Upload
others
View
30
Download
0
Embed Size (px)
Citation preview
Differential Mobility Spectrometry (DMS)
An orthogonal separation mechanism based upon charge-to-mass and
molecular shape
Lecture 2, Page 84
Hardware Overview
SelexIon – Planar DMS
Lecture 2, Page 85
Mass Spec Vacuum draws ions and gas through planar DMS electrodes
(5 millisecond flight time)
2.3 torr
2.8 L/min
1 mm
3 cm
760 torr
Lecture 2, Page 86
The physics and chemistry of the separation
principle.
Specificity from nuclear properties. •Radioactivity •High Mass Resolution.
• Specificity from molecular properties. • NMR • Collision-Induced Dissociation - MSn
• Specificity from chemical properties. • Chemical interactions of analyte with environment
• HPLC, CZE, immunochemsity
• Ion Molecule Chemistry (ICP-MS Dynamic Reaction Cell)
• Ion Molecule Chemistry Mobility
Sources of Selectivity
Lecture 2, Page 87
Chemical Enhanced Separations Driven by Mobility Changes Due to Clustering / Declustering.
Low field
clustering-
mobility decreases
+
HV=3kV
Schneider BB, Covey TR, Coy SL, Krylov EV, and Nazarov EG, “Chemical Effects in the Separation Process of a Differential Mobility/Mass
Spectrometer System”, Anal. Chem., 2010, 82, 1867-1880.
High field
declustering;
mobility increases
L V=0.3 kV
F ~ 1 MHz, T= 10-6 s
Lecture 2, Page 88
Ionograms of 3 compounds with/without clustering modifiers
Dianabol
Benoxinate
Clenbuterol
Nitrogen
transport gas
Nitrogen with
44% helium
transport gas
Nitrogen with
1.5% isopropanol
transport gas
Increased mobility with helium
favors hard sphere behavior
….peaks shift to higher CV
and narrow slightly.
Lecture 2, Page 89
Different effects with different modifiers
Ketamine (blue) and sulfadiazine (red)
Ethylacetate
Acetone
Acetonitrile
Methanol
Isopropanol
m/z 238.1 m/z 251.1
Lecture 2, Page 90
Lecture 2, Page 8
Effects of Different Modifiers-Gas phase LC?
1.0
0.8
0.6
0.4
0.2
0.0
Norm
aliz
ed S
ignal
-50 -40 -30 -20 -10 0
CV (V)
Isopropanol Separation
1.0
0.8
0.6
0.4
0.2
0.0
Norm
aliz
ed S
ignal
-50 -40 -30 -20 -10 0
CV (V)
Acetone Separation
1.0
0.8
0.6
0.4
0.2
0.0
Norm
aliz
ed S
ignal
-50 -40 -30 -20 -10 0
CV (V)
Acetonitrile Separation
Red: Ephedrine Black: Acyclovir Green: Norfentanyl Blue: Clenbuterol Purple: Imipramine Brown: Diazepam Pink: Quinoxifen
Lecture 2, Page 91
Applications where Chromatography is
employed and integrated with DMS.
Lecture 2, Page 92
Testosterone Female #3 Plasma Sample: LLE
DMS OFF/
289/109
DMS OFF/
289/97
DMS ON/
289/109 DMS ON/
289/97
Interference
Ion ratio is Peak of interest Interference
Peak of interest
Lecture 2, Page 93
Testosterone Female #3 Plasma Sample: PPT
DMS OFF/
289/109
DMS OFF/
289/97
DMS ON/
289/109
DMS ON/
289/97
Peak of interest
Peak of interest @
RT 3.37 min
Lecture 2, Page 94
Separation Science References
• Basics of HPLC – http://www.waters.com/waters/nav.htm?cid=100490
64&locale=en_US
• Basics of nano LC – http://www.nanoseparations.com/
• Basics of CE – http://matematicas.udea.edu.co/~carlopez/cnq533/C
E_Basics.pdf
• Basics of IC – http://www.melvynbecerra.cl/images/ICPractica.pdf
Lecture 2, Page 95