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Analysis of PPB Level Volatile Chemicals using Static Preconcentration

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Analysis of PPB Level Volatile Chemicals using Static Preconcentration Introduction to Sampling and Analysis of Volatile Chemicals Comparison with other VOC Methods Air Analysis - Canister Methods Liquids and Solids - Large Volume Static Headspace (LVSH) Technique Other Applications Summary

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Presentation Transcript
presentation overview
Introduction to Sampling and Analysis of Volatile Chemicals

Comparison with other VOC Methods

Air Analysis - Canister Methods

Liquids and Solids - Large Volume Static Headspace (LVSH) Technique

Other Applications

Summary

Presentation Overview
gc ms detection limits vs headspace sample volume
GC/MS Detection Limits vs Headspace Sample Volume

1000

100

10

1

0.1

0.01

10-3

10-4

10-5

Loop

Preconcentration

PPM

LOD

Vol vs Conc.

0.001 0.01 0.1 1.0 10 100 1000

MINIMUM VOLUME REQUIRED (CC)

slide4
Classical VOC Sampling and Analysis
  • Air
    • Tedlar Bags
    • Adsorbent Tubes
    • Stainless Steel Canisters (EPA TO14, TO15)
  • Liquids & Solids
    • Purge and Trap
    • Static Headspace - Loop Injection
slide5
Classical VOC Sampling and Analysis
  • Air
    • Tedlar Bags
    • Adsorbent Tubes
    • Stainless Steel Canisters (EPA TO14, TO15)
  • Liquids & Solids
    • Purge and Trap
    • Static Headspace - Loop Injection
    • Large Volume Static Headspace
slide7
Volume Determination
  • Loop or Syringe Injection
    • Must equilibrate Sample to Atmospheric
    • Canister must usually be at positive pressures.
    • For Sample Volumes under 5 cc

P

  • Mass Flow Time Integration
    • Canister Can be at Positive or Negative Pressure
    • Must verify leak free conditions before starting
    • MFC Downstream of trap reduces carryover
    • On-line Pressure Sensor monitors trap blockage
    • For Sample Volumes 10cc and larger

MFC

advantages of canisters over tubes
Canisters Tubes

Chance For Volume Measurement Errors No Yes

Traps Checked for Blank and Analyte Recovery Yes No

Allow Repeat Analyses Yes No

Chance for Post Cleaning Contamination Minor Yes

Permits Sample Screening Yes No

Allows Mild Trapping/Desorption Conditions Yes No to Maximize Yields

Requires Power for Sampling No Yes

Requires Conc. To be known Before Sampling No Yes

Advantages Of Canisters Over Tubes
slide15
1320 32-Position Field Sampler and 1L MiniCans

Bridging The Gap Between Tubes and Canisters

slide16
Six Sites Monitored with Just 2 Analyzers

CS6

CS1

Centralized Lab

Analyzers

CS2

CS5

1

2

CS3

CS4

slide18
Are 1 Liter Canisters Large Enough?

Instrument: 7100 Preconcentrator

Application Detector Sample Vol. LOD

PAMS FID 400cc 0.1 PPB(c)

PAMS 5973 MS 400cc 0.05 PPB(v)

Air Toxics 5973 MS 400cc 0.05 PPB(v)

Air Toxics (SIMS) 5973 MS 400cc 0.005 PPB(v)

Limited to Single Analysis - OK for Continuous Monitoring

slide19
Clean 21 (or 42) Canisters Simultaneously
  • 3 Batches a day equals 63 Canisters
  • Supports 7 sites with single 21 position manifold
  • Supports 14 sites with two 21 position manifolds
slide22
7032-LVSH / 7100 /5973

Large Volume Static Headspace Analyzer

M3

SL I/O

SL I/O

M2

6

M1

GC

MS

7100

7032-LVSH

slide23
7100 Heated Flow Path
  • Silonite tubing used throughout.
  • Complete heating of sample flow path. Easily accessed for trap and tubing replacement.
  • External Heaters outside each cryotrap

