New planar DMA designs for high transmission and resolution coupling to modern API-MS instruments

J. Rus �, D. Moro , J. A. Sillero and J. Fernández de la Mora

� juan.rus@seadm.comwww.seadm.com

SEADM overview

� Spanish R&D micro-business established in February 2005� Objective: developing a new technology for explosives

detection� Since 2005, SEADM has completed or is currently developing

the following projects :– EXPLOSIVE TRACE DETECTION

� Demonstrator built detecting vapour traces of explosives in the atmosphere at concentrations of 1 ppt

� Prototype development since January 2007: DETEV project. Explosive trace detector unit to be used in road control.

– DMA-MS INTEGRATION� MAIMS Program (Mobility Analysis Integrated with Mass

Spectrometry), since September 2006, to couple a DMA (Differential Mobility Analyzer) to an API Mass Spectrometer, in order to increase its resolution capability for biological analysis. MAIMS is an international Canadeka program and is partially funded by the Spanish Ministry of Industry within the 2004-2007 I+D+i National Plan.

� Located in Boecillo (Valladolid), 250 m2 laboratory. Staff of 6 engineers

DMA developments

Inlet slit of charged particles of several mobilities

Uniform flowat velocity U

∆

Exit hole of particles at mobility Z = U∆2/ LVDMA

Electric FieldE = VDMA / ∆

L

Mobility separation in a planar DMA

Mechanical design of the planar DMA

Sheath gas inlet

Sheath gas outlet

Sampled qoutto mass

spectrometer

Ions inlet

Ionization source

Upper electrode

Lower electrode

Isolator box

( )( )2 16ln 2 1/L ∆FWHH Pe∆ L

= +

Pe = Re ν/D

FWHH < 1 % requires Reynolds ~ 40.000 for ions of 1 cm2/Vs

The aerodynamical design has been operated under laminar conditions up

to Reynolds = 200.000

Planar DMA performance – Diffusion

qout

Q

∆

k∆

Planar DMA performance – qout

2-D sampling across the chamber � FWHH = qout/Q � FWHH < 0.1 %

FWHH ≈ (kqout/Q)1/2(1 + ∆2/L2)1/4

Typical values:qout = 0.5 lpmQ = 1000 lpm

FWHH ~ 3 %Resolving power ~ 30

102

103

101

Voltaje (V)

FW

HH

(%

)

Datos P1v2 THA+

Datos P1v2.5 THA+

P1v2 THA+

Datos P1v4c1

Datos P1v4.1c1

P1v4c1

Datos P1v2.5

P1v2, EtN+

Datos P1v6c1

P1v6c1 Cd=0,6

P1v6c1 Cd=0,78

102

103

104

100

101

Voltaje (V)

FW

HH

(%

)

P1v4c2

Datos P1v4c2

P1v5c2

Datos P1v5c2

Datos P1v6.2c2

P1v6c2

P1v6c2 Cd=0,78

First prototype (P1):- Not to be coupled to any other instrument- Many different configurations tested, for theories comparison and models adjustment- Barely below 2 % resolution (Resolving power < 50)

2 %

Prototypes progression – P1

Prototypes progression – P2

ES’s chamber Upper electrode

Sheath entrance

Lower electrode

Sheath exit

Teflon’s body

0.8

1

1.2

1.4

1.6

1.8

1500 1700 1900 2100 2300 2500 2700 2900 3100 3300 3500 3700 3900 4100 4300 4500

Voltage (V)

FWH

H %

,

Second prototype (P2):- Coupled to API 365 and API 3000 triple quads- qout = 0.3 - 0.5 lpm- Resolving power > 50- Currently at MDS Sciex, Toronto �published results of >5x sensitivity improvement (ASMS 08)

Tetraethylammonium+ (~ 1.8 cm2/Vs)

Prototypes progression – P3 (1/2)

DMA P2 and P3 resolution when analyzing the ion THA +

0

20

40

60

80

100

120

0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000

DMA Voltage (V)

Res

olut

ion

,

P3 series 1

Theory for THA +

P3 series 2

P3 series 3

P2

Third series of prototypes (P3)- Coupled to API 365 triple quad and to QStar QqTOF- Similar to P2 in aerodynamic design and operation- Mechanical redesign, higher operating voltages

Prototypes progression – P3 (2/2)

1000 5000

0

2

4

6

8

10

Sig

nal (

V)

DMA Voltage (V)

DMA - Prototype P3BTHA+ peak at different seath air speeds

Counterflow = 2 l/min

0

20

40

60

80

100

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

Mach in separation chamberR

esol

utio

n

,

THAB 25/1/07

Theory for THA+

A planar DMA coupled to a MS for tandem IMS-MS separation at high transmission, with IMS resolution approaching 100. Rus J.;

Estevez F.; Fernandez de la Mora J.; Proc. 57th ASMS Conf. Mass Spectrom. All. Top.; Indianapolis (Indiana) USA June, 2007

Contour Plot of resultados.wiff, Sample 25, (0.165 min to 37.833 min) Max. 139.0 cps.

