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Flame Ionization: Pyrolysis of organic compounds at the temperature of a hydrogen-air flame to produce ionic intermediates which can be collected and the resulting ion current measured by gas chromatography.
 Science Education: Essentials of Analytical Chemistry

Gas Chromatography (GC) with Flame-Ionization Detection

JoVE Science Education

Source: Laboratory of Dr. B. Jill Venton - University of Virginia

Gas chromatography (GC) is used to separate and detect small molecular weight compounds in the gas phase. The sample is either a gas or a liquid that is vaporized in the injection port. Typically, the compounds analyzed are less than 1,000 Da, because it is difficult to vaporize larger compounds. GC is popular for environmental monitoring and industrial applications because it is very reliable and can be run nearly continuously. GC is typically used in applications where small, volatile molecules are detected and with non-aqueous solutions. Liquid chromatography is more popular for measurements in aqueous samples and can be used to study larger molecules, because the molecules do not need to vaporize. GC is favored for nonpolar molecules while LC is more common for separating polar analytes. The mobile phase for gas chromatography is a carrier gas, typically helium because of its low molecular weight and being chemically inert. Pressure is applied and the mobile phase moves the analyte through the column. The separation is accomplished using a column coated with a stationary phase. Open tubular capillary columns are the most popular columns and have the stationary phase coated on the walls of the capillary. Stationary phases a

 JoVE Chemistry

Quantitative Detection of Trace Explosive Vapors by Programmed Temperature Desorption Gas Chromatography-Electron Capture Detector

1Chemical Sensing & Fuel Technology, Chemistry Division, U.S. Naval Research Laboratory, 2NOVA Research, Inc., 3Bio/Analytical Chemistry, Chemistry Division, U.S. Naval Research Laboratory, 4Navy Technology Center for Safety and Survivability, Chemistry Division, U.S. Naval Research Laboratory


JoVE 51938

 JoVE Environment

Measurement of Greenhouse Gas Flux from Agricultural Soils Using Static Chambers

1Office of Sustainability, University of Wisconsin-Madison, 2Department of Soil Science, University of Wisconsin-Madison, 3Department of Agronomy, University of Wisconsin-Madison, 4Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, 5USDA-ARS Dairy Forage Research Center, 6USDA-ARS Pasture Systems Watershed Management Research Unit


JoVE 52110

 JoVE Chemistry

Isolation and Preparation of Bacterial Cell Walls for Compositional Analysis by Ultra Performance Liquid Chromatography

1Department of Bioengineering, Stanford University, 2Department of Molecular Biology and Laboratory for Molecular Infection Medicine Sweden, Umeå Centre for Microbial Research, Umeå University, 3Campus de Cantoblanco, Universidad Autonoma de Madrid, 4Department of Microbiology and Immunology, Stanford University School of Medicine


JoVE 51183

 Science Education: Essentials of Earth Science

An Overview of Alkenone Biomarker Analysis for Paleothermometry

JoVE Science Education

Source: Laboratory of Jeff Salacup - University of Massachusetts Amherst

Throughout this series of videos, natural samples were extracted and purified in search of organic compounds, called biomarkers, that can relate information on climates and environments of the past. One of the samples analyzed was sediment. Sediments accumulate over geologic time in basins, depressions in the Earth into which sediment flows through the action of fluid (water or air), movement, and gravity. Two main types of basins exist, marine (oceans and seas) and lacustrine (lakes). As one might guess, very different types of life live in these settings, driven in large part by the difference in salinity between them. Over the last few decades, organic geochemists discovered a toolbox of biomarker proxies, or compounds that can be used to describe climate or environment, some of which work in marine environments and some of which work in lacustrine. We turn our attention here to the marine realm and alkenone paleothermometry using the Uk'37 sea surface temperature proxy. The most well-established and widely applied open-ocean biomarker sea surface temperature (SST) proxy is Uk'37. Uk'37 = (C37:2) / (C37:2 + C37:

 JoVE Environment

Extraction and Analysis of Microbial Phospholipid Fatty Acids in Soils

1Department of Renewable Resources, University of Alberta, 2Department of Science, Augustana Faculty, University of Alberta, 3Laboratoire Génie Civil et géo-Environnement, Université de Lille, 4Department of Earth and Environmental Sciences, Mount Royal University, 5Forest Ecology & Production, Great Lakes Forestry Centre, Natural Resources Canada


JoVE 54360

 Science Education: Essentials of Organic Chemistry

Solid-Liquid Extraction

JoVE Science Education

Source: Laboratory of Dr. Jay Deiner — City University of New York

Extraction is a crucial step in most chemical analyses. It entails removing the analyte from its sample matrix and passing it into the phase required for spectroscopic or chromatographic identification and quantification. When the sample is a solid and the required phase for analysis is a liquid, the process is called solid-liquid extraction. A simple and broadly applicable form of solid-liquid extraction entails combining the solid with a solvent in which the analyte is soluble. Through agitation, the analyte partitions into the liquid phase, which may then be separated from the solid through filtration. The choice of solvent must be made based on the solubility of the target analyte, and on the balance of cost, safety, and environmental concerns.

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 Science Education: Essentials of Organic Chemistry

Preparing Anhydrous Reagents and Equipment

JoVE Science Education

Source: Laboratory of Dr. Dana Lashley - College of William and Mary
Demonstrated by: Timothy Beck and Lucas Arney

Many reactions in organic chemistry are moisture-sensitive and must be carried out under careful exclusion of water. In these cases the reagents have a high affinity to react with water from the atmosphere and if left exposed the desired reaction will not take place or give poor yields, because the reactants are chemically altered. In order to prevent undesired reactions with H2O these reactions have to be carried out under an inert atmosphere. An inert atmosphere is generated by running the reaction under nitrogen gas, or in more sensitive cases, under a noble gas such as argon. Every component in such a reaction must be completely anhydrous, or free of water. This includes all reagents and solvents used as well as all glassware and equipment that will come into contact with the reagents. Extremely water-sensitive reactions must be carried out inside of a glovebox which provides a completely sealed off anhydrous environment to work under via a pair of gloves which protrudes out to one of the sides of the chamber.

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 Science Education: Essentials of Environmental Microbiology

Aseptic Technique in Environmental Science

JoVE Science Education

Source: Laboratories of Dr. Ian Pepper and Dr. Charles Gerba - Arizona University
Demonstrating Author: Luisa Ikner

Aseptic technique is a fundamental skill widely practiced in the field of environmental microbiology that requires a balance of mindfulness and practice in the laboratory. Proper use of this technique reduces the likelihood of bacterial or fungal contamination of reagents, culture media, and environmental samples. Aseptic technique is also vital to ensure data integrity and maintain the purity of culture libraries that may be comprised of very rare and difficult to culture isolates. Sources of contamination in the laboratory environment include airborne microorganisms (including those adhering to dust and lint particles), microbes present on the laboratory bench workspace or on unsterilized glassware or equipment, and microbes transferred from the body and hair of the researcher. The use of aseptic technique is also a safety measure that lowers the potential for the transmission of microorganisms to researchers, which is particularly important when working with pathogens.

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