Plenary
Lectures
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Biomimetic
adhesion surfaces |
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Eduard
Arzt
Scientific Director and Chairman (CEO),
INM - Leibniz Institute for New Materials
Saarland University
Germany
http://www.inm-gmbh.de
a
copy of the talk is available HERE
(11.2 MB) |
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Adhesive joining with molecular (van der Waals) interactions without chemical
glue is presently receiving much attention because of many potential applications.
Research on how insects, spiders and geckos stick to surfaces has inspired
a new paradigm: fibrillar surfaces with appropriate design can show much
higher adhesion performance than flat surfaces. The insight gained in
studying biological systems can be transferred to the development of optimized
artificial attachment devices. By systematic variations of fiber diameter,
aspect ratio and contact shape, we have produced, on a laboratory scale,
artificial structures with adhesion strengths similar to the gecko. Further
advances with switchable adhesion (“smart adhesives”) have
been demonstrated and may lead to interesting applications in medical
products, sports good, construction materials and microfabrication.
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Mass-based
metabolomics from solution and surfaces |
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Gary
Siuzdak
The Scripps Research Institute
Center for Mass Spectrometry
10550 North Torrey Pines Road
La Jolla, CA 92037
USA
http://masspec.scripps.edu
a
copy of the talk is available HERE
(10 MB) |
Quantitative
global analysis of endogenous metabolites from cells, tissues, fluids
or whole organisms - metabolomics, is becoming an integral part of functional
genomics efforts as well as a tool for finding diagnostic biomarkers.
Where the genome and proteome is largely enabled by the predictable fragmentation
pattern of peptides, metabolomics is complicated by the tremendous chemical
diversity of metabolites. The experimental aim in our global metabolomics
studies is to obtain a comprehensive quantitative with an unbiased view
of the metabolome. We have explored multiple novel mass spectrometry platforms
for metabolomics including both solution-based approaches and surface-based
mass spectrometry, such as nanostructure-initiator mass spectrometry (NIMS).
These platforms will also be presented in the context of specific biochemical
applications such as neonate screening, gut microbial influence, and tissue
imaging.
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Liquid
chromatography – mass spectrometry in sports drug testing |
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Mario
Thevis
German Sport University Cologne
Institute of Biochemistry
Carl-Diem Weg 6
50933 Cologne
Germany
www.dopinginfo.de
www.cepredo.de
a
copy of the talk is available HERE
(1.5 MB) |
LC-MS(/MS)
has gained considerable importance in sports drug testing due to its capability
to measure thermolabile compounds with great sensitivity and specificity
in complex biological matrices such as blood or urine. Numerous assays
formerly established using GC-MS approaches were transferred to LC-MS-based
methods, and complementing procedures particularly for peptide hormones
such as insulins or corticotrophins were developed. Consequently, the
instrumental equipment of doping control laboratories has changed over
the last decade, and with the growing number of prohibited compounds and
methods of doping, modified or additional screening methods are currently
utilized to cope with the ‘creativity’ of cheating athletes
and the virtually infinite pool of new therapeutic agents with potential
for misuse in sports.
A selection of analytical methods developed for doping control purposes
will be presented and outline the particular challenge that either the
compounds or their legal availability represent to sports drug testing
authorities.
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Pathway
analysis in expression proteomics: Toward pathway search engines |
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Roman
Zubarev
Molecular Biometry, Cell & Molecular Biology
Uppsala Biomedical Centrum
Husargatan 3
Box 583
SE-75 123 Uppsala
Sweden
http://www.bmms.uu.se/indexZubarev.html
Co-authors:
YM Eva Fung, Konstantin
Artemenko, Corina Meyrhofer |
| Analytical
Pathway Biology strives to develop a tool that uses proteomics datasets
as an input and yields activated signalling pathways as an output. Such
a "pathway search engine" (PSE) will find application in many
fields, from fundamental studies to search for novel disease biomarkers.
