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Carboxylic Acids: Organic compounds containing the carboxy group (-Cooh). This group of compounds includes amino acids and fatty acids. Carboxylic acids can be saturated, unsaturated, or aromatic.
 Science Education: Essentials of Earth Science

Conversion of Fatty Acid Methyl Esters by Saponification for Uk'37 Paleothermometry

JoVE Science Education

Source: Laboratory of Jeff Salacup - University of Massachusetts Amherst

The product of an organic solvent extraction, a total lipid extract (TLE), is often a complex mixture of hundreds, if not thousands, of different compounds. The researcher is often only interested in a handful of compounds or, if interested in many, may need to remove unwanted constituents that are"in the way" or co-eluting. For example, the concentrations of individual compounds in a sample are often determined on a gas chromatograph coupled to a flame-ionizing detector (GC-FID), because the relationship between FID response (in pA) and the amount of compound in a sample (e.g., ng/µL) is both linear and sensitive. The GC portion of the instrument separates different compounds in a sample based on their boiling point, chemical structure, and affinity with a solid phase that can change according to application. The result is a chromatogram (Figure 1), showing the separation of different chemical constituents in time, as well as their relative concentration (calculated as the area under the curve). However, sometimes more than one compound elutes off the GC at a time (Figure 1). In this case, sample purification is required before compounds can be confidently quantified

 JoVE Chemistry

Construction of Models for Nondestructive Prediction of Ingredient Contents in Blueberries by Near-infrared Spectroscopy Based on HPLC Measurements

1United Graduate School of Agricultural Science, Tokyo University of Agriculture and Technology, 2Faculty of Agriculture, Tokyo University of Agriculture and Technology, 3Institute of Agriculture, Tokyo University of Agriculture and Technology


JoVE 53981

 JoVE In-Press

Green and Low-cost Production of Thermally Stable and Carboxylated Cellulose Nanocrystals and Nanofibrils Using Highly Recyclable Dicarboxylic Acids

1Jiangsu Provincial Key Lab of Pulp and Paper Science and Technology, Nanjing Forestry University, 2State Key Lab of Pulp and Paper Engineering, South China University of Technology, 3Forest Products Laboratory, U.S. Forest Service, U.S. Department of Agriculture

Video Coming Soon

JoVE 55079

 JoVE Bioengineering

Techniques for the Evolution of Robust Pentose-fermenting Yeast for Bioconversion of Lignocellulose to Ethanol

1Bioenergy Research Unit, National Center for Agricultural Utilization Research, 2Mycotoxin Prevention and Applied Microbiology Research Unit, National Center for Agricultural Utilization Research, 3Chemical Engineering and Material Science, Great Lakes Bioenergy Center, Michigan State University


JoVE 54227

 Science Education: Essentials of Analytical Chemistry

Ion-Exchange Chromatography

JoVE Science Education

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

Ion-exchange chromatography is a type of chromatography that separates analytes based on charge. A column is used that is filled with a charged stationary phase on a solid support, called an ion-exchange resin. Strong cation-exchange chromatography preferentially separates out cations by using a negatively-charged resin while strong anion-exchange chromatography preferentially selects out anions by using a positively-charged resin. This type of chromatography is popular for sample preparation, for example in the cleanup of proteins or nucleic acid samples. Ion-exchange chromatography is a two-step process. In the first step, the sample is loaded onto the column in a loading buffer. The binding of the charged sample to the column resin is based on ionic interactions of the resin to attract the sample of the opposite charge. Thus, charged samples of opposite polarity to the resin are strongly bound. Other molecules that are not charged or are of the opposite charge are not bound and are washed through the column. The second step is to elute the analyte that is bound to the resin. This is accomplished with a salt gradient, where the amount of salt in the buffer is slowly increased. Fractions are collected at the end of the column as

 Science Education: Essentials of Earth Science

Purification of a Total Lipid Extract with Column Chromatography

JoVE Science Education

Source: Laboratory of Jeff Salacup - University of Massachusetts Amherst

The product of an organic solvent extraction, a total lipid extract (TLE), is often a complex mixture of hundreds, if not thousands, of different compounds. The researcher is often only interested in a handful of compounds. The compounds of interest may belong to one of several classes of compounds, such as alkanes, ketones, alcohols, or acids (Figure 1), and it may be useful to remove the compound classes to which it does not belong in order to get a clearer view of the compounds you are interested in. For example, a TLE may contain 1,000 compounds, but the Uk'37 sea surface temperature proxy is based on only two compounds (alkenones) and the TEX86 sea surface temperature proxy is based on only four (glycerol dialkyl glycerol tetraethers). It would behoove the researcher to remove as many of the compounds they are not interested in. This makes the instrumental analysis of the compounds of interest (alkenones or GDGTs) less likely to be complicated by other extraneous compounds. In other cases, an upstream purification technique may have produced compounds you wish to now remove from the sample, such as the production of carboxylic acids during saponification in our

 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:

 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

HKUST-1 as a Heterogeneous Catalyst for the Synthesis of Vanillin

1Autonomous Metropolitan University-Azcapotzalco, 2Institute of Catalysis and Petroleum Chemistry, ICP-CSIC, 3Department of Chemistry, Autonomous Metropolitan University-Iztapalapa, 4Department of Chemistry, Center of Investigation and Superior Studies (IPN), 5Research Institute of Material, National Autonomous University of Mexico


JoVE 54054

 JoVE Immunology and Infection

Ex Vivo Red Blood Cell Hemolysis Assay for the Evaluation of pH-responsive Endosomolytic Agents for Cytosolic Delivery of Biomacromolecular Drugs

1Department of Biomedical Engineering, Vanderbilt University, 2Vanderbilt Institute for Nanoscale Science & Engineering, Vanderbilt University, 3Interdisciplinary Materials Science Program, Vanderbilt University, 4Monroe Carell Jr. Children's Hospital, Vanderbilt University Medical Center, 5Department of Chemical & Biomolecular Engineering, Vanderbilt University, 6Department of Cancer Biology, Vanderbilt University


JoVE 50166

 JoVE In-Press

Analysis of the Ambient Particulate Matter-induced Chromosomal Aberrations Using an In Vitro System

1Department of Occupational and Environmental Health, University of Arkansas for Medical Sciences, 2Department of Environmental Health Sciences, University of Alabama at Birmingham, 3Division of Radiation Health, University of Arkansas for Medical Sciences

Video Coming Soon

JoVE 54969

 JoVE Environment

LC-MS Analysis of Human Platelets as a Platform for Studying Mitochondrial Metabolism

1Center for Cancer Pharmacology, University of Pennsylvania, 2Center for Excellence in Environmental Toxicology, University of Pennsylvania, 3Penn SRP and Department of Systems Pharmacology and Translational Therapeutics, University of Pennsylvania, 4Division of Traumatology, Department of Surgery, Critical Care and Acute Care Surgery, University of Pennsylvania, 5A.J. Drexel Autism Institute, Drexel University


JoVE 53941

 JoVE In-Press

Synthesis of Cationized Magnetoferritin for Ultra-fast Magnetization of Cells

1Bristol Centre for Functional Nanomaterials, University of Bristol, 2Department of Materials, Imperial College London, 3Self Assembly Group, CIC nanoGUNE, 4Ikebasque, Basque Foundation for Science, 5School of Cellular and Molecular Medicine, University of Bristol, 6H.H. Wills Physics Laboratory, University of Bristol

Video Coming Soon

JoVE 54785

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