April 12th 2024
Here are the top five articles that the editors of Spectroscopy published this week.
Multi-Residue Pesticide Analysis Using a GC Triple Quadrupole Mass Spectrometer
February 11th 2011There are currently more than 1000 pesticides in use worldwide in the production of foodstuffs. There is a significant risk to human health and the environment due to increased pesticide use, poor agricultural practices and illegal use.
Using Novel TOF-MS to Increase Sensitivity and Confidently Detect Drugs of Abuse in Urine
October 1st 2010The analysis of urine for drugs of abuse via chromatographic methods is commonplace but can be complicated by high matrix effects and frequent coelution. Novel time-of-flight mass spectrometry in combination with sophisticated deconvolution software was tested and found to provide increased confidence in results due to the high sensitivity and quality of spectra achieved.
Increasing Productivity of ADME Studies Using Accurate Mass Technology
October 1st 2010A new time-of-flight mass spectrometer was evaluated for performing simultaneous metabolic stability measurement and metabolite identification with ultrahigh-pressure liquid chromatography. Six representative compounds (clomipramine, diclofenac, imipramine, haloperidol, verapamil, and midazolam) were incubated in rat liver microsomes at a more physiologically relevant substrate concentration (1 ?M). High-resolution full-scan and product-ion spectra were acquired in a single injection using generic methodology. Quantitative clearance of the parent was measured using the full-scan data. Major metabolites were identified using the accurate mass product ion spectra. High scanning speed allowed for a sufficient number of data points to be collected across the chromatographic peak for quantitative analysis. Sensitivity was sufficient for obtaining meaningful kinetics with a 1 ?M initial substrate concentration.
Development of a High-Throughput LC–MS Assay for Drugs of Abuse from Biological Matrices
October 1st 2010A high-throughput LC–MS method using core-shell UHPLC columns to screen for a panel of 11 drugs of abuse (expanded SAMHSA) was developed. The corresponding SPE method allowed the reproducible separation and quantitation of these 11 components in less than 2 min. This method demonstrates the power of new-generation HPLC media as well as some of the factors one must consider when developing such methods for LC–MS analysis.
Dried Blood Spots and High-Resolution Mass Spectrometry for Discovery Fast PK Bioanalysis
October 1st 2010This article introduces the advantages of accurate mass high-resolution mass spectrometry LC–MS (HRMS) coupled to the dried blood spot (DBS) technique for fast PK applications in a discovery environment. Compared with the established norm of plasma bioanalysis using triple quadrupoles, HRMS coupled to DBS is a viable alternative. The benefit is access to critical new information (HRMS bioanalysis) and significantly less stress on the animal (DBS), both factors that potentially improve the quality of early PK data.
Reliable and Efficient Sulfur Detection in Proteins Using ICP-MS with Capillary LC
October 1st 2010With recent research, the University of Oviedo's analytical spectrometry research group has taken a step closer to the absolute quantification of proteins. Quantification based upon isotope dilution mass spectrometry of sulfur is hampered by gas-based polyatomic interferences. By implementing a quadrupole inductively coupled mass spectrometer with collision/reaction cell technology, the group has been able to overcome the issues and has increased reliability while optimizing the efficiency of its analyses.
Ultralow Quantification of Pesticides in Baby Food
July 1st 2010The safety of the food that our children eat is a global concern. Regulations are in place that limit the maximum level of pesticides that can be present in food meant for children, and methods to detect levels well below those limits are needed to ensure the safety of the food supply. Combining the speed and separation efficiency of ultrahigh-pressure liquid hromatography (UHPLC) with the sensitivity and selectivity of triple-quadrupole mass spectrometry (MS)-MS results in a method that can deliver ultralow quantification of pesticides in baby food, with limits of detection more than an order of magnitude below the allowed maximum levels.
Bioanalysis Using Dried Blood Spots: The Biggest Advancement in Bioanalysis Since LC–MS-MS?
July 1st 2010The collection of blood-derived samples from preclinical and clinical trial studies onto paper-based, Guthrie-type cards is gaining momentum within the pharmaceutical industry. This approach holds the potential to minimize animal usage, improve data quality, and reduce shipping costs. However, the small sample volumes and extra matrix effects from the cards result in method development and sensitivity challenges for bioanalysts. Here, we present a discussion on the analytical challenges that both liquid chromatography and mass spectrometry face as well as present some potential solutions to these issues.
