Location: Bowdoin / Chemistry / Instrumentation / MALDI & FTMS


Matrix Assisted Laser Desorption Ionization/ Fourier Transform Mass Spectrometer

An Ion Spec HiResMALDI-FTMS was installed at Bowdoin January 24, 2002. Bowdoin is the only undergraduate institution with a high field FTMS

4.7 T superconducting magnet during installation (left) and the MALDI-FTMS with vacuum cart, MALDI and EI source, and data system (right)
MALDI - Bowdoin College

What is it?
A Fourier transform ion cyclotron resonance mass spectrometer (FTMS) is a high resolution instrument that traps ions in a magnetic field. The ion cyclotron frequency, which is a function of the ion's mass and charge, can be measured with high precision and accuracy. The high resolution mass measurements can be used to identify compounds based upon their elemental composition. The ion trapping capabilities of an FTMS instrument can be used to study gas-phase ion-molecule reactions and probe molecular structures using ion dissociations (MS/MS).

Matrix assisted laser desorption ionization (MALDI) is a technique used to ionize very small quantities of biomolecules (peptides, proteins, oligonucleotides) and polymers. When coupled with an FTMS, these materials may be characterized using the high resolution, MS/MS, and ion-molecule reaction capabilities of FTMS.

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Example project using this instrument:

Noah Paul Gardner, '05
The Development of a Microscale Tissue Extraction and Delipidation Procedure for the Analysis of Crustacean Neuronal Tissues using Matrix Assisted Laser Desorption/Ionization-Fourier Transform Mass Spectrometry
An Honors Paper for the Department of Chemistry.

Maldi Paper
click to enlarge image

Noah Gardner, '05Matrix assisted laser/desorption ionization (MALDI) Fourier transform mass spectrometry (FTMS) has been used to study the neuropeptide distributions in nerve cells from the stomatogastric nervous system (STNS) of the Maine lobster, Homarus americanus.  Previous studies were conducted using direct tissue analysis involving peptide extraction on the face of the ionization surface.  In this study, a microextraction and delipidation procedure was designed to improve signal intensity and remove contaminants (phospholipids and salts).  Two different microextraction and delipidation procedures were attempted during the course of the project.  The second procedure, which used a tissue extraction solvent of methanol, nanopure water and acetic acid and a delipidation solvent of chloroform, resulted in efficient extraction of neuropeptides from both the sinus gland of H. americanus and the pericardial organ of Pugettia producta. Analysis of one-twentieth of the total extract resulted in spectra with signal-to-noise ratios comparable to or better than direct tissue spectra.  Permethylation reactions conducted on dried extracts showed a reduction in Asp-Xxx cleavages, which were abundant in direct tissue and extract spectra.  The permethylated extracts showed a complete permethylation of all known neuropeptides in the H. americanus sinus gland.