نتایج جستجو برای: headspace sampling
تعداد نتایج: 214473 فیلتر نتایج به سال:
This work describes the application of the previously presented solid phase microextraction (SPME) fiber in direct mode for sampling of C10-C20 n-alkanes from aqueous solution. The fiber has simple composition and is constructed from activated charcoal:PVC suspension in tetrahydrofuran. When the composition of the fiber was optimized that the optimum composition was 90:10 (activated charcoal:PV...
پسماند چوبی درشت ) coarse woody debris ( یکی از اجزای مهم اکوسیستم جنگل است که نقش مهمی در فرآیندهای این اکوسیستم ایفا میکند. طی دهه اخیر توجه فراوانی به این جزء مهم بومسازگان توسط بوم- شناسان و جنگلشناسان شده است و روشهایی برای نمونهبرداری این جزء مهم اکوسیستم معرفی شده که همگی قطعات cwd را با احتمال نابرابر به عنوان نمونه انتخاب می نمایند. pds ( perpendicular distance sampling ،) dls ( dis...
Microbial volatilization of selenium as dimethylselenide (DMSe) and dimethyldiselenide (DMDSe) from soil is an important part of the Se cycle in nature, but little is known about the stability and transformations of these gases during residence in the soil environment before dissipation to the atmosphere. Experiments monitored by gas chromatography and atomic absorption spectroscopy were made w...
Trace detection of illicit drugs challenges the scientific community to develop improved sensitivity and selectivity in sampling and detection techniques. Ion mobility spectrometry (IMS) is one of the prominent trace detectors for illicit drugs and explosives, mostly due to its portability, high sensitivity and fast analysis. Current sampling methods for IMS rely on wiping suspected surfaces or...
Early diagnosis of colorectal cancer is crucial to increase the survival rates patients and breath analysis represents a promising non-invasive tool obtain information on cancer-related variations human volatilome. A solid phase microextraction coupled gas chromatography–mass spectrometry method for determination seven selected compounds, representative volatilome secreted by colonic mucosa aff...
A headspace solid-phase microextraction (HS-SPME) method is developed for the determination of styrene in drinking water. Gas chromatography (GC)-mass spectrometry is utilized for qualitative analysis. A manual SPME holder with 85-microm polyacrylate coating is used to extract the styrene from water, which is determined to have good linearity (correlation coefficient r = 0.9999 for 1.00-100.00 ...
Volatile compounds from the headspace gas of ten brands of the Japanese fish sauce ishiru were analyzed by GC-MS with a thermal-desorption cold-trap system. Many volatile peaks were detected and 51 compounds were identified. The major volatile compounds in ishiru included aldehydes (such as 2-methylpropanal, 2-methylbutanal, 3-methylbutanal, and benzaldehyde), nitrogen-containing compounds (suc...
the purpose of this study was the relationship between problem – solvi ability with fdi cognitive style of students.the research method was correlation method. for data analysis pearson test was used. statistical society in this research was all the students of alligoodarz city in 1391-92 year.to sampling of statiscal population was used sampling multi-stage random the size of sample selected 2...
The potential of using tree core samples to detect and monitor natural attenuation of perchloroethene (PCE) in groundwater was investigated at a PCE-contaminated site. In the area of the known plume with PCE concentrations between 0.004 and > 40 mg/L, cores were collected from tree trunks at a height of about 1 m above ground surface. Tree sampling of the site was completed in under six hours. ...
A method for analysis of volatile organic compounds (VOCs) from microbial cultures was established using proton transfer reaction-mass spectrometry (PTR-MS). A newly developed sampling system was coupled to a PTR-MS instrument to allow on-line monitoring of VOCs in the dynamic headspaces of microbial cultures. The novel PTR-MS method was evaluated for four reference organisms: Escherichia coli,...
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