative to TMS internal standard. COSY-45, NOESY, HSQC, and HMBC two-dimensional correlation spectra of IVa, IVd, and IVe were recorded in order to confi rm the structures and refi ne the resonances. All experimental results were obtained and processed using Topspin 2.1 software. IR spectra were recorded from thin layers or KBr pellets on a Protege-460 FTIR spectrophotometer (Nicolet). UV spectra of EtOH solutions (1·10–4 M) were taken on a Cary-300 spectrophotometer (Varian). Mass spectra of the synthesized compounds were measured using an Agilent 6890N gas chromatograph with an Agilent 5975 Inert mass-selective detector operating in electron-impact mode (70 eV) and was tuned to maximum sensitivity for the determined compounds. An HP-5ms capillary column (30 m × 0.25 mm × 0.25 μm) was connected directly to the mass spectrometer ion source. Samples were injected as CH2Cl2 solutions. Results and Discussion. Structures of synthesized 9,9-dimethyl-12-[5-(4-nitrophenyl)furan-2-yl]-9,10-dihydrobenzo[a] acridin-11-(7H,8H,12H)-one (IVa), 9,9-dimethyl-12-[5-(4-methoxy-2-nitrophenyl)furan-2-yl]-9,10-dihydrobenzo[a]acridin11-(7H,8H,12H)-one (IVb), 9,9-dimethyl-12-[5-(4-nitrophenyl)thiophen-2-yl]-9,10-dihydrobenzo[a]acridin-11-(7H,8H,12H)one (IVc), 9,9-dimethyl-12-[5-(3-nitrophenyl)thiophen-2-yl]-9,10-dihydrobenzo[a]acridin-11-(7H,8H,12H)-one (IVd), 12-[5-(4-bromophenyl)-1-methyl-1H-pyrrol-2-yl]-9,9-dimethyl-9,10-dihydrobenzo[a]acridin-11-(7H,8H,12H)-one (IVe), and 12-[5-(2-bromophenyl)-1-methyl-1H-pyrrol-2-yl]-9,9-dimethyl-9,10-dihydrobenzo[a]acridin-11-(7H,8H,12H)-one (IVf) were elucidated using UV, IR, PMR, and 13C NMR spectroscopy and mass spectrometry. The results indicated that condensation of 2-naphthylamine (I), aromatic aldehydes IIa–IIf, and dimedone (III) produced 9,9-dimethyl-12-[5-(aryl)furan-(or thiophen,

Determination of Amaryllidaceae alkaloids in snowdrop (Galanthus elwesii) from Taurus Mountains

The family Amaryllidaceae, well known for their ornamental bulbous members and its chemically important and bioactive alkaloids, has attracted the interest of phytochemists. Among these alkaloids, galanthamine has been known as an anticholinesterase inhibitor and it is used in the treatment of mild to moderate Alzheimer's disease. Moreover, antitumor, anti-inflammatory and antiprotozoal alkaloids have been isolated from different Amaryllidaceae species [1]. Among the Amaryllidaceae genera, Galanthus L. is represented in 14 taxa and one hybrid in Turkey [2]. In this study, the aerial parts and bulbs of Galanthus elwesii Hook. was collected from Akseki, Antalya. The alkaloid profile of the samples was determined by gas chromatography-mass spectroscopy (GC-MS) using Thermo GC-Trace Ultra Ver: 2.0., Thermo MS DSQ II. A TR-5 MS (30 m x 0.25 mm x 0.25 µm) column was used and GC-MS system was operated in the electron impact mode (electron energy of 70 eV). Compound identification was performed with the help of the National Institute of Standards and Technology (NIST) standard library and, where available, by comparison with the retention times and mass fragmentation patterns of standard reference compounds. Totally, twenty-four different compounds were detected. Haemanthamine, galanthindole and 6-O-methylpretazettine have been found as major constituents, whereas galanthamine was detected in very small amounts in the tested samples.