Comparing the Capabilities of Time-of-Flight and Quadrupole Mass Spectrometers
July 1st 2010The authors explain some of the primary differences between quadrupole and time-of-flight mass analyzers and provide information regarding the benefits of each in their use for gas chromatography applications.
The Use of Novel Software for the Identification of Trace Compounds in Complex Mixtures
July 1st 2010Many volatile organic compounds (VOCs) found in a variety of consumer products are potentially harmful to human health and the environment. Within industry, to regulate product safety and quality, methods for measuring specific VOCs in a product, typically by thermal desorption gas chromatography–mass spectrometry (TD-GC–MS), are implemented. Such analysis provides a comprehensive VOC profile. However, the nature of some products, such as food, can be chemically complex. Within this complexity, trace-level or coeluting compounds can be difficult or time-consuming to identify. As a potential solution, new software tools are being developed to automate interpretation of the data.
Enhancing Mass Spectral Formula Determination by Heuristic Rules
May 1st 2010A 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.
Ultralow Detection of Estrogenic Compounds by GC–NCI-MS-MS
May 1st 2010A number of clinical situations now call for high-sensitivity measurement of estrogens, including monitoring during female hormone replacement therapy, antiestrogen treatment, and estrogen deficiency in men. Traditional immunoassay methods and liquid chromatography–tandem mass spectrometry (LC–MS-MS) do not provide the sensitivity and selectivity required for these applications. In contrast, a gas chromatography–negative chemical ionization–tandem mass spectrometry (GC–NCI-MS-MS) platform can provide detection limits below 1 pg/mL when used in conjunction with the appropriate derivatization protocol, with very short cycle times.
TOF-MS: A Viable Solution for Crude Oil Extract Analysis
May 1st 2010Crude oil is a generic term for the unrefined flammable liquid that is mined from the ground. It is an extremely varied and very complex medium that can contain many thousands of organic compounds, whose contents and concentrations vary enormously from one sample to another. This article discusses how recent advances in time-of-flight-mass spectrometry coupled with comprehensive two-dimensional gas chromatography is helping the petrochemical industry to characterize crude oils more fully and so provide solutions to common problems experienced during drilling, extraction, and refining.
Translating HPLC Performance Gains of Core-Shell Media to LC–MS Applications
May 1st 2010Adapting the use of "ultrahigh" performance chromatography for liquid chromatography–mass spectrometry (LC–MS) applications requires specific considerations in integrating the instrument platforms. Mobile phase options are limited to volatile buffers, and slow MS sampling rates can limit throughput advantages that such next-generation media offer. High-throughput LC–MS methods of different relevant pharmaceutical and environmental mixtures were developed using ultrahigh performance core-shell media. Such methods were developed using standard HPLC systems and back pressures, showing the ease and utility of using core-shell media for increasing throughput of LC–MS methods.
Branching Out: Mass Spectrometry and the Shape of Biotherapeutics
May 1st 2010Those fond of puns point out that mass spectrometry (MS) has become ever more focused in the last two decades, while at the same time offering ever more information. The dynamic market for biotherapeutics has driven a number of developments, particularly following the paradigm of well-characterized biopharmaceutical products (WCBP) (1,2). Partly as a result of automation and interfacing, those trained in biological or biochemical disciplines now use mass spectrometers routinely. This also means that the sorts of questions asked of MS have changed. Coping with biomolecule heterogeneity is a key challenge, not generally an issue for small molecule drugs. The data complexity means that mass information alone is insufficient. And at the submission stage, regulators are increasingly concerned about tertiary structure and conformation, something that was not previously an analytical requirement (2). Adding polyethylene glycol (PEG) to already heterogeneous molecules to prolong their half-lives in the body raises..
Rapid Chemical Threat Identification by SPME-GC–TMS
April 1st 2010A person-portable gas chromatography–mass spectrometry (GC–MS) system employing a toroidal ion trap mass spectrometry (TMS) detector was used to analyze chemical threat related compounds. Introduction of analytes into the heated injector of the instrument was by solid-phase microextraction (SPME), and fast resistive heating of a low thermal mass (LTM) gas chromatography column assembly provided rapid analysis times. Methodology for positive identification of chemical threats can combine chromatographic retention time, comparison to traditional electron ionization mass spectral libraries, and observation of expected pseudomolecular ions produced through self-chemical ionization. Methods are discussed for sampling by SPME with GC–MS analysis in the field to measure airborne analyte concentrations.