The task of PSE development is far from trivial as straightforward mapping
of up- or down-regulated proteins onto signalling pathways usually produces
incorrect results. We have developed a novel approach to pathway identification
(Zubarev et al, J Proteomics, 2008, 1, 89-96), and have extended this
approach to keynodes. Examples of application of this approach to different
biological systems will be demonstrated.
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Short
Communications
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Top
down mass spectrometry advances in protein quantitation based on stable
isotope labeling and protein-metallodrug binding characterization
Yury O. Tsybin (1), Thibaut
Douche (1), Adrien Schmid (1), Michael Affolter (2), Martin Kussmann (2),
Christian G Hartinger (1), Alexander Egger (1), Paul J Dyson (1)
1 Ecole Polytechnique Federale de Lausanne (EPFL), Lausanne, Switzerland
2 Nestle Research Centre, Vers-chez-les-Blanc, Switzerland
High performance mass spectrometry
platform based on Fourier transform ion cyclotron resonance mass spectrometer
(FT-ICR MS) with 11 T superconducting magnet has recently been installed
at EPFL’s Department of Chemistry. Herewith we will present recent
results in the domain of top down protein analysis carried out in collaboration
with Nestle Research Center and Medicinal Chemistry group of EPFL.
Top-down high-resolution mass spectrometry of ANIBAL stable-isotope labelled
proteins has revealed a high sample complexity and has indicated specific
advantages over the bottom-up approaches and the necessity for the high
resolving power of FT-ICR MS. Preliminary analysis of derivatized ubiquitin
has revealed a population of 10- to 12-fold aniline labelled protein molecules,
which corresponds to 83% to 100% yield of theoretically possible derivatization.
Complementary to bottom-up MS, the top-down MS approach allows localization
of ANIBAL labels on a protein sequence in heterogenous protein-label mixture
to indicate specific protein structural preferences for chemical derivatization.
We are applying this analytical approach, improved by coupling to LC,
to the quantification of proteins from biological tissues.
We have demonstrated for the first time that for metal-based drugs, e.g.
cisplatin, transplatin and oxaliplatin, the primary binding sites on ubiquitin
and model oligonucleotides could be directly determined by top-down FT-ICR-MS
and the uncertainties arising from post-digestion reactions from the bottom-up
approach have been eliminated. The top-down approach is likely to become
the standard method for determining metal binding sites to proteins and
DNA, especially in the domain of metal-based drugs, and it should ultimately
provide the data that would facilitate drug design and discovery.
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Quantification
of a peptide down to the low pg/mL concentration level using three different
LC-MS/(MS) approaches
Berthold Lausecker, K Heinig
F.Hoffmann-La Roche Ldt, Non-Clinical Safety, Basel Switzerland
Pharmaceuticals industry is
facing demanding challenges with respect to keep their productivity at
a level which guarantees revenues in the double digit range. One option
that started more than 10 years ago is to complement the small molecule
portfolio with large therapeutic bio-molecules. While the tools for the
quantification of low molecular drugs have been improved significantly
over the last 10 to 15 years by the implementation of LC-MS, ELISA as
the first choice for the quantification of e.g., mABs has not much improved
and no quick and powerful alternative has shown up. The aim of the presentation
is to discuss which strategies using LC-MS technologies could be used
to quantify bio-molecules in order to support the drug R&D compared
to the common used ELISA technologies. A peptide which shares to certain
extent small molecule and large biomolecule properties will be used to
demonstrate advantages and the limitations of the LC-MS approaches. Data
will demonstrate that for the peptide low pg/mL quantification limits
could be achieved using different sample preparation and LC-MS setups.
The LC-MS methods will be compared with respect to sample volume needed,
sample preparation time and instrument run time. Other mass spectrometric
features as the use of high resolution MS and high-field asymmetric waveform
ion mobility spectrometry (FAIMS) are evaluated with respect to the assays
sensitivity and specificity.
