Ion size (cross-section)
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1
Micro-fabricated Differential Mobility Spectrometers for
Process Monitoring and Control
Raanan A. Miller, Erkinjon G. Nazarov, David Wheeler, Quan Shi, Denise Zazzera
Sionex Corporation, Bedford, MA
2
1/ 21.1
3 2( )
16 ( )eff eff
e ZK
N kT T
L
VVKEK 12**
ION MOBILITY based technologies use VELOCITY of ion movement under effect of electric field for chemical identification
+
1V2V
Ion size (cross-section)Ion Mass
Ion charge
Ion Mobility as Characteristic of Chemicals
3
Differential Mobility Spectrometry Operation Principle
Compensation Voltage
Sig
nal
Species 2Species 1 Species 3
Compensation Voltage
Sig
nal
Species 2Species 1 Species 3
+Air Flow
+
Electrometer(+ Ions)
IonizationSource
Air Flow++
+
SampleIn
Tunable Ion Filter
++
Electrometer(- Ions)
RF Voltage Compensation Voltage (Vc)
+Air Flow
+
Electrometer(+ Ions)
IonizationSource
Air Flow++
+
SampleIn
Tunable Ion Filter
++
Electrometer(- Ions)
RF Voltage Compensation Voltage (Vc)
microDMXTM Chip
4
SVAC-V
Existing Product Platforms
2nd Generation Sensor and ElectronicsSVAC Analyzer
Thermo Fisher: EGIS Defender
Varian: CP4900 Gas Chromatograph
General Dynamics: JUNO
5
Competitive Advantages
• High sensitivity with specificity: Detection limits comparable to much larger, expensive commercial instruments
• Quantitative output: Instead of the qualitative outputs produced by many lower cost chemical sensors being developed today
• Ability to detect a very wide range of chemicals
• Near real-time detection (msec)
• Low cost: Ability to address high volume opportunities Ability to use multiple sensors in single control system
6
microDMx for Security Applications
0 10 200.0
0.5
1.0
AV
CV
NG DNB DNT TNT PETN
G. A Eicemen, et. al, Accepted for publication, Analytical Chemistry 2004
Chemical Warfare Agents
DMS Explosives Detection
Able to resolve all 14 TSA Explosives
Low PPB Detection Limits
0.080.09
0.10.110.120.130.140.150.160.17
-35 -25 -15 -5 5
Compensation Voltage (Volts)
Inte
nsity
(V
olts
) 0.14ug/l1482V,350cc/min,50% GA,pos
4.22
-2.78
0.08
0.085
0.09
0.095
0.1
0.105
0.11
0.115
0.12
0.125
-35 -25 -15 -5 5
Compensation Voltage (Volts)
Inte
nsi
ty (
Vo
lts)
0.14ug/l1482V,350cc/min,50% GA,neg
-10.65
-6.56
-1.9-13.25
positive mode
negative mode.
7
microDMx for Process Control
Standalone microDMx:• Suitable for monitoring small numbers of compounds or changes in gas
composition of reactors requiring tight parameter control • High sensitivity (parts-per-million – parts-per-trillion)• Quantitative• Low cost – allows distributed sensors – better diagnostic accuracy of
reactors (for example for NeSSI)
GC - microDMx:• Suitable for monitoring complex mixtures of compounds• High sensitivity (parts-per-million – parts-per-trillion)• Quantitative• Low cost compared with MS– allows distributed analyzers – better
diagnostic accuracy of reactors (compatible with NeSSI)
8
Applicability of Standalone microDMx Configuration for Process Control
Introduction of analyte molecules
Atmospheric pressure chemical ionization of
analyte molecules.
