combination of direct analysis in real tiem with ft-icr ms

1
C C 28 C 30 C n H 2n+1 COO í Na + O 2 Class 15 C 26 C n H 2n+1 COO Na DBE 10 5 C 32 C 24 10 40 20 5 0 30 Relative Abundance (% total) Carbon Number 10 40 20 30 C 34 C 22 m/z 200 300 400 500 600 700 Frequency (kHz) m/z Differential amplifier Frequency spectrum Mass Spectrum Transient A B C D B F L F C v r Excitation plates Detection plates B F L F C v r Excitation plates Detection plates (-) DART FT-ICR MS of Biotar 30 O 5 O 4 O 3 BE 20 O 5 15 25 O 4 O 3 DB 10 5 15 0 O 6 O 7 O 8 30 25 DBE 20 15 10 5 0 Relative Abundance (% total) Carbon Number 10 40 60 20 0 30 50 10 40 60 20 30 50 10 40 60 20 30 50 (-) DART FT-ICR MS of Biotar sample Heteroatom Class Distribution Plot m/z C 60 H + C 60 OH + Fullerene C 60 INTODUCTION Ultra-high resolution and mass accuracy provided by Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR MS) enables unambiguous assignment of thousands of elemental compositions for components constituting complex organic mixture. “Soft”, non-distructive atmospheric ionization methods such as electrospray ionization (ESI), atmospheric pressure chemical ionization (APCI) and atmospheric pressure photo ionization (APPI) are widely used in combination with FT-ICR MS for analysis of petroleum and petroleum derived products, bio-fuels, environmental samples etc. However their application sometimes require tedious sample preparation and therefore can be affected by the compounds solubility, interference with contaminants, and matrix signals. Ultimately this limits the range of samples and compounds that can be successfully analyzed with these ionization techniques. This is where direct analysis in real time (DART) becomes relevant. DART is a new ionization technique that enables rapid analysis of various samples at ambient conditions, requiring no sample preparation. Its been shown that DART in combination with time-of-flight mass spectrometers was successfully used for targeted analysis of low molecular weight compounds (up to 800 Da) in different matrices. In the frames of this work we couple the DART® ion source to FT-ICR mass spectrometer to investigate applicability of such configuration for analysis of complex organic mixtures and individual compounds. A custom-built 9.4 T FT-ICR mass spectrometer was used to acquire mass spectra. Calibration of the instrument was carried out with Agilent HP mix by ESI. A modular ICR data acquisition system (MIDAS) collected and processed the ICR data. EXPERIMENTAL FT-ICR MS. The Combination of Direct Analysis in Real Time with Fourier Transform Ion Cyclotron Resonance Mass Spectrometry ACKNOWLEDGEMENTS The authors acknowledge IonSense, Inc. for providing DART source and NSF for financial support (grant # DMR-00-84173). One of us (Terrie Kweifio) thanks NSF and the National High Magnetic Field Laboratory (Tallahassee, FL) for research experience provided through the REU program. CONCLUSIONS DART source coupled with FT-ICR MS demonstrated successful analysis of compounds within a complex matrix. We detected traces of cocaine on all analyzed dollar bills . The detection of DART demonstrates potential of this ionization method for analysis of compounds with high boiling (sublimation) temperature exceeding operational temperature of the DART source. Combination of DART with FT-ICR MS was successfully used for direct analysis of complex mixtures such as naphthenate deposits and biotar. This approach required no sample preparation and provides rapid identification of components of the mixtures. targeted and nicotine in tobacco of cigarette C fullerene with 60 RESULTS AND DISCUSSION Figure 1. Transformation of ion cyclotron motion into a mass spectrum. (A) sche- matic representation of ion cyclotron rotation