New Compact and Versatile Sampler for Uninterrupted, Time- resolved - - PowerPoint PPT Presentation

• S. Hering1, G. Lewis1, S. Spielman1, A. Hecobian2, J. Collett2

1Aerosol Dynamics Inc., Berkeley, CA 2Colorado State University, Fort Collins, CO

Acknowledgements:

National Institutes of Health (ES014997 & ES014997) Carl Camp (ARB – Stockton)

New Compact and Versatile Sampler for Uninterrupted, Time- resolved Chemical Speciation of Ambient Particulate Matter

8th Asian Aerosol Conference Sydney, 2-5 December 2013

Arantzazu Eiguren Fernandez

Filter-based methods: SASS, IMPROVE

simple field operations, but time-consuming laboratory steps limited data coverage, delayed results

Real-time instruments: AMS / PILS

no laboratory analysis, but complex and expensive field operation continuous data sets, immediate results

AMS SASS

Aim: To combine the simplicity of filter sampling with the data completeness and automation of real time instruments.

Approach: To provide a collector with directly analyzable samples and an automated interface to lab- based analytical instruments.

Standard Instrumentation

New Challenges for New Applications

WCPC output, like mixing instruments, is warm and humid... Collection / concentrator applications want output at ambient temperature & RH

New approach to laminar flow, water-based condensation

1.6 1.4 1.2 1.0 Saturation Ratio 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.0 x/Q (s/cm2) 30 20 10 T or DP (°C) Saturation Ratio Temperature = 27 Dew Point = 32

• 1. Development, Validation and

Applications

Sequential Spot Sampler (S3)

Conditioner (2-5oC) Initiator (32-35oC) Modulator (8-10oC) Collection chamber

Nearly the same as in Original Configuration

APS GT

Directly coupled Growth Tube to APS

8000 6000 4000 2000

dN/dLogDp

10 8 6 4 2

Droplet Diameter (µm)

Original: 06 / 40 / 40 °C 3-Stage: 06 / 40 / 25 °C

Output Droplet Size

APS GT

With humidified makeup air to Aerodynamic Sizer

3000 2000 1000 dN/dLogDp 10 8 6 4 2 Droplet Diameter (µm)

At Variable Flow 3-stage (5/40/25) 0.4 lpm 0.6 lpm 1.0 lpm 1.5 lpm 1.8 lpm 2.5 lpm

Output Droplet Size with Flow Rate

Collection chamber Dry collection at 26oC

Collection:

• 1. Particles collected as dry deposits
• 2. Spot size: ~400 µm to ~1 mm

PEEK plate Aluminum plate

Arizona Road Dust

Bouncing?

• 1. Performance characterization: laboratory tests

Nebulizer DMA High voltage Upstream Downstream UHASH S3 PM2.5 ambient air

a) Collection efficiency

Collection efficiencies >95% for particles larger than 10nm Collection efficiencies >99% for concentrations up to 106 #/cc

Lab generated aerosols

Ambient PM

Ambient air Upstream CPC

Downstream CPC

10:45 AM 12:00 PM 1:15 PM 2:30 PM

UPSTREAM CPC DOWNSTREAM CPC

#/cc

1x104

Collection efficiencies were >95% by number for ambient PM

1x102

Automated analysis by IC: extraction and injection handled by autosampler

Plate location in the autosampler Autosampler dispenses the extraction solvent (DDW) and injects the sample

b) Reproducibility and Linearity

Lab generated aerosol: Ammonium sulfate and ammonium nitrate

Collection Time (min) 5 (n=6) 30 (n=6) Sulfate (%STDEV) 4.21 3.52 Nitrate (%STDEV) 5.36 4.25 Reproducibility: collection and analysis Linearity

Time (min)

Mass on well (ug)

y = 0.005x - 0.005 R² = 0.99 y = 0.007x - 0.01 R² = 0.99 0.0 0.1 0.2 0.3 5 10 15 20 25 30

sulfate nitrate

c) Volatilization losses

Collected Anion Mass (ng) Nitrate / Sulfate Ratio 2000 1500 1000 500 20 15 10 5

Sample Duration (hrs)

1.0 0.8 0.6 Sulfate: Set 1 Set 2 Nitrate: Set 1 Set 2 Set 1 Set 2

Nitrate losses were not significant for collection periods up to 20 hrs.

