TANDEM DIFFERENTIAL MOBILITY SPECTROMETER: AN IONIZATION DETECTOR FOR GC WITH HIGH SPEED, SELECTIVITY, SMALL SIZE, AND LOW COST G.A. Eiceman & M. Menlyadiev Department of Chemistry & Biochemistry New Mexico State University Las Cruces, NM 88003 geiceman@nmsu.edu
ION MOBILITY SPECTROMETERS: MILITARY PREPAREDNESS AND COMMERCIAL AVIATION SECURITY
GC WITH IMS DETECTOR ON INTERNATIONAL SPACE STATION: ~2002 TO 2012. THE VOLATILE ORGANIC ANALYZER
TANDEM DIFFERENTIAL MOBILITY SPECTROMETER: AN IONIZATION DETECTOR FOR GC WITH HIGH SPEED, SELECTIVITY, SMALL SIZE, AND LOW COST G.A. Eiceman & M. Menlyadiev Department of Chemistry & Biochemistry New Mexico State University Las Cruces, NM 88003 geiceman@nmsu.edu
Intensity, V GOAL: ADD FURTHER DIMENSIONS OF ANALYTICAL INFORMATION TO IONIZATION DETECTORS Gas Chromatograph Ionization Detector 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1 2 3 4 5 6 7 8 9 10 retention time, min
INSIDE THE ELECTRON CAPTURE DETECTOR: gas phase ion chemistry not often described N 2 + e - (mean 17keV) N 2 +. + 2e - N 2 + N 2 +. N 4 +. N 4 +. + H 2 O H 2 O +. + 2N 2 H 2 O +. + H 2 O H 3 O +. + HO H 3 O +. + H 2 O H + (H 2 O) 2 O 2 + e - O 2 - O 2 - + O 2 O 2 O 2 - O 2 - + CO 2 CO 2 O 2 - O 2 - + CO 2 CO 3 - + O
INSIDE THE ELECTRON CAPTURE DETECTOR: gas phase chemistry not often described M [MH + (H 2 O) n (N 2 ) x ]* Intermediate + + Neutral Molecule of Sample H + (H 2 O) n (N 2 ) x + Product Ion
MOBILITY OF IONS IN GASES AT AMBIENT PRESSURE V,d Drift Velocity Ion Swarm MH + (H 2 O) n + K = v d / E v d = drift length/t d Electric Field, E = V/dist K = (3e/16N)(2 / kt eff ) 1/2 [(1+ )/ D (T eff )] D = MH + (H 2 O) n (N 2 ) x Collision area D will depend upon moisture, temperature, drift gas, and molecule Units of K are cm 2 /Vs v d = 4.0 m/s E = 200 V/cm K = 2.0 cm 2 /Vs
ION MOBILITY SPECTROMETRY IN 2013 CONVENTIONAL TIME OF FLIGHT OR DRIFT TUBE ASPIRATOR DESIGNS FIELD ASYMMETRIC WITH CURVE SURFACES FIELD ASYMMETRIC PLANAR a. microscale b. nanoscale Sub Ambient Pressure IMS 1 to 4 torr in helium
ION MOBILITY SPECTROMETRY IN 2013 CONVENTIONAL TIME OF FLIGHT OR DRIFT TUBE ASPIRATOR DESIGNS FIELD ASYMMETRIC WITH CURVE SURFACES FIELD ASYMMETRIC PLANAR a. microscale b. nanoscale Sub Ambient Pressure IMS 1 to 4 torr in helium
SMALL DRIFT TUBE FOR IMS R.A. Miller, G.A. Eiceman, E.G. Nazarov and A.T. King, Sensors and Actuators B. Chemical 2000, 67, 300-306.
