نتایج جستجو برای: headspace sampling
تعداد نتایج: 214473 فیلتر نتایج به سال:
2 Headspace sampling for gas chromatographic (GC) analysis has many advantages, the most important of which is the elimination of many interferences from the sample matrix. In addition to the standard methods for headspace sampling, the technique of solid-phase microextraction (SPME) has found wide acceptance because it is simple and inexpensive. More recently, single-drop microextraction (SDME...
The determination of VOCs is widely used in many fields of chemistry. Two common sample preparation techniques for this analysis are static and dynamic headspace. Static headspace is a relatively simple sampling method that is dependent upon the formation of equilibrium conditions in a closed system. Dynamic headspace continually sweeps the headspace of the sample concentrating the analytes ont...
A new method for rapid sampling and qualitative characterization of the headspace gases of closed in vitro cultures using solid phase microextraction (SPME) was evaluated for ruminal fluid and ruminal fluid with feed containing a feed additive. Gas sample collection was achieved by exposing a DVB/Carboxen/PDMS 50/30 m SPME fiber to the headspace of cultures for 1 min every hour. This was follow...
A solid-phase microextraction (SPME) procedure was evaluated for its application in measuring solute release in the headspace (HS) and in the liquid phase (DI) from emulsified and nanostructured materials. Limonene, a hydrophobic flavor compound present in many foods and beverages, was used as a model solute for evaluating the SPME method. Sampling conditions, including SPME fiber type, samplin...
This study demonstrates the use of solid-phase microextraction (SPME) to extract and pre-concentrate volatile signatures from static air above plastic explosive samples followed by detection using ion mobility spectrometry (IMS) optimized to detect the volatile, non-energetic components rather than the energetic materials. Currently, sample collection for detection by commercial IMS analyzers i...
Static headspace analysis can provide reasonably good sensitivity for halogenated hydrocarbons and aromatic compounds. But USEPA Method 524.2 Revision 4 requires the evaluation of several analytes containing different functional groups such as ketones, ethers, and esters. Such compounds can be particularly difficult to analyze at low concentration using static headspace due to the affinity of p...
Volatile organic compounds (VOCs) and odors in cattle rumen gas have been characterized by in-vivo headspace sampling by solid-phase microextraction (SPME) and analysis by gas chromatography-mass spectrometry-olfactometry (GC-MS-O). A novel device enabling headspace SPME (HS-SPME) sampling through a cannula was designed, refined, and used to collect rumen gas samples from steers. A Carboxen-pol...
A new analytical method for the determination of halogenated and aromatic volatile organic compounds in groundwater, mineral water, and drinking water at concentrations ranging between 1-10000 ng/L is developed. A new type of headspace sampler that combines static headspace sampling with a trap is used, yielding very low detection limits and good repeatability without carryover effects. An unex...
Odours emitted by human skin are of great interest to biologists in many fields, with practical applications in forensics, health diagnostic tools and the ecology of blood-sucking insect vectors of human disease. Convenient methods are required for sampling human skin volatiles under field conditions. We experimentally compared four modern methods for sampling skin odours: solvent extraction, h...
Plant volatiles (PVs) mediate manifold interactions between plants and their biotic and abiotic environments (Dicke and Baldwin, 2010; Holopainen and Gershenzon, 2010). An understanding of the physiological and ecological functions of PVs must therefore be based on measurements of PV emissions under natural conditions. Yet sampling PVs in natural environments is difficult, limited by the need t...
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