Comprehensive Two-Dimensional Gas Chromatography coupled ...
Comprehensive Two-Dimensional Gas Chromatography coupled ...
Comprehensive Two-Dimensional Gas Chromatography coupled ...
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GACID<br />
<strong>Comprehensive</strong> <strong>Two</strong>-<strong>Dimensional</strong><br />
<strong>Gas</strong> <strong>Chromatography</strong> <strong>coupled</strong> with Time-of-Flight<br />
Mass Spectrometry<br />
for Broad Spectrum Organic Analysis<br />
GCxGC-TOFMS<br />
GACID -Group for Analytical Chemistry Instrument Development<br />
Harsh Environment Mass Spectrometry workshop<br />
09/22/2003<br />
Sarasota, FL<br />
Stefan Scherer<br />
Department for Atmospheric, Oceanic, and Space Sciences<br />
Space Physics Research Laboratory<br />
University of Michigan<br />
09/23/2005 S. Scherer 1
Presentation Outline<br />
GACID<br />
• Separation using <strong>Comprehensive</strong> 2-<strong>Dimensional</strong> <strong>Gas</strong> <strong>Chromatography</strong><br />
(GCxGC)<br />
– 1-D GC versus 2-D GC<br />
• Identification using Time-of-Flight Mass Spectrometry TOFMS<br />
– Capabilities of TOFMS<br />
• Applications for GCxGC-TOFMS (selected examples)<br />
– Tholins<br />
– CWA simulants detection in gasoline<br />
– Breath analysis<br />
• Field deployment at UMBS<br />
• Subsystem development activities<br />
– Thermal Modulator<br />
• Future steps<br />
• Acknowledgement<br />
09/23/2005 S. Scherer 2
1-<strong>Dimensional</strong> <strong>Gas</strong> <strong>Chromatography</strong> (GC)<br />
GACID<br />
Standard 1D-GC technique<br />
<br />
<br />
<br />
<br />
narrow sample plug injection<br />
into the chromatographic<br />
column<br />
Sample transport happens in<br />
the mobile phase by the flow<br />
of an inert carrier gas<br />
separation of the sample<br />
occurs along the coated<br />
column with various stationary<br />
phases by interaction of the<br />
sample material with the<br />
column coating<br />
Retention time of the effluent<br />
is detected<br />
09/23/2005 S. Scherer 3
<strong>Comprehensive</strong> 2-<strong>Dimensional</strong> <strong>Gas</strong> <strong>Chromatography</strong> (GC x<br />
GC)<br />
GACID<br />
09/23/2005 S. Scherer 4
1-<strong>Dimensional</strong> versus 2-<strong>Dimensional</strong> <strong>Gas</strong> <strong>Chromatography</strong> (1/2)<br />
GACID<br />
1-<strong>Dimensional</strong> GC<br />
<strong>Comprehensive</strong> 2-<strong>Dimensional</strong> GC<br />
I<br />
I<br />
C<br />
C 1<br />
C 2<br />
D<br />
TM<br />
D<br />
TIC (a.u.)<br />
Time (s)<br />
Time (s) in C2<br />
TIC (a.u.)<br />
Time (s) in C2<br />
Time (s) in C1<br />
Time (s) in C1<br />
09/23/2005 S. Scherer 5
1-<strong>Dimensional</strong> versus 2-<strong>Dimensional</strong> <strong>Gas</strong> <strong>Chromatography</strong> (2/2)<br />
GACID<br />
(a)<br />
(b)<br />
TIC TIC<br />
0<br />
2-<strong>Dimensional</strong> separation (modulated)<br />
1-<strong>Dimensional</strong> separation (non-modulated)<br />
1000 2000 3000 4000 5000<br />
Time (s)<br />
(c)<br />
Time (s)<br />
10<br />
5<br />
0<br />
1000 2000 3000 4000 5000<br />
Time (s)<br />
2-<strong>Dimensional</strong> view of GCxGC<br />
0<br />
0<br />
1000 2000 3000 4000 5000<br />
Time (s)<br />
09/23/2005 S. Scherer 6
Measurement capabilities of GCxGC<br />
GACID<br />
Analysis of organic carbon compounds C 5 to C 25<br />
High peak capacity (several thousand peaks per chromatogram)<br />
Typical analysis cycle duration 30 min<br />
Various sampling methods are available<br />
Solid samples using pyrolysis<br />
(10-100 µg/cycle sample material using Flash or Stepped Pyrolysis)<br />
Volatile samples using direct sampling/pre-concentration<br />
Liquid sampling using split/splitless injection<br />
