What are your operating hours?
The service is normally open Monday-Friday 8:00am-5:00pm.
What is your typical turn-around time?
Our turn-around time is typically 1-2 business days, but analyses can take longer if some method development is required for the request, if we have a heavy volume of submitted samples or in case of a technical problem on an instrument. Submissions will be ordered by time of entry.
What is the impact of the solvent and buffer used in my samples on the direct MS analysis?
Using the appropriate solvents is very important. Volatile solvents such as methanol and acetonitrile are ideal solvents for direct mass spectrometry. Avoid using DMSO. Always use spectroscopic grade solvents to prepare the samples. Salts and buffers are, in general, detrimental to MS analysis. Salts normally form adducts peaks which compete with the molecular ion peaks and broaden the overall signal (especially for protein analysis). ESI-MS is very sensitive to salts and buffers (especially sodium and potassium salts even below 1 mM), resulting in signal suppression. Less than 1mM salts and buffers are recommended although higher salt concentrations may be tolerated for MALDI ionization (on-target washing protocols help). Volatile salts such as ammonium acetate, ammonium formate, and ammonium biocarbonate can be used below 20mM.
How do I get my results?
You can take the results in printed format, available in the entrance of the service BCH1522 (right desk, blue racks) and/or get the spectra directly from eln if the option “Store analysis result in ChemInfo” has been selected.
To visualize the MS spectra, select the compound, click on “View mass Spectrum”, and select the MS spectrum among the list of experimental spectra available. PDF files of spectra can be sent by mail under request.
Can I look at raw data myself?
Yes, you can look at raw data on eln (see previous paragraph) and use the various MS tools developed for data interpretation (Mass superimposition, Fragmentation, Exact mass, contaminants, peptide, etc…)
Is there a training class available for the use of software for data interpretation and processing?
Contact us for specific requests of data analysis or Luc patiny for eln data analysis.
Do I need training before using the open-access instruments?
Yes, you should never use them without a training given by ourselves. The training on the ESI-MS takes 30 min, the training on the MALDI-TOF-MS takes 2 hours (minimum 2 persons per training). You will need to make an appointment with us for those trainings.
Are you open to collaborations?
Yes! Please contact us for a consultation appointment. Collaborative projects that require non-routine analysis generally entail co-authorship.
What MS method of ionization (ESI, MALDI, IE/CI, APPI) and detection (Quadrupole, Ion traps, TOF, or FT analyzers) should I use?
This all depends on what results you are trying to achieve. If you require accurate mass (below 5 ppm), such analyses require TOF or Orbitrap mass analyzers, which means that the samples must be ionizable by ESI, APCI or APPI. Accurate mass analyses are useful in order to confirm the molecular formula of a sample and for publication purposes. Additional tandem mass spectrometry can be achieved to get more structural information’s of the compound. There is generally more than 1 method available for MS analysis of a given compound. You should consider the size of the molecule (macromolecules such as polymers may require MALDI), the presence of protonation sites, how fragile the compound is (to water, air or temperature for example), and the need of a separation step prior to MS detection. We are always available to advice you on this topic. If you don’t know, please mention it on the sample submission form.
What kinds of adducts are commonly observed in MS?
For Electrospray MS in the positive mode, it is typical to detect [M+H]+, [M+Na]+ and [M+K]+ ion species, whilst with the negative ion mode [M-H]– molecular ions are normally observed. It is also common to observe clusters as well. Molecules tend to cluster and form dimers when run by electrospray, particularly if the sample concentration is high. Larger molecules that readily take on multiple charges, such as proteins and oligonucleotides, commonly appears as multiple groups of ions with increasing charges.
For CI with ammonia, [M+H]+ and (M+NH4)+ adduct ions are commonly observed in positive mode. IE is always performed in positive mode and always interfaced with the GC.
For MALDI analyses, it is typical to detect [M+H]+, [M+Na]+ and [M+K]+ adducts, and more rarely adduct ions from the matrix.
How is performed the accurate mass analysis on the ESI-Q-TOF?
Accurate mass analyses on a Q-TOF require the Lock-Spray module to reach the 5 ppm mass accuracy. The lock-spray interface sprays alternatively the analyte and a reference compound (lock mass) to correct for drifts in the mass scale. The correction factor is applied to provide accurate mass information (<5 ppm) on the most abundant species (generally [M+H]+) and, for complex isotopic profiles, on the most abundant isotope.
Can I run infusion ESI-MS and MS/MS if I have very limited sample available?
YES. In such cases, we can run nanochip-based infusion experiments using the Nanomate Triversa (Advion) robot interfaced with the FT-Orbitrap mass analyzers (Thermo). The flow rates used for spraying are in the nL/min range.
Which compounds are suitable for GC-MS analysis?
Volatile and low molecular mass compounds (m/z < 600). Chemical derivatization (trimethylsilylation, methylation, acetylation…) can often be done to increase volatility of compound’s containing polar functional groups, but this chemical reaction is generally conducted by the submitter.
What information does GC-MS provide?
The MS analyzer is a triple quadrupole that can be operated in scan mode, but also SIM or MRM modes for quantitative purposes by integration of selected ion chromatogram peaks. The GC offers a high resolution separation of compounds. IE mass spectra of each eluted peak can be submitted to the NIST17 database (more than 800’000 IE mass spectra) for identification of unknowns.