G.A. Eiceman

Department of Chemistry & Biochemistry

New Mexico State University

Las Cruces, NM 88003

TANDEM CONFIGURATIONS OF ION MOBILITY

SPECTROMETERS AT AMBIENT PRESSURE

CONCEPTS AND PRACTICES

Department of Chemistry

Loughborough University

Loughborough, Leics LE11 3TU

PRINCIPLE I. TANDEM ANALYZERS HAVE

ADVANTAGES AND ALSO SOME DISADVANTAGES.

NET RESULT IN QUANT. MEASUREMENTS = POSITIVE

APPLICATION. IONS DERIVED FROM ESI SOURCES AND

CERTAIN SAMPLES CAN BE COMPLEX MIXTURES. ION

FILTERING BY MOBILITY AT ~AMBIENT PRESSURE

BETWEEN SOURCE AND MS IMPROVES S/N.

clenbuterol in urine 5 pg/µl

MS ESI

MS ESI IMS

“if we spent a tiny fraction of the effort and

resources on ionic processes outside the vacuum

system compared to those occurring in vacuum,

progress in mass spectrometry would be

accelerated.”

Graham Cooks 2013

PRINCIPLE II. ION HANDLING AT OR NEAR

AMBIENT PRESSURE HAS ADVANTAGES OF:

a. LOW COST AND HIGH CONVENIENCE

b. OPPORTUNITY IN ION PROCESSES AVAILABLE ONLY WITH

HIGH COLLISION FREQ.

POSSIBLE CONSEQUENCE OR GOAL OF R&D PROGRAM

MASS SPECTROMETER IMS LC

MASS SPECTROMETER IMS LC

2013

2016

Eiceman, et al. “Characterization of positive and negative ions simultaneously through determination of K & ΔK by tandem DMS-IMS2 ”, ISIMS 2005, Chateau de Maffliers, France

PRINCIPLE III. ANALYTICAL PERFORMANCE WITH

TANDEM MEASUREMENTS IS NOT IMPROVED

WITHOUT SIGNIFICANT TRANFORMATION OF IONS BETWEEN STAGES

WHICH FORM OF MOBILITY SPECTROMETRY?

Asymmetric Waveform 1.1 MHz 30KV/cm +

-

1 to 10 ms RESIDENCE TIME

R.A. Miller, G.A. Eiceman, E.G. Nazarov and A.T. King, Sensors and

Actuators B. Chemical 2000, 67, 300-306.

SMALL ION MOBILITY ANALYZERS*

*See Owlstone Nanotech for very small analyzers

ACTIVE COMPONENTS IN A DMS ANALYZER

Analyzer

Region Faraday

Detector

+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

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

CLOSE OBJECTIVE OF DMS DMS: Fast 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

NOT ONLY K(E/N)-ALSO DIFFERENCES IN K(E/N)

-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

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

DMS DMS ANALYZER

LABORATORY STUDIES WITH GC DMS DMS

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

STUDIES AND MEASUREMENTS ON

SELECTIVITY AND SPEED OF RESPONSE FOR

DMS DMS

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

1-Hexanol DMMP

5-5-10 0

Compensation voltage, V

-15

1500

1200

900

600

Se

pa

ratio

n v

olta

ge

, VDMS1

DMS2

5-5-10 0

Compensation voltage, V

-15

1500

1200

900

600

Se

pa

ratio

n v

olta

ge

, V DMS2

DMS1

DISPERSION PLOTS FOR TWO CONSITUTENTS

IN MIXTURE. SELECT TWO PAIRS FOR:

SV AND CV

Retention time, min

Inte

nsity,

V

2 4 6 8 10

0.6

0.8

1.0

0.4

0.5

0.5

0.6

1-hexanol

DMMP

SIGNAL VS CHEM NOISE BY DMS/DMS ALONE

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

EARLY CONCLUSIONS

B. Alpha function alone contained orthogonality

enough to select an ion over “chemical noise”.

