IMPROVE Carbon Analysis

Transcription

1 IMPROVE Carbon Analysis Judith C. Chow John G. Watson Jerome A. Robles Xiaoliang Wang Dana L. Trimble Desert Research Institute, Reno, NV Presented at the IMPROVE Steering Committee Meeting Frostburg, MD October 26, 2011

2 Objectives Report status and improvements of IMPROVE carbon analyses Show results from recent carbon analysis research

3 Summary of Carbon Lab Operations Maintained 24 hours per day/6-7 days per week operation with five staff Average 17 days from sample receipt to carbon analysis (Jul 2010 to Jun 2011) Averaged ~800 samples per month in the queue (fluctuated between 0 and 1800); work schedule is adjusted accordingly Analyzed ~22,000 IMPROVE samples (Jul 2010 to Jun 2011) Started new contract April 2011

4 IMPROVE Carbon Analysis following the IMPROVE_A a Protocol (7/10 6/11) Sampling Period Samples Received Analysis Completion Date b 7/1/10-12/31/10 11,013 2/3/11 1/1/11-6/30/11 11,046 8/29/11 a Chow et al. (2007) b Currently analyzing July 2011 samples (latest batch received)

5 Absolute laser reflectance highly correlates with EC R measurements -ln(r absolute ) n=522 IMPROVE samples EC R (µg C/cm 2 )

6 Recursive testing allows the optimization of OC1 and OC2 Temperatures

7 SOP revisions to be completed by December 2011 Verify carbon standards (sucrose and KHP) with the TOC analyzer (within ±5% of 1800 ppm C). Shorten carbon standard usage from 40 days to 30 days (documented in the electronic maintenance logbook). Purchase sieved MnO 2 for packing (size range to mm) Use Brillo Pad to smooth push rod to prevent sticking Enhance documentation of laboratory blank analysis

8 Additional QA/QC activities are added to SOP Requirement Calibration Standard Calibration Range Calibration Frequency System Blank Check N/A N/A Beginning of analysis day. Leak Check N/A N/A Beginning of analysis day. Performed By Carbon Analyst Carbon Analyst Acceptance Criteria Corrective Action 0.2 µg C/cm 2. Check instrument and filter lots. Oven pressure drops less than 0.52 mmhg/s. Locate leaks and fix. Laser Performance Check N/A N/A Beginning of analysis day. Carbon Analyst Transmittance >700 mv; Reflectance >1500 mv Check laser and filter holder position. Calibration Peak Area Check NIST 5% CH 4 /He gas standard. 20 µg C (Carle valve injection loop, 1000 µl). Every analysis. Carbon Analyst Counts >20,000 and % of average calibration peak area of the day. Void analysis result and repeat analysis with second filter punch. Auto-Calibration Check NIST 5% CH 4 /He gas standard. 20 µg C (Carle valve injection loop, 1000 µl). Beginning of analysis day. Carbon Analyst % recovery and calibration peak area % of weekly average. Troubleshoot and correct system before analyzing samples. Manual Injection Calibration NIST 5% CH 4 /He or NIST 5% CO 2 /He gas standards. 20 µg C (Certified gas-tight syringe, 1000 µl). End of analysis day. Carbon Analyst % recovery and calibration peak area % of weekly average. Troubleshoot and correct system before analyzing samples Sucrose Calibration Check 10μL of 1800 ppm C sucrose standard. 18 µg C. Thrice per week (began March, 2009). Carbon Analyst % recovery and calibration peak area % of weekly average. Troubleshoot and correct system before analyzing samples Multiple Point Calibrations 1800 ppm C Potassium hydrogen phthalate (KHP) and sucrose; NIST 5% CH 4 /He, and NIST 5% CO 2 /He gas standards µg C for KHP and sucrose; 2-30 µg C for CH 4 and CO 2. Every 6-months or after major instrument repair. Carbon Analyst All slopes ±5% of average. Troubleshoot instrument and repeat calibration until results within stated tolerances. Sample Replicates N/A N/A Every 10 analyses. Carbon Analyst on same or different analyzer ±10% when OC, EC, TC 10 µg C/cm 2 or <±1 µg/cm 2 when OC, EC, TC <10 µg C/cm 2 Investigate instrument and sample anomalies and rerun replicate when difference > ±10%. Temperature Calibrations Tempilaq (Tempil, Inc., South Plainfield, NJ, USA). Three replicates each of 121, 184, 253, 510, 704, and 816 C. Every 6- months, or whenever the thermocouple is replaced. Carbon Analyst Linear relationship between thermocouple and Tempilaq values with R 2 >0.99. Troubleshoot instrument and repeat calibration until results are within stated tolerances. Oxygen Level in Helium Atmosphere Certified gas-tight syringe ppmv. Every 6- months, or whenever leak is detected. Carbon Analyst using a GC/MS system. Less than the certified amount of He cylinder. Replace the He cylinder and/or O 2 scrubber. Chow et al., ABC, 2011

9 Daily instrument auto-calibration is within ±5%

10 Quarterly calibration is within ±5% (Sucrose; thrice per week)

11 Oxygen content in OC analyses is well below 100 ppb (Tested every six months, April-June 2011)

12 Low OC and EC levels found on pre-fired quartz-fiber filters (Acceptance testing, April-June 2011)

13 Model 2001 DRI carbon analyzer integrated with photoionization-time-of-flight mass spectrometer (PI-TOFMS; U. of Rostock, Germany) Grabowski, ABC, submitted

