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Mario Francesco Mirabelli, Renato Zenobi
A novel capillary ionization source based on atmospheric pressure photoionization (cAPPI) was developed and used for the direct interfacing between solid-phase microextraction (SPME) and mass spectrometry (MS). The efficiency of the source was evaluated for direct and dopant-assisted photoionization, analyzing both polar (e.g., triazines and organophosphorus pesticides) and nonpolar (polycyclic aromatic hydrocarbons, PAHs) compounds. The results show that the range of compound polarity which can be addressed by direct SPME-MS can be substantially extended by using cAPPI, compared to other sensitive techniques like direct analysis in real time (DART) and dielectric barrier discharge ionization (DBDI)...
March 14, 2018: Analytical Chemistry
Juan Zheng, Junlong Huang, Fei Xu, Chuyi Ni, Xintong Xie, Fang Zhu, Dingcai Wu, Gangfeng Ouyang
Hollow carbon nanospheres (HCNs) with numerous nanopores in their ultrathin carbon shells have been prepared and applied as SPME fiber coatings. Benefiting from its ultrahigh surface area, short diffusion distance, and nitrogen doping, the HCNs-coated fiber demonstrates excellent properties of fast mass transfer, broad-spectrum adsorption and high extraction efficiencies. These encouraging results could offer a benchmark for developing advanced SPME in environment analyses requiring high-performance enrichment of abundant analytes, especially for unknown compounds...
March 14, 2018: Nanoscale
Yan Liu, Yifu Huang, Guosheng Chen, Junlong Huang, Juan Zheng, Jianqiao Xu, Shuqin Liu, Junlang Qiu, Li Yin, Wenhong Ruan, Fang Zhu, Gangfeng Ouyang
Sensitivity and selectivity of the solid phase microextraction (SPME) in analysis are mostly determined by the coating material of the fiber used. Graphene oxide (GO) has attracted great attention because of its large specific surface area, rich oxygen functional groups, good dispersibility in aqueous solution and high reactivity. However, the low thermal stability of the functional groups limits the wide application of GO in SPME coating design. Highly cross-linked polyoxyethylene (POE) is a substrate widely used for composite material construction, which could significantly improve the thermal stability, water resistance as well as biocompatibility of the functional materials...
July 26, 2018: Analytica Chimica Acta
Ariel Fontana, Isaac Rodríguez, Rafael Cela
The suitability of dispersive liquid-liquid microextraction (DLLME) and gas chromatography accurate mass spectrometry (GC-MS), based on a time-of-flight (TOF) MS analyzer and using electron ionization (EI), for the characterization of volatile and semi-volatile profiles of grape marc distillates (grappa) are evaluated. DLLME conditions are optimized with a selection of compounds, from different chemical families, present in the distillate spirit. Under final working conditions, 2.5 mL of sample and 0.5 mL of organic solvents are consumed in the sample preparation process...
March 3, 2018: Journal of Chromatography. A
Baree Chilcote, LaTara Rust, Katie D Nizio, Shari L Forbes
At outdoor crime scenes, cadaver-detection and blood-detection dogs may be tasked with locating blood that is days, weeks or months old. Although it is known that the odour profile of blood will change during this time, it is currently unknown how the profile changes when exposed to the environment. Such variables must be studied in order to understand when the odour profile is no longer detectable by the scent-detection dogs and other crime scene tools should be implemented. In this study, blood was deposited onto concrete and varnished wood surfaces and weathered in an outdoor environment over a three-month period...
March 2018: Science & Justice: Journal of the Forensic Science Society
Oscar van Mastrigt, Tjakko Abee, Søren K Lillevang, Eddy J Smid
During food fermentation processes like cheese ripening, lactic acid bacteria (LAB) encounter long periods of nutrient limitation leading to slow growth. Particular LAB survive these periods while still contributing to flavour formation in the fermented product. In this study the dairy Lactococcus lactis biovar diacetylactis FM03-V1 is grown in retentostat cultures to study its physiology and aroma formation capacity at near-zero growth rates. During the cultivations, the growth rate decreased from 0.025 h-1 to less than 0...
August 2018: Food Microbiology
A Soto, B Ballesteros, E Jiménez, M Antiñolo, E Martínez, J Albaladejo
The relative-rate technique has been used to determine the rate coefficient for the reaction of Cx F2x+1 CHCH2 (x = 1, 2, 3, 4 and 6) with ozone at (298 ± 2) K and (720 ± 5) Torr of air by FTIR (Fourier Transform Infrared Spectroscopy) and by GC-MS/SPME (Gas Chromatography-Mass Spectroscopy with Solid Phase Micro Extraction) in two different atmospheric simulation chambers. The following rate coefficients, in units of 10-19  cm3 molecule-1 s-1 , were obtained: (3.01 ± 0.10) for CF3 CHCH2 , (2...
