M.R. Menlyadiev, G.A. Eiceman

Department of Chemistry and Biochemistry

New Mexico State University

Las Cruces, NM 88003, USA

J.A. Stone

Department of Chemistry

Queen`s University

Kingston, ON K7L 3N6, Canada

TANDEM DIFFERENTIAL

MOBILITY SPECTROMETRY

1

TA

ND

EM

IO

N M

OB

ILIT

Y

SP

EC

TR

OM

ET

ER

198

5

(C

on

tra

ct

DA

AA

15-8

5-C

-0030)

2

TANDEM DMS-IMS2

G.A Eiceman, et al., Characterization of positive and negative ions

simultaneously through determination of K & ΔK by tandem DMS-

IMS2 ISIMS 2005, Paris 3

TANDEM DMS-IMS2

4

2 4 3

0

5

CV

(vo

lts

)

Drift Time (ms)

MH+

DMS-IMS2 & ORTHOGONALITY IN K AND ΔK

Alpha function modification

AH+ + B -------> AHB+ -------> AH+ + B

Stable ion/neutral cluster formation

AH+ + B -------> AHB+

Charge stripping

AH+ + B -------> A + BH+

Ion fragmentation (thermal, field, photo)

AH+ -------> M + BH+

RF field

6

POSSIBLE CHEMICAL PATHS TO ION

MODIFICATIONS

Purified air 0.1% CH2Cl2 in air

G.A

. E

icem

an

et

al.

, A

nal.

Ch

em

. 2004,

76,

4937-4

944

7

EXAMPLE OF CHEMICAL MODIFICATION

WITH CHANGE IN ALPHA PARAMETER

Most of today`s DMS have R<80 (typically ~20)

Ions with MW> ca. 150 are poorly resolved under normal conditions

One DMS analyzer is easily used to isolate ions for later ion chemistry studies

A tandem DMS/DMS is mechanically convenient and functionally simple

8

MOTIVATIONS FOR DMS/DMS

9

FIRST DMS/DMS/MS STUDY (PITTCON 2010)

Eiceman G.A. “Ion preparation before differential mobility spectrometry

including DMS/DMS analyzers”, Pittcon 2010

10

EXPERIMENTAL APPARATUS FOR

DMS/DMS/MS STUDIES

-20 -15 -10 -5 0 5

-20

-15

-10

-5

0

5

Inte

nsity

(a.u

.)

HeptanoneC:\Documents and Settings\hschmidt\My Documents\Hartwig\DMS DMS\20100226\

&G - Graph3D_heptanoneonly - 2/26/2010 21:23

Compensation Voltage fast (V)

Com

pensation V

oltage s

low

(V

)

10000

1.825E5

3.55E5

5.275E5

7E5

11

DMS/DMS ANALYSIS OF TRACE VAPOR

LEVELS OF 2-HEPTANONE IN PURIFIED AIR

CV

DM

S1

CVDMS2

-20 -15 -10 -5 0 5 -20

-15

-10

-5

0

5

RIP

MH+

M2H+

Purified air w/butanol

12

ION SELECTIVE PLOT FOR MH+ (m/z 115) OF

2-HEPTANONE

CV

DM

S1

CVDMS2

-20 -15 -10 -5 0 5

-20

-15

-10

-5

0

5

m/z 115C:\Documents and Settings\hschmidt\My Documents\Hartwig\DMS DMS\20100226\

20100226_1922_heptanone_extr_masses_DMSDMS - Graph115 - 2/28/2010 00:07

Inte

nsity (

a.u

.)

Compensation Voltage fast (V)

Com

pensation V

oltage s

low

(V

) 100.0

1.258E4

2.505E4

3.753E4

5E4

-15 -10 -5 0 5

-15

-10

-5

0

5

-20 -20

-20 -15 -10 -5 0 5

-20

-15

-10

-5

0

5

m/z 115

Inte

nsity (

V)

C:\Documents and Settings\hschmidt\My Documents\Hartwig\DMS DMS\20100226\

20100226_2024_extr_masses_butanol_heptanone - Graph115 - 2/27/2010 23:50

Compensation Voltage fast (V)

Com

pensation V

oltage s

low

(V

)

1000

7.075E4

1.405E5

2.103E5

2.8E5

-15 -10 -5 0 5

-15

-10

-5

0

5

-20 -20

(-3.5;-6.5) (-3.5;-1.5)

0.5 mm

DMS 1 Electronics &

PC Control

DMS 2 Electronics & PC

Control

Gas Flow Control with

Sample

Gas Flow Control with

Dopant

Faraday Plate &

Amplifier

5 mm

CVDMS1

SVDMS1

Det (-)

Det (+)