Sensitivity in the low parts per trillion (ppt) range<br />
Increased detectability<br />
Linearity over more than 3 orders of magnitude (ppb - ppt)<br />
Thermal Modulator (TM) is key component of GCxGC<br />
- commercial TM require consumables<br />
- consumable-free TM under development<br />
09/23/2005 S. Scherer 7
GCxGC-TOFMS<br />
GACID<br />
Inlet<br />
Separation<br />
Identification<br />
Identification by TOFMS<br />
Full mass spectrum with every extraction pulse firing<br />
without necessity of scanning the entire mass range<br />
Repetition rates up to 100kHz achievable, which allows<br />
monitoring fast sample composition changes on time<br />
scales much smaller than milliseconds<br />
High initial energy spread of ions up to several hundred<br />
eV is admissible<br />
Neither static nor dynamic magnetic fields are required<br />
Performance depends mainly on electrical circuits rather than<br />
mechanical alignment<br />
Mass scale calibration for TOFMS is simple and reliable<br />
09/23/2005 S. Scherer 8
Chromatogram of tholins using GCxGC-TOFMS technique (1/2)<br />
GACID<br />
sample (tholin) analyzed by commercial laboratory equipment (LECO<br />
Corp.) using pyrolysis injection (CDS).<br />
09/23/2005 S. Scherer 9
Chromatogram of tholins using GCxGC-TOFMS technique (2/2)<br />
GACID<br />
09/23/2005 S. Scherer 10
Chemical Warefare Agent Simulants in Complex Organic Mixtures<br />
GACID<br />
09/23/2005 S. Scherer 11
Human Breath Analysis<br />
GACID<br />
Human breath analysis<br />
before smoking<br />
Human breath analysis<br />
shortly after smoking<br />
09/23/2005 S. Scherer 12
Commercial GCxGC-TOFMS<br />
GACID<br />
LECO Pegasus 4D<br />
GCxGC – TOFMS<br />
• Resource intensive liquid LN 2 cooled four jet Thermal Modulator<br />
(dewer of LN2 /week)<br />
http://www.leco.com<br />
09/23/2005 S. Scherer 13
GCxGC–TOFMS breadboard using closed-loop air-cooled TM<br />
GACID<br />
GCxGC – TOFMS breadboard<br />
• Custom made pre-concentrator<br />
• Integrated packaged columns (RVM Scientific)<br />
• Custom made closed-loop air-cooled consumable-free TM<br />
• TOFMS (Ionwerks)<br />
09/23/2005 S. Scherer 14
Breadboard results of GCxGC - TOFMS<br />
GACID<br />
09/23/2005 S. Scherer 15
Field deployment of the GCxGC-TOFMS breadboard<br />
GACID<br />
GCxGC–TOFMS breadboard field deployed during summer 2005 campaign<br />
at the PROPHET tower laboratory at the University of Michigan<br />
Biological Station (Northern Michigan); refer to poster from Judy Yu<br />
Measurement Goal: VOCs and isoprene measurements<br />
09/23/2005 S. Scherer 16
2-Stage Thermal Modulator<br />
• <strong>Two</strong>-Stage Thermal Modulator designed<br />
and prototyped at the<br />
University of Michigan<br />
• Set Industry Standard for Modulators<br />
• <strong>Two</strong>-Stage will eliminate sweep through<br />
GACID<br />
1 st Stage<br />
2 nd Stage<br />
Drawing Courtesy of Bruce Block – AOSS University of Michigan<br />
09/23/2005 S. Scherer 17
Single Stage versus 2-Stage Thermal Modulator<br />
GACID<br />
Single-Stage Air-Cooled<br />
A<br />
• limited quantitative analysis<br />
• Breakthrough observed<br />
• Peak Tailing as<br />
concentration inside<br />
modulator increases<br />
<strong>Two</strong>-Stage Air-Cooled<br />
B<br />
• Improved quantitative<br />
analysis<br />
• Minimal Breakthrough<br />
• No Peak Tailing<br />
0 5 10 15 20 25 30 35<br />
Time (s)<br />
1 ppm Octane<br />
09/23/2005 S. Scherer 18
Future of GCxGC using Micro-Fabricated Columns<br />
GACID<br />
• Further miniaturize the separation section<br />
by using MEMS technology for the GCxGC<br />
subsystem<br />
• Decrease physical size as well as reduce<br />
resource requirements with on-chip heating<br />
• Collaboration with the WIMS center at<br />
