Instrumentation

Organic and Biological Mass Spectrometry

High Performance Laboratory (Chemistry)

  • Bruker Ultraflex II MALDI-TOF

This instrument is designed for the analysis of very polar or high molecular weight compounds.  Vaporization and ionization are facilitated by co-dissolving the sample and a light adsorbing matrix which is also typically either acidic or basic.  A microliter of the sample/matrix solution is evaporated on a target that is placed in the path of a laser beam. Since ionization is accomplished by proton transfer, the sample must have a heteroatom that can either accept or donate a proton to effect a charge.  Typically the heteroatom is either a nitrogen or an oxygen.   (Nitrogen gives better results, it is typically more basic.)   An exception is that salts or molecules which already have a net charge do not require a proton transfer, and need only be desorbed from the matrix.  This instrument is also configured for tandem MS operations aimed at the detection of spontaneous fragments from mass selected precursor ions.   In addition to providing clues regarding molecular structure this technique is well suited for peptide sequencing.  Because of the abundant matrix compound, this method is usually applied to molecules with a mass of over 500 Daltons.   The upper mass limit of this instrument is about 80 Kda.

  • Bruker Amazon Ion Trap Capillary LC/MS/MS

This electrospray LC/MS instrument is interfaced with a capillary reverse phase HPLC system and used almost exclusively for the analysis of protein digests.   With dedicated proteomics software it is capable of identifying peptides in complex mixtures produced by digestion of proteins, whose resulting peptide fragments are HPLC separated and sequenced using tandem mass spectrometry.  The protein identifications can also incorporate peptide mass fingerprinting data, obtained on this instrument or externally.  While not as capable as the myriad of dedicated high throughput proteomics instruments located in our sister-facility at the University of Arkansas for Medical Sciences, these instruments are useful for screening applications and preliminary experiments that can be conducted using this much less expensive technology.  They are also well suited for targeted applications.

  • Bruker Ultraflex 9.4T ESI/MALDI FTMS

This instrument is capable of measuring accurate mass values, sometimes to the sub-ppm level, and for measurements requiring ultra-high (>100K) mass resolution.  This instrument is primarily a research tool for studying FTMS and its applications.   The instrument is not interfaced with chromatographic separation so some samples must be purified prior to analysis.  Likewise this instrument does not have the inherent sensitivity of some other mass spectrometers, so larger quantities of material (micrograms-milligrams) may be needed to facilitate analysis.  The ion guides focusing the ions into the superconducting magnet have been optimized to transmit ions in the 200 – 5000 Da mass window, which is ideally suited for analysis of ESI produced ions (including multi-charged species) and MALDI produced peptide mass fingerprint.

  • Varian 320 Headspace GC/MS/MS

This triple quadrupole GC/MS (Varian 450 GC) is interfaced to a CombiPal robotic headspace sample inlet system.  GC/MS is intended for samples that are volatile or semi-volatile.  Generally this corresponds to samples that are soluble in hexane or other organic solvents rather than water.  Ionization is effected by electron impact, giving library searchable fragmentation profiles which are used in conjunction with the NIST mass spectral database for tentative compound identification.  The system is capable of classical liquid injection (GC/MS) or, alternatively a vapor sample can be injected.  This arrangement facilitates headspace analysis and with minor modifications can also be used with SPME.  This instrument is available for limited supervised self-service for facility trained users working in metabolomics or related areas involving trace analysis.

  • Shimadzu 8040 UPLC/MS/MS   

This triple quadruple LC/MS system is interfaced to UPLC rather than standard reverse phase HPLC, producing peak widths on the order of 6 seconds.   This allows liquid based separations comparable to the benchmark of on-line chromatography, namely capillary GC separation.  This capability dramatically increases the number of components that can be separated on line from a complex mixture.   This instrument utilizes an electrospray ionization source, and is suitable for water soluble compounds that can be ionized by proton transfer or that are already ionic in nature.  These instrument are designed primarily for quantification of targeted compounds, based on UPLC separation and tandem mass spectrometry (multiple reaction monitoring) and can produce state-of-the-art limits of detection for ESI compatible samples.   The preliminary, discovery-phase or qualitative experiments are better accomplished using our ion-trap based HPLC MS systems, both because of their versatility in full-mass scan operation and to minimize sample carry over when this instrument is used for trace analysis.   It should also be pointed out that sample preparation is critical to successful ultra-trace analysis, and samples have to be properly processed prior to mass spectral analysis, even using these advanced instruments.   The new technology does not eliminate the need for sample clean up, rather it lowers the detection limits and increases the linear dynamic ranges possible in the overall method.

  • Shimadzu 8050 UPLC/MS/MS

This triple quadruple LC/MS system is a more advanced version of the 8050 described above.  It is on loan to us under a Memorandum of Understanding (MOU) for the Development on Advanced Methods of Ultra-trace Analysis.  Currently quantitative methods development activities are underway in the areas ranging from environmental and water quality analysis, to endocrine disruptors, food-related heterocyclic amines and selected targeted peptides.

 

Agricultural Applications and Supervised Self Service Laboratory (Poultry Science)

  • Bruker Reflex III MALDI-TOF

This instrument is designed for the analysis of very polar or high molecular weight compounds.  Vaporization and ionization are facilitated by co-dissolving the sample and a light adsorbing matrix which is also typically either acidic or basic.  A microliter of the sample/matrix solution is evaporated on a target that is placed in the path of a laser beam. Since ionization is accomplished by proton transfer, the sample must have a heteroatom that can either accept or donate a proton to effect a charge.  Typically the heteroatom is either a nitrogen or an oxygen.   (Nitrogen give better results, it is typically more basic.)   An exception is that salts or molecules which already have a net charge do not require a proton transfer, and need only be desorbed from the matrix.  Because of the abundant matrix compound, this method is usually applied to molecules with a mass of over 500 Daltons.   The upper mass limit of this instrument is about 80 Kda.  This instrument is operated by the facility staff and is also sometimes available for supervised self-service for facility trained users.    

  • Bruker Esquire-LC Ion Trap LC/MS

This is a quadrupole ion trap mass spectrometer, equipped with an electrospray ionization source and interfaced with a Hewlett Packard 1100 reverse phase HPLC. Samples can be introduced directly from the liquid chromatograph or in solution through a sample infusion interface. The instrument has a mass range of 20 to 2000 m/z when scanning at 13,000 amu per second with unit mass resolution. This instrument is operated by the facility staff and is also sometimes available for supervised self-service for facility trained users.   

The Stable Isotope Ratio Mass Spectrometry Laboratory (This link leads to the webpage for this part of our facility.)