Compounds of magnesium and calcium are common components of pharmaceutical formulations. Spectroscopic imaging can provide a complete understanding of a formulation. This paper compares two spectral imaging techniques — energy dispersive X-ray fluorescence (EDXRF) microscopy and Raman microscopy.
The 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.
Due to its high information, vibrational content, the Raman spectrum provides important and specific molecular information. In this article, Raman microanalysis and instrumentation is discussed with specific application to the forensic science laboratory, where evidence integrity is of the utmost importance.
The acquisition of Raman spectra can be eased greatly through the use of surface-enhanced Raman spectroscopy (SERS). In this article, the authors discuss a new substrate technology that delivers reliable and consistent surface enhancement.
Raman spectroscopy has been employed to detect Bacillus cereus spores, an anthrax surrogate, collected from a letter as it passed through a mail sorting system. Raman spectroscopy also has the ability to identify many common substances used as hoaxes. A three-step method also is described for the detection of dipicolinic acid extracted from surface spores by SERS.
This 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.
A review of the five-day conference dedicated to promoting mass spectrometry and its allied topics held earlier this month in San Antonio, TX.
Spectroscopists separate light from the sun into spectra and look for the presence or absence of particular lines that give hints regarding its chemical composition. The same method can be applied to studying the composition of other matter in the universe.
This paper discusses two atomic force microscopy (AFM) techniques that have been used successfully to quantify step movement: direct and indirect measurement. The benefits and difficulties associated with each method are discussed.
Therapeutic drug monitoring is performed routinely by liquid chromatography–mass spectrometry (LC–MS) using instrumentation and methods originally developed and systematically configured for the high-volume, high-throughput analysis of drugs of abuse. An example of LC–MS monitoring of the drug clozapine and its metabolite, desmethylclozapine, is detailed along with a description of the overall system architecture, workflow, and maintenance routines that support a large-scale clinical therapeutic drug monitoring program. The relative advantages of LC–MS over immunoassay and LC–UV, the current standard techniques for therapeutic drug monitoring, are discussed in the light of these results.
Back by popular demand, Spectroscopy's resident MS expert, Ken Busch, presents a list of common acronyms used in the field.
The author reviews the Digital Library for the Analytical Sciences (ASDLib) Web site, its philosophy, a summary of its MS resources, and how it can be useful to mass spectrometry practitioners.
A transportable miniature Fourier-transform ion cyclotron resonance mass spectrometer is used to identify chemical species and remove isobaric interferences in gas analysis. Experimental results use real time direct analysis without the need for additional separation.
The annual event will continue its tradition of promoting knowledge of all things mass spectrometry, with a few new features mixed in.
The European-built Huygens probe made history on January 14 by becoming the first spacecraft to land on Saturn's largest moon. The Huygens gas chromatography–mass spectrometry team concluded that methane rain occurs on the moon, and GC–MS can distinguish between two isotopic forms of carbon — carbon-12 and carbon-13. By comparing the carbon-12/13 ratios it might be possible to pin a biological source to the methane arising from the interior of Titan.
Time-of-Flight (TOF) is rapidly becoming the most popular method of mass separation for proteomics and conventional analytical chemistry. The development of very high temporal resolution ion detectors and low-cost high-speed digitizers has rendered this technique easily deployed and able to produce very high mass resolution. The performance of a TOF mass spectrometer is dependent upon a number of critical components. This article will focus on the ion detector.
The 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.
The exploding field of proteomics has highlighted the need to improve the performance of mass spectrometry, both quantitatively and qualitatively. These needs have led instrument manufacturers to produce instruments of increasingly higher quality, but little work has been done to address the fundamental errors inherent in the measurement technique itself. This paper examines these errors and demonstrates that the appropriate mathematical correction of MS data can significantly improve the performance of both low- and high-resolution instruments.
Off-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.
Time-dependent density functional theory and ZINDO/S methods have been used to compute and analyze the electronic spectra of benzazoles, 2-phenylbenzazoles, and 2-(4-aminophenyl)benzazoles. The observed spectra of the studied antitumor drugs are diffuse and highly solvent-dependent. Spectral analysis of the charge density distributions and relative polarities of the ground and excited states have enabled understanding of the observed solvent effects.
Spectroscopy is proud to present its annual review of products displayed at our industry's premier trade show, the Pittsburgh Conference. The Spectroscopy editorial staff spent a good portion of the show investigating and collecting information on exhibitors' offerings, and a sampling of those instruments appear below, including a brief product description and the company's name and Web address. We have made every effort to provide as comprehensive a listing as possible, but as in years past, we cannot claim to have made a complete record of every product shown at the conference.
Photonic 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.
The authors describe their work characterizing archaelogical ceramics by means of Fourier-transform infrared (FT-IR) absorption. Semiquantitative analyses using the technique can identify the main components and trace elements constituting the ceramics. An accurate knowledge of the chemical composition of the samples gives useful information for their classification.
MEMS are small, microfabricated devices that are finding application in a variety of industries in both analytical and manufacturing settings. This paper reviews the properties of diffractive MEMS devices and examines their application in chemical spectroscopy.
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