SMALL DRIFT TUBES FOR MOBILITY SPECTROMETRY Faraday Detector Analyzer Region
ION MOTION IN DMS AT AMBIENT PRESSURE Asymmetric Waveform 1.1 MHz 30KV/cm + - 1 to 10 ms RESIDENCE TIME
MOBILITY SPECTRUM : 1 to 3 s SCAN TIMES 4 PROTON BOUND DIMER 3 2 + K - K PROTONATED MONOMER 1-20 -15-10 -5 0 5 10 COMPENSATION VOLTAGE (V)
fmobility dependence ADVANTAGE DMS: SEPARATION VOLTAGES, ALPHA PLOTS, & COMPENSATION VOLTAGE 20 15 MH + (H 2 O) 10 5 0 2 0-2 -4 M 2 H + (H 2 O) -6 0 20 40 60 80 100 E,Td SEPARATION VOLTAGE COMPENSATION 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. Separation Voltage Compensation Voltage
LONG OBJECTIVE OF DMS DMS: High Selectivity by ion modification DMS 1 DMS 2 Fragmentation by E Fragmentation by hv Formation of clusters Charge stripping Other
Separation Voltage CLOSE OBJECTIVE OF DMS DMS: High Selectivity based on E/N dependence. Time: 10 ms DMS 1 DMS 2 SV 1000 V Compensation Voltage
BLOCK DIAGRAM of DMS/DMS WITH FARDAY PLATE DETECTORS Gas Flow Control with Sample Faraday Plate & Amplifier GC 63 Ni DMS 1 Electronics & PC Control DMS 2 Electronics & PC Control SV DMS1 2 mm SV DMS2 CV DMS1 CV DMS2 Det (-) 5 mm Det (+) 0.5 mm 0.5 mm
LABORATORY STUDIES WITH GC DMS DMS
DMS DMS DRIFT TUBE
OPTIONS ON MEASUREMENTS USING GC DMS DMS Gas Chromatograph DMS 1 DMS 2 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)
Retention Time (min) GC DMS DMS OF 4 ALCOHOL MIXTURE DMS 1 DMS 2 ALL PASS (no Separation Voltage) SCANNING CV (at a Separation Voltage) SV DMS2 850 V n-buoh SV DMS2 950 V 2 iproh -12-8 -4 0 EtOH MeOH Compensation Voltage DMS2, V -12-8 -4 0
Separation Voltage, V COMPOSITE DISPERSION PLOTS OF 4 ALCOHOLS methanol butanol 1100 1000 IPA clusters 0.4120 0.4500 0.4750 0.5800 900 800 ethanol 0.6430 0.7007 0.7585 0.8163 0.8740 700 600-16 -12-8 -4 0 Compensation Voltage, V
Retention Time (min) ION SELECTION USING FIRST MOBILITY SECTION DMS 1 DMS 2 FIXED CV (at Fixed Separation Voltage) SCANNING CV (at SV + 50V) SV DMS1 = 850V, CV DMS1 = -5.4V (fixed); SV DMS2 = 900V SV DMS1 = 850V, CV DMS1 = -2.5V (fixed); SV DMS2 = 900V Methanol Proton Bound Dimer 3 Ethanol Proton Bound Dimer 2 2-5.8V 1-2.8V -12-8 -4 0 0-12 -8-4 0 Compensation Voltage DMS2, V
Retention Time (min) ION SELECTION USING FIRST MOBILITY SECTION DMS 1 DMS 2 FIXED CV (at Fixed Separation Voltage) SCANNING CV (at SV + 50V) SV DMS1 = 850V, CV DMS1 = -1.0V (fixed); SV DMS2 = 900V Iso-propanol Proton Bound Dimer SV DMS1 = 850V, CV DMS1 = -0.4V (fixed); SV DMS2 = 900V n-butanol Proton Bound Dimer -0.4V 2 2-1.0V -12-8 -4 0-12 -8-4 0 Compensation Voltage DMS2, V
Intensity, V ION SELECTION USING BOTH MOBILITY SECTIONS DMS 1 DMS 2 FIXED CV (at Fixed Separation Voltage) FIXED CV (at SV + 50 V) Iso-propanol, Proton Bound Dimer SV DMS1 = 850V, CV DMS1 = -1.0V (fixed); SV DMS2 = 950V, CV DMS2 = -1.6V( fixed) n-butanol, Proton Bound Dimer SV DMS1 = 850V, CV DMS1 = -0.4V (fixed); SV DMS2 = 950V, CV DMS2 = 0.6V( fixed) Retention Time (min)