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CREDEX-MS:
Molecular elucidation of carbohydrate recognition epitopes in lectins
and glycosylated proteins by proteolytic excision- mass spectrometry
Michael Przybylski (1), Adrian
Moise (1), Hans-Christian Siebert (2)
Hans-Joachim Gabius2
1 Laboratory of Analytical Chemistry and Biopolymer Structure Analysis,
Department of Chemistry, University of Konstanz, Germany
2 Department of Physiological Chemistry,
Ludwig-Maximilians-University of Munich, Germany
The emerging relevance of glycan-encoded
information in a plethora of biological events directs increasing attention
to interaction structures between bioactive glycan determinants and their
endogenous receptors, such as lectins. Structures of carbohydrate complexes
with lectins and antibodies have been determined in a few cases by X-ray
crystallography and NMR, however both methods are limited by large amounts
and high purity of material required. We report here a new direct method
for molecular mapping of peptide motifs in lectin carbohydrate domains
(CRD) by the combination of proteolytic excision of protein-carbohydrate
complexes and mass spectrometry (CREDEX: Carbohydrate-REcognition-Domain-EXcision).
The CREDEX-MS method was applied to the identification of CRDs of human
galectin-3 and galectin-1, for which X-ray crystal structures of their
lactose complexes have been determined. Lactose was covalently coupled
to epoxy-activated Sepharose, galectins added to the affinity matrix and
the lectin complexes digested using trypsin. After removal of unbound
fragments, competitive elution of remaining affinity-bound gal-peptides
with lactose followed by MALDI-MS provided the identification of specific
peptides, gal-3(152-162) and –(177-183), and gal-1(37-48) and (64-73),
in complete agreement with CRDs from the crystal structures. In the same
manner, two specific, discontinuous gal-3 peptide epitopes were identified
for blood group tri-A . Their specificity was confirmed by affinity-MS
of the synthetic CRD peptides, and by inhibition studies with gal-3 in
human lymphoma cells. Most recent applications to CRD identifications
of hitherto unknown lectin-carbohydrate complexes ascertain the CREDEX-MS
approach as a powerful tool for the direct determination of CRDs in solution,
suggesting a wide range of applications to define contact sites for lectin
ligands of human sugar receptors in biological material.
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Are
LC/MS-MS fragmentation patterns unequivocal confirmation criteria?
Anton Kaufmann; Kantonales
Labor Zürich
Relative abundances of product
ions as obtained by LC/MS-MS experiments, are often used to confirm the
presence of trace analytes in complex matrices. Such ratios are mostly
obtained by measuring multi reaction monitoring (MRM) traces followed
by the integration of the resulting chromatographic peaks. Maximum tolerable
deviations of such MRM ratios (between a suspected peak in a sample and
in a standard) have been written into the European legislation (2002/657/EC).
Samples were analyzed in the author's laboratory where a chinolone (dicloxacillin)
was present. However, the relative peak intensity between the observed
ratio in the sample strongly deviated from the ratio observed in the standard.
This would have led to a false negative finding. A detailed investigation
showed that deviating ratios were not caused by endogenous compounds which
happened to produce one of the monitored transitions. Matrix effects were
observed, which suppress certain MRM traces. Although matrix induced signal
suppression is well known in LC/MS-MS, no such matrix induced deviations
of MRM ratios were reported in the literature. Furthermore, a shift of
MRM ratios could also be observed when analyzing matrix free standards
under different source temperatures. A closer evaluation of a dicloxacillin
ESI spectra [M+H]+ m/z = 400 showed the presence of the double charged
analyte (m/z = 200.5). This interpretation could be confirmed by a number
of experiments.
A double charged ion indicates that there are two different sites of protonation.
This lead to the theory that the analyte molecule can also be single protonated
at these two different locations, resulting in two different, isobaric
ions. These two ions can not be separated in the first quadrupole. However,
the presence of a charge at different sites will affect the stability
of the resulting ions. Hence the fragmentation in the collision chamber
will be different. It is likely that factors like the presence of the
matrix or the change of the desolvation temperature in the interface will
affect the ratio of these two differently protonated ions.
