Mass Spectrometry

This tutorial illustrates the technical principles and typical applications of the most common mass analyzers used in bioanalytical laboratories today, as well as novel techniques and mass analyzer designs. Examples are based upon the authors' research in small molecule applications.

New mid-infrared spectroscopic sources, based upon advances in fiber lasers and in nonlinear frequency conversion, are now enabling high-resolution laser spectroscopy in the 2–4 μm wavelength region and beyond. With this in mind, the authors discuss continuous wave (CW) optical parametric oscillators (OPOs) in particular.

Part III of this four-part series continues the discussion of mass calibration.

High-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.

The authors describe an in-situ cleaning verification technique that promises to be faster and more efficient than traditional methods, which use swab sampling followed by HPLC analysis. The technique is based upon FT-IR spectroscopy in the middle-infrared (mid-IR) range using reflection at a grazing angle.

A report published earlier this year (1) discussed a UV–vis-NIR instrument designed for use on NASA Mars rover missions. This article follows up with coverage of the Planetary Fourier Spectrometer on the European Space Agency's Mars Express orbiter mission.

In this X-ray tutorial, the authors attempt to answer the frequently asked question, "How deep do the X-rays penetrate my sample?"

The fate and transport of organic contaminants and their impact upon plant development has been an important topic in environmental science. Here the authors report the use of synchrotron radiation Fourier-transform infrared microspectroscopy (SR-IMS) as a direct method for monitoring the fate and effects of 2,6-dinitrotoluene (2,6-DNT) in maize (Zea mays L.) root tissue.

Previous methods for linearity testing discussed in this series contain certain shortcomings. In this installment, the authors describe a method they believe is superior to others.

Innov-X Corporate Profile (PDF)

Spectroscopy previews products and sessions for attendees to see and participate in at the 54th Annual Denver X-Ray Conference, to be held August 1–5 in Colorado Springs, CO.

In this study X-ray absorption was used to determine the effect of pH on the coordination of lead to humin and sphagnum peat moss. The authors determined the oxidation state and the coordination of lead to both humin and sphagnum peat moss using X-ray near edge structure and extended X-ray absorption fine structure spectroscopy. In addition, inductively coupled plasma optical emission spectroscopy was used to determine the amount of lead bound to the humin and sphagnum peat moss in the pH range 2–6.

Laser ablation ICP-MS enables identification and comparison of physical crime-scene evidence. Discriminating elemental and isotopic differences of solid samples directly at the parts-per-billion level provides forensic scientists with a powerful analytical tool.

Confocal Raman microscopy can be useful when applied to all samples that are heterogeneous on the micrometer to millimeter scale and that generally can be investigated by Raman spectroscopy. This article presents examples of confocal Raman microscopy from various fields of application including pharmaceutical analysis and stress measurements in semiconductors.

A new system for multitechnique spectral searching is described that utilizes analysis of several hit lists resulting from spectral similarity searches performed simultaneously in reference databases for multiple complementary analytical techniques. This paper demonstrates the benefits of this multitechnique approach using the complementary techniques of IR and Raman spectroscopy.

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.