Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99


Any time

2019 ( 111 )

2018 ( 509 )

2017 ( 547 )

2016 ( 634 )

Custom range...

Search Results: 1 - 10 of 16973 matches for " gas chromatography-mass spectrometry. "
All listed articles are free for downloading (OA Articles)
Page 1 /16973
Display every page Item
Quality Evaluation of Policosanol Film-Coated Tablets by Simultaneous Determination of Eight Ingredients Using GC- FID and GC-MS  [PDF]
Han Yao, Chunmin Wei, Haibo Song, Ruichen Guo
Journal of Analytical Sciences, Methods and Instrumentation (JASMI) , 2012, DOI: 10.4236/jasmi.2012.21005
Abstract: A new and simple gas chromatographic (GC) method using flame ionization detector (FID) and mass spectrometry (MS) for the simultaneous determination of eight fatty alcohols in 10 mg policosanol film-coated tablets was established and applied to the quality control (QC) of policosanol film-coated tablets. A DB-35MS capillary column (30 m × 0.32 mm, 0.25 um) was employed for the separation. GC-FID was used to quantitatively analyze the eight ingredients with 1-eicosanol as internal standard, three of which were identified using GC-MS due to the lack of standard. The linearity, accuracy, precision, stability, robustness and sensitivity within the detection limits were evaluated. The average recovery of the method was 96.3-100.4% and linearity was (R > 0.999). The average drug content was found to be 96.8% of the labeled amount (10 mg).
Multiresidue Method for Determination of 67 Pesticides in Water Samples Using Solid-Phase Extraction with Centrifugation and Gas Chromatography-Mass Spectrometry  [PDF]
Abir Kouzayha, Abdul Rahman Rabaa, Mohamad Al Iskandarani, Daniel Beh, Hélène Budzinski, Farouk Jaber
American Journal of Analytical Chemistry (AJAC) , 2012, DOI: 10.4236/ajac.2012.33034
Abstract: A new multi-residue method based on solid-phase extraction (SPE) with centrifugation was developed for determination and quantitation of 67 pesticides in water samples. Two SPE cartridges were tested: Chromabond C18 and Oasis HLB. Parameters that influence the extraction efficiency such as the eluent volume, the sample loading volume, the addition of organic solvent to water sample, sorbent drying and elute concentration were optimized. The innovation of this work was the examination of the use of a centrifugation technique in both the drying and elution steps. When combined with centrifugation, the volume of the elution solvent was reduced to 2 mL and the time for sorbent drying decreased also to 10 min under vacuum. Under the optimized conditions, this method showed good recoveries higher than 65% - 68% for the 67 analyzed pesticides using the C18 and HLB cartridges with relative standard deviations lower than 9.7% - 12.3%. Limits of quantification were between 2 and 20 ng.L–1. The simplicity of the described method, use of less of organic solvent, short procedure time, and good recoveries demonstrate the advantages of this environmentally friendly approach for routine analysis of numerous samples.
A Greener Way to Screen Toothpaste for Diethylene Glycol  [PDF]
Yale Fu, Zhigang Hao, Barry Parker, Michael Knapp
American Journal of Analytical Chemistry (AJAC) , 2011, DOI: 10.4236/ajac.2011.28109
Abstract: A method developed for the screening of diethylene glycol (DEG) in toothpaste was released by the FDA in 2007. This method could not only quantify the DEG but also confirm if any potential interfering peak is pre- sent. However, disadvantages of this method such as intermittent shortages of the key reagent acetonitrile and the shorter than expected column-life issues have prompted a search for alternative solutions. An im- provement with an alternate “greener” extraction solvent is presented, and the method comparison and vali- dation are described in this article. The greener extraction solvent, ethanol with limited water, provided a better efficiency for the toothpaste sampling procedures. The limit of detection (LOD) and limit of quantita- tion (LOQ) are 0.0025% and 0.0084% in (w/w) unit, respectively. The sample recovery is 101.2%.
Direct Determination of Polychlorinated-Biphenyls in Automotive Shredder Residues by Gas Chromatography-Mass Spectrometry  [PDF]
María de los D. E. Otero, Mohamed N. K. Sayadi, Luis María Polo Díez
Journal of Analytical Sciences, Methods and Instrumentation (JASMI) , 2013, DOI: 10.4236/jasmi.2013.32011

An easy and rapid method is proposed for the determination of PCBs in automotive shredder residues, using gas chromatography combined with low resolution mass spectrometry (GC-MS). It is based on direct n-hexane solid-liquid extraction, subtracting background of the lineal aliphatic hydrocarbon interferences and integration of chromatographic peaks containing selected ion PCBs masses (256, 292 and 326 m/z), which are common in all PCBs formulations. Recoveries were in the 80% - 120% range; PCBs were detected and quantified in shredder samples from an automotive shredder industry, thus indicating the validity of the method.

