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Self-Calibration of Mass Spectral Line-Shapes for Improving the Formula Identification of Unknown CompoundsMass spectrometry has become a fundamental tool for compound identification or confirmation by virtue of its ability to obtain elemental composition determination (formula identification) by accurate mass measurements. The speed, sensitivity, and ease of interfacing the technique with gas chromatography and liquid chromatography make it the technique of choice for many applications. However, accurate mass measurements must be made with care, and sometimes they can require careful calibration procedures and validation methods. In addition to accurate mass measurements, the isotope abundance distribution also provides information unique to a given chemical formula. However, the mass spectral accuracy required for accurate isotope modeling has not been easy to obtain previously. More recent approaches (1–3) that calibrate the spectral line-shape show promise in obtaining the necessary level of spectral accuracy but still require careful calibration methods with the use of known standards. This article..
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Efficient Raman Lasing in Tapered Silicon WaveguidesThe authors review the operating principles of a silicon Raman laser and show that by introducing a longitudinal variation of the waveguide width in the cavity, the lasing efficiency can be increased significantly.
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New Capabilities of High-Resolution Ultrasonic Spectroscopy: Titration AnalysisHigh-resolution ultrasonic spectroscopy titration analysis is a powerful new tool in research and analytical laboratory work for quantitative measurements of different processes and compounds. Here, the authors explore its potential.
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Fully Integrated Analysis of Metabolites, Impurities, and Degradants Using LC–NMR–MSCombining the three techniques of LC, MS, and NMR into one integrated system provides optimal use of NMR intrument time by using information-rich MS data to automatically guide the NMR operation. Here, the authors explore just this type of system.
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Chemically Selective Imaging with Broadband CARS MicroscopySeptember 2006. The authors rapidly acquire complete vibrational spectra in the fingerprint region using a single femtosecond laser for broadband coherent anti-Stokes Raman scattering (CARS) microscopy to image spatially variant compositions of condensed-phase samples.
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Differentiation of Hydrocarbon Homologs Using EP-IR SpectroscopyEP-IR Spectrometry -- a cost-effective, rugged and compact high scanning speed full-spectrum technology -- provides a means to simultaneously measure spectrally overlapping compounds without false positive response, considerably exceeding TUEV and MCERTS analytical requirements for cross sensitivity.
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Enhanced Sensitivity to Detect Phthalates by FT-IR AnalysisRecent evidence that the phthalate plasticizers may cause health problems, particularly in children, has resulted in many countries prohibiting the use of phthalates in toys and clothing. The United States Child Safety Law actually prohibits the presence of several phthalate compounds at levels exceeding 0.1 wt % even though the commercial levels are often greater than 10%. While ATR spectroscopy works well for identifying phthalates at commercial levels, a more sensitive technique is required to detect trace levels.
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ICP-MS Studies of Plutonium in the EnvironmentPlutonium is distributed globally in the Earth's surface environment as a result of atmospheric weapons tests, nuclear accidents, and nuclear fuel reprocessing. Mass spectrometry (MS), in particular, sector field ICP-MS, now is used widely to determine Pu activities and isotope ratios; 240Pu/239 is very useful in determining Pu origin. Determination of Pu by ICP-MS involves dissolution, column separation, and the MS determination; detection limits are 0.1–10 fg for each isotope. Applications of the determination of sector field ICP-MS to studies of environmental Pu include discerning sources of contamination near the Chernobyl reactor, and chronology of recent aquatic sediments.
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On-line and Off-line 2-D LC–ESI MS-MS Methods in Proteomic AnalysisOff-line 2-D LC–MS-MS represents a powerful alternative to on-line methodologies for protein identification from complex proteomes, improving the chromatographic resolution of digest peptide mixtures, even for low-abundance proteins. Here, the authors provide a detailed comparison of the two techniques.
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Refractive Index and Thickness Analysis of Natural Silicon Dioxide Film Growing on Silicon with Variable-Angle Spectroscopic EllipsometryOctober 2006. The authors investigate the optical properties and thickness of natural SiO2 thin films grown on silicon substrates simultaneously with a VASE system by choosing different angles of incidence and wavelength ranges.
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The Determination of Mercury in Copper Concentrates by Thermal Decomposition, Amalgamation and Cold Vapor Atomic AbsorptionMercury is a toxic, persistent pollutant found in many native ores rich in copper, silver and gold. As such ores are processed mercury can be released to the environment.
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Refractive Index and Thickness Analysis of Natural Silicon Dioxide Film Growing on Silicon with Variable-Angle Spectroscopic EllipsometryOctober 2006. The authors investigate the optical properties and thickness of natural SiO2 thin films grown on silicon substrates simultaneously with a VASE system by choosing different angles of incidence and wavelength ranges.
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Mid-infrared Microspectroscopy of Difficult Samples Using Near-Field Photothermal Microspectroscopy (PTMS) [PDF]The authors discuss progress in near-field IR microspectroscopy using a photothermal probe and show how it can be applied to the spectroscopic characterization of real-world samples.
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Mid-infrared Microspectroscopy of Difficult Samples Using Near-Field Photothermal Microspectroscopy (PTMS) [PDF]The authors discuss progress in near-field IR microspectroscopy using a photothermal probe and show how it can be applied to the spectroscopic characterization of real-world samples.
