Microfabricated GC for Sub-ppb v Determinations of TCE in Vapor Intrusion Applications Jim Reisinger 1 , Hungwei Chang 2 , Sun Kyu Kim 2 , Thitiporn Sukaew 2 , Edward Zellers 2 and David Burris 1 1 Integrated Science & Technology, Inc. 2 University of Michigan, Department of Environmental Health Sciences, School of Public Health FRTR General Meeting November 10, 2009
Project Team ● Jim Reisinger, MS – PI ● Dave Burris, PhD, PG – Co-PI ● Rob Hinchee, PhD Integrated Science & Technology, Inc. ● Ted Zellers, PhD – U of MI Project Manager University of Michigan Center for Wireless Integrated MicroSystems ● Kyle Gorder, PE & Jarrod Case, PE Hill AFB, UT ● Paul Johnson, PhD Arizona State University 2
Technical Objectives ● Overall: Build & demonstrate new VI analyzer tools using existing & emerging technologies. “Big picture” is ultimately have analyzers that are compound- specific for many VOCs – this project focuses on TCE, the most serious current DoD VI concern. This will promote future evolution of analyzers. ● Portable “sniffer” µ GC unit for hand-held short term compound-specific “forensic” identification. ● Fixed “smoke alarm” µ GC unit for long-term compound- specific exposures with remote communications. 3
Specific µ GC Project Goals ● Fast Sample Turn-around Times (approaching 15 minutes) ● Detect TCE in Presence of Common Indoor Air VOCs (i.e., compound-specific determinations) ● Low Detection Limit for TCE (0.06 ppb v for portable µ GC and 0.03 ppb v for fixed µ GC) ● Portable µ GC – Forensic Assessment: VI or Indoor Source? ● Fixed µ GC – Long-Term (weeks, months) Exposure Monitoring with Wireless Remote Communications 4
Advances in Component & System Designs Toward a Wireless µ GC JUPITER SPIRON Gen 0.6 INTREPID MERCURY ORION iPOD-size MARS multi-VOC analyzers 5
SPIRON – Prototype µ GC inlet µ PCF to pump 1 st µ column 2 st µ column chemiresistor array detector detector temperature pump controller A Versatile µ -Analytical 6 System
Key Component: µ Preconcentrator/Focuser ( µ PCF) 1-Stage Granular Sorbent High-flow Sampler Si/glass Carbopack X 3.2mm Carrier Micro- Pump Column 3.45mm ● µ GC requires a µ PCF to minimize “injection” volume (room temp to 200 o C in 0.2 sec) ● µ PCF fluidics limits volumetric flow rate ● High-volume samples obtained with high-flow sampler / µ PCF combo 7
Key Component: µ Column 11, 12, 13 • 36 cmpds in 8.2 min 17-19 DRIE-Si/Pyrex Channels 7 10 • Air carrier gas 6 9 • FID detector 15 31 30 SPIRON 16 24 14 23 3 20 Dual-Column 26 22 25 28 4 21 5 Separation 1 2 33 27 32 29 8 36 35 34 1 2 3 4 5 6 7 8 Reproducible, Efficient Coatings time (min) Golay Plot Stable in Air up to ~200 o C 8
Key Component: µ Detector Gold Nanoparticle Chemiresistor Array Chemresistor Array – More “Information” C8 C8 OPH OPH O O CCN CCN N N O O HME HME O O DPA DPA CF 3 CF 3 HFA HFA OH OH F 3 C F 3 C Response Patterns – Peak ID ● Resistance based on analyte partitioning ● Partitioning based upon conc. not mass ● Allows scaling down in size ● Rapid, reversible, partially-selective Flow Cell Volume: as small as ~ 1.5 µ L ● Micro-interdigital Au/Cr electrodes 9
SPIRON – Prototype with High-Flow Sampler (Mock-Up) High-Flow Sampler High-flow sampler is needed for VI applications. 10
Preliminary SPIRON µ GC Results Unique Determination of TCE & PCE among 6 common Response interferences found at Hill AFB Patterns 1 TCE toluene benzene TCE ethylbenzene m-xylene 2-butanone 0.5 PCE C8 0 C8 OPH HME DPA 1 OPH PCE 0.5 DPA 0 C8 OPH HME DPA 1 Benzene HME 0.5 0 1 2 3 0.5 1.5 2.5 3.5 Time (min) 0 C8 OPH HME DPA 11