Comparison of electron and chemical ionization modes for the quantification of thiols and oxidative compounds in white wines by gas chromatography–tandem mass spectrometry

A rapid, sensitive method for assaying volatile impact compounds in white wine was developed using gas chromatography–tandem mass spectrometry (GC–MS/MS) technology, with a triple quadrupole analyzer operating in chemical ionization and electron impact mode. This GC–MS/MS method made it possible to assay volatile thiols (3SH: 3-sulfanylhexanol, formerly 3MH; 3SHA: 3-sulfanylhexyl acetate, formerly 3MHA; 4MSP: 4-methyl-4-sulfanylpentan-2-one, formerly 4MMP; BM: benzenemethanethiol; E2SA: ethyl 2-sulfanylacetate; and 2FM: 2-furanmethanethiol) and odoriferous oxidation markers (Sotolon: 4,5-dimethyl-3-hydroxy-2(5)H-furanone, methional, and phenylacetaldehyde) simultaneously in dry white wines, comparing electron impact (EI) and chemical ionization (CI) modes. More molecular ions were produced by CI than protonated molecules, despite the greater fragmentation caused by EI. So, even using the best reactant gas giving the highest signal for thiols, EI was the best ionization mode, with the lowest detection limits. For all compounds of interest, the limits of quantification (LOQ) obtained were well below their detection thresholds (ranging from 0.5 to 8.5ng/L for volatile thiols and 65–260ng/L for oxidation markers). Recovery rates ranged from 86% to 111%, reproducibility (in terms of relative standard deviation; RSD) was below 18% in all cases, with correlation coefficients above 0.991 for all analytes. The method was successfully applied to the analysis of compounds of interest in Sauvignon Blanc wines from a single estate and ten different vintages.

Application of gas chromatography-tandem mass spectrometry (GC/MS/MS) for the analysis of deuterium enrichment of water.

Incorporation of deuterium from deuterium oxide ((2) H2 O) into biological components is a commonly used approach in metabolic studies. Determining the dilution of deuterium in the body water (BW) pool can be used to estimate body composition. We describe three sensitive GC/MS/MS methods to measure water enrichment in BW. Samples were reacted with NaOH and U-(13) C3 -acetone in an autosampler vial to promote deuterium exchange with U-(13) C3 -acetone hydrogens. Headspace injections were made of U-(13) C3 -acetone-saturated air onto a 30-m DB-1MS column in electron impact-mode. Subjects ingested 30 ml (2) H2 O, and plasma samples were collected. BW was determined by standard equation. Dual-energy X-ray absorptiometry scans were performed to calculate body mass, body volume and bone mineral content. A four-compartmental model was used to estimate body composition (fat and fat free mass). Full-scan experiments generated an m/z 45 peak and to a lesser extent an m/z 61 peak. Product fragment ions further monitored included 45 and 46 using selected ion monitoring (Method1), the 61 > 45 and 62 > 46 transition using multiple reaction monitoring (MRM; Method2) and the neutral loss, 62 > 45, transition (Method3). MRM methods were optimized for collision energy (CE) and collision-induced dissociation (CID) argon gas pressure with 6 eV CE and 1.5 mTorr CID gas being optimal. Method2 was used for final determination of (2) H2 O enrichment of subjects because of lower natural background. We have developed a sensitive method to determine (2) H2 O enrichment in BW to enable measurement of FM and FFM.

Selective determination of dimenhydrinate in presence of six of its related substances and potential impurities using a direct GC/MS method

A novel simple, direct and selective gas chromatography–mass spectrometry (GC/MS) procedure was developed for the determination of the antihistamine drug dimenhydrinate (DMH) in presence of six of its related substances and potential impurities, namely, diphenylmethane, diphenylmethanol, benzophenone, orphenadrine, caffeine and 8-chlorocaffeine. The method involved resolution of the underivatized compounds using a trifluoropropylmethyl polysiloxane (Rtx-200) capillary column and the mass spectrometric detection was carried out in the electron-impact (EI) mode. Excellent baseline separation of DMH and the cited related substances was achieved in less than 15min. Quantification of the parent drug DMH was based on measuring its peak area. The reliability and analytical performance of the proposed method were validated with respect to linearity, range, precision, accuracy, specificity, robustness, detection and quantification limits. Calibration curve of DMH was linear over the range 50–500μg/mL with determination coefficient (R2)=0.9982. The proposed method was successfully applied for the assay of DMH in tablets dosage form with recoveries>96.80%.