in an ICR cell , (B) time-domain image- current signal from opposed detection electrodes, (C) frequency-domain spectrum obtained by fast Fourier transform of the digitized time-domain signal, and (D) mass spectrum obtained by frequency-to-m/z conversion. Figure 2. Scheme of the DART source. Figure 6. (-) DART FT-ICR mass spectrum of sodium naphthenate deposit. Sodium naphthenates are natural sufactants and stabilize water-oil emulsion. Analysis of the naphthenates with (-) ESI requires tedious sample preparation, whereas DART enables straightforward analysis through direct sample introduction. Figure 7. (-) DART FT-ICR MS of Biotar sample. Inset is a heteroatom class distribution plot which shows the relative abundance of O classes detected. x Figure 3. Analysis of over ten U.S. currency bills with DART showed traces of cocaine detected on every bill. (+) DART FT-ICR spectrum from the surface of U.S. dollar bill. The most abundant peak in mass spectrum corresponds to protonated cocaine. Figure 4. cigarette (Marlboro gold pack). The most abundant peak corresponds to protonated nicotine molecule. Nicotine is a natural alkaloid constituting up to 3% of tobacco dry weight. (+) DART FT-ICR spectrum of tobacco leaf obtained from a Figure 5. (+) DART FT-ICR spectrum of C fullerene. The detection of fullerene at these conditions is surprising because sublimation temperature ( of 60 The mass spectrum displays [M+H] ion as the main peak, whereas [M+O+H] ion corresponds to analyte oxidation. T ) C is ~ C from the probe surface. + + sub 60 60 500 C and significantly higher than temperature of the DART source (370 C). We hypothesize direct desorption/ionization of o o Terrie Kweifio , Vladislav V. Lobodin , Alan G. Marshall 1 2 2 1 2 Department of Chemistry, Virginia Polytechnic Institute and State University, Blacksburg, VA24061-0002 National High Magnetic Field Laboratory, Florida State University, 1800 East Paul Dirac Drive, Tallahassee, FL32310-4005 m/z 304.2 304.189 304.179 304.169 304.159 304.148 304.138 304.128 304.118 304.108 m/z 163.149 163.144 163.139 163.133 163.128 163.123 163.118 163.113 163.108 163.103 Direct Analysis In Real Time (DART). Figure 2 Within the DART source, ionization occurs from exposure of sample with meta-stable heated gas molecules emerging from the source tip. Various components of DART can be regulated and modified to accomplish desired ionization for different compounds. Factors such as temperature, gas flow, voltage potential, and gas source can be controlled to uniquely accomplish ionization ( ). Fourier Transform He(2 3 S) + nH O 2 ? [(H 2 O) n-1 + H] + + OH - + He(1 1 S) Meta-stable helium gas is created through mechanism of electric glow discharge where an electric current is passed through gas molecules thus exciting the atom to a higher energetic state creating plasma. Helium, with a 19.8 eV energetic excited state, is an ideal gas since ionization energies of most atmospheric gases and organic molecules are lower than 19.8 eV. Excited He atoms interact with atmospheric gases (N , H O, O ) and analyte molecules which leads to ion formation by direct Penning ionization of reagent ions (Eq. 2) and subsequent ionization of analyte ( . 2 2 2 (Eq. 1) as well as formation Eq. 3) [(H 2 O) n-1 + H] + +M ? [M + H] + + nH 2 O Figure 7. Isoabundance color contoured plots of double bond equivalent (DBE= number of rings plus double bonds) vs. carbon number for six most abundant heteroatom classes detected in biotar sample. The increase in DBE indicates increase in aromaticity . Cocaine MW = 303.35 g/mol [M + H] + [M + H] + Nicotine MW = 162.26 g/mol m/z = 304.1543 m/z = 163.1297 =~ T sub 500 C o He* + M ? M +. + He + ē (3) (2) (1) U.S. Dollar Bill Cigarette (Marlboro Gold) m/z m/z m/z