Preliminary SPIRON µ GC Results TCE Calibration Curves 0.25 OPH Sensor 0.3 C8 Sensor OPH Sensor Peak Area C8 Sensor Peak Area 0.2 0.2 0.15 0.1 y = 0.0069x y = 0.0048x 0.1 R2= 0.9977 R2= 0.9993 0.05 0 0 0 10 20 30 40 50 0 10 20 30 40 50 TO-15 TCE Conc. (ppb) TO-15 TCE Conc. (ppb) Sensor calibrations are linear 12
Preliminary SPIRON µ GC Results TCE Limits of Detection (LOD, ppb) C8 OPH DPA HME Sensitivity (V/ppb v ) 0.1095 0.0465 0.0643 0.0493 SD of noise (V) 0.0212 0.1539 0.0821 0.0643 LOD (ppb v in 1L) 0.58 9.9 3.8 3.9 LOD (ppb in 6L) 0.10 1.7 0.64 0.65 PCE TCE PCE PCE TCE TCE 4-ppb TCE & PCE C8 C8 C8 measurement OPH OPH OPH • 2 L sample • ambient RH HME HME HME • raw data DPA DPA DPA 0 0 0.5 0.5 1 1 1.5 1.5 2 2 2.5 2.5 3 3 3.5 3.5 0.5 1 1.5 2 3 3.5 2.5 time (min) time (min) Time (min) 13
Sampling 3-m microcolumn 3-m microcolumn Column#1 Column#2 2-ways valve µ PCF CR sensor array OFF Sampler Tee 3-way valve Pre-trap Inlet Carrier Pump Sampling Pump ON OFF 14
Focusing 3-m microcolumn 3-m microcolumn Column#1 Column#2 PCB Carrier Board 2-ways valve µ PCF CR sensor array Sampler Tee Pre-trap 3-way valve Inlet Sampling Pump Carrier Pump 15
Separation & Analyzing 3-m microcolumn 3-m microcolumn Column#1 Column#2 PCB Carrier Board 2-ways valve µ PCF CR sensor array TCE PCE C8 OPH Sampler DPA HME 0 1 2 3 0.5 1.5 2.5 3.5 Time (min) Tee Pre-trap 3-way valve Inlet Sampling Pump Carrier Pump 16
Cooling & Regeneration 3-m microcolumn 3-m microcolumn Column#1 Column#2 PCB Carrier Board 2-ways valve µ PCF CR sensor array Sampler Tee Pre-trap 3-way valve Inlet Sampling Pump Carrier Pump 17
Demonstration Site Description Hill AFB, UT Areas of Shallow Groundwater Contamination General Area of Indoor Air Sampling Locations Residential homes near Hill AFB are impacted by VI of TCE & are part of on-going indoor air sampling program TCE Mitigation Action Level = 2.3 ppb v • Will coordinate with Hill AFB personnel on residential homes used in demo. • Will also use SERDP Hill AFB VI-impacted research house (Dr. Paul Johnson) for portable and fixed µ GC demonstration. 18
Phase II: Develop Field µ GC Prototypes ● Improve TCE LOD (fraction of Hill AFB MAL of 2.3 ppb) - optimize high-flow sampler/ µ PCF system - optimize chemiresistor detector for sensitivity ● Robust-ize µ GC – dependable operation is required - improve µ PCF design for long-term operation - improve long-term stability of chemiresistor detector - dependable long-term retention time stability ● Rugged-ize µ GC – dependable field operation - package µ GC platform for field portability - ease of sampling and standardization - AC operation 19
Phase II: Develop Field µ GC Prototype ● Develop chemometrics for co-elution with TCE - can be used to deconvolute an interfering peak ● Lab test with Hill AFB field samples - actual field interferences - address problematic interferences ● Automate field µ GC operation ● Establish wireless communications with µ GC ● Fabricate four field µ GC prototypes 20
Schedule ● First Field µ GC Prototype – January 2010 ● Testing and Optimization – Spring 2010 ● 4 Field µ GC Prototypes (2 portable, 2 fixed) – Spring 2010 ● Portable and Fixed µ GC Field Demonstrations at Hill AFB – Summer 2010 21
Conclusions ● Adequate field analysis tools for VI do not presently exist (with exception of mobile analytical laboratories) ● µ GC Prototype development has demonstrated compound-specific determination of TCE at low detection limit – Optimization is in-progress ● Will be first field demonstration of µ GC ● µ GC will provide a tool for VI investigations where none currently exists ● µ GC can be adapted to other environmental analysis applications 22
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