1. Quadropole Mass Analyzer
Four electromagnetic poles
Rapidly oscillating RF potential with a fixed DC potential
If mass of ion and frequency of oscillation are comparable then the ion will oscillate towards the detector and be measured
A certain mass range can be selected depending on the pole diameter

2. Secondary Ion Mass Spectrometry
“Ionization” - + e-
10 ion
20 particles
Ga+
Static SIMS = < 1 x 1013 ions/cm2

3. Time-of-Flight Analyzerd
Field Free Region +V M+
MCP
detector -V
Sample
Translational kinetic energy
e = charge on an electron
1.6 x C
t = time for ion to reach detector
m = mass
v = velocity
V = stage voltage
d = length of field free region
V = voltage of detector

4. TOF-SIMS Molecule-Specific Imaging
Ion Gun x y
m/z, +ions
total ion image
570 µm x 570 µm
Intensity
Si+
Ag+
Cu+
copper grid affixed to silicon substrate with silver paste
molecule-specific image
Just as Si, Cu, and Ag have specific masses so do lipids as shown here
Cu+
Si+

5. TOF-SIMS Identification of Plasma Membrane Lipids
DPPE – dipalmitoylphosphatidylethanolamine + -
m/z 142
+2H *
m/z 552
m/z 682 (M+H)+
m/z 369
cholesterol
m/z 385 (M-H)+

6. Are there Lipid Domains in the Inner Leaflet of the Membrane?
Total Ion DPPE/Cholesterol
Cholesterol
cholesterol
250 µm x 250 µm
Intensity Au
DPPE
Cholesterol-poor and cholesterol-rich areas; due to PE inter headgroup hydrogen bonding thereby reducing the number of PE molecules to bond to cholesterol +
552 -
A. G. Sostarecz; C. M. McQuaw et. al. J. Am. Chem. Soc
C. M. McQuaw; A. G. Sostarecz et. al. Langmuir 2005.

7. Multi-Isotope Imaging Mass Spectrometry
Atomic Mass Images
14N
nucleus
lamellipodia
endothelial cell
Image from Claude Lechene
Harvard Medical School

8. Magnetic and Electric Sector
focus
mass
separate
B = strength of magnetic field
V = ion accelerating voltage
r = radius of ion curvature
m = mass of ion
z = charge of ion
M = 1-50 (change by changing B)

9. MIMS uses an Electrostatic and Magnetic Sector Mass
Analyzer
mass separate
focus
14N
ion 1
Parallel detection limits the worry about destruction or sample drift, electron multipliers, single ion of an element
84 %
16 %
Image from Claude Lechene
*** MIMS analysis is performed as a collaborative project with Dr. Claude Lechene
at the National Resource for Imaging Mass Spectrometry at Harvard Medical School