G.A. Eiceman & M. Menlyadiev
Department of Chemistry & Biochemistry
New Mexico State University
Las Cruces, NM 88003
TANDEM DIFFERENTIAL MOBILITY SPECTROMETER:
AN IONIZATION DETECTOR FOR GC WITH HIGH SPEED, SELECTIVITY,
SMALL SIZE, AND LOW COST
ION MOBILITY SPECTROMETERS: MILITARY
PREPAREDNESS AND COMMERCIAL AVIATION
SECURITY
GC WITH IMS DETECTOR ON INTERNATIONAL SPACE
STATION: ~2002 TO 2012. THE VOLATILE ORGANIC ANALYZER
G.A. Eiceman & M. Menlyadiev
Department of Chemistry & Biochemistry
New Mexico State University
Las Cruces, NM 88003
TANDEM DIFFERENTIAL MOBILITY SPECTROMETER:
AN IONIZATION DETECTOR FOR GC WITH HIGH SPEED, SELECTIVITY,
SMALL SIZE, AND LOW COST
1 2 3 4 5 6 7 8 9 10
1.2
1.1
1.0
0.9
0.8
0.7
0.6
0.5
Inte
nsity
, V
retention time, min
GOAL: ADD FURTHER DIMENSIONS OF ANALYTICAL
INFORMATION TO IONIZATION DETECTORS
Gas Chromatograph
Ionization Detector
INSIDE THE ELECTRON CAPTURE DETECTOR:
gas phase ion chemistry not often described
N2 + e- (mean 17keV) N2+. + 2e-
O2 + e- O2-
O2- + O2 O2O2
-
O2- + CO2 CO2O2
-
O2- + CO2 CO3
- + O
N4+. + H2O H2O
+. + 2N2
H2O+. + H2O H3O
+. + HO
N2 + N2+. N4
+.
H3O+. + H2O H+(H2O)2
INSIDE THE ELECTRON CAPTURE DETECTOR:
gas phase chemistry not often described
+ +
[MH+(H2O)n(N2)x]*
M
H+(H2O)n(N2)x
Intermediate
Neutral
Molecule of
Sample
+
Product Ion
V,d
Ion Swarm
Drift Velocity
Electric Field, E = V/dist
vd = drift length/td
Units of K are cm2/Vs
E = 200 V/cm
K = 2.0 cm2/Vs
vd = 4.0 m/s
MH+(H2O)n
K = (3e/16N)(2 /kTeff)1/2[(1+ )/ D(Teff)]
Collision area D will depend upon moisture, temperature, drift
gas, and molecule
+ K = vd / E
D= MH+(H2O)n(N2)x
MOBILITY OF IONS IN
GASES AT AMBIENT
PRESSURE
ION MOBILITY SPECTROMETRY IN 2013
CONVENTIONAL
TIME OF FLIGHT
OR DRIFT TUBE
FIELD ASYMMETRIC
WITH CURVE
SURFACES
FIELD ASYMMETRIC
PLANAR
a. microscale
b. nanoscale
ASPIRATOR
DESIGNS
Sub Ambient Pressure IMS
1 to 4 torr in helium
ION MOBILITY SPECTROMETRY IN 2013
CONVENTIONAL
TIME OF FLIGHT
OR DRIFT TUBE
FIELD ASYMMETRIC
WITH CURVE
SURFACES
FIELD ASYMMETRIC
PLANAR
a. microscale
b. nanoscale
ASPIRATOR
DESIGNS
Sub Ambient Pressure IMS
1 to 4 torr in helium
R.A. Miller, G.A. Eiceman, E.G. Nazarov and A.T. King, Sensors and
Actuators B. Chemical 2000, 67, 300-306.