Experiments were performed, where none and very intense in source collision
induced fragmentation was provoked. A very intense fragmentation regime
leaves only a small precursor ion abundance. If there is a stability difference
among the two postulated isobaric ions, then only the more stable one
is expected to survive. Selecting the [M+H]+ precursor in the first MS
stage and maintaining identical fragmentation conditions, produced - as
postulated - very different product ion spectra under the two source collision
regimes. Two different fragmentation paths could be elucidated, supporting
the theory of two isobaric precursor ions.
The reported observation is of significance for analytical work, where
the confirmation of a suspected compound relies on MRM ratios. The use
of tolerances as defined by the mandatory Commission Decision 2002/657/EC
can lead for certain compounds to false negative findings.
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LC-APPI-MS
for the analysis of 27-hydroxycholesterol as candidate biomarker for atherosclerosis
student award lecture
Ratna Karuna, Arnold von Eckardstein,
Katharina M Rentsch
Institute of Clinical Chemistry, University Hospital Zurich
Raemistrasse 100, CH-8091, Zurich, Switzerland
Due to its role in maintaining
whole-body cholesterol homeostasis, 27-Hydroxycholesterol is a potential
biomarker for atherosclerosis and reverse cholesterol transport. Evaluation
of this candidate biomarker in plasma samples of humans and animal models
requires a sensitive and robust analytical method.
APPI (Atmospheric Pressure Photoionization) is the state-of-the-art of
ionization techniques interfacing liquid chromatography and mass spectrometry
(LC-MS) system. With the help of toluene as dopant and MeOH as LC eluent,
APPI has improved the sensitivity of the analysis, in comparison to the
published LC-APCI-MS method, allowing the quantification of 27-hydroxycholesterol
from as little as 15 µL plasma with a limit of quantification (LOQ)
of 40 ng/ml plasma. The method was validated also for the quantification
of 27-hydroxycholesterol from 50 µL plasma, with LOQ of 10 ng/ml.
A further advantage is that no prior derivatization is needed, unlike
the previously established LC-ESI-MS or GC-MS methods.
Preliminary results from analyses of plasmas from different knock-out
mice show the potential of 27-hydroxycholesterol as a novel biomarker
of atherosclerosis.
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Rapid
affinity classification of kinase inhibitors by mass spectrometry
student award lecture
Matthias C Jecklin (1), David
Touboul (1), Rishi Jain (2), Estee Naggar Toole (2), John Tallarico (2),
Paul Ramage (3), and Renato Zenobi (1)
1 Department of Chemistry and Applied Biosciences, ETH Zürich, CH-8093
Zürich, Switzerland
2 Novartis Institutes for Biomedical Research, Global Discovery Chemistry,
Lead Synthesis & Chemogenetics, Cambridge MA, USA
3 Novartis Institutes for Biomedical Research, Protein Structure Unit,
CH-4002 Basel, Switzerland.
Protein kinases have emerged
as a major drug target in the last years. Since more than 500 kinases
are encoded in the human genome, cross-reactivity of a majority of kinase
inhibitors causes problems for the design of specific drugs. Tools are
required for a rapid classification of inhibitors according to their affinity
for a certain target in order to refine the search for new, more specific
lead compounds. We are comparing different nanoelectrospray mass spectrometry
(nanoESI-MS) based methods to quantify binding affinities and qualitatively
determine, by competition experiments, the affinity of several clinical
inhibitors. Our results are then compared with standard IC50 measurements
as well as with literature.
All samples (2 proteins: Lck and p38, and 17 clinical inhibitors including
BIRB796, Iressa, Tarceva, VX-745, SB202190, PP1, PP2) were provided by
Novartis. All samples were diluted in ammonium bicarbonate (10 mM, pH
7.9). A chip-based nanoESI robot (NanoMate, Advion Biosystems) was fitted
to a Q-ToF Ultima (Waters). Different MS-based methods were compared in
order to qualitatively classify the binding affinities of the compounds
to the protein targets. The first method has been introduced by Tjernberg
et al. [Anal. Chem. 2004, 76 (15), 4325], and the second method was developed
in our lab [Wortmann et al., JMS, 2007, in press].