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FACSS 2009 PreviewSpectroscopy previews the 36th FACSS, to be held October 18–22, 2009, in Louisville, Kentucky.
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Savitzky–Golay Smoothing and Differentiation Filter of Even Length: A Gram Polynomial ApproachIn various fields such as signal processing, imaging processing, analytical chemistry, and spectroscopic analysis, smoothing and differentiation is important and necessary. With a matrix approach, the Savitzky–Golay smoothing and differentiation filter was extended recently to even length. In this article, a more general approach is proposed for convenient computation.
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Reducing the Impact of Spectral Interferences on the Determination of Precious Metals in Complex Geological Matrices Using DRC ICP-MSThe potential for signal drift, matrix suppression, and spectral interference, in addition to demanding sample preparation, can make geological matrices some of the most difficult to analyze by conventional inductively coupled plasma-mass spectrometry.
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Acronyms in Mass SpectrometrySpectroscopy columnist Ken Busch once again brings readers his comprehensive list of common acronyms used in the field of mass spectrometry.
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Enhancing Mass Spectral Formula Determination by Heuristic RulesA new approach to enhancing the performance of formula identification of true unknowns beyond high mass and spectral accuracy was evaluated. Three heuristic rules on upper limits and ratios of elements were tested for their effectiveness in filtering out false positive formulas with both high- and low-resolution mass spectrometry data. The rule on elements' upper limits was found to be the most effective one in eliminating incorrect formulas.
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Rapid, Cost-Effective, and Routine Biomedical Analysis Using ICP-MSElemental analysis in biological samples generally is achieved using flame atomic absorption spectrometry (AAS) and graphite furnace AAS (GFAAS). Flame AAS is fast, easy-to-use, and economical, but insufficiently sensitive for assays such as Se in serum and Pb/Cd in whole blood. These measurements require use of the more sensitive GFAAS. Inductively coupled plasma-mass spectrometry (ICP-MS), despite its low detection limit capabilities and wide elemental range, has had relatively little impact to date on biomedical analysis because of the popularly held conception that it is complex to use and expensive. In recent years, the instrumentation has been simplified and purchase, running, and maintenance costs have fallen. As a result, clinicians are becoming more interested in ICP-MS, although the perception that it is still much more expensive than GFAAS remains. This article provides a comparison of the costs of ICP-MS and GFAAS for biomedical sample analysis and illustrates the performance of ICP-MS for..
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MS Detection of Waste in Public Swimming FacilitiesThere is often insufficient prevention to ensure safe swimming environments. Recreation water illness (RWI), most commonly in the form of digestional track illness as well as skin, ear, and respiratory infections, are often caused by water contamination from human waste. Stercobilin is a very stable and suitable chemical biomarker of human waste that has the potential to be used for waste monitoring in public swimming facilities. Using solid phase extraction (SPE) techniques paired with high-resolution mass spectrometry (HRMS), we have developed a robust method used for swimming pool water monitoring to create safer swimming environments.
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On-line and Off-line 2-D LC–ESI MS-MS Methods in Proteomic AnalysisOff-line 2-D LC–MS-MS represents a powerful alternative to on-line methodologies for protein identification from complex proteomes, improving the chromatographic resolution of digest peptide mixtures, even for low-abundance proteins. Here, the authors provide a detailed comparison of the two techniques.
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Advances in the Separation and Detection of As, Cr, and Se Species in Potable Waters Using HPLC Coupled with Dynamic Reaction Cell ICP-MSHere, the authors discuss a multielement method for the simultaneous determination of inorganic As, Cr, and Se species in potable waters using a HPLC system coupled to a dynamic reaction cell indusctively coupled plasma mass spectrometer.
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ICP-MS Interface Cones: Maintaining the Critical Interface between the Mass Spectrometer and the Plasma Discharge to Optimize Performance and Maximize Instrument ProductivityA detailed look at the most critical component of an ICP-MS instrument: the interface cones
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Reducing the Impact of Spectral Interferences on the Determination of Precious Metals in Complex Geological Matrices Using DRC ICP-MSThe potential for signal drift, matrix suppression, and spectral interference, in addition to demanding sample preparation, can make geological matrices some of the most difficult to analyze by conventional inductively coupled plasma-mass spectrometry.
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The Analysis of Food Substances by ICP-MSElemental analysis of food substances presents a challenge because of the wide variety of food types and range of concentrations that need to be analyzed. This article discusses the analysis of a variety of food matrices with a single digestion procedure and instrumental method.
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RoHS/WEEE Application of a Miniature X-Ray SpectrometerThe RoHS/WEEE directive requires the electronics industry to certify that products comply with maximum concentration amounts of particular elements and compounds (Cr VI, Pb, Cd, Hg, Br PBB/PBDE) by July 2006. Instrumentation must be developed to perform the certification.
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New Capabilities of High-Resolution Ultrasonic Spectroscopy: Titration AnalysisHigh-resolution ultrasonic spectroscopy titration analysis is a powerful new tool in research and analytical laboratory work for quantitative measurements of different processes and compounds. Here, the authors explore its potential.
Latest:
New Capabilities of High-Resolution Ultrasonic Spectroscopy: Titration AnalysisHigh-resolution ultrasonic spectroscopy titration analysis is a powerful new tool in research and analytical laboratory work for quantitative measurements of different processes and compounds. Here, the authors explore its potential.
