Ionized Nonionized Forms
Ionized Nonionized Forms - Related Videos
03:12
Ionization Energy
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2020
The amount of energy required to remove the most loosely bound electron from a gaseous atom in its ground state is called its first ionization energy (IE1). The first ionization energy for an element, X, is the energy required to form a cation with 1+ charge: The energy required to remove the second most loosely bound electron is called the second ionization energy (IE2). The energy required to remove the third electron is the third ionization energy, and so on. Energy is always required...
06:21
Imaging of Biological Tissues by Desorption Electrospray Ionization Mass Spectrometry
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Cited by 21 •
2013
Desorption electrospray ionization mass spectrometry (DESI-MS) is an ambient method by which samples, including biological tissues, can be imaged with minimal sample preparation. By rastering the sample below the ionization probe, this spray-based technique provides sufficient spatial resolution to discern molecular features of interest within tissue sections.
07:31
Characterization of Recombination Effects in a Liquid Ionization Chamber Used for the Dosimetry of a Radiosurgical Accelerator
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Cited by 2 •
2014
A growing number of radiation therapy devices offer the advantage of delivering the dose through very small beams to the tumor, allowing for increased conformity and higher doses per fraction. Many different detectors can be used for the dosimetry of these small fields. In the present study, the effect of ion recombination is investigated for a liquid ionization chamber using a stereotactic radiation therapy system.
09:22
Gas Chromatography (GC) with Flame-Ionization Detection
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2023
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.
08:54
Characterizing Bacterial Volatiles using Secondary Electrospray Ionization Mass Spectrometry (SESI-MS)
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Cited by 40 •
2011
Secondary electrospray ionization mass spectrometry (SESI-MS) enables the detection of volatile organic compounds (VOCs) without the need for any sample pretreatment. This protocol provides instructions for the rapid (within minutes) characterization of bacterial VOCs using SESI-MS.
FAQs
The pKa provides a reference for understanding a compound’s acid-base equilibrium, while surrounding pH shifts the balance between its charged and uncharged forms. Because body fluids and tissue environments can differ in pH, the same compound may not exist in the same proportion of each form everywhere. This variation helps explain changes in pharmacological behavior across locations.
Membrane passage depends partly on whether molecules can interact with lipid barriers. The nonionized fraction generally crosses these barriers more readily, whereas the ionized fraction tends to remain more compatible with aqueous surroundings. Consequently, a change in the proportion of each form can alter how efficiently a compound moves from a solution into cells or across tissue boundaries.
pH-dependent trapping occurs when a compound encounters an environment that changes the balance between its ionized and nonionized forms. If the resulting form crosses a membrane less readily, the compound can become relatively retained on one side. This concept helps explain why differences in pH between body compartments may influence tissue distribution and local drug concentrations.
During absorption, the proportion of nonionized molecules can influence how readily a compound crosses lipid-containing biological barriers. After entry into tissues, local pH conditions may shift the acid-base equilibrium and change membrane passage or retention. Thus, the same drug can show different movement patterns during absorption and tissue penetration rather than behaving identically throughout the body.
Ionization affects whether a compound remains relatively water-soluble or crosses lipid barriers efficiently, properties that are relevant to movement through biological compartments involved in elimination. Considering pKa and environmental pH therefore helps pharmacologists interpret why changes in ionized and nonionized proportions may influence renal handling and the eventual removal of a drug from the body.
Evaluating ionized and nonionized forms connects a compound’s acid-base behavior with practical pharmacology. Researchers can consider how pKa and pH may influence absorption, distribution, tissue penetration, renal excretion, and pH-dependent trapping. This information supports comparisons among candidate compounds and helps inform the clinical use of medicines whose behavior changes across different biological environments.