Recognizing the diversity of research interests on- and off-campus, the Center offers the following three “for fee” services to the scientific community: Submitted Sample Analysis; Investigator Instrument Use; and Protocol Development. A breakdown of charges for services under each category may be found under Rates.
Submitted Sample Analysis
Listed below are the types of analyses routinely performed by Center personnel on submitted samples. A rate schedule for these analyses may be found in Rates under Submitted Sample Analysis. Sample preparation and submission requirements are discussed in Sample Submission. Please contact the Center prior to submission of samples requiring “special” handling or analysis.
TYPE | DESCRIPTION |
I | LR (MALDI, ESI & APcI; ± eV) Low Resolution (LR unit mass) analysis of gases, liquids and solids by an appropriate sample inlet system |
II | HR (MALDI, ESI & APcI; ± eV) High Resolution accurate mass measurement (AMM) coupled with empirical formula or amino acid determination; mass range < 2000 Dalton; Resolving Power (RP) 5000 – > 400,000. |
III | LC-MS, LR (ESI & APcI; ± eV) Liquid Chromatographic (LC) separation combined with LR mass spectral analysis; mass range < 3000 Dalton |
IV | LR LC-MS and LC-MS/MS Quantification and/or Detection LC separation coupled with the selected ion monitoring (SIM), or selected and multiple reaction monitoring techniques, SRM and MRM, respectively, using tandem mass analyzers (MS/MS). |
V | HR LC-MS/MS Structure Elucidation and/or Component Scouting Use of collisional induced dissociation (CID) in product (daughter) ion, precursor (parent) ion or neutral loss scanning analysis. |
VI | Intact Protein and Peptide Molecular Weight Multiple charge state ESI spectra of a biopolymer(s) are deconvoluted to determine the zero charge mass of the component(s). (Depending on presence of salts, detergents or other ionic impurities in the sample, on-line LC-MS or other off-line cleanup procedures may be required.) |
VII | Biotransformation
Use of multiple disciplines to determine compound stability and metabolism. Focuses on MetID/TDI/Parent disappearance in conjunction with various different enzymatic assays (depending on request). |
N.B. | Ionization Modes (Instrument dependent) HR-High mass resolution, LR-Low mass resolution ESI-electrospray ionization APcI-atmospheric pressure chemical ionization MALDI-matrix assisted laser desorption ionization |
See Ionization Methods and Operational Modes for more information relating Center instrumentation and capabilities.
Investigator Instrument Use
“Hands-on” instruction in the use of all Center instruments is available on all of our equipment. The level of instruction is such that following the completion of training (usually 2 to 4 hrs) and several periods of supervised use, the researcher may exercise independent unattended use of an instrument with instructor approval. Instruction is instrument specific and is provided at the discretion of the management based on anticipated project or research group needs. Charges for instruction and investigator use may be found under Investigator Instrument Use.
Protocol Development
The Center offers both Sample Preparation and Mass Spectrometry Assay protocol development services. Dependent upon the need, assay protocol development may include: a methodology appropriate for sample preparation prior to MS analysis; a methodology for on-line LC-MS separations, if necessary; the running of preliminary Standard Curves, Reproducibility Studies; and the determination of Limits of Detection (LOD). The transfer of the final protocol to project personnel may also be included, however, complete validation of the method is not.
Protocol development services are provided at the discretion of the management and are based, in part, on the expectation that Center instrumentation will be used in carrying out subsequent studies. For information on the costs associated with this service, please check Rates under Protocol Development or contact Dale Whittington of our Staff.
The Center is not equipped or licensed to handle radioisotopes and, consequently, will NOT work with radioactive materials. However, the Center will consult on sample preparations involving these media.
Quantitative Proteomics
We apply LC-MS/MS proteomics (MRM) for the quantification of proteins in complex biological systems, e.g., tissues, blood, urine and cerebrospinal fluid (CSF). The advantages of MRM proteomics are: i) selectivity, i.e., it can distinguish highly homologous proteins; ii) quantification of multiple proteins in a short time (approximately 10 proteins in 20 min) with almost similar or better sensitivity than western blotting; iii) antibodies are not required for quantification; iv) it offers absolute protein expression, and; v) data quality is better than western blotting as MRM relies on multiple signals, i.e., multiple peptides and multiple MRM transitions.
We offer research support to projects such as 1) targeted quantification of proteins (in tissues and biofluids) to investigate disease pathophysiology, and 2) discovery/validation of hypothesis driven biomarkers of diseases/drug efficacy and toxicity.
Ionization Methods and Operational Modes
Positive and negative ions may be generated in all modes of ionization. The choice of an appropriate ionization mode and its polarity is dependent on the nature of the compound of interest (functional groups, volatility, stability, etc.) and on the method of sample introduction amenable to it.
In addition, the mass analyzer (time-of-flight, quadrupole, etc.) used in conjunction with a particular ionization and sample inlet technique will set limits on the resolution and mass range of the analysis. The following table attempts to give an overview of useful combinations based on the instrumentation available in the Center.
Ionization Mode | ESI | APcl | MALDI |
Mass Range Daltons (Da) | 50 – > 6,000 | 50 – 6,000 | 500 – 100,000 |
Analyte Polarity | Medium – Very High | Medium – High | Low – Very High |
Ion Charge electron Volts (eV) | ± | ± | ± |
LC-MS | Yes | Yes | Yes |
HR High Resolution | Yes | Yes | Yes |
CID Collision Induced Dissociation | Yes | Yes | Yes |