63Ni, ESI, UV, plasma ion sources
Detection by Differential
Mobility Spectrometry
Process controlAnalyzer
M (?)M±; MH+; (M-H)-; MO2
- ; M2±;
M(H2O)H+;
Differential Mobility Spectrometer
ReactorAdjust parameters
of Reactoror alert operator
9
Standalone microDMx System for Monitoring Trace Level Compounds in Bulk Gases
microDmx response to a mixture of Acetone and Benzene
-20 -10 0 10 20
Compensation Voltage (V)
Abu
ndan
ce
Benzene+Acetone
Acetone Peak
Benzene Peak p-xylene m-xylene
microDMx response for Xylenes
10
Retention Time
Co
mp
en
satio
n V
olta
ge
A,B,C
GFED
CBA
GC+microDMx SeparationGC Separation
5 Components?Retention Time
7 ComponentsGC Separations are time based
FID detector
DMS
GC+microDMx for Complex Mixture Analysis
11
1,1,2,2-tetrachloroethane44)Cyclohexanone21)
Iodopentane45)o-xylene22)
Bromoform43)m-xylene20)
Bromopropane31)Tetrahydrofuran8)
1,1,1-trichlkoroethane32)3-methyl-2-butanone9)
1,2-dichloropropane33)Benzene10)
Iodopropane34)Thiophene11)
Bromobutane35)Ethylene glycol dimethyl ether12)
Bromobenzene23)
1-chlorohexane42)Ethyl benzene19)
Iodobutane41)Butyl acetate18)
Tetrachloroethylene40)2-hexanone17)
Chlorodibromomethane39)Toluene16)
1-iodo-2-methyl propane38)4-methyl-2-pentanone15)
1-chloropentane37)2-ethylfuran14)
1,3-dichloropropene36)2-pentanone13)
Chloroform30)Tert-butyl ethyl ether7)
Iodoethane29)Ethyl acetate6)
Carbon disulfide28)Propionitrile5)
Dichloromethane27)Acetonitrile4)
Ethyl Bromide26)Isopropyl Alcohol3)
Iodomethane25)Methyl Sulfide2)
Propyl benzene24)Pentane1)
NumberComponentNumber
1,1,2,2-tetrachloroethane44)Cyclohexanone21)
Iodopentane45)o-xylene22)
Bromoform43)m-xylene20)
Bromopropane31)Tetrahydrofuran8)
1,1,1-trichlkoroethane32)3-methyl-2-butanone9)
1,2-dichloropropane33)Benzene10)
Iodopropane34)Thiophene11)
Bromobutane35)Ethylene glycol dimethyl ether12)
Bromobenzene23)
1-chlorohexane42)Ethyl benzene19)
Iodobutane41)Butyl acetate18)
Tetrachloroethylene40)2-hexanone17)
Chlorodibromomethane39)Toluene16)
1-iodo-2-methyl propane38)4-methyl-2-pentanone15)
1-chloropentane37)2-ethylfuran14)
1,3-dichloropropene36)2-pentanone13)
Chloroform30)Tert-butyl ethyl ether7)
Iodoethane29)Ethyl acetate6)
Carbon disulfide28)Propionitrile5)
Dichloromethane27)Acetonitrile4)
Ethyl Bromide26)Isopropyl Alcohol3)
Iodomethane25)Methyl Sulfide2)
Propyl benzene24)Pentane1)
NumberComponentNumber Component
Analysis of Multi-functional Mixture
12
Temperature Programmed from 30-120 C @ 10 C/min
50 100 150 200 250 300 350 400 450
24
234522,44
21
20,43
19,42
18,40,41
17,39
38
1637
15
35,36
34
1433
13
11,129,10
8,32
40 60 80 100 120
7
6,31
29,30
54
5,25,26,27
3,28
GC-FID Analysis of Multi- functional Mixture
13
5
350
-20 -15 -10 -5 0
300
250
200
150
100
50
0
400
450
Compensation Voltage (volts)
Tim
e (s
)
1
65
4 32
109
8 7
15
141312 11
2019
18
17
16
23
2221
24
37
42
39
3536
Compensation Voltage (volts)
0-20-25-30-35 -15 -10 -5
25
30 29
2827 26
3433
3231
41
37
36 35
40
39 38
45
44
4342
Chl
orin
e
Bro
min
e Iodi
ne
350
300
250
200
150
100
50
400
450
Tim
e (s
)
Positive Negative
GC-microDMx Analysis of Multi-functional Mixture
14
microDMx Selectivity for Sulfur CompoundsG
C w
ith T
CD
Det
ecto
r
Odorant Peak (MES)
-0.4
-0.20
0.20.4
0.60.8
11.2
1.41.6
1.8
0 50 100 150 200
Retention time (s)
GC
with
DM
SD
etec
tor
(UV
ion
iza
tion
)
Odorant Peak (MES)
Odorant Peak (MES)
Hydrocarbon (Natural gas related) Peak Trace level control of Sulfur Compounds is important in :
Hydrocarbon processing industryPrevent Corrosion of pipes and equipmentPrevent degradation of catalysts Increase quality of end products
Fuel CellsPrevent catalyst poisoning
SafetyRequires control of level of odorants added to natural gas
Environmental ConcernsControl sulfur levels emitted into the atmosphere
15
TBMTBM
MESTHT
Hydrocarbons
GC-microDMx Chromatogram
GC-microDMx Topographic Plot
GC retention time + orthogonal DMS spectra => Selective detection of odorants in natural gas
TBMMES
THT
microDMx Selectivity for Sulfur Compounds
16