0.0 0.5 1.0

sulfate (µg/m3)

08/20/11 08/21/11 08/22/11 08/23/11 08/24/11 08/25/11

0.0 0.5 1.0

nitrate (µg/m3)

Temporal variability of sulfate and nitrate in ambient PM (Berkeley)

• 2. Field Performance

• 1. San Bernardino Mountains

Deployment at San Gorgonio, IMPROVE site (7,000 ft) June 12 – July 5, 2012 Anion measurements: sulfate and nitrate Instruments Spot Samplers: mostly 1-hr resolution PILS: ~17 min resolution URG Denuder-Filter Packs: 12-hr samples Analysis: Dionex IC with modified autosampler

Spot Samplers PILS Denuders URG-filters

10 5 Sulfate (µg/m3) 6/16/2012 6/21/2012 6/26/2012 7/1/2012

a) S3 vs PILS: sulfate

Sulfate Spot Sampler PIILS

PILS

30 20 10 Nitrate (µg/m3) 6/16/2012 6/21/2012 6/26/2012 7/1/2012 Nitrate Spot Sampler PIILS

PILS

b) S3 vs PILS: nitrate

10 5 Sulfate (µg/m3) 6/16/2012 6/21/2012 6/26/2012 7/1/2012

c) S3 vs URG: sulfate

Sulfate Spot Sampler Filter

30 20 10 Nitrate (µg/m3) 6/16/2012 6/21/2012 6/26/2012 7/1/2012 Nitrate Spot Sampler Filter

d) S3 vs URG: nitrate

Deployment at Stockton, CA - ARB monitoring station Nov 2011 – Feb 2012 Instruments Spot samplers in triplicate 12hr samples @ 1.5 lpm for PAHs 6 hr samples @ 1.0 lpm for trace elements Parallel 48-hr filter collection (25mm, 9 lpm) Run unattended for weeks Analysis CTC-PAL autosampler: automated extraction/injection Agilent HPLC-FL: 15 EPA-PAHs 22 min analysis

• 2. Stockton, CA

a) Automated extraction and analysis

CTC- PAL autosampler Sonication bath

b) Optimization of the extraction method

Soaking the sample for 30 min was not enough to extract PAHs at high concentrations

y = 1.76x + 41.76 R² = 0.81 200 400 600 800 1000 1200 200 400 600 800 1000 1200 Sonication (pg/m3) Soaking (pg/m3) 1:1

Sonication for 20 sec was more efficient than mechanical agitation for 1 min

y = 1.36x - 14.9 R² = 0.91 500 1000 1500 2000 2500 500 1000 1500 2000 2500 Sonication (pg/m3) Mechanical agitation (pg/m3)

soaking vs. mechanical agitation vs. sonication

Individual PAH concentrations measured on filters and averaged of 12-hr spot samples

0.0 0.5 1.0 1.5 2.0 0.0 0.5 1.0 1.5 2.0 Plate (ng/m3) Filter (ng/m3) PHE FLT PYR BAA CRY BBF BKF BAP DBA BGP IND

c) Comparison with filter collection

Good correlation between filters and S3

200 400 600 800 1000 1200 1400 1600 400 800 1200 1600

System 2 (pg/m3) System 1 (pg/m3)

PHE ANT FLT PYR BAA CHY BBF BKF BAP DBA BGP IND

d) Spot Sampler intercomparison:

System reproducibility for individual PAHs (n=26)

All correspond to the same sample

Excellent reproducibility between samplers for all PAHs

e) Temporal variability: PM2.5 in Stockton, CA

200 400 600 800 1000 1200 1400 1600 1800 PAH (pg/m3) PHE BAA BBF BKF BAP BGP IND

• ΣPAHs reached concentrations up to 9.53 ng/m3
• BBF (401 pg/m3) and BGP (380 pg/m3) showed the highest concentrations
• PHE highest among the semivolatile

f) Trace Elements by LIBS

Intensity (a.u.) Wavelength (nm)

• Obtain elemental spectra in minutes
• Toxic elements such as iron and copper can be identified

Summary

• Collection efficiency >95% for a broad range of particle

types, sizes and concentrations

• Reproducibility & precision between 3% - 5 %
• Systems can run unattended for several weeks
• Collection plate can be extracted and analyzed directly

(automated extraction and analysis)

• Good correlation with standard anion measurements (PILS

and URG-filters)

• Sequential spot sampler is capable of measuring peak

concentration missed by filter collection systems

• PAH - Filter Comparison: → 15% for individual PAHs
• Spots allow fast trace elements analysis using LIBS

The Sequential Spot Sampler is a simple and reliable collection system that can be streamlined with lab equipment for un- interrupted, time-resolved chemical characterization of ambient PM.

I.S. PAHs I.S. n-alkanes n-alkanes

February 18, 2013

Volatility separation Polarity separation

Theodore Roosevelt National Park (ND)

Organic speciation: TD-GCxGC-HRTOFMS

Chemical Mass Balance (CMB8.2)

Vehicular emission profile from Eiguren-Fernandez and Miguel (2005) Wood burning emission profile from Li and Kamens (1993)

10 20 30 40 50 60 70 80 90 100

Source Contribution wood diesel gasoline