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Page 1: Combination of Direct Analysis in Real TIem with FT-ICR MS

CC28

C30

CnH

2n+

1CO

ON

a+

O2 C

lass

15

C26

CnH

2n+

1CO

ON

a

DBE10 5C

32C

24

1040

20

5 030

Rel

ativ

e A

bu

nd

ance

(%

to

tal)

Car

bo

n N

um

ber

1040

2030

C34

C22

m/z

200

300

400

500

600

700

Freq

uenc

y (k

Hz)

m/z

Diff

eren

tial

ampl

ifier

Freq

uenc

y sp

ectr

umM

ass

Spec

trum

Tran

sien

tA

B

CD

B

F LF Cv

r•

Excitation plates

Det

ecti

on p

late

sB

F LF Cv

r•

Excitation plates

Det

ecti

on p

late

s

(-)

DA

RT

FT-

ICR

MS

of

Bio

tar

30O

5O

4O

3

BE20

O5

1525O

4O

3

DB 10 515 0

O6

O7

O8

30 25 DBE20 15 10 5 0 Rel

ativ

e A

bu

nd

ance

(% t

ota

l)C

arb

on

Nu

mb

er10

4060

200

3050

1040

6020

3050

1040

6020

3050

(-)

DA

RT

FT

-IC

R M

S o

f B

iota

rs

am

ple

Hete

roato

m C

lass D

istr

ibu

tio

n P

lot

m/z

C60H

+

C60O

H+

Fu

lle

ren

eC

60

INT

OD

UC

TIO

N

Ultra

-hig

hre

solu

tion

and

mass

accura

cy

pro

vid

ed

by

Fourier

Tra

nsfo

rmIo

nC

yclo

tron

Resonance

Mass

Spectr

om

etr

y(F

T-I

CR

MS

)enable

sunam

big

uous

assig

nm

ent

of

thousands

of

ele

menta

lcom

positio

ns

for

com

ponents

constitu

ting

com

ple

xorg

anic

mix

ture

.“S

oft”,

non-d

istr

uctive

atm

ospheric

ioniz

ation

meth

ods

such

as

ele

ctr

ospra

yio

niz

ation

(ES

I),

atm

ospheric

pre

ssure

chem

ical

ioniz

ation

(AP

CI)

and

atm

ospheric

pre

ssure

photo

ioniz

ation

(AP

PI)

are

wid

ely

used

incom

bin

ation

with

FT-I

CR

MS

for

analy

sis

ofpetr

ole

um

and

petr

ole

um

derived

pro

ducts

,bio

-fuels

,environm

enta

lsam

ple

setc

.H

ow

ever

their

applic

ation

som

etim

es

require

tedio

us

sam

ple

pre

para

tion

and

there

fore

can

be

affecte

dby

the

com

pounds

solu

bili

ty,

inte

rfere

nce

with

conta

min

ants

,and

matr

ixsig

nals

.U

ltim

ate

lyth

islim

its

the

range

of

sam

ple

sand

com

pounds

that

can

be

successfu

llyanaly

zed

with

these

ioniz

ation

techniq

ues.

This

isw

here

directa

naly

sis

inre

alt

ime

(DA

RT

)becom

es

rele

vant.

DA

RT

isa

new

ioniz

ation

techniq

ue

thatenable

sra

pid

analy

sis

ofvarious

sam

ple

satam

bie

ntconditio

ns,re

quirin

gno

sam

ple

pre

para

tion.Its

been

show

nth

atD

AR

Tin

com

bin

ation

with

tim

e-o

f-flig

ht

mass

spectr

om

ete

rsw

as

successfu

llyused

for

targ

ete

danaly

sis

of

low

mole

cula

rw

eig

ht

com

pounds

(up

to800

Da)

indiffe

rent

matr

ices.

Inth

efr

am

es

oft

his

work

we

couple

the

DA

RT

®io

nsourc

eto

FT-I

CR

mass

spectr

om

ete

rto

investigate

applic

abili

tyof

such

configura

tion

for

analy

sis

of

com

ple

xorg

anic

mix

ture

sand

indiv

idualc

om

pounds.

Acusto

m-b

uilt

9.4

TF

T-I

CR

mass

spectr

om

ete

rw

as

used

toacquire

mass

spectr

a.

Calib

ration

of

the

instr

um

ent

was

carr

ied

out

with

Agile

nt

HP

mix

by

ES

I.A

modula

rIC

Rdata

acquis

itio

nsyste

m(M

IDA

S)colle

cte

dand

pro

cessed

the

ICR

data

.

EX

PE

RIM

EN

TA

L

FT-I

CR

MS

.

Th

eC

om

bin

ati

on

of

Dir

ec

tA

na

lys

isin

Re

al

Tim

ew

ith

Fo

uri

er

Tra

ns

form

Ion

Cy

clo

tro

nR

es

on

an

ce

Ma

ss

Sp

ec

tro

me

try

AC

KN

OW

LE

DG

EM

EN

TS

The

auth

ors

acknow

ledge

IonS

ense,

Inc.

for

pro

vid

ing

DA

RT

sourc

eand

NS

Ffo

rfinancia

lsupport

(gra

nt#

DM

R-0

0-8

4173).

One

ofus

(Terr

ieK

weifio

)th

anks

NS

Fand

the

National

Hig

hM

agnetic

Fie

ldLabora

tory

(Talla

hassee,

FL)

for

researc

hexperience

pro

vid

ed

thro

ugh

the

RE

Upro

gra

m.