March 1, 2018: Chemosphere
Lucyna Konieczna, Mariusz Belka, Magdalena Okońska, Magdalena Pyszka, Tomasz Bączek
In recent years, there has been an increasing worldwide interest in the use of alternative sample preparation methods that are proceeded by separation techniques. Fused deposition modeling (FDM) is a 3D printing technique that is based the consecutive layering of softened/melted thermoplastic materials. In this study, a group of natural steroids and sexual hormones - namely, aldosterone, cortisol, β-estradiol, testosterone, dihydrotestosterone, and synthetic methyltestosterone and betamethasone - were separated and determined using an optimized high-performance liquid chromatography coupled to mass spectrometry (LC-MS) method in positive ionization mode...
February 21, 2018: Journal of Chromatography. A
M Demirkurt, Y A Olcer, M M Demir, A E Eroglu
Parabens are used as antimicrobial preservatives in food, cosmetic products and pharmaceuticals regardless of their endocrine disrupting effect. In this study, highly selective molecular imprinted polymers (MIPs) were synthesized in submicron-sizes and converted to an SPME fiber coating through electrospinning process in order to determine parabens in water samples. Conversion of MIP to a fiber is achieved via creation of spacial knitting around MIP by polystyrene. The selectivity and extraction ability of the fibers were compared with the commercial fibers and the corresponding non-imprinted polymer (NIP) coated fiber...
July 19, 2018: Analytica Chimica Acta
Xiao-Fei Wu, Min Zhang, Bhesh Bhandari, Zhongqin Li
BACKGROUND: Microwave-assisted pulse-spouted bed freeze-drying (MPSFD) uses microwave heating to substitute the customary conduction heating during FD, resulting in high-quality dried samples with short drying time. The aim of this study was to determine the effect of MPSFD on volatile compounds and structural aspects of Cordyceps militaris. In order to highlight the effect of MPSFD, the freeze-drying (FD, recognized for its high-quality products) and hot air dying (HD, the most commonly used) were also evaluated using headspace solid phase micro-extraction combined with gas chromatography-mass spectrometry (HS-SPME-GC-MS) and mid-Fourier transform infrared (FTIR) spectroscopy...
March 8, 2018: Journal of the Science of Food and Agriculture
Razieh Mohebat, Mina Zare Bidoki
The volatile compounds from various parts of Echinops ilicifolius (Compositae) such as flowers, leaves and roots obtained by hydrodistillation (HD) and headspace solid-phase microextraction (HS-SPME) methods were subsequently analysed by GC and GC/MS and compared. Thirty-seven and 20 components of the flower of E. ilicifolius were characterized, representing 99.7% and 100.0% of the total compositions using the HD and HS-SPME methods, respectively. The major constituents of the hydrodistilled oil were identified as linalool (58...
February 2018: Royal Society Open Science
Lucia Škulcová, Kerstin E Scherr, Lukáš Chrást, Jakub Hofman, Lucie Bielská
The fate of organic chemicals and their metabolites in soils is often investigated in model matrices having undergone various pre-treatment steps that may qualitatively or quantitatively interfere with the results. Presently, effects associated with soil sterilization by γ-irradiation and soil spiking using an organic solvent were studied in one freshly spiked soil (sterilization prior to contamination) and its field-contaminated (sterilization after contamination) counterpart for the model organic compound 1,1-Dichloro-2,2-bis(4-chlorophenyl)ethene (p,p'-DDE)...
March 3, 2018: Ecotoxicology and Environmental Safety
Silvia Giovanelli, Marinella De Leo, Claudio Cervelli, Barbara Ruffoni, Daniela Ciccarelli, Luisa Pistelli
Helichrysum genus consists of about 600 species widespread throughout the world, especially in South Africa and in the Mediterranean area. In this study the aroma profile (HS-SPME) and the EO compositions of seven Helichrysum species (H. cymosum, H. odoratissimum, H. petiolare, H. fontanesii, H. saxatile, H. sanguineum and H. tenax) were evaluated. All the plants were grown in Italy under the same growth conditions. The volatile constituents, particularly monoterpenes, depended by the plant's genotype and ecological adaptation...