Seconds
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40
mV
olt
-0.25
0.00
0.25
0.50
0.75
1.00
1.25
1.50
1.75
2.00
2.25
2.50
2.75
3.00
3.25
3.50
mV
olt
-0.25
0.00
0.25
0.50
0.75
1.00
1.25
1.50
1.75
2.00
2.25
2.50
2.75
3.00
3.25
3.50Channel 1 CP-4900 Column Module, 8m 5CB Heated Inj Channel 2 Sionex DMD
Detection of Methyl Isocyanate in Air
Concentration 1 ppm (v/v) of MIC
• Methyl Isocyanate – highly toxic (Bophal, India)
• Need to measure low level methyl Isocyanate in air
• Technology tried but unsuccessful FID, E-Nose, SAW
TCD
microDMx
0.4 ppm (v/v)microDMx
17
Detection of Methyl Isocyanate in Air
100000
120000
140000
160000
180000
200000
220000
240000
0 1 2 3 4 5 6 7 8 9 10
Injection number
Are
a C
ou
nts
1.8 ppm MIC
Stability as a function of time
Days
18
microDMx Chip
microAnalyzer
+
GC Column
GC + microDMx Sionex microAnalyzer™
19
DetectionIon Filtering
Sample trap GC column
Ionization
Interpretation
Molecules
Information
Ions
Molecules
Ions Ions
RadioactivePlasmaCoronaUV
Sionex microDMx™ Sensor
AlgorithmChromatography SWSionex EXPERT™
MicroAnalyzer System Architecture
20
Carrier gas Air
External cylinders No
Dimensions 8 x 5 x 3 (in)
Average power consumption ~20-30 W
Warm-up time <15min
Weight 1.81kg
Column 10m
Molecular sieve cartridge (up to 6 month life )
8”5”
3”
Sionex microAnalyzer™
21
2D GC-DMS Chromatogram for BTEX
300
250
200
150
100
50
0
-10 -8 -6 -4 -2 0
Coveron_60sec_500pressure_neworf_1
Positive
Ret
enti
on
tim
e
Compensation voltage
R.T(s) Vc
O- Xylene232.12 -2.00
M,P -Xylene218.81 -1.76
Ethylbenzene
232.12 -2.73
Toluene162.8 -4.18
Benzene123.35 -7,94
Micro trap material Carbopack B 60/80mesh
(RF=1187V)
22
0.70
0.65
0.60
0.55
0.50
0.45
300250200150100500
Resp
on
se (
arb
itra
ry
un
its)
Seconds
Be
nze
ne
To
lue
ne
Eth
ylbe
nze
ne
M,P
Xyle
ne O
Xyle
ne
CompoundSample amount
(ng)R.T(s) Peak width (s) Theoretical plates
Benzene 5.1 123.35 2.94 28164.6
Toluene 2.2 162.60 3.08 44702.0
Ethylbenzene 1.4 210.95 3.25 67408.1
M,P Xylene 1.3 218.81 3.98 48360.2
O Xylene 0.9 232.12 3.43 73275.2
GC - microDMx™ Chromatogram
23
•Relative standard deviation (RSD) for intensity is below 10% on multiple runs.
•RSD Retention Times were less than 0.5% over 40 runs of data.
Compound
LOD S/N=3 (parts-per-trillion)
Benzene 170
Toluene 50
Ethylbenzene 30
M,P -Xylene 10
O -Xylene 20
Ultra Trace Detection of BTEX by Sionex microAnalyzer™ Samples
24
• Differential Mobility Spectrometry provides a flexible platform for:• High sensitivity• High reliability• Quantitative• Near real time• Multi-sensor implementation • Can be made NeSSI compliant• Suitable for online / at line applications
• Thoughts and ideas for additional applications of Differential Mobility Spectrometry in process control and monitoring would be greatly appreciated
Conclusions
25
• Sionex Corporation wishes to thank:
• Dr. Jim Luong and Dr. Ronda Gras of Dow Chemical Corporation.
• Dr. G.M. Lambertus and Dr. R.D. Sacks of University of Michigan.
Acknowledgements
26
27
Measurement of Differential Mobility
lVhV KK ~
- -
-1.6
1.7
1.8
0 10000 20000 30000
Electric Field Strength (V/cm)
Mob
ility
K(E
) (a
. u.)
~ 0.6 microsecond
AA
B
Differential Mobility
a b
28
microDMx™ Ion Filter Operation
Bottom Electrode
1.6
1.7
1.8
0 10000 20000 30000
Electric Field Strength (V/cm)
Mob
ilit
y K
(E)
(a. u
.) Emin
EmaxSpecies A
Species BSpecies C
Time
Emax
Emin
t 2
t1
RF field
t2
t1
z
y
Carrier Gas Flow
ToDetector
Top Electrode
Species A
Species B
Species C
29
MeOHH2S
COS
CH3SH
Column: PoraBondTemperature 60°CCarrier: He, 150kPaTransport gas AirLDL: <100 ppb
MeOH, H2S, COS, and CH3SH
Detection of Epichlorohydrin
88 ppb (v/v) of Epichlorohydrin in Air
Epichlorohydrin (EPI) - an extremely versatile chemical intermediate. 76% of the world’s consumption of (EPI) is used to make epoxy resins.
Need to measure low levels of epichlorohydrin in air at a concentration below 1 ppm (v/v)
microDMx Epichlorohydrin Peak
TCD Detector
TCD Trace
Epichlorohydrin Glycerol