Essential Oil Secondary Metabolites Variation of Salvia palaestina Leaves Growing wild from Different Locations in Palestine

Article history: Received on: 05/10/2015 Revised on: 20/10/2015 Accepted on: 09/11/2015 Available online: 27/11/2015 Herbal medicine is widely practiced in Palestine. Salvia palaestina (Lamiaceae) in particular is heavily used because of its acquired traditional reputation over the years rather than scientific basis. S. palaestina essential oils contain secondary metabolites whose production is influenced by many factors that determine their composition and yield. Wild leaves of S. palaestina were collected from eight different locations in Palestine. Air dried leaves were subjected to steam distillation (SD) and the composition of essential oils was determined for the first time by GC-MS in the electron impact mode. Twenty volatile and semi-volatile components were identified. The major components in all samples were eucalyptol and the percentages ranged from 51.9% to 63.06%. Other components were found but to a lesser extent mainly β-Thujene, -Myrcene, (±)-Camphor, α-Terpineol, and βCaryophyllene.

EI-GC/MS/MS를 이용한 니트로사민류의 수질분석

This study assessed analysis of N-nitrosamines by separation, identification, and quantification using a gas chromatography (GC) mass spectrometer (MS) with electron impact (EI) mode. Samples were pretreated by a automated solid phase extraction (SPE) and a nitrogen concentration technique to detect low concentration ranges. The analysis results by EI-GC/MS (SIM) and EI-GC/ MS/MS (MRM) on standard samples with no pretreatment exhibited similar results. On the other hand, the analysis of pretreated samples at low concentrations (i.e. ng/L levels) were not reliable with a EI-GC/MS due to the interferences from impurity peaks. The method detection limits of eight (8) N-nitrosamines by EI-GC/MS/MS analysis ranged from 0.76 to 2.09 ng/L, and the limits of quantification ranged from 2.41 to 6.65 ng/L. The precision and accuracy of the method were evaluated using spiked samples at concentrations of 10, 20 and 100 ng/L. The precision were 1.2~13.6%, and the accuracy were 80.4~121.8%. The R 2 of the calibration curves were greater than 0.999. The recovery rates for various environmental samples were evaluated with a surrogate material (NDPA-d14) and ranged 86.2~122.3%. Thus, this method can be used to determine low (ng/L) levels of N-nitrosamines in water samples.

Linear Nitramine (DNDA-57): Synthesis, Scale-Up, Characterization, and Quantitative Estimation by GC/MS

Dinitro-diaza-alkanes (DNDA-57) are linear nitramine plasticizers and find use in low-temperature sensitivity coefficient propellants. DNDA-57 is a mixture of 2,4-dinitro-2,4-diazapentane (DNDA-5), 2,4-dinitro-2,4-diazahexane (DNDA-6), and 3,5-dinitro-3,5-diazaheptane (DNDA-7) with percentage composition of 40 ± 5%, 44 ± 5% and 11 ± 2%, respectively. The synthesis process of DNDA-57 was established with slight modification of the reaction parameters to obtain good yield and the process was scaled up. The synthesized compound was thoroughly characterized by spectroscopic as well as thermal methods. The present study emphasizes gas chromatographic–mass spectrometric (GC/MS) characterization by electron impact (EI) mode and chemical ionization (CI) mode to determine the fragmentation pattern. Further, the identified components were confirmed with general characterization. The study reveals that DNDA-5, DNDA-6, and DNDA-7 follow identical decomposition pattern. The friction and impact sensitivity study unveils the insensitive nature of DNDA-57.