SVDMS2

CVDMS2

2 mm

13

BLOCK DIAGRAM of DMS/DMS WITH

FARDAY PLATE DETECTORS

0.5 mm

-20 -15 -10 -5 0 5 10-20

-10

0

10

Negative

CV 2, Volts

CV

1, V

olts

0.06000

0.09500

0.1300

0.1650

0.2000

0.2350

0.2700

0.3050

0.3400

-20 -15 -10 -5 0 5 10

-20

-15

-10

-5

0

5

10

Positive

CV2, Volts

CV

1, V

olts

0.05000

0.09375

0.1375

0.1813

0.2250

0.2688

0.3125

0.3563

0.4000

Positive Polarity Negative Polarity

-20 -15 -10 -5 0 5 10-20

-10

0

10

CV 2, Volts

CV

1, V

olts

0.06500

0.07250

0.08000

0.08750

0.09500

0.1025

0.1100

0.1175

0.1250

-20 -15 -10 -5 0 5 10

-20

-15

-10

-5

0

5

10

Positive

CV 2, Volts

CV

1, V

olts

0.08000

0.09375

0.1075

0.1213

0.1350

0.1488

0.1625

0.1763

0.1900

-20 -10 0 10-20

-15

-10

-5

0

5

10

Positive

CV 2, Volts

CV

1, V

olts

0.08000

0.09750

0.1150

0.1325

0.1500

0.1675

0.1850

0.2025

0.2200

H+(H2O)n

H+(H2O)n

H+(H2O)n O2

-(H2O)n

CVDMS2, V

CV

DM

S1, V

14

RF STEERING OF ION PEAKS FOR RIP

(IDENTICAL OPERATION TEST)

O2-(H2O)n

O2-(H2O)n

SVDMS1=SVDMS2=0VV

SVDMS1=500V VDMS2=900VV

SVDMS1=900V VDMS2=500VV

-20 -10 0 10-20

-10

0

10Negative

CV 2, Volts

CV

1, V

olts

0.06000

0.07125

0.08250

0.09375

0.1050

0.1163

0.1275

0.1388

0.1500

-20 -10 0 10

-20

-10

0

10

O2-(H2O)n

(0;0) (0;0)

(-4;-18) (-3;-15)

(-18;-4) (-15;-3)

CV

DM

S1, V

CVDMS2, V 15

RF STEERING OF ION PEAKS FOR SAMPLE

(IDENTICAL OPERATION TESTS)

-30 -20 -10 0 10

-30

-20

-10

0

10

CV 2, Volts

CV

1,

Vo

lts

0.06000

0.08000

0.1000

0.1200

0.1400

0.1600

0.1800

0.2000

0.2200

O2-(H2O)n

MO2-(H2O)n

SVDMS1=SVDMS2=700VV

(-3;-3)

(-10;-10)

connection

DMS1 DMS2 Tube

a

b

Sample gas flow 1.5 L/min

Dopant gas flow 0.2 L/min

c

Flo

w v

elo

city

, m/

s

16

COMSOL FLOW MODELING IN DMS/DMS

(FLOW DINAMICS TEST)

Flow velocity map

Flow velocity map

Pressure map

17

ORTHOGONALITY W/DOPANT: MSAL

M M

IPA

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

- (C3H7OH)m

2) O2-(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

CV 2, Volts

CV

1,

Vo

lts

0.06000

0.08000

0.1000

0.1200

0.1400

0.1600

0.1800

0.2000

0.2200

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

CV2, Volts

CV

1,

Volts

0.007000

0.008125

0.009250

0.01038

0.01150

0.01263

0.01375

0.01488

0.01600

O2-(H2O)n

MO2-(H2O)n

O2-(C3H7OH)m

O2-(C3H7OH)m

(-3;-16)

(-10;-16)

(-3;-3)

(-10;-10)

CVDMS2, V

18

Low concentration, ~ tens of ppb

CV, V

RIP

MH + M2H+

ID (characteristic CV for

each OPC)

CV, V

Higher concentration or interferences

M2H+

Difficult to identify

HOW TO INCREASE PEAK

CAPACITY FOR OPCs IN DMS?

