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Metals, Heavy: Metals with high specific gravity, typically larger than 5. They have complex spectra, form colored salts and double salts, have a low electrode potential, are mainly amphoteric, yield weak bases and weak acids, and are oxidizing or reducing agents (From Grant & Hackh's Chemical Dictionary, 5th ed)
 JoVE Environment

Development of Sulfidogenic Sludge from Marine Sediments and Trichloroethylene Reduction in an Upflow Anaerobic Sludge Blanket Reactor

1Bioprocesses Department, Laboratory of Environmental Biotechnology, Unidad Profesional Interdisciplinaria de Biotecnología, Instituto Politécnico Nacional, 2Laboratory of Molecular Biology, Escuela Superior de Medicina, Instituto Politécnico Nacional


JoVE 52956

 JoVE Environment

Removal of Trace Elements by Cupric Oxide Nanoparticles from Uranium In Situ Recovery Bleed Water and Its Effect on Cell Viability

1Division of Physical Therapy, Department of Orthopedics & Rehabilitation, University of New Mexico, 2Department of Ecosystem Science and Management, University of Wyoming, 3School of Pharmacy, University of Wyoming, 4Department of Environmental and Radiological Health Sciences, Colorado State University, 5Center for Environmental Medicine, Colorado State University, 6College of Pharmacy, California Northstate University


JoVE 52715

 JoVE Engineering

Characterization of Electrode Materials for Lithium Ion and Sodium Ion Batteries Using Synchrotron Radiation Techniques

1Environmental Energy Technologies Division, Lawrence Berkeley National Laboratory, 2Department of Chemistry, University of Illinois at Chicago, 3Stanford Synchrotron Radiation Lightsource, 4Haldor Topsøe A/S, 5PolyPlus Battery Company


JoVE 50594

 Science Education: Essentials of Analytical Chemistry

Sample Preparation for Analytical Preparation

JoVE Science Education

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

Sample preparation is the way in which a sample is treated to prepare for analysis. Careful sample preparation is critical in analytical chemistry to accurately generate either a standard or unknown sample for a chemical measurement. Errors in analytical chemistry methods are categorized as random or systematic. Random errors are errors due to change and are often due to noise in instrument. Systematic errors are due to investigator or instrumental bias, which introduces an offset in the measured value. Errors in sample preparation are systematic errors, which will propagate through analysis, causing uncertainty or inaccuracies through improper calibration curves. Systematic errors can be eliminated through correct sample preparation and proper use of the instrument. Poor sample preparation can also sometimes cause harm to the instrument.

 JoVE Bioengineering

Fabrication of a Dipole-assisted Solid Phase Extraction Microchip for Trace Metal Analysis in Water Samples

1Department of Biomedical Engineering and Environmental Sciences, National Tsing Hua University, 2Center for Measurement Standards, Industrial Technology Research Institute, 3National Synchrotron Radiation Research Center, 4Department of Chemistry, National Changhua University of Education


JoVE 53500

 Science Education: Essentials of Organic Chemistry

Schlenk Lines Transfer of Solvents

JoVE Science Education

Source: Hsin-Chun Chiu and Tyler J. Morin, laboratory of Dr. Ian Tonks—University of Minnesota Twin Cities

Schlenk lines and high vacuum lines are both used to exclude moisture and oxygen from reactions by running reactions under a slight overpressure of inert gas (usually N2 or Ar) or under vacuum. Vacuum transfer has been developed as a method separate solvents (other volatile reagents) from drying agents (or other nonvolatile agents) and dispense them to reaction or storage vessels while maintaining an air-free environment. Similar to thermal distillations, vacuum transfer separates solvents by vaporizing and condensing them in another receiving vessel; however, vacuum transfers utilize the low pressure in the manifolds of Schlenk and high vacuum lines to lower boiling points to room temperature or below, allowing for cryogenic distillations. This technique can provide a safer alternative to thermal distillation for the collection of air- and moisture-free solvents. After the vacuum transfer, the water content of the collected solvent can be tested quantitatively by Karl Fischer titration, qualitatively by titration with a Na/Ph2CO solution, or by 1H NMR spectroscopy.