Determination of Phthalic Acid Ester in Dunaliella by GC-MS

The aim of this study was to evaluate the levels of PAEs in Dunaliella Salina algae. A determination of PAEs in Dunaliella Salina algae was discussed. After concentration, the samples were directly injected into GC-MS in positive-ion electron impact mode. The method was applied to real sample and could potentially overcome the interference from large amounts of pigment. It was shown to be a reliable method for determination of PAEs in routine analysis.

2nd dimensional GC-MS analysis of sweat volatile organic compounds prepared by solid phase micro-extraction.

The characteristics of an individual's odor from sweat, breath and skin provide important information for criminal tracking in field of forensic science. Solid phase micro-extraction gas chromatography/mass spectrometry (SPME-GC/MS) was used to determine human sweat volatile organic compounds (VOCs) profiles. The mass spectrometric analysis (with electron impact mode) followed by 2nd dimensional separation with two different GC columns (one polar and one relatively nonpolar) connected in parallel were used to identify the 574 compounds from sweat samples. The components included alcohols, aldehydes, aliphatics/aromatics, carboxylic acids, esters, ketones, and other organic compounds (amides/amines, thio/thioesters, oxide, sulfides, nitro compounds). Of these compounds, 1-tridecanol, 1,3-bis(1,1-dimethyl ethyl)-benzene, 4,4'-(1-methylethylidene) bis-phenol and 7-acetyl-6-ethyl-1,1,4,4,-tetramethyl-tetraline were common components in all donor's sweat volatile samples. Age-related specific compounds were also detected. The results suggest that characteristic volatile profiles of human sweat emanations could provide the valuable information to forensic scientists.

Dependence of Mass Spectrometric Fragmentation on the Bromine Substitution Pattern of Polybrominated Diphenyl Ethers

This study investigates the link between the bromine substitution and the mass spectrometric fragmentation of polybrominated diphenyl ethers (PBDEs). The mass spectra of 180 PBDEs were obtained in both electron impact (EI) and electron capture negative ionization (ECNI) modes using a single quadrupole mass spectrometer (MS) as well as EI using a tandem MS (MS/MS). The major ions are M(+), [M-2Br](+), [M-2Br](2+) and [M-nBr-28](+) in EI, and Br(-), [HBr2](-) and [C6BrnO](-) in ECNI. In EI-MS, congeners without ortho bromine or having 2,3 substitution on one ring and no ortho bromines on the other were more robust than the others in each homolog. These congeners generated low [M-2Br](+) but relatively high [M-2Br](2+) in EI-MS and negligible [HBr2](-) in ECNI-MS. In EI-MS/MS, the molecular ions of these congeners required higher collision energy to debrominate, and produced additional ions of [M-nBr](+) and [M-nBr-28](+). Full ortho substitution promotes C-O cleavage forming [C6BrnO](-) in ECNI for congeners with >5 bromines. The relationship between the abundance of M(+) and collision energy of the EI-MS/MS was well characterized with a logistic regression model. Principle component analysis found associations between the inflection point collision energy and a few molecular descriptors. Quantum chemistry simulations revealed different EI-induced fragmentation mechanisms among four dibrominated congeners, supporting the hypothesized formation of a stable dibenzofuran-like intermediate during the fragmentation of some congeners but not of others.