Determination of Five (5) Possible Contaminants in Recycled Cardboard Packages and Food Simulants Using Ultrasound Assisted Extraction Coupled to GC-MS  [PDF]
Ioanna-Efpraxia Parigoridi, Konstantoula Akrida-Demertzi, Panagiotis G. Demertzis
Materials Sciences and Applications (MSA) , 2014, DOI: 10.4236/msa.2014.510075
A modified analytical procedure has been developed to test for 5 organic pollutants [benzophenone, 2 diisopropylnaphthalenes (DIPNs) {2,6- and 2,7-diisopropylnapthalene} and 2 hydrogenated terphenyls (HTPs) {m-terphenyl and o-terphenyl}] that can be found as residues in recycled cardboards intended for use as food packaging materials and to test for migration levels of these compounds in a food simulant (Tenax). A main objective was to develop a modified rapid and reliable method for the identification and quantification of these compounds at low concentrations. The method was based on ultrasound-assisted solvent extraction (UAE) followed by gas chromatography-mass spectrometry (GC-MS) analysis. The developed method was applied to analyze 3 commercially available recycled carton board food-packaging materials and also to study the potential migration of the 5 organic pollutants from these materials into Tenax to check if these recycled cardboards can be considered as suitable for use in direct contact with foodstuffs. The limits of detection (LODs) of standard solutions of the 5 compounds were determined at a signal-to-noise ratio of 3. The LODs and the limits of quantification (LOQs) of examined pollutants ranged between 0.005 to 0.5 mg/kg, and 0.1 to 1 mg/kg, respectively. The extremely low amounts of most contaminants that migrate from packaging materials to Tenax indicate that the recycled cardboards tested can be safely used for direct food contact applications.
The analysis of volatile flavor components of Jin Xiang garlic and Tai’an garlic  [PDF]
Changsong Shan, Chao Wang, Jin Liu, Peng Wu
Agricultural Sciences (AS) , 2013, DOI: 10.4236/as.2013.412101

The volatile flavor compounds of Jin Xiang garlic and Tai’an garlic in chemical composition were detected and analyzed and the contents of them were compared and determinated. The volatile constituents of Jin Xiang garlic and Tai’an garlic were compared and analyzed by automatic static headspace and gas chromatography-mass spectrometry. Qualitative analysis of samples was made through the analysis of gas chromatography-mass spectrometry and NIST mass spectral library computer retrieval, and quantitative analysis was made by using area normalization method. The analysis results show that the slight difference of the volatile flavor compounds was detected in different places of origin garlic and Jin Xiang garlic was detected more total sulfur-containing compounds than Tai’an garlic. Meanwhile, the contents of sulfur compounds of the fresh garlic were more than the stored garlic and there were significant differences between them. The tests results indicated that flavor substances’ types were slightly different between Jin Xiang garlic and Tai’an garlic, and regional differences cannot affect the garlic flavor substances type. Jin Xiang garlic has more obvious flavor substances than Tai’an garlic which play a decisive role in the garlic flavor, such as 1,3-dithiane, and allyl trisulfide and allyl disulfide and diallyl tetrasulphide. The result of this research indicates that Automatic static headspace and gas chromatography-mass spectrometry is a fast, easy, efficient and accurate method to analyze and identify the volatile flavor components of garlic.