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An
additional dimension of separation - MALDI MS Imaging with high-efficiency
ion mobility
Marten F Snel, Keith Compson,
Emmanuelle Claude, Therese McKenna, James Langridge
Waters Corporation, Manchester, UK
Introduction: Imaging Mass
spectrometry is an emerging tool in proteomics, lipidomics and metabolomics.
Biomolecules (i.e. proteins, lipids and drugs) are analysed directly from
a tissue section, providing spatial information.
It can provide complementary information to traditional costly and time
consuming techniques, such as autoradiography. The two main instrumental
challenges for the mass spectrometric analysis of tissue samples are sensitivity
and specificity, i.e. how well the compound of interest can be distinguished
from background ions. A means of increasing the separating power of a
MALDI imaging experiment is the use of high efficiency ion mobility spectrometry,
coupled with time-of-flight mass spectrometry which offers a new dimension
of separation. Using this technique it is possible to separate different
compound classes.
Methods: The samples studied were thin sections of animal tissue. Sections
of 12µm thickness were produced using a cryotome and deposited onto
thick aluminium foil. Several coats of a-cyano-4-hydroxycinnamic acid
matrix were evenly deposited onto the samples using an airbrush, and the
samples were subsequently mounted onto MALDI target plates. The tissue
areas were selected and imaged by MALDI IMS-MS. All data were acquired
on a MALDI hybrid orthogonal acceleration time-of-flight mass spectrometer.
After acquisition IMS-MS data were evaluated in software to export regions
of drift time vs m/z. Data were converted into Analyze file format and
subsequently analysed using BioMap (Novartis, CH).
Results: It is desirable to increase the specificity of the imaging experiment,
typically achieved by adding additional dimensions of separation, but,
unlike complex samples in the liquid phase, where a number of additional
separation and clean-up techniques such as liquid chromatography, affinity
based depletion etc. are well developed, for tissue samples clean-up protocols
are limited. Here we show how ion mobility separation can be used to provide
a additional dimension of separation, post ionisation and hence can be
utilised in a MALDI imaging experiment. The feasibility of this approach
has been shown previously , here we further develop this method through
the use of a high efficiency ion mobility separation device.
We will show data demonstrating that different compound classes, such
as peptides and lipids can be separated, as well as examples where the
intensity contribution of MALDI matrix ions could be eliminated from an
ion intensity image. Furthermore we will show examples of ion mobility
separation of isobaric peptides generated by on tissue digestion of formalin
fixed paraffin embedded samples.
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DNA-nuclear
receptor interaction studied by mass spectrometry
student award lecture
Claudia Bich (1), Cédric
Bover (1), Natacha Rochel (2), Carole Peluso-Iltis (2), Alexis Nazabal
(1,3), Ryan Wenzel (1,3), Dino Moras (2), and Renato Zenobi (1)
1 Department of Chemistry and Applied Biosciences, Zurich, Switzerland
2 Institut de Génétique et de Biologie Moléculaire
et Cellulaire CNRS, Illkirch, France
3 CovalX AG, Technoparkstrasse 1, Zurich, Switzerland
Nuclear receptors, such as
retinoic acid receptor (RAR), interact not only with their ligands but
also with other types of receptors. Previous biological analyses (gel-shift)
have shown that two coactivators and a specific DNA sequence bind to the
receptor but also induce a partial homodimerization of RAR. Mass spectrometry
(MS) has been shown to be a powerful technique to analyze changes such
as these. Here, two different methods were used to study the interactions:
nondenaturing nanoelectrospray (nanoESI- MS), under soft conditions, and
high-mass matrix-assisted laser desorption ionization MS (MALDI-MS) combined
with chemical cross-linking.