Essential Oil Composition of Justicia brandegeeana

The results of the essential oil analysis of J. brandegeeana are presented in Table 1. GC and GC-MS analysis showed 32 compounds, representing 96.19% of the total oil. Alcohols are the dominant class of compounds, constitute 68.42% of the total oil, including phytol (33.12%), 1-octen-3-ol (14.45%), 3-octanol (14.30%), 9,12,15-octadecatrien-1-ol (6.10%), and trans-2-pinanol (0.45%). Aldehydes and ketones constitute 9.92% of the total oil. Ester and alkanes constitute only 6.59% and 1.10% of the total oil, respectively. The aerial parts of J. brandegeeana were collected during the flowering stage from Guilin, Guangxi, China in June 2011. A voucher specimen have been deposited in the Herbarium of the Guangxi Institute of Botany (IBK00055519). The fresh leaves of the plant (300 g) were subjected to hydrodistillation for 4 h using a Clevenger-type apparatus. The clear yellowish oil was isolated in a yield of 0.1% (w/w). The constituents of the oil were analyzed by GC and GC/MS. GC analysis of the volatile components was carried out using an Agilent 7890 instrument coupled to a flame ionization detector (FID). Compounds were separated on a HP-5 capillary column (30 m 0.25 mm, film thickness 0.25 m). The column temperature was kept at 50C for 1 min and programmed to 230C at a rate of 5C/min, and kept constant at 230C for 6 min and then programmed to 300C at a rate of 10C/min. Injector and detector temperatures were 250C, and the flow rate of helium as carrier gas was 1 mL/min. Retention indices (RI) were determined in relation to a homologous series of n-alkanes (C8–C24) under the same conditions. Relative concentrations of the components were obtained by peak area normalization. No response factors were calculated. GC/MS analysis was performed using an Agilent 5975 mass spectrometer coupled to an Agilent 7890 gas chromatograph equipped with an HP-5MS capillary column (30 m 0.25 mm, film thickness 0.25 m). The carrier gas was helium, and the chromatographic conditions were as above. All mass spectra were acquired in the electron-impact (EI) mode with an ionization voltage of 70 eV. Identification of the individual oil components was accomplished by comparison of their mass spectral data with the MS library (NIST 98 and Wiley 5) and literature values. Identification of the oil components was also possible by comparison of their linear retention indices with those from the literature [9–13] and those stored in the MS library [NIST database ChemStation data system]. For the purpose of quantitative analysis, the area percent obtained by FID was used as base.

Effects of small interfering RNA-mediated hepatic glucagon receptor inhibition on lipid metabolism in db/db mice

Hepatic glucose overproduction is a major characteristic of type 2 diabetes. Because glucagon is a key regulator for glucose homeostasis, antagonizing the glucagon receptor (GCGR) is a possible therapeutic strategy for the treatment of diabetes mellitus. To study the effect of hepatic GCGR inhibition on the regulation of lipid metabolism, we generated siRNA-mediated GCGR knockdown (si-GCGR) in the db/db mouse. The hepatic knockdown of GCGR markedly reduced plasma glucose levels; however, total plasma cholesterol was increased. The detailed lipid analysis showed an increase in the LDL fraction, and no change in VLDL HDL fractions. Further studies showed that the increase in LDL was the result of over-expression of hepatic lipogenic genes and elevated de novo lipid synthesis. Inhibition of hepatic glucagon signaling via siRNA-mediated GCGR knockdown had an effect on both glucose and lipid metabolism in db/db mice.

Simultaneous determination of 23 flavor additives in tobacco products using gas chromatography–triple quadrupole mass spectrometry

A method based on gas chromatography coupled to triple quadrupole tandem mass spectrometry (GC–QqQ MS/MS) was developed for the determination of 23 widely used flavor additives in tobacco products in this paper. The MS/MS fragmentation pathway of the cinnamic esters additives was illustrated. The new analytical method was defined based on two main axes, ultrasonic solvent extraction procedure with dichloromethane and analyte detection performed by GC–QqQ MS/MS in electron impact mode. The excellent selectivity and sensitivity achieved in multiple reactions monitoring (MRM) mode allowed satisfactory confirmation and quantitation for the tobacco flavor additives. The linear range of the 23 flavor additives is 0.2–500.0μg/L with good correlation coefficients (r2>0.9963). The limits of detection (LODs) and limits of quantitation (LOQs) of these compounds were in the range 0.1–2.0μg/L and 0.4–6.0μg/kg, respectively. The average recoveries at three spiked levels (LOQ, 2LOQ, 4LOQ) were all in the range 62.1–93.8% with RSDs (n=6) lower than 7.8%. The method of GC–QqQ MS/MS developed in this study was initially applied to the research of flavor additives in 12 retail cigarette samples and proved to be accurate, sensitive, convenient and practical.