Intensity, V ION EXTRACTION AS GC PEAKS MERGE: CONTROL Acetone Iso-propanol Total ion chromatogram -1.8V Extracted ion chromatogram SV1=600V, CV1= -2.4V SV2=550V; -0.8V Extracted ion chromatogram SV1=600V, CV1= -0.5V SV2=550V; 1.4 2.2 Retention Time (min)
Intensity, V ION EXTRACTION AS GC PEAKS MERGE: MERGED Iso-propanol Acetone Total ion chromatogram -1.8V Extracted ion chromatogram SV1=600V, CV1= -2.4V SV2=550V; -0.8V Extracted ion chromatogram SV1=600V, CV1= -0.5V SV2=550V; 0.6 1.2 Retention Time (min)
Intensity, V GC DMS/DMS SEPARATION OF 23 CONSTITUTENTS DMS 1 DMS 2 1.1 ALL PASS (600 V) SCANNING CV (at fixed SV, -12 to 2 V) 1.0 0.9 0.8 0.7 0.6 0.5 1 2 3 4 5 6 7 8 9 10 Retention Time (min)
Retention Time (min) GC DMS DMS SEPARATION OF 23 CONSTITUTENTS 11 10 Separation Voltage 700V 9 8 7 6 5 4 3 2 1-12 -10-8 -6-4 -2 0 2 0.3650 0.4888 0.6125 0.7362 0.8600 0.9838 1.107 1.231 1.355 Compensation Voltage (V) for DMS 2
Retention Time (min) GC DMS DMS SEPARATION OF 23 CONSTITUTENTS 11 10 Separation Voltage 1000V 9 8 7 6 5 4 3 2 1-15 -12-9 -6-3 0 3 6 0.3600 0.4607 0.5615 0.6623 0.7630 0.8638 0.9645 1.065 1.166 Compensation Voltage (V) for DMS 2
Intensity, V EXTRACTED ION CHROMATOGRAM IN 23 CMPD MIX Total ion chromatogram GC DMS Extracted ion chromatogram SV2=550V; CV2= -1.4V -1.4V GC DMS DMS Extracted ion chromatogram SV1=600V, CV1= -0.5V SV2=1200V; Retention Time (min)
CONCLUSIONS A. DMS DMS with fixed SV and CV provide response with selectivity and response time at 100 ms---->10ms. B. Chromatographic interface trivial; size, complexity compatible with ionization detectors. C. Analytical performance may approach functionality of tandem MS for faction of costs D. Suitable for portable GC
ACKNOWLEDGEMENTS ChemRing Detection Systems..aid in electronics and software.
Weekly report Marlen Menlyadiev May 10, 2013
COMSOL FLOW MODELING IN DMS/DMS (FLOW DYNAMICS TEST) Flow velocity, m/s Dopant gas flow 0.2 L/min Flow velocity map a Sample gas flow 1.5 L/min Flow velocity map b Pressure map c DMS1 DMS2
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 Separation Voltage, V 1400 1200 (DMMP) H + (Cyclohex)H + methan ol (Cyclohex) 2 H + IPA cluster s (DMMP) 2 H + 0.4260 0.4500 0.4700 0.5767 1000 RIP ethanol 0.6270 0.6773 800 RI P (Hept) 2 H + 0.7275 0.7778 0.8280 ammo nia (Hept)H + 600-20 -15-10 -5 0 5 10 Compensation Voltage, V
Detector Response (V) 1.3 1.2 1.1 1.0 Heptanol-1 Cyclohexanone 0.9 0.8 DMMP 0.7 0.6 0.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0 Retention Time (min) GC-DMS2 experiment: SV2 500V, CV2 scanning at 1Hz. CV2= -0.4V extracted chromatogram 1ng
1ng GC-DMS2 experiment: SV2 500V, CV2 scanning at 1Hz. CV2= - 0.4V extracted chromatogram 2ng GC-DMS1-DMS2 experiment: SV1 1000V, CV1-0.8 V; SV2 500V CV2 scanning at 1Hz. CV2= -0.4V extracted chromatogram Heptanol-1 3ng GC-DMS1-DMS2 experiment: SV1 1400V, CV1 2.2V; SV2 600V CV2 scanning at 1Hz. CV2=0V extracted chromatogram Cyclohexanone 3ng GC-DMS1-DMS2 experiment: SV1 1500V, CV1 4.0V; SV2 700V CV2 scanning at 1Hz. CV2= 0V extracted chromatogram DMMP