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| Tip
of the Month: Ion Tree Experiments |
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When performing
an Ion Tree experiment, the Finnigan™ ion trap mass
spectrometer can collect MSⁿ data automatically. The user can
specify a particular ion for fragmentation, or let the mass
spectrometer determine parent ions automatically and fragment
them to any level between MS2 and MS10. The mass spectrometer
then automates the collection of data by deciding what actions
need to occur next for the experiment to progress. The results
of a Data Dependent™ Ion Tree can be viewed in the Xcalibur
Qual Browser window and the results are displayed as a
structure tree that originates from a particular parent
ion. |
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| Proteomics:
Preserving PTMs - ECD on the Finnigan LTQ
FT™ |
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| Electron capture
dissociation (ECD) has recently evolved as an alternate
activation method, especially for peptide and protein
sequencing with Fourier-transform ion cyclotron resonance-mass
spectrometry (FTICR-MS). The most commonly used activation
methods such as collision induced dissociation (CID) and
infrared multiphoton dissociation (IRMPD) induce dissociation
by vibrational excitation of the precursor. These activation
methods induce “ergodic” processes, i.e. they add internal
energy to the precursor slower than the rate of energy
randomization, which leads to cleavage of the weakest bonds
within the precursor. ECD, being non-ergodic in nature,
preserves co- and post-translational modifications. |
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| Download Full
Article [PDF 172 kB] |
| Quantum Waves:
Analysis of Antibiotics in Environmental Water
Samples |
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Growing concern
over the presence of antibiotics in environmental sources of
water has caused environmental and government labs to develop
LC/MS methods to monitor water supplies for the presence of
antibiotics. The low-concentration of antibiotics in
environmental water sources makes extensive sample
preconcentration and cleanup a necessity. Preparation of water
samples (100-1000 mL) prior to LC/MS analysis, even with an
“unlimited” sample volume, is time consuming and reduces
sample throughput. |
| Download Full
Article [PDF 190 kB] |
| Achieve Lower Levels
of Quantitative Bioanalysis with H-SRM™ |
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Highly-Selective Reaction
Monitoring (H-SRM) enables efficient analysis of complex
biological samples. Thermo's patented HyperQuad™ quadrupoles
yield higher ion transmission, minimizing false positives and
maximizing sensitivity. In addition, the heated ESI probe with
Dual Desolvation Zone technology further optimizes
performance. Learn more by ordering your bioanalysis resource
kit that includes:
- Chapter reprints from “Using Mass
Spec. for Drug Metabolism Studies”
- The Finnigan TSQ
Quantum™ and H-ESI Technology Demo DVD
- Tech. Note:
“Achieve Ultra-low Levels of Quantitative Bioanalysis with
H-SRM”
- Tech. Note: “Heated Electrospray Ionization
(H-ESI) Probe” |
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| Order your
bioanalysis resource kit
now |
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| The Finnigan LXQ™ in
Forensics |
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The new Finnigan LXQ
linear ion trap provides:
- Simultaneous identification and
quantification of multiple analytes
- Superior sensitivity
in complex matrices, even with minimal cleanup
- Enhanced
selectivity of co-eluting compounds
- More information per
sample per run |
| Download Poster
Now |
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| The Finnigan LXQ in
Drug Discovery |
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The new Finnigan LXQ
linear ion trap provides:
- Exhaustive metabolite profiling
from a single LC-MS analysis
- Identification of low
abundance metabolites and resolving co-eluting compounds
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Obtaining important structural information with Data Dependent
scan functions and excellent MSⁿ spectral quality
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Simplifying the analysis of complex samples |
| Download Poster
Now |
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| Software: Your
Fingerprint Confirms Your Identity |
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Think about what
you do day-in and day-out to determine structures of your
compounds of interest. Often this involves using a Data
Dependent experiment to acquire MSⁿ information. Depending on
the class of compound, the MS², MS³ or MSⁿ can be critical to
providing clues about the structure. But what you really want
is to retain all those Data Dependent relationships -- to keep
the spectral tree intact. This tree is the fingerprint of your
molecule. Imagine if these relationships or trees weere
created automatically, if they could be databased, searched,
and matched, if fragments were assigned structures. Imagine
Mass Frontier 4.0. To get your own evaluation version, email
brenda.kesler@thermo.com. |
| Do you know what
the fingerprints of your compounds
are? |
| Contribute to
Critical Mass |
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| Critical Mass is now
accepting contributions from subscribers. If selected for
publication, contributors will receive a Thermo-branded
memento as a token of our appreciation. You are welcome to
send contributions in all areas of Mass Spectrometry. Critical
Mass will accept a wide range of contributions including but
not limited to your research interests in mass spectrometry or
using mass spectrometry, tips, new applications, interesting
stories on using Thermo's mass spectrometers, etc. Please
click on the link provided below to read the Terms and
Conditions for making contributions. |
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| Read Terms and
Conditions for Making
Contributions |
| Trap
Talk: DDCNL for Metabolite Identification |
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A Data Dependent
Constant Neutral Loss (DDCNL) experiment performs an MS scan
followed by an MS/MS scan of the most intense peak to look for
a user-defined neutral loss. If the MS/MS scan produces a
fragment with the targeted neutral loss, an MS³ scan of the
product ion is triggered. However, if the fragments in the
MS/MS scan do not correspond to the targeted neutral loss, the
software moves on to the next most intense peak in the MS scan
and performs another MS/MS experiment. This sequence is
repeated for a preset number of ions in the MS scan. DDCNL is
a technique that increases selectivity for identification of
metabolic modifications. It also simplifies the analysis of
complex mixtures in biological matrices, and enables... |
| Download Full
Article [PDF 83
kB] |
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