CO

NC

LU

SIO

NS

● ● ●

DA

RT

sourc

ecouple

dw

ith

FT-I

CR

MS

dem

onstr

ate

dsuccessfu

lanaly

sis

of

com

pounds

within

acom

ple

xm

atr

ix.W

edete

cte

dtr

aces

ofcocain

eon

all

analy

zed

dolla

rbill

s.

The

dete

ction

of

DA

RT

dem

onstr

ate

spote

ntialofth

isio

niz

ation

meth

od

for

analy

sis

of

com

pounds

with

hig

hboili

ng

(sublim

ation)

tem

pera

ture

exceedin

gopera

tionalt

em

pera

ture

oft

he

DA

RT

sourc

e.

Com

bin

ation

ofD

AR

Tw

ith

FT-I

CR

MS

was

successfu

llyused

for

directanaly

sis

of

com

ple

xm

ixtu

res

such

as

naphth

enate

deposits

and

bio

tar.

This

appro

ach

required

no

sam

ple

pre

para

tion

and

pro

vid

es

rapid

identification

ofc

om

ponents

oft

he

mix

ture

s.

targ

ete

d

and

nic

otine

into

bacco

ofc

igare

tte

Cfu

llere

ne

with

60

RE

SU

LT

SA

ND

DIS

CU

SS

ION

Fig

ure

1.

Tra

nsfo

rmation

of

ion

cyclo

tron

motion

into

am

ass

spectr

um

.(A

)sche-

matic

repre

senta

tion

ofio

ncyclo

tron

rota

tion

inan

ICR

cell

,(B

)tim

e-d

om

ain

image-

curr

ent

sig

nalfr

om

opposed

dete

ction

ele

ctr

odes,

(C)

frequency-d

om

ain

spectr

um

obta

ined

by

fastF

ourier

transfo

rmofth

edig

itiz

ed

tim

e-d

om

ain

sig

nal,

and

(D)

mass

spectr

um

obta

ined

by

frequency-t

o-m

/zconvers

ion.

Fig

ure

2.S

chem

eoft

he

DA

RT

sourc

e.

Fig

ure

6.(-

)D

AR

TF

T-I

CR

mass

spectr

um

ofsodiu

mnaphth

enate

deposit.S

odiu

mnaphth

enate

sare

natu

rals

ufa

cta

nts

and

sta

bili

ze

wate

r-oil

em

uls

ion.A

naly

sis

ofth

enaphth

enate

sw

ith

(-)

ES

Ire

quires

tedio

us

sam

ple

pre

para

tion,

where

as

DA

RT

enable

sstr

aig

htf

orw

ard

analy

sis

thro

ugh

directs

am

ple

intr

oduction.

Fig

ure

7.

(-)

DA

RT

FT-I

CR

MS

of

Bio

tar

sam

ple

.In

set

isa

hete

roato

mcla

ss

dis

trib

ution

plo

twhic

hshow

sth

ere

lative

abundance

ofO

cla

sses

dete

cte

d.

x

Fig

ure

3.

Analy

sis

of

over

ten

U.S

.curr

ency

bill

sw

ith

DA

RT

show

ed

traces

ofcocain

edete

cte

don

every

bill

.

(+)

DA

RT

FT-I

CR

spectr

um

from

the

surf

ace

of

U.S

.dolla

rbill

.T

he

most

abundant

peak

inm

ass

spectr

um

corr

esponds

topro

tonate

dcocain

e.

Fig

ure

4.

cig

are

tte

(Marlboro

gold

pack).

The

most

abundant

peak

corr

esponds

topro

tonate

dnic

otine

mole

cule

.Nic

otine

isa

natu

rala

lkalo

idconstitu

ting

up

to3%

oft

obacco

dry

weig

ht.

(+)

DA

RT

FT-I

CR

spectr

um

of

tobacco

leaf

obta

ined

from

a

Fig

ure

5.(+

)D

AR

TF

T-I

CR

spectr

um

ofC

fulle

rene.

The

dete

ction

of

fulle

rene

at

these

conditio

ns

issurp

risin

gbecause

sublim

ation

tem

pera

ture

(of

60

The

mass

spectr

um

dis

pla

ys

[M+

H]

ion

as

the

main

peak,

where

as

[M+

O+

H]

ion

corr

esponds

toanaly

teoxid

ation.