14 Resonance Enhanced Multi-Photon Ionization-Time-of-flight-Mass Spectrometry (REMPI-TOFMS) allows identification of compounds in each thermal fraction Grabowski et al., 2011, ABC, accepted

15 y-scale x 1 Mass spectra for thermal fractions from Model 2001 with REMPI-TOFMS detector OC I y-scale x 0.25! OC II y-scale x 0.25! OC III IP S n S 0 REMPI Zimmermann, 2011

16 Potential configuration for next generation of thermal/optical analysis for elemental and optical properties Flow Control Network He, CH4 UV-VIS-NIR Light Source (λ= nm) Filter Thermocouple Oven Filter Loading Push Rod He, O2, NO, SO2 He Optical Fibers 98% He,2% O2 Optical Spectrometer (Reflectance) Flow Splitter Filter Holder Optical Spectrometer (Transmittance) O Reactor (C/Ni) O CO Unoxidized species H 2 O/Gas Trap Soda Lime Mg(ClO 4) 2 CHNS Reactor (MnO 2 ) C CO 2, H H 2 O, N NO x /N 2, S SO 2 Oxidation Oven (CuO) CO CO2 Oxidation Oven (CuO) CO CO2 Heated Fused Silica Capillary NDIR CO 2 Detector Mass Spectrometer Vent Four-Way Solenoid Valve Outputs: Reflectance/ Transmittance Spectra O Mass Spectra C, H, N, S Calibration Gases Carrier/Reaction Gases

17 C,H,N,S, and O can be determined using current processes Carbon Mass by Elemental Analyzer (µg) Ion Signal (a.u.) NDIR Signal (mv) 1.2e+6 1.0e+6 8.0e+5 1.2e+5 1.0e+5 8.0e+4 6.0e+4 4.0e+4 2.0e (b) (a) 140 C 100% He 98% He / 2% O C m/z=44 (CO + 2 ) 740 C 280 C Temperature 480 C 580 C Calibration CH 4 Injection m/z=28 (CO +, N 2 + ) m/z=18 (H 2 O + ) m/z=30 (NO + ) m/z=64 (SO 2 + ) Time (min) time vs Temp Time vs m/z18 NDIR Time vs m/z28 Time vs m/z30 Time vs m/z C 280 C 140 C Temperature 100% He 580 C Calibration O 2 Injection Time (min) Oven Temperature ( C) Oven Temperature ( C) Thermogram of Fresno ambient aerosol sample for (a) CHNS, and (b) O following the IMPROVE_A protocol. Comparison of carbon fractions measured by elemental analyzer and DRI thermal/optical carbon analyzer EC3 y = 0.926x R² = OC1 EC2 OC4 OC2 OC3 1:1 Line Carbon Mass by Carbon Analyzer (µg) EC1

18 Expected N (µg) Expected S (µg) Expected C (µg) Expected H (µg) C,H,N,S Calibration of MS-TOA instead of FID using Sulfanilamide (C 6 H 8 N 2 O 2 S) C: y = 22.81x R² = Normalized m/z=44 (CO 2+ ) Signal H: y = 99.94x R² = Normalized m/z=18 (H 2 O + ) Signal N: y = 98.84x R² = S: y = 59.07x R² = Normalized m/z=30 (NO + ) Signal Normalized m/z=64 (SO 2+ ) Signal

19 NDIR Signal (AU) O Calibration of MS-TOA y = 1.105x R² = Sucrose KHP Levoglucosan Expected O (µg)

20 H/C vs. O/C molar ratios varied by source HOA 5 Lipid 3 Cooking 6,c Protein 3 Oak Smoke Burn Fresno Cellulose 3 OOA 5 Molar Ratio of H/C Lake Tahoe Biomass burn Vehicle Exhaust 7,c Mexico City 5,b Diesel Ambient HULIS 4 Wood burning 8,c 0.8 Lignin Condensed PAH 3 Fulvic Acids Diesel Soot 2,a Diesel Soot 0.2 Carbon Black 1,a Molar Ratio of O/C

21 Extending from single to multiple wavelengths can obtain more information on IMPROVE samples EC Absorption Efficiency (Mm -1 /mg/m 3 ) (EC absorption efficiency varies by source and wavelength) 70 EC Absorption Efficiency Based on Attenuation 60 Smoldering Biomass Diesel Flaming Biomass 50 Smoldering Diesel DRI Model 2001 Thermal/Optical Carbon Analyzer with an Oceans Optic Spectrometer Flaming Wavelength (nm)

22 Experimental Configuration Using Laser Diodes with Different Wavelengths

23 Proof of concept: Multi-wavelength transmittance and reflectance during charring of sucrose

24 Publications using IMPROVE data and carbon analysis methods since last meeting

25 Future Activities Test specific source samples for C, H, N, S, and O Improve understanding of compounds evolving in each temperature fraction Examine EC absorption efficiencies as a function of wavelength on laboratorysimulated vegetative burning samples Determine practicality of enhancing information from IMPROVE sample analyses while maintaining consistency with the long-term database