7100 Preconcentrator

slide25
7100 Water and CO2 Management Techniques

MFC

PUMP

Loading Internal Standard

N2, O2

Helium Carrier

Helium

To

GC

Focuser

Glass Beads

Tenax

Sample

Internal

Standard

Calibration

Standard

Sample

Cryogen in

slide26
7100 Water and CO2 Management Techniques

MFC

PUMP

Loading Calibration Standard

Helium Carrier

N2,O2

Helium

To

GC

Focuser

Glass Beads

Tenax

Sample

Internal

Standard

Calibration

Standard

Cryogen in

slide27
7100 Water and CO2 Management Techniques

MFC

PUMP

Loading Sample

Helium Carrier

N2, O2,

Ar, CH4

Helium

To

GC

CO2

H2O

Focuser

VOCs

Glass Beads

Tenax

Sample

Internal

Standard

Calibration

Standard

Cryogen in

slide28
7100 Water and CO2 Management Techniques

MFC

PUMP

Flushing Traps

Helium Carrier

N2, O2,

Ar, CH4

Helium

To

GC

CO2

H2O

Focuser

VOCs

Glass Beads

Tenax

Sample

Internal

Standard

Calibration

Standard

Cryogen in

slide29
7100 Water and CO2 Management Techniques

MFC

PUMP

Removing Water and CO2

CO2

Helium Carrier

Helium

To

GC

H2O

VOCs

Focuser

Glass Beads

Tenax

Sample

Internal

Standard

Calibration

Standard

Cryogen in

slide30
7100 Water and CO2 Management Techniques

MFC

PUMP

Focusing Sample before Injection

Helium Carrier

Helium

VOCs

To GC

VOCs

Focuser

Glass Beads

Tenax

Sample

Internal

Standard

Calibration

Standard

Cryogen in

slide31
7100 Water and CO2 Management Techniques

MFC

PUMP

H2O

Post-Injection Bakeout

Helium Carrier

Helium

To

GC

Focuser

Glass Beads

Tenax

Sample

Internal

Standard

Calibration

Standard

Cryogen in

slide32
Fast Injection and Proper Water Management Minimizes Tailing of Polar VOCs

Column: HP1, 60m, 0.32mm ID, 1um film.

Flow rate: 1.5 ccm

Carrier: He

slide33
1 Week TO14 Stability Test

1 Liter MiniCan

Concentration: 10 PPB

Volume: 400cc

Instrument: 7100/5973 GCMS

Column: HP1, 60m, 0.32ID, 1um

Column Start Temp: 35 deg. C

slide34
TO15 Precision Study using

7100 Preconcentrator and 5973 GCMS

Data Compliments of:

Columbia Analytical

Jacksonville, Florida

slide35
TO15 Precision Study using

7100 Preconcentrator and 5973 GCMS

Data Compliments of:

Columbia Analytical

Jacksonville, Florida

slide36
TO15 Precision Study using

7100 Preconcentrator and 5973 GCMS

Data Compliments of:

Columbia Analytical

Jacksonville, Florida

slide37
C2-C10 GC/FID Analysis - Light Ends

GC: 5890

Column: 60m, 0.32mmID, 1um, DB1

Preconc: MP&T, 400cc, 30ppbc Std

GC Start Temp: -50 for 4 minutes

advantages of 7100 multi stage preconcentration
Multiple Preconcentration Options Depending on Target Compounds and Matrix (CO2, ETOH)

Better Recovery of Thermally Labile Flavor and Odor Compounds:

Strong Carbon Based Adsorbents are Avoided

Inert, Silonite Tubing used Throughout

Reduced Temperature Trapping Minimizes Sample Stress

Advantages of 7100 Multi-Stage Preconcentration
large volume static headspace autosampler
Introduces 10-200cc of headspace to the 7100 Preconcentrator

Accommodates solids and liquids

Detection limits 100x lower than conventional loop injection headspace

“See what you can smell”

Large Volume Static Headspace Autosampler
slide41
LVSH Sample Platforms and Enclosures
  • Samples are placed in disposable vials, reducing potential for contamination of sample platforms.
  • Sample Platforms use quick connects, simplifying removal for oven bakeout.
slide42
Cheddar Cheese by LVSH/GCMS

Cheddar Cheese, Brand A

100cc, LVSH

60m, HP1, 0.32mm ID, 1um

7032LVSH/7100/5973

Cheddar Cheese, Brand B

100cc, LVSH

60m, HP1, 0.32mm ID, 1um

7032LVSH/7100/5973

Toluene

slide43
Beer by LVSH/GCMS

Beer, EtOH Removed

200cc, LVSH

60m, HP1, 0.32mm ID, 1um

7032LVSH/7100/5973

EtOH

slide44
Advantages of Large Volume Static Headspace (LVSH) over Purge and Trap
  • Cleaner. No aerosols or foaming to contaminate sample transfer lines
  • Better Recovery of Thermally Labile Flavor and Odor Compounds:
    • Strong carbon based adsorbents are avoided
    • Inert, Silonite tubing used throughout
    • Reduced temperature trapping minimizes sample stress, improving recovery and reducing artifact formation
  • Better matrix elimination using 3-stage trapping
  • More accurate determination of steady state distribution of chemicals in the sample headspace
  • Allows direct comparison of liquid, solid, and gas phase collected samples
slide45
Advantages of Large Volume Static Headspace (LVSH) over SPME
  • Less discrimination against light end compounds
  • LVSH is a closed system. Little chance of contamination with room air
  • Lower detection limits, especially for more volatile compounds
  • SPME cannot compare liquid, solid, and gas phase collected samples
slide50
Using LVSH to Determine Product Quality Markers in Fruits and Vegetables
  • Analysis of 100cc of Headspace allows detection of VOCs indicating condition of food products.
  • Monitoring changes in VOC ratios as food spoils allows quantitative evaluation of extent of spoilage.
  • Once specific “Markers” are determined, remote headspace techniques can be used to predict food condition and time until spoilage in storage containers and warehouses.
slide51
100cc LVSH Analysis of Tomato