T)

Cis

~

Cfr

om

the

pro

be

surf

ace.

++

sub

60

60

500

Cand

sig

nific

antly

hig

her

than

tem

pe

ratu

reo

fth

eD

AR

Ts

ou

rce

(37

0C

).W

eh

yp

oth

es

ize

dir

ec

tdesorp

tion/ioniz

ation

of

o o

Te

rrie

Kw

eif

io,

Vla

dis

lav

V.

Lo

bo

din

,A

lan

G.

Ma

rsh

all

12

2

1

2

Depart

ment

of

Chem

istr

y,V

irgin

iaP

oly

technic

Institu

teand

Sta

teU

niv

ers

ity,

Bla

cksb

urg

,V

A2

40

61

-00

02

NationalH

igh

Magnetic

Fie

ldLabora

tory

,F

lorida

Sta

teU

niv

ers

ity,

1800

East

PaulD

ira

cD

rive

,Ta

llah

asse

e,F

L3

23

10

-40

05

m/z

304.

230

4.18

930

4.17

930

4.16

930

4.15

930

4.14

830

4.13

830

4.12

830

4.11

830

4.10

8

m/z

163.

149

163.

144

163.

139

163.

133

163.

128

163.

123

163.

118

163.

113

163.

108

163.

103

Dir

ectA

naly

sis

InR

ealT

ime

(DA

RT

).

Fig

ure

2

Within

the

DA

RT

sourc

e,

ioniz

ation

occurs

from

exposure

ofsam

ple

with

meta

-sta

ble

heate

dgas

mole

cule

sem

erg

ing

from

the

sourc

etip.

Various

com

ponents

of

DA

RT

can

be

regula

ted

and

modifie

dto

accom

plis

hdesired

ioniz

ation

fordiffe

rentcom

pounds.F

acto

rssuch

as

tem

pera

ture

,gas

flow

,voltage

pote

ntial,

and

gas

sourc

ecan

be

contr

olle

dto

uniq

uely

accom

plis

hio

niz

ation

().

Four

ier

Tran

sfor

m

He(

23 S)

+nH

O 2�

[(H

2O) n

-1+

H]+

+O

H-+

He(

11 S)

Me

ta-s

tab

leh

eliu

mg

as

iscre

ate

dth

rou

gh

me

ch

an

ism

of

ele

ctr

icg

low

dis

charg

ew

here

an

ele

ctr

iccurr

ent

ispassed

thro

ugh

gas

mole

cule

sth

us

excitin

gth

eato

mto

ahig

her

energ

etic

sta

tecre

ating

pla

sm

a.

Heliu

m,

with

a19.8

eV

energ

etic

excited

sta

te,

isan

ideal

gas

sin

ce

ioniz

ation

energ

ies

of

most

atm

ospheric

gases

and

org

anic

mole

cule

sare

low

erth

an

19.8

eV

.

Excited

He

ato

ms

inte

ract

with

atm

ospheric

gases

(N,

HO

,O

)and

analy

tem

ole

cule

sw

hic

hle

ads

toio

nfo

rmation

by

directP

ennin

gio

niz

ation

ofr

eagenti

ons

(Eq.2

)and

subsequenti

oniz

ation

of

analy

te(

.

22

2(E

q.1)as

well

as

form

ation

Eq.3

)

[(H

2O) n

-1+

H]+

+M�

[M+

H]+

+nH

2O

Fig

ure

7.

Isoabundance

colo

rconto

ure

dplo

tsof

double

bond

equiv

ale

nt

(DB

E=

num

ber

of

rings

plu

sdouble

bonds)

vs.

carb

on

num

ber

for

six

most

abundant

hete

roato

mcla

sses

dete

cte

din

bio

tar

sam

ple

.T

he

incre

ase

inD

BE

indic

ate

sin

cre

ase

inaro

maticity

.

Co

ca

ine

MW

=3

03

.35

g/m

ol

[M+

H]+

[M+

H]+ N

ico

tin

e

MW

=1

62

.26

g/m

ol

m/z

=304.1

543

m/z

=163.1

297

=~

Tsub

500

Co

He*

+M�

M+

.

+H

e+

ē

(3)

(2)

(1)

U.S

.D

oll

ar

Bil

l

Cig

are

tte

(Marl

bo

roG

old

)

m/z

m/z

m/z