ORTHOGONALITY THROUGH DOPANT:

OPCs CASE

19

ORTHOGONALITY THROUGH DOPANT:

OPCs CASE

DMMP

CVDMS2, V

20

Inte

nsi

ty,

V

DMS2 SPECTRUM OF (DMMP)2H+ ION

SELECTED BY CV IN DMS1

10 -10 -20 -30 0

0

0.1

0.2

CVDMS2, V

M

0

10 -10 -20 -30 0

Inte

nsity,

V

CVDMS2, V -30 -20 -10 0 10

0.10

0.12

0.14

0.16

0.18

0.20

0.22

0.24

Inte

nsity

, V

CV, Volts

isopropanol

0.1

21

1% IPA CONTROL SPECTRUM

IPA

IPA

0

10 -10 -20 -30 0

Inte

nsity,

V

CVDMS2, V

-30 -20 -10 0 10

0.10

0.12

0.14

0.16

0.18

0.20

0.22

0.24

Inte

nsity

, V

CV, Volts

DMMP

isopropanol

0.1

22

DMS2 SPECTRUM OF (DMMP)2H+ ION

SELECTED BY CV IN DMS1 with 1% IPA AS DOPANT

M

IPA

23

Inte

nsity,

V

10 -10 -20 -30 0

0

0.1

TBP

CVDMS2, V

DMS2 SPECTRUM OF (TBP)2H+ ION

SELECTED BY CV IN DMS1

M

24

DMS2 SPECTRUM OF (TBP)2H+ ION

SELECTED BY CV IN DMS1 with 1% IPA AS DOPANT In

ten

sity

, V

CVDMS2, V -30 -20 -10 0 10

0.10

0.12

0.14

0.16

0.18

0.20

Inte

nsi

ty, V

CV, Volts

TBP

0

0.1

10 -10 -20 -30 0

b isopropanol

M

IPA

-30 -20 -10 0 10

0.10

0.12

0.14

0.16

0.18

0.20

Inten

sity,

V

CV, Volts

TBP

0

0

0.1

10 -10 -20 -30 0

Inte

nsity,

V

CVDMS2, V

-30 -20 -10 0 10

0.10

0.12

0.14

0.16

0.18

0.20

0.22

0.24

Inten

sity,

V

CV, Volts

DMMP

isopropanol

0.1

a

b isopropanol

25

COMPARISON OF DOPANT EFFECTS FOR

(DMMP)2H+ AND (TBP)2H

+ IONS

1) M2H+ + nC3H7OH M2H+ (C3H7OH)n

2) M2H (C3H7OH)n M2H+ (C3H7OH)n-x + M+ xC3H7OH

26

PRELIMINARY INTERPRETATION OF REACTION

OF (DMMP)2H+ AND (TBP)2H

+ IONS WITH

ISOPROPANOL

M. R. Menlyadiev, J.A. Stone, G.A. Eiceman, “Tandem differential mobility

spectrometry with chemical modification of ions,” Int. J. Ion Mobil. Spec. 2012

(to be published, now available online)

27

ION FRAGMENTATION: A WAY TO INCREASE

PEAK CAPACITY IN DMS

MO2 (M-H)- + HO2-

RF field

CVDMS2 , V

CV

DM

S1 ,

V

-20 -10 0

-30

-20

-10

0

10

CV 2, Volts

CV

1, V

olts

0.06000

0.08000

0.1000

0.1200

0.1400

0.1600

0.1800

0.2000

0.2200

O2-(H2O)n

M*O2-(H2O)n

(-3:-3)

(-10:-10)

SVDMS1= 700V

SVDMS2= 700V

SVDMS1= 700V

SVDMS2= 1400V

-20 -10 0

-30

-20

-10

0

10

CV 2, Volts

CV

1, V

olts

0.07500

0.08188

0.08875

0.09563

0.1025

0.1094

0.1163

0.1231

0.1300

(M-H)-

(-3:-8)

28

DMS/DMS OPERATION MODES

1.DMS1 CV ion selection, DMS2 CV scan (similar to

product ion scan in MS/MS)

2. DMS1 CV scan, DMS2 CV ion selection (similar to

parent ion scan in MS/MS)

3. DMS1 CV scan and DMS2 CV scan with fixed

(CV2-CV1) offset value (similar to neutral loss scan

in MS/MS)

4. DMS1 ion selection, DMS2 ion selection (similar

to SRM in MS/MS)

DMS/DMS in mobility spectrometry, as MS/MS in mass

spectrometry, is based on idea that chemical properties of

ions, can be employed to increase specificity of ion

characterization and identification in mobility analyses

DMS/DMS is a versatile platform for studying chemical

orthogonality in DMS by exploring various gas phase

chemical phenomena

The tandem system is flexible with multiple modes of

operation, tailorable to specific applications

29

SUMMARY

Better control of DMS1 and DMS 2 electronics

and synchronicity of operation

Mass identification with new reactions

Elimination of excessive neutrals present in

DMS1 (for ESI work)

30

FUTURE PLANS

Dr. H. Schmidt (Morpho

Detection)

Dr. E. Nazarov (Draper

laboratory)

John Tobin (NMSU)

Aldo Maldonado (NMSU)

31

ACKNOWLEDGEMENTS