3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 11.0 12.0 13.0 14.0 15.0 16.0 17.0 18.0 19.0 20.0 21.0 22.0 23.0 24.0Time, min

1400

1600

1800

2000

2200

2400

2600

2800

3000

3200

3400

3600

3800

4000

4200

4400

4600

4800

m/z

, Da

No Data 1.5% - 6.3%

Prototypes progression – P4

Coulombic denaturing of gas phase proteins electrosprayed from

neutral aqueous solutions studied by IMS (DMA) MS; Fernandez de

la Mora J.; Proc. 58th ASMS Conf. Mass Spectrom. All. Top.;

Denver (Colorado) USA June, 2008

Shadows & charge loss

z=4

z=10

Trimer

Dimer

Monomer

- Coupled to API 365 triple quad and to QStar QqTOF- qout = 0.5 lpm- Resolving power > 50- Improved transmission through outlet- Optimized for larger (less mobile) analytes

Lysozyme

Fourth series of prototypes (P4):

Latest developments and future work

Higher flow rates sampled (qout ) and delivered to the MS

Coupling to modern API instruments, which sample higher flow rates:

- Shimadzu’s LCMS2010EV single quad: 1.0 lpm- API 5000 triple quad: 2.9 lpm

Measuring DMA � MS transmission

Target

Method Tandem DMA-DMA system developed by P. McMurry (U. Minnesota)

AuxiliaryDMA

TestedDMA

IS (Electrospray)

A Iaux

Flowmeter � qaux

A Iout

Flowmeter � qout

Transmission = Iout/Imax

Imax = Maximum signal through the DMA: qout*nin

nin= Iaux / qaux

Delivers a flow of monomobile ions at a concentration nin to be sampled by the second DMA (the one tested for transmission)

Flowmeter � qin

Excess flow

Transmission measurements (1/2)

0 5 10 15 20 25 30 35 400

10

20

30

40

50 DMA at M~0.17, THA+ peak at 2000 V DMA at M~0.10, THA+ peak at 1250 V

Tra

nsm

issi

on (

%)

qin/ q

out (%)

Flows per unit length. 3D effects at the outlet not considered

Transmission measurements (2/2)

Auxiliary DMA

2 way valve

Tested DMA

Auxiliary electrometer

Higher qout delivered to the MS (1/2)

- Modified P3 instrument- Delivers ions to a capillary MS inlet (instead of chocked orifice)- Highest resolving powers achieved (> 100) even with the doubled qout

2900 2950 3000 3050 3100 3150 32000

2

4 qo = 1.7 lpm qo = 1.0 lpm qo = 0.6 lpm qo = 0.3 lpm

Sig

nal (

pA)

DMA Voltage (V)

0,0 0,5 1,0 1,5 2,00

2

4

6

Resolution ∆V Signal Theory

Res

olut

ion/

10, ∆

V (

%)

or s

igna

l (pA

)

Sampled flow (lpm)0 2000 4000 6000 8000

0

10

20

30

40

50

60

70

80

90

100

110

120 Previous prototype P3Bv0, 0,3 lpm sampling Modified prototype P3Bv3, sampling 1 lpm Modified prototype P3Bv3, sampling 2 lpm

Theory for P3Bv3 sampling 1 lpm Theory for P3Bv3 sampling 2 lpm

Res

olut

ion

DMA voltage (V)

Resolution improvement by decreasing inlet flow of ions

Higher qout delivered to the MS (2/2)

- Already coupled to Shimadzu’s LCMS 2010 EV single quad

0 2 4 6 8 100

5000

10000

15000

20000

25000

30000

35000

40000

Inte

nsity

Time (min)

TIC SIM 410 SIM 411

0.09 %1.16 %860.406500

0.09 %1.25 %800.315300

0.13 %1.50 %650.233900

sFWHHResolving

power

Mach

number

THA+ peak

voltage (V)

THABr 100 µM

DMA Voltage

Conclusions

� Series of planar DMA prototypes designed and manufactured with resolving powers exceeding 50, approaching 100

� Different designs have been coupled to Sciex’s API 365, API 3000, QStar and Shimadzu’s LCMS2010EV

� Full transmission of ions from the inlet to the outlet. Transmission limited by achievable inlet flow: inserted up to 50% of MS flow rate � 50 % DMA-MS transmission

� New designs tackle the qout/Q limitation approaching the target qout = 3 lpm while keeping resolving power 50-100

Acknowledgments – SEADM DMA team

And thank you!