Super Antibiotics, Part IV. Hyperforin, Relative and Absolute Stereochemistry Elucidated by Gas-Chromatography Mass-Spectrometry with Supersonic Molecular Beams  [PDF]
Ilia Brondz
International Journal of Analytical Mass Spectrometry and Chromatography (IJAMSC) , 2017, DOI: 10.4236/ijamsc.2017.53005
Abstract: Relative and absolute stereochemistry for hyperforin has been proposed by Brondz et al. was supported and new isomer of hyperforin-perforatrin has been discovered. Relative and absolute stereochemistry for perforatrin was proposed and elucidated by using gas-chromatography mass-spectrometry with supersonic molecular beams (SMB). The possibility of the existence of ambiguities in chirality as a hypothesis for the existence, and a new understanding, of chiral substances with shifting chirality is presented.
Study on the Difference between Volatile Constituents of the Different Parts from Elsholtzia ciliata by SHS-GC-MS  [PDF]
Xiaoming Wang, Lili Gong, Haiqiang Jiang
American Journal of Analytical Chemistry (AJAC) , 2017, DOI: 10.4236/ajac.2017.810045
Abstract: In this study, the comparison of Elsholtzia ciliata volatile compounds from the stem (with leaf) and flower was acquired. The volatile compounds of these two parts from Elsholtzia ciliata aerial parts were respectively analyzed by a rapid and convenient static headspace injection technique coupled with gas chromatography-mass spectrometry and the relative contents of each constituent between the two different parts were determined by peak area normalization. 61 compounds were identified in the stem (with leaf) and flower, among which 39 components simultaneously exist. 47 and 53 compounds were separated and identified in the volatile compounds from the different parts of Elsholtzia ciliata, respectively. There were differences among some volatile constituents of the two parts, but the main constituents were all Elsholtzia ketone, caryophyllene, 3-octanol and Dehydroelsholtzia ketone. The most abundant components in the stem (with leaf) included Elsholtzia ketone (84.20%), caryophyllene (4.3%) and 3-octanol (3.11%), while Elsholtzia ketone (88.03%), caryophyllene (3.33%) and 3-octanol (1.53%) were the main components in the flower. 8 single constituents were identified in the stem (with leaf) volatiles including 3-heptanone and linalool, while 14 constituents only including 2-methylbutanoic acid and Perillene have been found in the flower volatiles. Elsholtzia ketone was the main compound, and its concentration was significantly higher than other substances (>80% of the total oils in Elsholtzia ciliata). The study provided an important scientific base for the further utilization of Elsholtzia ciliata resources and may be helpful for systematically understanding the constituents of volatile compounds of Elsholtzia ciliata.
Multi-Residue Analysis of Organophosphorus Pesticides in Vegetable Using GC-MS  [PDF]
Dhia Eldin Elhag, Babeker S. Abdalla, Suliman A. Suliman, Imtinan Ali
Journal of Agricultural Chemistry and Environment (JACEN) , 2017, DOI: 10.4236/jacen.2017.64016
Abstract: This study investigates the levels of pesticide residues in Cucumbers (Cucumis sativus), potatoes (Solanum tuberosum subsp. Tuberosum) and tomatoes (Lycopersicon esculentum). The samples were minced in a food processor initially subjected to extraction followed by cleanup using solid phase extraction (SPE) column. Separation was performed on a GC capillary column (Rtx-5 ms-30 m × 0.25 mm× 0.25 μm). The sample was injected by using splitless mode, helium as the carrier gas followed by quadrupole mass spectrometry detection. The mobile phase flow rates, column temperatures, and MS parameters were all optimized to reach high sensitivity and selectivity. Seven pesticides were detected in tomatoes sample, six in cucumber and four in potatoes samples. The findings indicate risks and concerns for public health.
Gel Permeation Chromatography Purification and Gas Chromatography-Mass Spectrometry Detection of Multi-Pesticide Residues in Traditional Chinese Medicine  [PDF]
Wan-E Zhuang, Zhen-Bin Gong
American Journal of Analytical Chemistry (AJAC) , 2012, DOI: 10.4236/ajac.2012.31005
Abstract: The measurement of 23 organochlorine, organophosphorus, and pyrethroid pesticides in typical traditional Chinese medicine (TCM), flos lonicerae, was made using gel permeation chromatography (GPC) purification and gas chroma- tography-mass spectrometry (GC-MS) detection. The pesticides were extracted with ultrasonic device and 5.0 mL mixture of ethyl acetate and cyclohexane (1:1, v/v). Coextractants from sample matrices which may have interfere to the qualitative and quantitative analysis, such as pigments, were removed using GPC purification. Simultaneous full scan and selective ion monitor (scan/SIM) mode for GC-MS was used for qualitative and quantitative analysis, which pro- vided retention time and characteristic fragments ratio for each pesticide so as to positively identify each analyte. Rela- tive standard deviations (RSDs) were within 7.7% (5.0 - 22.5 μg/kg, n = 3). The recoveries of pesticide standards at the spiked concentration of 5.0 - 22.5 μg/kg were between 87.1% and 110.9%. Limits of detection (LODs) for the analytes were 0.16 - 3.2 μg/kg, which could meet the demand of routine analysis and TCM quality control.
Page 1 /16973
Display every page Item

Copyright © 2008-2017 Open Access Library. All rights reserved.