Mass Charge Separation
Mass Charge Separation - Related Videos
13:29
Harvesting Solar Energy by Means of Charge-Separating Nanocrystals and Their Solids
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2012
A general strategy for the development of charge-separating semiconductor nanocrystal composites deployable for solar energy production is presented. We show that assembly of donor-acceptor nanocrystal domains in a single nanoparticle geometry gives rise to a photocatalytic function, while bulk-heterojunctions of donor-acceptor nanocrystal films can be used for photovoltaic energy conversion.
03:27
Ions and Ionic Charges
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2020
In ordinary chemical reactions, the nucleus — which contains the protons and neutrons of each atom and thus identifies the element — remains unchanged. Electrons, however, can be added to atoms by transfer from other atoms, lost by transfer to other atoms, or shared with other atoms. The transfer and sharing of electrons among atoms govern the chemistry of the elements. During the formation of some compounds, atoms gain or lose electrons to form electrically charged particles called ions. When...
09:12
Electric Charge in a Magnetic Field
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2023
Source: Andrew Duffy, PhD, Department of Physics, Boston University, Boston, MA This experiment duplicates J.J. Thomson's famous experiment at the end of the 19th century, in which he measured the charge-to-mass ratio of the electron. In combination with Robert A. Millikan's oil-drop experiment a few years later that produced a value for the charge of the electron, the experiments enabled scientists to find, for the first time, both the mass and the charge of the electron, which are key...
02:42
Formal Charges
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2020
In some cases, there are seemingly more than one valid Lewis structures for molecules and polyatomic ions. The concept of formal charges can be used to help predict the most appropriate Lewis structure when more than one reasonable structure exists. Calculating Formal Charge The formal charge of an atom in a molecule is the hypothetical charge the atom would have if the electrons in the bonds are evenly distributed between the atoms. Alternatively, formal charge results when from the number...
02:59
Anion-Exchange Chromatography-Based Protein Purification: A Separation Technique to Isolate a Protein of Interest From Dialyzed Bacterial Lysate Based on Net Charge
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2025
In this video, we demonstrate an anion-exchange chromatography technique to purify human calcium-binding protein S100A12 based on the net surface charge of the protein from an Escherichia coli culture.
FAQs
Mass-to-charge ratio provides the basis for distinguishing ions in the analyzer. Because the measured behavior depends on both an ion’s mass and its charge, ions can be directed along different paths or reach the detector at different times. This combined measurement allows biological molecules to be differentiated even when molecular mass alone does not describe the analyzer’s response.
Electric or magnetic fields guide the ions after ionization and acceleration. Ions with different mass-to-charge ratios respond by following different paths through the instrument or by arriving at different times. The analyzer converts these differences in movement into a measurable separation, allowing the instrument to distinguish components within a biological sample.
An ion’s trajectory or arrival time provides information used to assign its mass-to-charge ratio. The collection of these measurements forms a mass spectrum, which can reveal molecular mass and composition. The signal associated with the separated ions also provides information about their abundance, helping characterize the contents of a biological sample.
The process begins by converting sample components into ions. The ions are then accelerated or guided through an electric or magnetic field, where their different mass-to-charge ratios produce distinct paths or arrival times. A detector records the separated ions, and the resulting measurements are organized into a mass spectrum for biological analysis.
In biology, this separation supports protein identification, metabolomics, biomarker analysis, and characterization of complex biological samples. Each application uses the resulting mass spectrum to examine molecular mass, composition, or abundance. Together, these uses make the technique relevant to both targeted investigation of biomolecules and broader analysis of biological mixtures.
Complex biological samples contain multiple molecular components that must be distinguished before their measurements can be interpreted. Separating ions according to mass-to-charge ratio produces differentiated signals in the mass spectrum. Researchers can then examine molecular mass, composition, and abundance, supporting the characterization of mixtures and the identification of biologically relevant molecules.