UofM<br />
09/23/2005 S. Scherer 19
Future of GCxGC using Micro-Fabricated Columns<br />
GACID<br />
3.2 cm<br />
• Capillary length 3m<br />
• Chip size (3.2cmx3.2cm)<br />
• cross section<br />
150 µm wide x 240 µm<br />
deep<br />
• Side ports etched in Si for<br />
more mechanical stability<br />
• Etched back structure for<br />
reduced thermal mass<br />
150 µm<br />
240 µm<br />
Digital Picture of 3-<br />
meter micro fabricated<br />
column<br />
09/23/2005 S. Scherer 20
Future of GCxGC using Micro-Fabricated Columns<br />
GACID<br />
• Separation of series of<br />
n-alkanes (C 5 to C 15 ) at<br />
3 temperature<br />
programs<br />
a) 10 K/min<br />
b) 20 K/min<br />
c) 30 K/min<br />
• Design of a mesoscale<br />
TM using<br />
thermo-electric cooling<br />
and resistive heating<br />
attached to columns in<br />
MEMS technology<br />
09/23/2005 S. Scherer 21
The GACID Team<br />
GACID<br />
… By the enthusiastic effort of the following team members at the<br />
University of Michigan the results have been made possible …<br />
College of<br />
Engineering<br />
Charlie Hasselbrink<br />
Atmospheric,<br />
Oceanic, and Space<br />
Sciences<br />
Hunter Waite<br />
Megan McGuigan<br />
Bruce Block<br />
Stefan Scherer<br />
Chemistry<br />
Richard Sacks<br />
Amy Payeur<br />
PT Stevens<br />
Mark Libardoni<br />
09/23/2005 S. Scherer 22
Pre-Concentrator<br />
GACID<br />
Column one<br />
Stainless Steel Mesh<br />
Beds<br />
Y B X C<br />
Nut<br />
Glass Wool<br />
<strong>Gas</strong> Flow During Sample Collection<br />
<strong>Gas</strong> Flow During Sample Desorption<br />
Carbon Molecular Sieve<br />
Graphitized Carbon<br />
Symbo<br />
l<br />
Adsorbent<br />
Carboxen<br />
1000<br />
Carbopack X<br />
Adsorbent<br />
Strength<br />
Application<br />
C Strongest C 2 to C 5<br />
X<br />
B<br />
Y<br />
Carbopack B<br />
Carbopack Y<br />
Stronger<br />
Weaker<br />
Weakest<br />
C 3 to C 5<br />
C 5 to C 12<br />
C 12 to C 20<br />
09/23/2005 S. Scherer 23
Custom designed Thermal Modulator<br />
GACID<br />
Dual stage Thermal Modulator<br />
- resistively heated -air-cooled<br />
09/23/2005 S. Scherer 24
<strong>Gas</strong> Chromatographic columns<br />
GACID<br />
RVM Scientific integrated columns<br />
Add photo of<br />
the RVM<br />
columns<br />
09/23/2005 S. Scherer 25
Murchinson Meteorite analysis using Pyrolysis-GCxGC-TOFMS<br />
GACID<br />
09/23/2005 S. Scherer 26
Time-of-Flight principle<br />
GACID<br />
U<br />
L in d s<br />
U extr<br />
Time focus<br />
U drift<br />
ion source<br />
1<br />
fieldfree driftpath<br />
reflectron<br />
detector<br />
2<br />
U<br />
L out<br />
d<br />
s<br />
Time focus<br />
L in + L out = L<br />
Mamyrin et al., 1972<br />
09/23/2005 S. Scherer 27
Electron Impact Storage Ion Source<br />
GACID<br />
repeller A<br />
filament<br />
repeller B<br />
extraction grid<br />
A 1<br />
A 2<br />
lens<br />
drift<br />
simulated peak<br />
backplane<br />
Dt tat<br />
3 ns<br />
Dt eds<br />
< 1 ns<br />
∆t<br />
turn-around time<br />
tat<br />
( m)<br />
= 2⋅<br />
2mU<br />
q E<br />
extr<br />
0<br />
trap<br />
1. Time focus<br />
501 504<br />
TOF [ns]<br />
U<br />
U extr<br />
z<br />
U drift<br />
09/23/2005 S. Scherer 28
Orthogonal Extraction Ion Source<br />
GACID<br />
anode<br />
filament<br />
extractor<br />
entrance lens<br />
skimmer<br />
trap<br />
extraction grid<br />
A1 A2 lens drift<br />
simulated peak<br />
backplane<br />
Dt pbd<br />
2 ns<br />
Dt eds<br />
09/23/2005 S. Scherer 30<br />
GACID
Thermal Modulators: Overview of techniques<br />
GACID<br />
P.S.<br />
N 2<br />
gas<br />
J.B. Phillips - 1991<br />
E.B. Ledford and J. Beens - 2000<br />
J.B. Phillips - 1993<br />
P.J. Marriott - 1997<br />
E.B. Ledford - 2002<br />
09/23/2005 S. Scherer 31