Chemical variability and antioxidant activity of Eryngium maritimum L. essential oils from Corsica and Sardinia

ABSTRACTThe chemical compositions of Corsican and Sardinian Eryngium maritimum L. essential oils were investigated using column chromatography, gas chromatography with flame ionization detection and gas chromatography–mass spectrometry in electron impact mode. Sixty‐three compounds were identified accounting for 85.8–95.7% of the total amount. With germacrene D (13.7–45.9%), three uncommon oxygenated sesquiterpenes, 4βH‐cadin‐9‐en‐15‐al (18.4–27.6%), 4βH‐cadin‐9‐en‐15‐ol (2.2–14.3%) and 4βH‐muurol‐9‐en‐15‐al (4.3–9.3%), were identified as main components of the essential oils obtained from the plant aerial parts. Relative to these, essential oils from the roots differed drastically with high contents of 2,4,5‐trimethylbenzaldehyde (39.8%), 2,3,6‐trimethylbenzaldehyde (29.0%) and α‐muurolene (23.5%). The chemical variability of Corsican and Sardinian E. maritimum essential oils was studied using statistical analysis. A direct correlation between the island of origin of the sample essential oils and their chemical compositions was assessed. Corsican essential oils exhibited higher amounts of hydrocarbon terpenes than Sardinian samples. Relative to other Eryngium species, Corsican and Sardinian E. maritimum essential oils exhibited original compositions with sesquiterpene aldehydes. These compounds, together with total essential oil, were tested for antioxidant properties using the DPPH and ABTS radical‐scavenging activity tests. No meaningful activity could be attributed to sesquiterpene aldehydes and the corresponding alcohols but the total essential oil and the oxygenated fraction of E. maritimum both demonstrated strong antioxidant properties. Copyright © 2013 John Wiley & Sons, Ltd.

Seasonal variations of particle-associated nitrosamines by gas chromatography–mass spectrometry in the atmospheric environment of Zonguldak, Turkey

A gas chromatography-mass spectrometry method has been proposed for the determination of low-level mutagenic and carcinogenic nitrosamines in particulate matter. The method includes the collection of particulate matters (PM2.5 and PM10) using a dichotomous Partisol 2025 sampler and extraction of the compounds from aqueous solution with dichloromethane/2-propanol after sonication with a slightly basic water solution prior to their GC-MS analysis in electron impact mode. The obtained recoveries of nitrosamines ranged from 92.4 to 99.2 %, and the precision of this method, as indicated by the relative standard deviations, was within the range of 0.95-2.46 %. The detection limits obtained from calculations using the GC-MS results based on S/N=3 were found within the range from 4 to 22 pg/m(3). The predominant nitrosamines determined in particulate matter were N-nitrosodimethylamine, N-nitrosodiethylamine, N-nitrosodibutylamine and N-nitrosomorpholine. Furthermore, N-mono- and dinitrosopiperazine and N-nitrosoethylbutylamine were also determined. N-dinitrosopiperazine was detected in PM2.5 samples at the highest concentrations of up to 22.85 ng/m(3) and in PM2.5-10 samples at concentrations up to 7.60 ng/m(3) in winter, whereas it was found in PM2.5 samples up to 5.15 ng/m(3) and in PM2.5-10 samples up to 3.12 ng/m(3) in summer. The total concentrations of nitrosamines were up to 161.4 ng/m(3) in fine and 53.90 ng/m(3) in coarse fractions in winter, whereas in summer were up to 35.24 and 12.60 ng/m(3), respectively. The concentration levels of nitrosamines fluctuated significantly within a year, with higher means and peak concentrations in the winter compared to that in the summertime. The seasonal variations of particle-associated nitrosamine concentrations were investigated together with their relationships with meteorological parameters using Pearson's correlation analysis in the winter and summer periods. Analysis of variance was used to determine which concentrations of nitrosamines were statistically different from one another and, together with meteorological parameters and discriminant analysis, was used to classify the particle samples by particle size according to seasons. The classification results of the particle samples in different seasons were very satisfactory, allowing 99.5 % of cases to be correctly grouped.