SMALL DRIFT TUBE FOR IMS
SMALL DRIFT TUBES FOR MOBILITY
SPECTROMETRY
Analyzer
Region
Faraday
Detector
+
-
ION MOTION IN DMS AT AMBIENT PRESSURE
Asymmetric Waveform 1.1 MHz 30KV/cm
1 to 10 ms RESIDENCE TIME
+K
COMPENSATION VOLTAGE (V)
4
3
-20 -15 -10 -5 0 5 10
1
2
PROTON BOUND DIMER
-K
PROTONATED MONOMER
MOBILITY SPECTRUM : 1 to 3 s SCAN TIMES
0
5
10
15
20
-6
-4
-2
0
2
0 20 40 60 80 100
E,Td
fMo
bili
ty d
ep
en
de
nce
ADVANTAGE DMS: SEPARATION VOLTAGES, ALPHA PLOTS, &
COMPENSATION VOLTAGE
MH+(H2O)
M2H+(H2O)
COMPENSATION VOLTAGE SEPARATION VOLTAGE
HAND HELD DMS INSTRUMENTS AND
LIFE CRITICAL MEASUREMENTS
GAS CHROMATOGRAPH WITH DMS DETECTOR
Replaces GC IMS on ISS
DISPERSION PLOTS: Ion evaluation from field
dependence of mobility: Time: 1 to 3 min. S
ep
ara
tio
n V
olt
ag
e
Compensation Voltage
LONG OBJECTIVE OF DMS DMS: High
Selectivity by ion modification
DMS 1 DMS 2
Fragmentation by E
Formation of clusters
Charge stripping
Other
Fragmentation by hv
CLOSE OBJECTIVE OF DMS DMS: High Selectivity
based on E/N dependence. Time: 10 ms
DMS 1 DMS 2
Sep
ara
tio
n V
olt
ag
e
Compensation Voltage
SV 1000 V
0.5 mm
DMS 1 Electronics &
PC Control
DMS 2 Electronics & PC
Control
Gas Flow Control with
Sample
Faraday Plate &
Amplifier
5 mm
CVDMS1
SVDMS1
Det (-)
Det (+)
SVDMS2
CVDMS2
2 mm
BLOCK DIAGRAM of DMS/DMS WITH
FARDAY PLATE DETECTORS
0.5 mm
GC 63Ni
LABORATORY STUDIES WITH GC DMS DMS
DMS DMS DRIFT TUBE
ALL PASS (no Separation Voltage) SCANNING CV (& SCAN Separation V)
FIXED CV (at a Separation Voltage) SCANNING CV (at a Separation Voltage)
FIXED CV (at a Separation Voltage) SCANNING CV (at SV + 50 V)
FIXED CV (at a Separation Voltage) FIXED CV (at SV + 50 V)
DMS 1 DMS 2
Gas
Chromatograph
OPTIONS ON MEASUREMENTS USING GC DMS DMS
GC DMS DMS OF 4 ALCOHOL MIXTURE
-12 -8 -4 0
2
-12 -8 -4 0
SVDMS2
850 V
SVDMS2
950 V
ALL PASS (no Separation Voltage) SCANNING CV (at a Separation Voltage)
DMS 1 DMS 2
Compensation VoltageDMS2, V
n-BuOH
iPrOH
Rete
ntion T
ime (
min
)
MeOH
EtOH
COMPOSITE DISPERSION PLOTS OF 4 ALCOHOLS
-16 -12 -8 -4 0
600
700
800
900
1000
1100
Compensation Voltage, V
Se
para
tio
n V
olta
ge
, V
0.4120
0.4500
0.4750
0.5800
0.6430
0.7007
0.7585
0.8163
0.8740
methanol
IPA
butanol
ethanol
clusters
SVDMS1= 850V, CVDMS1= -5.4V (fixed);
SVDMS2= 900V
SVDMS1= 850V, CVDMS1= -2.5V (fixed);
SVDMS2= 900V
ION SELECTION USING FIRST MOBILITY SECTION
-12 -8 -4 0
2
-12 -8 -4 0
0
1
2
3
-5.8V
Compensation VoltageDMS2, V
Rete
ntion T
ime (
min
)
Methanol Proton
Bound Dimer
Ethanol Proton
Bound Dimer
-2.8V
FIXED CV (at Fixed Separation Voltage) SCANNING CV (at SV + 50V)
DMS 1 DMS 2
SVDMS1= 850V, CVDMS1= -1.0V (fixed);
SVDMS2= 900V
SVDMS1= 850V, CVDMS1= -0.4V (fixed);
SVDMS2= 900V
-12 -8 -4 0
2
-12 -8 -4 0
2
Iso-propanol Proton
Bound Dimer
n-Butanol Proton
Bound Dimer
-1.0V
FIXED CV (at Fixed Separation Voltage) SCANNING CV (at SV + 50V)
-0.4V
Compensation VoltageDMS2, V
DMS 1 DMS 2
Rete
ntion T
ime (
min
) ION SELECTION USING FIRST MOBILITY SECTION
SVDMS1= 850V, CVDMS1= -1.0V (fixed); SVDMS2= 950V, CVDMS2= -1.6V( fixed)
SVDMS1= 850V, CVDMS1= -0.4V (fixed); SVDMS2= 950V, CVDMS2= 0.6V( fixed)
FIXED CV (at Fixed Separation Voltage) FIXED CV (at SV + 50 V)
Iso-propanol,
Proton Bound Dimer
n-Butanol,
Proton Bound Dimer
DMS 1 DMS 2
Retention Time (min)
Inte
nsity, V
ION SELECTION USING BOTH MOBILITY SECTIONS
Iso-propanol
Acetone
ION EXTRACTION AS GC PEAKS MERGE: CONTROL
Extracted ion chromatogram
SV1=600V, CV1= -2.4V
SV2=550V;
-1.8V
Extracted ion chromatogram
SV1=600V, CV1= -0.5V
SV2=550V;
-0.8V
Total ion chromatogram