A. DMS DMS with fixed SV and CV provide

response times near 100 ms ----> 10ms (in theory).

C. Results suggest demands on mass

spectrometers may be lessened by ion “handling”

outside vacuum chamber.

LONG OBJECTIVE OF DMS DMS: High

Selectivity by ion modification at ambient

pressure

DMS 1 DMS 2

Fragmentation by E

Formation of clusters

Charge stripping

Other

Fragmentation by hv

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

ORTHOGONALITY WITH REAGENT CHEMISTRY Methyl salicylate and isopropanol

M M

IPA

1) MO2-(H2O)n + mC3H7OH M + nH2O + O2

- (C3H7OH)m

2) MO2-(H2O)n + mC3H7OH nH2O + MO2

- (C3H7OH)m

`

SPARTAN

ab initio modeling

∆H = 44kJ/mol at m=1

∆H = -23kJ/mol at m=2

-30 -20 -10 0 10

-30

-20

-10

0

10

O2-(H2O)n

MO2-(H2O)n

CV

DM

S1, V

(-3;-3)

(-10;-10)

CV

DM

S1,

V

-30 -20 -10 0 10

-30

-20

-10

0

10

O2-(C3H7OH)m

O2-(C3H7OH)m

(-3;-16)

(-10;-16)

CVDMS2, V

ELECTRIC FIELD FRAGMENTATION OF GAS

IONS AT AMBIENT PRESSURE

DMS 1 DMS 3 MS/MS

MS/MS

Final Design

Stage 1 Studies

DMS 2

DMS

FIELD DIRECTED DISSOCIATION &

FRAGMENTATION OF GAS IONS

Compensation Field (Td)

-4.92 -3.28 -1.64 0 1.64

Sep

ara

tio

n F

ield

(T

d)

59

117

176

M2H+

F+

RIP

MH+

At 100°C

MH+

F+

M2H+

0.00

0.50

1.00

80 110 139 168

DMS

Separation Field (Td)

No

rma

lize

d I

nte

nsit

y

59 94 129 164 0.00

0.50

1.00 F+

M2H+

MH+

DMS/MS

DMS MS OF M2H+ AND CID OF MH+

Rela

tive I

nte

ns

ity

50 100 150 200

43 61

97

m/z

55 73

121

139

205 (a) 70 Td

97

121 79 73

205 (b) 117 Td

97

79

(c) 164 Td

40 60 80 100

79

73: (H2O)4H+

55: (H2O)3H+

97: CH3COOH2+(H2O)2

79: CH3COOH2+(H2O)

61: CH3COOH2+

43: CH3CO+

Fragment Ions

205: M2H+

139: MH+ (H2O)2

121: MH+(H2O)

Ions of Ester

Reactant ions

(d) CAD of m/z 97

POSSIBLE FRAGMENTATION PATHWAY:

THROUGH THE PROTONATED MONOMER

energy changes were computed and compared favorably to literature

values; Can. J. Chem. 57 (1979) 2996-3004

87

117

147

30 70 110 150

Temperature (°C)

Sep

ara

tio

n F

ield

(T

d)

144

130

116

102

116

Ethyl hexanoate

Ethyl Propionate 102

Propyl

propionate

130

144

Propyl butyrate

-0.68 + 0.06 Td/°C

or

1.5°C/Td Acetates

E/N THRESHOLDS FOR FIELD INDUCED

REACTIONS AS ƒ(TEMP)

CONCLUSIONS

A. DMS DMS is demonstrated as a comparatively simple

and method with consistent control of ion behavior

B. DMS DMS with fixed SV and CV

provide response with selectivity

and response time at 100 ms----

>10ms.

C. Routes to addition of

orthogonality through ion

chemistry demonstrated in a few

examples all at ambient pressure.

ACKNOWLEDGEMENTS

Financial Support

National Science Foundation, Award

No.

CHE-1306388

Material Support:

CHEMRING Detection

Systems

ACKNOWLEDGEMENTS