Gourt > Science > Chemistry > Analytical > Mass Spectrometry (8)
Mass spectrometry is an analytical technique used to measure the mass-to-charge ratio of ions. It is most generally used to find the composition of a physical sample by generating a mass spectrum representing the masses of sample components. The technique has several applications, including:
- identifying unknown compounds by the mass of the compound molecules or their fragments
- determining the isotopic composition of elements in a compound
- determining the structure of a compound by observing its fragmentation
- quantifying the amount of a compound in a sample using carefully designed methods (mass spectrometry is not inherently quantitative)
- studying the fundamentals of gas phase ion chemistry (the chemistry of ions and neutrals in vacuum)
- determining other physical, chemical or even biological properties of compounds with a variety of other approaches
A mass spectrometer is a device used for mass spectrometry, and produces a mass spectrum of a sample to find its composition. This is normally achieved by ionizing the sample and separating ions of differing masses and recording their relative abundance by measuring intensities of ion flux. A typical mass spectrometer comprises three parts: an ion source, a mass analyzer, and a detector.
How it works: simple example
Different chemicals have different masses, and this fact is used in a mass spectrometer to determine what chemicals are present in a sample. For example, table salt (NaCl), is vaporized (turned into gas) and ionized (broken down) into electrically charged particles, called ions, in the first phase of the mass spectrometry. The sodium ions and chloride ions have specific atomic weights. They also have a charge, which means that their path can be controlled with an electric or magnetic fields. The ions are sent into an acceleration chamber and passed through a slit in a metal sheet. A magnetic field is applied to the chamber. The field pulls each ion with equal force and deflects them (makes them curve instead of travelling straight) onto a detector. The lighter ions deflect farther than the heavy ions because according to the Newton's second law of motion the acceleration of a particle is inversely proportional to its mass. The detector measures exactly how far each ion has been deflected, and from this measurement, the ion's 'mass to charge ratio' can be worked out. From this information it is possible to determine with a high level of certainty the chemical composition of the original sample. More on [ Mass spectrometry ]
[Editorials] Cerebrospinal Fluid Biomarkers in the Evaluation of Alzheimer Disease
Verbeek, M. M., Olde Rikkert, M. G.M. Mon, 29 Sep 2008 00:00:00 -0000
[Editorials] Rapid and Effective Screening for Lysosomal Storage Disease: How Close Are We?
Millington, D. S. Mon, 29 Sep 2008 00:00:00 -0000
[Editorials] Requesting and Interpreting Urine Albumin Measurements in the Primary Health Care Setting
McQueen, M. J., Don-Wauchope, A. C. Mon, 29 Sep 2008 00:00:00 -0000
[Editorials] Multiple Thiopurine S-Methyltransferase Variation Detection: A Step toward Personalized Medicine
Tsui, N. B. Y. Mon, 29 Sep 2008 00:00:00 -0000
[Mini-Review] Utility of Kallikrein-Related Peptidases (KLKs) as Cancer Biomarkers
Emami, N., Diamandis, E. P. Mon, 29 Sep 2008 00:00:00 -0000
Background: The human kallikrein-related peptidase (KLK) family consists of 15 highly conserved serine proteases, which are encoded by the largest uninterrupted cluster of protease genes in the human genome. To date, several members of the family have been reported as potential cancer biomarkers. Although primarily known for their biomarker value in prostate, ovarian, and breast cancers, more recent data suggest analogous roles of KLKs in several other cancers, including gastrointestinal, head and neck, lung, and brain malignancies. Among the proposed KLK cancer biomarkers, prostate-specific antigen (also known as KLK3) is the most widely recognized member in urologic oncology. Content: Despite substantial progress in the understanding of the biomarker utility of individual KLKs, the current challenge lies in devising biomarker panels to increase the accuracy of prognosis, prediction of therapy, and diagnosis. To date, multiparametric KLK panels have been proposed for prostate, ovarian, and lung cancers. In addition to their biomarker utility, emerging evidence has revealed a number of critical functional roles for KLKs in the pathogenesis of cancer and their potential use as therapeutic targets. Summary: KLKs have biomarker utility in many cancer types but individually lack sufficient specificity or sensitivity to be used in clinical practice; however, groups of KLKs and other candidate biomarkers may offer improved performance.