The RAR protein was incubated with either coactivators peptides (PF108
and PF124) or with various DNA sequences (DR5, A9 and C9) then analyzed
with high-mass MALDI MS and nanoESI-MS. Prior to high-mass MALDI analysis,
a cross-linking protocol (K200, CovalX, Switzerland) was used to stabilize
the noncovalent complexes. MALDI mass spectra were acquired on a TOF mass
spectrometer (Reflex IV, Bruker Daltonics, Germany) equipped with a high-mass
detection system (HM1, CovalX, Switzerland). ESI mass spectra were acquired
on a Q-TOF Ultima mass spectrometer (Waters, UK) equipped with a chip-based
nanoESI system (Nanomate, Advion Biosciences, USA) after an overnight
incubation of RAR with DNA or peptides.
When measured alone, the RAR showed no significant homodimer judging from
results obtained with both MS methods. The single strand (A9 and C9) and
double strand (DR5) DNA fragments were detected by both of these methods.
NanoESI revealed that PF108 and PF124 bind to RAR under native conditions.
After chemical cross-linking, the high-mass MALDI MS spectra show a binding
for PF124 but not for PF108. In both cases, the RAR dimer was still not
observed. A complex between protein RAR and the double strand DR5 was
detected with nanoESI. After cross-linking the high-mass MALDI showed
that RAR binds the single strand DR5. Moreover, DNA induced the dimerization
of RAR and this dimer could bind not only the single strand but also the
double strand. Using nanoESI, we were able to detect the RAR-DR5 complex
in the presence of the peptides PF108 and PF124. This complex was not
detected using high-mass MALDI. The specificity of the binding between
RAR and DR5 was tested by incubating RAR with other single strand DNA
(A9 or C9). These DNA fragments did not bind to RAR and did not induce
a dimerization.
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High-mass
MALDI ToF mass spectrometry and chemical cross-linking for interaction
analysis
Alexis Nazabal, Benoit Plet,
Ryan Wenzel
CovalX AG, Technoparkstrasse, 1, CH-8005, Zürich, Switzerland
The analysis of intact protein
complexes by mass spectrometry is still challenging. Here we present an
approach based on high-mass MALDI ToF mass spectrometry and chemical cross-linking.
To circumvent the problem of dissociation when using MALDI ionization,
a specific cross-linking protocol has been developed to stabilize covalently
the samples. To solve the problem of detection, we are using a specially
developed high-mass detection system, allowing sub-µM detection
up to 1000 kDa. The use of this methodology presents a number of advantages:
Sensitivity (sub-µM), tolerance for samples impurity, speed. We
will present with details the high-mass technology used and show comparison
spectra with MCP detection, the technology used in most of standard MALDI
ToF instruments. We will also present examples of applications of this
methodology in the field of protein complex analysis (intact protein complexes
ranging from 40 to 1000 kDa), antibody characterization (Interaction analysis,
Sandwich assays, Epitope mapping), Therapeutic protein aggregates analysis
and drug discovery.
High-Mass MALDI ToF MS analysis
of IgM (945.74 kDa; 300 nM) using CovalX Hm1 high-mass detection system
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Analysis
and quantitation of pharmaceutical drugs using different HPLC-chip approaches
Martin Vollmer and Lukas Trojer
Agilent Technologies Waldbronn
Quantitation of drugs and drug
metabolites in the early drug discovery phase is usually challenged by
small sample volume and complex biological matrices. Studies using small
animals and microdosing would reduce significantly costs and enhance throughput.
HPLC-chip/MS provides an easy to use tool to achieve superior sensitivity
without the limitations usually encountered by conventional Nano-HPLC/MS
due to integration of
connections, valving, and separation on a single polymeric chip. Robustness,
leak-tightness, repeatability and chromatographic performance are therefore
significantly increased.
In addition pre-concentration and sample cleanup which is normally conducted
by a separate SPE step can directly be performed on the HPLC-chip enrichment
column, prior to transfer of the sample to the on-chip separation column.
