Molecular weight analysis by Mass Spectrometry: ESI by MS-QTOF, MS-ION TRAP, Orbitrap-MS, FT-ICR-MS , TSQ-MS or MALDI-TOF

Service description

Molecular masses and fragmentation patterns (MSn) of selected masses are determined by obtaining spectra with MALDI-TOF/TOF and with Electrospray-Ion Trap (ESI-IT). This type of analysis is performed from samples in solution at known concentrations (or lyophilized samples in estimated quantities). Samples can be proteins, peptides, small to medium-sized molecules, DNA/RNA oligonucleotides, PNAs, and other types of biological or synthetic polymers. The procedure includes the dilution of the sample to the optimal concentration for the analysis, the acquisition of the mass spectra and the writing of a report in which the procedure followed is indicated and the spectra and mass lists are included along their intensities obtained. It is recommended that the samples be dialyzed or dissolved in a volatile buffer as concentrated as possible, in order to allow their dilution with suitable solvents. In the case of samples that contain components (surfactants, salts, etc.) that interfere with the crystallization and/or ionization process, a clean-up procedure will be carried out to eliminate the interferents (not included in this service), for which additionally must complete the corresponding application. Quantities in the picomole/µl range are needed for protein and oligonucleotide analysis and femtomole/µl for peptides and small molecules. For MALDI analysis, a minimum volume of about 5 ul will be required. The larger the size of the molecules to be analyzed, the greater the sample quantity required. For molecules between 0.5 - 5 KDa, the analysis will be carried out in reflector mode, with an estimated error of 10 ppm. For molecules larger than 5KDa, the linear mode will be used, whose estimated error is 0.01% (100 ppm). For ESI analysis, the minimum volume will be 25-50 µl of sample. The resolution of the equipment can be up to 0.1 amu resolution mode of the equipment. INSTRUCTIONS FOR SUBMITTING SAMPLES 1.- The samples in solution or lyophilized must go in a 0.5 ml tube, clearly identified with the sample name labeled on the lid. 2.- The samples will be delivered or sent along the corresponding application properly filled (MOLECULAR WEIGHT MASS DETERMINATION REQUEST), where the concentration and solvent composition (or amount in the case of lyophilized samples) must be specified. 3.- It is important to take into account the different contaminants that can interfere with the analysis process using mass spectrometry (INTERFERENTS).

Service description

ESI and APCI techniques are very soft ionization techniques that hardly produce fragmentation in the molecule of interest. The (M+H)+ and (M-H)- ions are observed depending on whether the work is in positive or negative mode. In addition, the appearance of ions (M+Na)+, (M+K)+, (M+NH4)+ in positive mode and (M+Cl)¿, (M+Br)¿, (M+CH3COO) is frequent. ¿, (M+HCOO)¿, (M+CF3COO)¿ in negative mode, depending on the eluents that we use. Electrospray (ESI): labile molecules or of high polarity, which in solution (with or without additives) give rise to ions. Molecules with charge in their internal structure are very suitable to be analyzed by this technique. In the event that the molecule does not have a charge in its structure, the addition of a volatile acid or base is normally used in order to generate them. It is not possible to analyze insoluble samples. Atmospheric pressure chemical ionization (APCI): compounds of lower polarity and a certain thermal stability. The analysis request will specify the technique to be used (ESI, APCI) and its polarity mode (positive or negative), and various modalities may be indicated if deemed necessary. If the choice is left to the technician, it will be mandatory to clearly indicate the molecular structure assumed for the sample. If not specified otherwise, spectra will be recorded at different fragmentation voltages, chosen by the technician. If the bibliography recommends the use of a technique, modality or conditions for compounds similar to the sample, it is very convenient to indicate these data in the Analysis Request. Mass range: Molecular weight between 10 and 2000 u for monocharged ions and higher masses for multiply charged ones. With this technique, multiply charged ions (z > 1) can be generated, which allows the study of molecules with a molecular mass above the limit of the analyzer, as long as the multicharge process occurs. Solvents: Volatile solvents are the most suitable Preferred: methanol, acetonitrile, and water Avoid solvents with high boiling points, such as DMSO, which are problematic in mass spectrometry. Please consult before using other solvents and additives Available equipment: -UHPLC-MS Liquid chromatograph coupled to the mass spectrometer with a quadrupole mass analyzer. FEATURES: Mass range: 10-2000 u. Ionization sources: ESI APCI

Service description

Mass Spectrometry Service has a mass spectrometer ESQUIRE 6000 (Bruker), with these qualities: - Soft ionization mode sources: electrospray (ESI), atmospheric pressure chemical ionization (APCI) or Atmospheric Pressure Photoionization (APPI). - Ion trap analyzer - Mass Range: from 20 to 3000Da - Possibility of analysis positive and negative ions , and ion fragmentation (MS/MSn). Mass Spectrometry Service has a mass spectrometer MicroTOF-Q (Bruker), with these qualities: - Soft ionization mode sources: electrospray (ESI), atmospheric pressure chemical ionization (APCI) or Atmospheric Pressure Photoionization (APPI). - time of flight analyzer - Mass Range: from 20 to 3000Da - Possibility of analysis positive and negative ions , HIGH resolution mesure and ion fragmentation (MS/MSn). Molecular weight determination of a big variety of substances, from 200 and 300.000 u, with medium and high polarity and low volatility. Molecular weight determinationo f polymers, dendrimers, and biopolimers (peptides, proteins, glycosides, polysaccharides) Mass Spectrometry Service has two mass spectrometers MALDI-TOF matrix-assisted laser desorption/ionization (MALDI) time-of-flight (TOF) mass spectrometer system Bruker MicroFlex. MALDI-TOF Mass Spectrometer Bruker AutoFlex III. MALDI-TOF Mass Spectrometer with tandem TOF/TOF capabilities using Lift.