Retention Time (min)
Inte
nsity, V
1.4 2.2
Iso-propanol Acetone
ION EXTRACTION AS GC PEAKS MERGE: MERGED
Extracted ion chromatogram
SV1=600V, CV1= -2.4V
SV2=550V;
-1.8V
Extracted ion chromatogram
SV1=600V, CV1= -0.5V
SV2=550V;
-0.8V
Total ion chromatogram
Retention Time (min)
Inte
nsity, V
0.6 1.2
GC DMS/DMS SEPARATION OF 23 CONSTITUTENTS
1 2 3 4 5 6 7 8 9 10
0.5
0.6
0.7
0.8
0.9
1.0
1.1
ALL PASS (600 V) SCANNING CV (at fixed SV, -12 to 2 V)
DMS 1 DMS 2
Retention Time (min)
Inte
nsity, V
-12 -10 -8 -6 -4 -2 0 2
1
2
3
4
5
6
7
8
9
10
11
Compensation Voltage (V) for DMS2
Rete
ntion T
ime (
min
)
0.3650
0.4888
0.6125
0.7362
0.8600
0.9838
1.107
1.231
1.355
Separation Voltage 700V
GC DMS DMS SEPARATION OF 23 CONSTITUTENTS
-15 -12 -9 -6 -3 0 3 6
1
2
3
4
5
6
7
8
9
10
11
Compensation Voltage (V) for DMS2
Rete
ntion T
ime (
min
)
0.3600
0.4607
0.5615
0.6623
0.7630
0.8638
0.9645
1.065
1.166
Separation Voltage 1000V
GC DMS DMS SEPARATION OF 23 CONSTITUTENTS
GC DMS
Extracted ion chromatogram
SV2=550V; CV2= -1.4V
GC DMS DMS
Extracted ion chromatogram
SV1=600V, CV1= -0.5V
SV2=1200V;
Total ion chromatogram
-1.4V
EXTRACTED ION CHROMATOGRAM IN 23 CMPD MIX
Retention Time (min)
Inte
nsity, V
CONCLUSIONS
B. Chromatographic interface
trivial; size, complexity compatible
with ionization detectors.
C. Analytical performance may
approach functionality of tandem
MS for faction of costs
A. DMS DMS with fixed SV and CV provide response with
selectivity and response time at 100 ms---->10ms.
D. Suitable for portable GC
ChemRing Detection Systems…..aid in electronics and
software.
ACKNOWLEDGEMENTS
Weekly report Marlen Menlyadiev
May 10, 2013
DMS1 DMS2
a
b
Sample gas flow 1.5 L/min
Dopant gas flow 0.2 L/min
c
Flo
w v
elo
cit
y,
m/s
COMSOL FLOW MODELING IN DMS/DMS
(FLOW DYNAMICS TEST)
Flow velocity map
Flow velocity map
Pressure map
Ethyl acetate Methyl butyrate Isobutyl Acetate Methyl Valerate Isopropenyl acetate Tert-butyl acetate Sec-butyl acetate Isopropyl acetate Ethanol Isopropanol 1-butanol 1-pentanol 1-hexanol 1-heptanol Pinacolone 2,4-dimethyl-3-pentanone Cycloheptanone Acetone Hexanone-2 2-metyl-3-pentanone 2,6-dimethyl-4-heptanone 3-methylcycylohexanone cyclohexanone
IMS MS CIRCA 1970
Plasma Chromatography™—A New Dimension for Gas Chromatography
and Mass Spectrometry Journal of Chromatographic Science 1970 8 (6) 330-337.
Martin J. Cohen, Franklin GNO Corporation, West Palm Beach, Florida 33402 F. W. Karasek, University of Waterloo, Waterloo, Ontario, Canada
Composite dispersion plot of heptanol-1, cyclohexanone and DMMP
methan
ol IPA
ethanol
cluster
s
ammo
nia
RI
P
-20 -15 -10 -5 0 5 10
600
800
1000
1200
1400
Compensation Voltage, V
Se
para
tio
n V
olta
ge
, V
0.4260
0.4500
0.4700
0.5767
0.6270
0.6773
0.7275
0.7778
0.8280
(Hept)H+
RIP
(Hept)2H+
(Cyclohex)H+
(Cyclohex)2H+
(DMMP)2H+
(DMMP) H+
5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0
0.5
0.6
0.7
0.8
0.9
1.0
1.1
1.2
1.3
Det
ecto
r R
espo
nse
(V)
Retention Time (min)
GC-DMS2 experiment: SV2 500V, CV2 scanning at 1Hz. CV2= -0.4V extracted chromatogram 1ng
Heptanol-1
Cyclohexanone
DMMP
GC-DMS2 experiment: SV2 500V, CV2 scanning at 1Hz. CV2= -0.4V extracted chromatogram
GC-DMS1-DMS2 experiment: SV1 1000V, CV1 -0.8 V; SV2 500V CV2 scanning at 1Hz. CV2= -0.4V extracted chromatogram
GC-DMS1-DMS2 experiment: SV1 1400V, CV1 2.2V; SV2 600V CV2 scanning at 1Hz. CV2=0V extracted chromatogram
GC-DMS1-DMS2 experiment: SV1 1500V, CV1 4.0V; SV2 700V CV2 scanning at 1Hz. CV2= 0V extracted chromatogram
1ng
2ng
3ng
3ng
Heptanol-1
Cyclohexanone
DMMP