 JoVE In-Press

Quantitative Magnetic Resonance Imaging of Skeletal Muscle Disease

1Institute of Imaging Science, Vanderbilt University, 2Department of Radiology and Radiological Sciences, Vanderbilt University, 3Department of Biomedical Engineering, Vanderbilt University, 4Department of Molecular Physiology and Biophysics, Vanderbilt University, 5Department of Physical Medicine and Rehabilitation, Vanderbilt University, 6Department of Physics and Astronomy, Vanderbilt University

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JoVE 52352

 Science Education: Essentials of Environmental Science

Lead Analysis of Soil Using Atomic Absorption Spectroscopy

JoVE Science Education

Source: Laboratories of Margaret Workman and Kimberly Frye - Depaul University

Lead occurs naturally in soil, in levels ranging from 10-50 ppm. However, with the widespread use of lead in paint and gasoline in addition to contamination by industry, urban soils often have concentrations of lead significantly greater than background levels – up to 10,000 ppm in some places. Ongoing problems arise from the fact that lead does not biodegrade, and instead remains in the soil. Serious health risks are associated with lead poisoning, where children are particularly at risk. Millions of children in the U.S. are exposed to soil containing lead. This exposure can cause developmental and behavioral problems in children. These problems include learning disabilities, inattention, delayed growth, and brain damage. The Environmental Protection Agency has set a standard for lead in soil at 400 ppm for play areas and 1,200 ppm for non-play areas. Lead is also of concern in soil, when it’s used for gardening. Plants take up lead from the soil. Therefore, vegetables or herbs grown in contaminated soil can lead to lead poisoning. In addition, contaminated soil particles can be breathed in while gardening or brought into the house on clothing and footwear. It is recommended that s

 JoVE Bioengineering

Measurement of Maximum Isometric Force Generated by Permeabilized Skeletal Muscle Fibers

1Department of Orthopaedic Surgery, University of Michigan Medical School, 2Department of Molecular & Integrative Physiology, University of Michigan Medical School, 3Department of Biomedical Engineering, University of Michigan Medical School, 4Department of Surgery, Section of Plastic Surgery, University of Michigan Medical School


JoVE 52695

 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

 JoVE Environment

Methods of Soil Resampling to Monitor Changes in the Chemical Concentrations of Forest Soils

1New York Water Science Center, U.S. Geological Survey, 2School of Forest Resources, University of Maine, 3Natural Resources Canada, Canadian Forest Service, 4Northern Research Station, U.S. Forest Service, 5Department of Plant and Soil Science, University of Vermont, 6Ottauquechee NRCD, USDA Natural Resources Conservation Service, 7Green Mountain National Forest, U.S. Forest Service, 8Direction de la Recherche Forestière, Ministère du Québec, 9Department of Civil and Environmental Engineering, Syracuse University, 10Division of Environmental Science, SUNY College of Environmental Science and Forestry, 11White Mountain National Forest, U.S. Forest Service, 12Natural Resources and Earth System Sciences, University of New Hampshire, 13Greenwich, NY Field Office, USDA Natural Resources Conservation Service


JoVE 54815

 JoVE Medicine

A Murine Model of Stent Implantation in the Carotid Artery for the Study of Restenosis

1Institute for Molecular Cardiovascular Research, RWTH Aachen University, 2Institute for Textile Technology and Mechanical Engineering, RWTH Aachen University, 3Institute for Applied Medical Engineering, Helmholtz-Institute of RWTH Aachen University, 4Department of Experimental Molecular Imaging, RWTH Aachen University, 5Department of Oral and Maxillofacila Surgery, RWTH Aachen University


JoVE 50233

 JoVE Engineering

Failure Analysis of Batteries Using Synchrotron-based Hard X-ray Microtomography

1Department of Materials Science and Engineering, University of California Berkeley, 2Materials Science Division, Lawrence Berkeley National Laboratory, 3Advanced Light Source Division, Lawrence Berkeley National Laboratory, 4Department of Chemical and Biomolecular Engineering, University of California Berkeley, 5Environmental Energy Technology Division, Lawrence Berkeley National Laboratory


JoVE 53021

 JoVE Neuroscience

In vivo Imaging of Optic Nerve Fiber Integrity by Contrast-Enhanced MRI in Mice

1Hans Berger Department of Neurology, Jena University Hospital, 2Immunology, Leibniz Institute for Age Research, Fritz Lipmann Institute, Jena, 3Institute of Diagnostic and Interventional Radiology, Medical Physics Group, Jena University Hospital


JoVE 51274

 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

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