Novel chip designs developed for the analysis of a wide range of pharmaceutical
molecules (from hydrophilic to hydrophobic) were tested. In order to cover
for a wide polarity range chips with C18 packing material were compared
against chips containing different HILIC and ionexchange materials. Combinations
of orthogonal techniques were investigated and advantages and disadvantages
will be discussed regarding simplification of DMPK workflows.
Since nanoflow-setups bear the drawback that runtimes are usually significantly
longer than with standard flow setups, concepts will be presented which
outline processing of samples on chip in order to obtain acceptable runtimes
and throughput.
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Exactive
– Combining qualitative and quantitative analysis in one run
Heike Schäfer, Paul-Gerhard
Lassahn
Thermo Fisher Scientific, Reinach, Switzerland
Compound screening in biological
or environmental samples is becoming increasingly important in analytical
sciences. Often, a sample can contain hundreds or even thousands of potentially
important compounds like pesticides, metabolites or toxins in complex
matrices. The goal is the identification and quantification of the screening-candidates
in one single analytical run. The charm of the analytical method is further
increased, if it is able to yield information of unknown compounds in
the same experiment. This combination of quantitative and qualitative
analysis in a single run is one of the new challenges in LC-MS development.
So far, iontrap, triple stage quadrupole, TOF and FT instruments are used
to do this type of experiment, each with its own advantages and limitations;
such as dynamic range, scan speed sensitivity or selectivity. Instrument
price might be a barrier, and price often excludes high performance techniques
like FT-MS.
In an ideal world high resolution HPLC in combination with a fast-scanning
high resolution Mass Spectrometer yielding superior sensitivity and a
wide dynamic range could be the answer to these needs. The ability to
yield accurate mass information would greatly facilitate the identification
of unknowns and would certainly increase the value of the analytical procedure.
The talk discusses a new member of the Thermo Orbitrap product series
(Exactive) that fulfills many of the described features. It is based on
Orbitrap technology, and it features all the characteristics of this revolutionary
MS technique.
In the present study we have used the new instrumental setup to develop
a workflow for screening of complex biological samples. It could be shown,
that the detection and quantification of hundreds of components is possible
in a single run. Comparison of medium and high resolution MS data clearly
showed the benefit of resolution for screening applications. A new screening
software is used permitting fast component detection, identification and
quantification.
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In-mouth
and in-nose analysis of volatile flavour compounds in chewing gum, using
SIFT-MS
Stephen Guilfoyle (1), Greg
Francis (1), Vaughan Langford (2), Matthias Herzog (3)
1 Syft Technologies UK Ltd, Daresbury Innovation Centre, WA4 4FS, UK
2 Syft Technologies Ltd, Middleton, Christchurch, New Zealand
3 Brechbuehler AG, CH-8952, Schlieren, Switzerland
Release of volatile flavour
compounds from food as it is chewed and swallowed is a very complicated
process, because it depends on the properties of the food itself and the
physiological characteristics of the person who is eating. In order to
better understand how flavour is released and perceived, the last decade
has seen substantial work published on real-time analysis of flavour compounds
in vivo as they are eaten.
Selected Ion Flow Tube Mass Spectrometry (SIFT-MS) is a newly commercialised
technology that analyses gas samples for volatile organic compounds (VOCs)
and certain inorganic compounds. It can accurately detect and quantify
these compounds in real time at very low concentrations (often to parts-per-trillion
levels), even at breath humidity. These characteristics make it ideally
suited to in vivo flavour release measurements as food is consumed.
In this work we describe the first application of Selected Ion Flow Tube
Mass Spectrometry (SIFT-MS) to the in vivo analysis of several chewing
gum flavours (peppermint, spearmint and fruity). We find that SIFT-MS
readily detects and quantifies key flavour compounds both in static headspace
experiments and in real time as gum is chewed. In flavour release measurements,
individual chewing events are observed on the breath-by-breath concentration
profiles, demonstrating the high speed and sensitivity of the technique.
Flavour release measurements also enable SIFT-MS to differentiate release
rates of flavour compounds from different formulas of gum.
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