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Life Sciences Mass Spectrometry
| Tip of the Month: Adjusting the HESI-II Probe Position to Maximize Sensitivity |
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To maximize the sensitivity, you can adjust the probe depth. If you have the Ion Max API source housing, you can also adjust the side-to-side and front-to-back probe position by a few millimeters.
» Download the Complete HESI-II User Guide to See How! [PDF 2.02 MB]
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| Bioanalysis: LC-FAIMS-MS Validated Quantitation Method for a Peptide in Rat Serum |
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Bioanalytical method development of peptides poses special problems for conventional LC-MS/MS technology. During the ionization step, the ion current is distributed among several charge states owning to the fact that there are multiple basic sites for protonation. This leads to many multiply charged species in a distribution envelope. At the outset of development, the method has less absolute signal than is often seen with singly charged small molecules.
FAIMS (high-Field Asymmetric waveform Ion Mobility Spectrometry) increases the selectivity of an assay based on ion mobility prior to mass analysis. In this application note, FAIMS was used in combination with SIM at unit resolution (0.7 u FWHM) to validate a quantitative method for peptide analysis in rat serum according to GLP standards.
» Download Full Application Note [PDF 274 kB]
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| Upcoming European Events |
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Moving Science Forward
Visit the Thermo Scientific booths for more information about products and workflows to meet your challenges.
For more information:
» BASIS 2009 (April 2-3, 2009, Bruges, Belgium) - Stable Isotopes
» ESAC 2009 (April 16, 2009, Copenhagen, Denmark) - Life Sciences Mass Spectrometry
» EGU (April 19-24, 2009, Vienna, Austria) - Geosciences
» Frontier Lipidology: Lipidomics in Health and Disease (May 10-13, 2009, Gothenburg, Sweden) - Lipidology
» Achema 2009 (May 11-15, 2009, Frankfurt, Germany) - Chemical, Environmental & Biotechnology
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| Proteomics: Relative Quantitation of Protein Digests Using TMT and PQD |
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Quantitation of differentially expressed proteins is one of the most challenging areas in proteomics. A variety of quantitation methods have been developed, including isotope labeling approaches such as: ICAT®, SILAC, iTRAQ™, AQUA, and Tandem Mass Tag® (TMT).
In contrast to MS-based quantitation methods, iTRAQ- and TMT-labeled peptides are identified and quantitated by MS/MS. Pulsed-Q Dissociation (PQD) has been developed to facilitate quantitating of the low-mass reporter ions in MS/MS spectra of iTRAQ-or TMT-labeled peptides. The PQD technique enables the detection of low-mass fragments in MS/MS mode including y1- and b1-type fragment ions, and also allows the quantitation of peptides using the TMT reporter ions which appear in the 100 m/z range. This application note demonstrates the benefits of the PQD-based quantitation of isobarically labeled peptides in protein digests.
» Download Full Application Note [PDF 1.14 MB]
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Metabolism: Tools That Facilitate Metabolite Identification - Mass Spec Technology Drives Drug Metabolism Studies Forward
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Recent advances in both mass spectrometry hardware and software have helped in isolating potential drug candidates. Coupling a Thermo Scientific Orbitrap mass analyzer to a linear ion trap mass spectrometer, for example, simplifies metabolite identification, making it faster, more sensitive, more precise (with resolution higher than 100K and mass accuracies better than three ppm) and capable of revealing rich structural information. With high-resolution and accurate mass data, researchers can resolve and identify metabolite peaks from background matrix ions. New data processing techniques, such as mass defect filtering, can be used to remove the vast majority of matrix-related background ions and reduce the number of false-positives, providing a more confident result.
» View Full Article (Genetic Engineering & Biotechnology News, Feb 15, 2009, Vol. 29, No. 4 by Yingying Huang, Ph.D. Thermo Fisher Scientific, San Jose, CA, USA)
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| Metabolism: Case Study - LC/MSn Ion Trap Technology for High-Throughput Drug Discovery |
| In drug discovery and development, the immense quantity of information available from high-throughput digitalized biology can be overwhelming, reducing the focus on the quality of the data. Dr. Jonathan Josephs, principal scientist for Bristol-Myers Squibb, has developed novel ways to obtain the most valuable information – identity, purity, and metabolic profiles – of drug candidate compounds. His protocols accurately characterize candidate compounds, including structural integrity and quantitative assays and kinetics of metabolism. Compounds are investigated with greater depth, while time and valuable resources are saved. Thermo Scientific ion trap-based mass spectrometers provide the high sensitivity, precision, and accuracy necessary for these assays.
» Download Full Case Study [PDF 299 kB]
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| Chromatography: Exploiting Particle Size to Reduce Solvent Consumption in Analytical HPLC |
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The global shortage of acetonitrile is causing concern for many LC/MS operators. In this article, the use of sub-2 µm particle packed columns as a strategy to help reduce acetonitrile consumption in analytical test methods is presented.
» Download Full Article [PDF 371 kB]
Thermo Scientific UHPLC Filter
Learn how you can protect your Thermo Scientific Hypersil GOLD 1.9 µm columns without losing performance with our new UHPLC filter.
» Learn more
» View the On-Demand Webinar
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| Environmental: Analysis of Haloacetic Acids in Drinking Water by IC-MS/MS |
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Haloacetic acids (HAAs) are formed as disinfection by-products when water is chlorinated to remove microbial content. According to the U.S. Environmental Protection Agency (EPA), there might be an increased risk of cancer associated with long-term consumption of water containing levels of HAAs that exceed 0.6 mg/L.
In comparison to the conventional EPA methods using gas chromatography (GC) with electron capture detection (ECD), the combination of ion chromatography and mass spectrometry (IC-MS/MS) offers sensitive and rapid detection without the need for sample pre-treatment. Coupling IC with the highly selective detection of a triple quadrupole mass spectrometer allows unambiguous identification of substance peaks. Matrix interference effects are greatly reduced, which improves the sensitivity and lowers the detection limits.
» Download Full Application Note [PDF 636 kB]
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| Trap Talk: Understanding High Resolution and Accurate Mass – see more details in your sample |
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Separation of isobaric peaks at different resolution settings
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The terms high (mass) resolution and resolving power are often used interchangeably. High resolution is necessary to separate peaks of one mass from those of another and ensure that ions of only one exact mass contribute to a particular measurement. The measurement may be accurate mass determination or a highly specific quantification. High resolution is particularly important for all types of experiments involving complex mixtures, such as the analysis of samples generated from a matrix (e.g. biological, environmental), since these will contain a significant number of background ions. In such cases high resolving power will make, for example, the difference between, detecting compounds at low concentration or not detecting them due to the masking effect of isobaric interferences.
» Learn more [PDF 448 kB]
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