March 6, 2018: Chemistry & Biodiversity
Jiwoo An, Jared L Anderson
A double-confined polymeric ionic liquid (PIL) sorbent coating was fabricated for the determination of nine ultraviolet (UV) filters in sample solutions containing high salt content by direct immersion solid-phase microextraction (DI-SPME) coupled to high-performance liquid chromatography (HPLC). The IL monomer and crosslinker cations and anions, namely, 1-vinyl-3-decylimidazolium styrenesulfonate ([VImC10 ][SS]) and 1,12-di(3-vinylbenzylimidazolium) dodecane distyrenesulfonate ([(VBIm)2 C12 ] 2[SS]), were co-polymerized to create a highly stable sorbent coating which allowed for up to 120 direct-immersion extractions in 25% NaCl (w/v) solution without a decrease in its extraction capability...
May 15, 2018: Talanta
Ling-Ling Ying, De-Yin Wang, Hui-Ping Yang, Xi-Yan Deng, Chao Peng, Chao Zheng, Bei Xu, Lin-Yi Dong, Xu Wang, Liang Xu, Yan-Wen Zhang, Xian-Hua Wang
A combination between modification with porous layer and grafting of polyethyleneimine (PEI) on the inner face of capillary was for the first time developed for boronate affinity in-tube solid-phase microextraction (SPME) material to enhance the extraction capacity for cis-diol-containing polyphenols. The successful synthesis of boronate-decorated polyethyleneimine-grafted porous layer open tubular (BPPLOT) capillary was confirmed by scanning electron micrograph, Fourier transform-infrared spectra and absorption experiments...
February 21, 2018: Journal of Chromatography. A
Jie Wang, Allison Taylor, Daniel Schlenk, Jay Gan
Risk assessment of hydrophobic organic contaminants (HOCs) using the total chemical concentration following exhaustive extraction may overestimate the actual availability of HOCs to non-target organisms. Existing methods for estimating HOC bioavailability in soil have various operational limitations. In this study, we explored the application of isotope dilution method (IDM) to quantify the accessible fraction (E) of DDTs and PCBs in both historically-contaminated and freshly-spiked soils. After addition of13 C or deuterated analogues to a soil sample, the phase distribution of isotope-labeled and native chemicals reached an apparent equilibrium within 48 h of mixing...
February 27, 2018: Environmental Pollution
Yan-Qin Yang, Hong-Xu Yin, Hai-Bo Yuan, Yong-Wen Jiang, Chun-Wang Dong, Yu-Liang Deng
In the present work, a novel infrared-assisted extraction coupled to headspace solid-phase microextraction (IRAE-HS-SPME) followed by gas chromatography-mass spectrometry (GC-MS) was developed for rapid determination of the volatile components in green tea. The extraction parameters such as fiber type, sample amount, infrared power, extraction time, and infrared lamp distance were optimized by orthogonal experimental design. Under optimum conditions, a total of 82 volatile compounds in 21 green tea samples from different geographical origins were identified...
2018: PloS One
Kseniya Dryahina, David Smith, Patrik Španěl
RATIONALE: The major objective of this exploratory study was to implement selected ion flow tube mass spectrometry, SIFT-MS, as a method for the on-line quantification of the volatile organic compounds, VOCs, in the headspace of the ground roasted coffee. METHODS: The optimal precursor ions and characteristic analyte ions were selected for real-time SIFT-MS quantification of those VOCs that are most abundant in the headspace or known to contribute to aroma. NO+ reagent ion reactions were exploited for most of the VOC analyses...
February 27, 2018: Rapid Communications in Mass Spectrometry: RCM
Jihong Zhang, Li Zeng, Shaoyang Chen, Helong Sun, Shuang Ma
Salinity stress can impede development and plant growth adversely. However, there is very little molecular information on NaCl resistance and volatile emissions in Lycopersicum esculentum. In order to investigate the effects of salt stress on the release of volatile compounds, we quantified and compared transcriptome changes by RNA-Seq analysis and volatile constituents with gas chromatography/mass spectrometry (GC/MS) coupled with solid-phase microextraction (SPME) after exposure to continuous salt stress...
February 17, 2018: Plant Physiology and Biochemistry: PPB
Yanmei Huang, Haiyan Li, Mindong Bai, Xiaojia Huang
Efficient extraction of perfluorocarboxylic acids (PFCAs) is a key step for the accurate and sensitive determination of PFCAs due to their low concentration and the complexity of sample matrices. Herein, according to the chemical characteristics of PFCAs, a new adsorbent based on poly (2,2,3,3,4,4,5,5,6,6,7,7-dodecafluoroheptyl acrylate/(vinylbenzyl)trimethylammonium chloride-co-divinylbenzene/ethylenedimethacrylate) monolith was fabricated and utilized as the extraction medium of multiple monolithic fiber solid-phase microextraction (MMF-SPME)...
June 29, 2018: Analytica Chimica Acta
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