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Molecular Spectroscopy Workbench Near-infrared Chemical Imaging and the PAT Initiative (PDF)NIR-CI adds a completely new dimension to conventional spectroscopy.
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2006 Salary Survey: Salary Changes and Job Satisfaction in the Spectroscopy CommunityThis year's survey of salaries and job attitudes reveals that the market seems stable, but many spectroscopists are feeling the pressure of the economy at work.
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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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Detection of g-Hydroxybutyrate and g-Butyrolactone by Ion Mobility Spectrometry (PDF)The authors discuss g-hydroxybutyrate (GHB), a drug of abuse that is not detected in the drug-detection mode or positive polarity of commercial ion mobility spectrometers, but can be detected by ion mobility spectrometry (IMS) instruments in negative mode.
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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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Raman Microscopy as a Valuable Tool for Failure Analysis (PDF)The authors discuss several sample types encountered in their laboratory for which Raman spectroscopy is the only reliable method of analysis. The technique is shown to be a routine and cost-effective tool for the industrial laboratory.
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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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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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Test of an In Vivo Method to Detect Chloroplast Division in Crop Plants, Part III: Statistical Proofs of Observation and General Utility of the Method (PDF)This article is the third installment in a series about a novel spectrofluorometric method that allow for in vivo observation of the division of chlorplast populations in leaves of Arabidopsis thalania.
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In-Line Process Analysis of Residual Moisture in a Fluid Bed Granulator-Dryer Using NIR Spectroscopy (PDF)The authors describe the in-line moisture measurement of a pharmaceutical granulation of lactose, microcrystalline cellulose, and crospovidone in a fluid bed granulator-dryer using top sprayed granulating liquid. A near-infrared (NIR) prediction model was developed for moisture on spectra collected during a calibration run. Subsequent granulations were analyzed for moisture content real-time throughout the granulation and drying process using the NIR process instrument.
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Criteria for High-Quality Raman MicroscopyFive key qualitative factors–speed, sensitivity, resolution, modularity and upgradeability, and combinability–contribute to the quality of confocal Raman imaging microscopes. Using application examples, this article introduces modern Raman imaging and correlative imaging techniques, and presents state-of-the-art practice examples from polymer research, pharmaceutics, low-dimensional materials research, and life sciences.
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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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New Developments in Wavelength-Dispersive XRF and XRD for the Analysis of Foodstuffs and Pharmaceutical MaterialsSeptember 2006. The authors discuss the benefits of X-ray fluorescence (XRF) for the determination of elemental nutrients in foodstuffs and X-ray diffraction (XRD) for the measurement and characterization of different compounds used in the pharmaceuticals industry.
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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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Calibration Stability for Formula Determination on a Single-Quadrupole GC–MS SystemWith electron ionization (EI) used in most gas chromatography–mass spectrometry (GC–MS) applications, the molecular ion typically is broken apart into multiple fragment ions during the EI process.
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Sample Introduction for ICP-MS and ICP-OES (PDF)This article discusses the key components of a typical liquid sample introduction system for inductively coupled plasma spectroscopy, and offers troubleshooting tips for problems commonly encountered by practitioners.
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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.
Latest:
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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Comparing Standard CCD and Electron Multiplication CCD for Low Light Level SpectroscopyThis article compares different CCD platforms by outlining CCD and EMCCD noise sources as well as an explanation of the two calculations to arrive at the signal-to-noise ratio for each. The data presented will show that a liquid nitrogen-cooled CCD camera still is the proper choice for low light level applications, such as Raman spectroscopy.
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New Sample Fractionation Strategies for Proteomic Analyses by LC–MSMass spectrometry has long been a preferred tool for protein identification and biomarker discovery, but preparation of biological samples remains a challenge. Hindrances include the wide range of protein concentrations, sample complexity, and loss or alteration of important proteins due to sample handling. This article describes recent developments in sample fractionation technologies that are overcoming these challenges in interesting ways and are enabling in-depth proteomic studies that were not possible in the past.
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High-Throughput Trace Analysis Using SERS-Coated Microtiter Plates with a Raman Plate ReaderSurface-enhanced Raman spectroscopy (SERS) has been studied extensively over the last few decades with many advances in preparation of SERS substrates and coatings. While the bulk of the research in SERS substrate preparation has been devoted to pushing detection limits to higher sensitivity for measurement of single samples, the application of SERS to high-throughput analysis has been largely ignored. In this article, we present the use of commercially available SERS-coated microtiter plates in a dedicated Raman microtiter plate reader, enabling high-throughput trace analysis measurements. This article also describes the SERS substrate, the high-throughput plate reader, and preliminary results from samples representing trace analysis of explosives, nerve agents, pharmaceuticals, and biological compounds.
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Looking Below the Surface of Breast Tissue During SurgeryIn this article, we present a method that provides prompt detection of the presence of cancer cells inside the 2-mm margin of tissue surrounding the tumor after excision using spatially offset Raman spectroscopy (SORS). SORS was developed to detect subtle changes in soft tissue spectra in the 100–2000 ?m range and tested on excised breast tissues. The results display a very high specificity and sensitivity (100% and 95%, respectively) of classification between positive and negative tumor margins. SORS is a clinically feasible method, suitable for the real-time, intraoperative assessment of tumor margins at the micrometer level.
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Strategies for Higher Throughput MS Analyses (PDF)The authors discuss current approaches for increasing throughput in MS analyses, including improved software information flow, data management and effective sample preparation, and how researchers should consider each of these with regard to their own needs.
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LC–MS Characterization of Mesquite Flour ConstituentsGiven the wide range in polarity of the components of mesquite flour, it is advantageous to study the health benefits of this flour using methods that combine the complementary approaches of reversed-phase and aqueous normal phase LC.
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Measurement of Metabolic Stability Using SIM and Identification of Metabolites by Data-Dependent full-Scan MS-MS and CNL ScanningIn this article, the role of a triple-quadrupole mass spectrometer in performing in vitro studies of compound metabolic stability and identification of Phase I and II metabolites is demonstrated.
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Grating Corrected Laser Stabilization: A Case Study in Pharmaceutical Raw Material IdentificationThe authors present a novel technique for obtaining very high stability and reproducibility of a Raman spectrum, using grating corrected laser stabilization. An externally stabilized laser with a grating spectrometer provides exceptional quantum efficiency in the entire dynamic range. These components then are used to build a library of pharmaceutical raw materials and tested on samples of unknown material.
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Photonic Bandgap Fibers in Gas DetectionPhotonic crystal fibers are novel optical waveguides that offer promising alternatives for various sensing applications. This article describes an experiment in which the absorption spectrum of acetylene was measured to demonstrate the effectiveness of photonic bandgap fibers for high sensitivity gas detection. Methane also was studied to determine the same capability in weakly absorbing gases.
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A New Tool for Mass Analysis of Unknown Molecules: High-Resolution Multistep Tandem MS with Wide Dynamic Range Quantitative AnalysisMass spectrometers are effective for identifying and quantifying unknown molecules, such as disease-related proteins and small molecules in pharmaceutical research and medical diagnosis. In addition, mass spectrometry (MS) can be particularly powerful when analyzing molecules with complex structures, such as posttranslationally modified proteins. Among various MS approaches, high-resolution multistep tandem MS (MS-MS) is an emerging methodology for accurate identification of complex molecules. In this article, we describe a new approach for mass analysis with enhanced quantitative capability combined with high-resolution multistep MS-MS, where the dynamic range of quantitation covers four orders of magnitude.