[Mini-Review] High-Abundance Polypeptides of the Human Plasma Proteome Comprising the Top 4 Logs of Polypeptide Abundance
Hortin, G. L., Sviridov, D., Anderson, N. L. Mon, 29 Sep 2008 00:00:00 -0000
Background: Plasma contains thousands of proteins, but a small number of these proteins comprise the majority of protein molecules and mass. Content: We surveyed proteomic studies to identify candidates for high-abundance polypeptide chains. We searched the literature for information on the plasma concentrations of the most abundant components in healthy adults and for the molecular mass of the mature polypeptide chains in plasma. Because proteomic studies usually dissociate proteins into polypeptide chains or detect short peptide segments of proteins, we summarized data on individual peptide chains for proteins containing multiple subunits or polypeptides. We collected data on about 150 of the most abundant polypeptides in plasma. The abundant polypeptides span approximately the top 4 logs of concentration in plasma, from 650 to 0.06 µmol/L on a molar basis or from about 50 000 to 1 mg/L mass abundance. Conclusions: Data on the concentrations of the high-abundance peptide chains in plasma assist in understanding the composition of plasma and potential approaches for clinical laboratory or proteomic analysis of plasma proteins. Development of more extensive databases regarding the plasma concentrations of proteins in health and diseases would promote diagnostic and proteomic advances.
Harsh-Environment Mass Spectrometry - Biannual four day workshop, including applications under-water and in outer space, with abstracts and presentations at Sarosota, Florida.
I-Mass - Resource featuring monthly focus, mass spectrometry journals and books, conferences, history, guides, software and laboratories.
Meta Description: [ mass spectrometry, mass spectrometry resource, international mass spectrometry resource ]
IMSC 2006 - Details of 17th International Mass Spectrometry Conference held for six days in Prague, Czech Republic.
Meta Description: [ Information about News ]
Introduction to Mass Spectrometry - Definitions and biological applications at Astbury Centre for Structural Molecular Biology, University of Leeds, England.
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LCMS Montreux Symposium - International Association of Environmental Analytical Chemistry meeting on LC/MS. The three day meeting, includes short courses held at Montreux, Switzerland.
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Mass Spectral Molecular Weight - This site lists mass occurrence probabilities and gives simple rules for upper and lower limits to the molecular weight of an unknown from mass spectral data. Relevant publications are listed.
Meta Description: [ MOLECULAR WEIGHTS FROM MASS SPECTRAL DATA, EXPERT SYSTEMS FOR MOLECULAR WEIGHTS, MASS OCCURRENCE PROBABILITIES ]
Mass Spectrometry and Biotechnology Resource - Provides reference materials for scientists working with mass spectrometry in the biotechnology industry.
Meta Description: [ A mass spectrometry and biotechnology resource web site, featured are printable reference tables and chemistry topics. ]
Mass Spectrometry Blog - Web log of MS web sites and other links and items of interest, maintained from Department of Chemistry Louisiana State University.
Meta Description: [ A Web log of mass spectrometry Web sites, discussion groups, mailing lists and other links and items of interest to the mass spectrometry community ]
Mobile Miniature Mass Spectrometer - Resource focusing on field-portable MS instruments, with classification by probe, links to project, development, MSDS, software and databases.
Meta Description: [ Commented links to miniature mass spectrometer and mobile GC/MS ]
Network Developing Forensic Applications of Stable Isotope Mass Spectrometry - Overview of techniques and information about the second conference. Maintained at the University of Reading, England.
NIST Polymers Division: Maldi Recipes - Matrix assisted laser desorption ionization application to polymer science. Includes links to meetings and presentations by researcher in field, at Gaithersburg, Maryland.
Meta Description: [ NIST Materials Science and Engineering Laboratory - Polymers Division MALDI Recipes ]
Sci Techniques Mass Spec - Archives of forum, with categories for groups, troubleshooting, tutorials, professional, societies, listservers, journals, companies, supplies and services, maintained at Georgia Institute of Technology, Atlanta.
Selected Ion Flow Tube Mass Spectrometry - Introduction to SIFT-MS for trace gas analysis of air, breath and liquid headspace, in medicine, biology and environmental applications. Includes links to related articles.
Time Of Flight Mass Spectrometer Tutorial - Stepwise guide on the fundamentals of the method through ionisation, acceleration and detection, and instrument components required, by manufacturer and supplier R M Jordan Co Inc, Grass Valley, California.
Meta Description: [ Time Of Flight Mass Spectrometer Tutorial by Jordan TOF Products, Inc. This is an instructional tutorial dealing with the fundamentals of Time of Flight (TOF) technology. ]
Underwater Mass Spectrometry - Information and talks from the Workshop on Harsh-Environment Mass Spectrometry, hosted by the Center for Ocean Technology at the University of South Florida.
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