2

1. CO2

2. Methanol

3. Ethanol

4. Acetone

5. 2-Methyl Furan

6. DHHN

1

6

5

1

4

Loop Injection

Detection Limit

3

IS

3

IS

4

5

2

6

slide53
Tomato Chemical Markers Indicating Quality
  • Heavy aldehydes increased as food spoils
  • The largest increase was from a semi-volatile tentatively identified as DHHN
  • In this study, the ratio of DHHN to 2-Methyl Furan was determined to be an excellent indicator of product quality
slide54
Multiple Applications for Static VOC Analysis

- Personal Exposure Monitoring/Industrial Hygiene

- Breath Analysis

- Sulfur Gas Analysis

- Product Outgassing

- Product Quality Testing

- Arson Investigation

- Emergency Response

personal sampling with the minican
Personal Sampling with the MiniCan
  • Whole Air Sample Collection Provides a More Universal Approach
  • Sampling Times from 1 Minute to 8 Hours
  • Does not Require Volume Determination in the Field
comparing monitoring techniques
Comparing Monitoring Techniques

Vol Measured During Samp

Yes Yes No NN

NN - Not Necessary

slide57
1. When target compound list is not well known (initial investigations)

2. When specified target compound list requires 2 or more different tubes

3. When no OSHA/NIOSH method exists for the target compounds (Literally thousands of compounds fall into this category)

4. When GCMS is desired to provide better identification certainty and to resolve co-eluting compounds.

When to use MiniCans for Personal Sampling

slide58
Soil Gas Sampling
  • Collects soil gas at 1m depths
  • Ideal for screening applications
slide60
Solvent Enhancement Enclosure

for Surface Contaminants

slide61
VOCs in Soil by LVSH
  • Easier sample prep and clean-up than Purge and Trap
  • Large Sample Loading (25 grams)
  • Samples can be heated to 150 deg. C
silonite tm coating improves recovery of reactive compounds
Fused Silica coating prevents chemical interaction with underlying stainless steel surface

Improves VOC Stability

Ideal for sulfur and nitrogen containing compounds

SiloniteTM Coating Improves Recovery of Reactive Compounds
slide63
Chemicals in Human Breath
  • Chemicals equilibrate with alveolar air proportional to their concentration in the blood
  • Monitoring VOCs in breath provides information on:
    • Exposure to Chemicals
    • Disease Conditions
slide65
Surrogate Spiking and Automated Analysis

7032 Autosampler

Surrogate Spiking

slide66
5973/7100/7032 200cc Injection10 PPB Sulfur Std., ECTD

5

1. CO2

2. H2S

3. COS

4. MeSH

5. DMS

6. CS2

6

4

3

1

2

slide67
2-Day Stability Study of Sulfur Compounds in

Fused Silica Lined vs Electropolished Canisters

7000 / HP5973 Data

slide71
40 Day Formaldehyde Stability in Silonite Coated MiniCan

Analysis of Cylinder - 9 December 1999

2.52 ppm

2.65 ppm

2.54 ppm

Analysis of Mini Canister #1086 - 10 December 1999

2.56 ppm

2.44 ppm

Analysis of Mini Canister #1087 - 10 December 1999

2.57 ppm

2.56 ppm

Let time pass....

Analysis of Mini Canister #1086 - 20 January 2000

2.46 ppm

2.53 ppm

Analysis of Mini Canister #1087 - 20 January 2000

2.37 ppm

2.47 ppm

Data Courtesy of

Dr. Daniel Riemer,

NCAR

additional applications benefiting from trace level analysis of airborne chemicals
Forensics

Identification of Illegal Drug Laboratories

Breath Analysis: The “Reverse Fingerprint”

Arson Investigation

Rapid Sampling and Analysis On-Site

Emergency Response

Fast yet Complete Compound Identification and Quantitation

Fire Inspection / Chemical Inventory Determination

Developing fire fighting strategies based on chemicals present

Detection and remediation of potentially hazardous conditions

Additional Applications Benefiting from Trace Level Analysis of Airborne Chemicals
slide73
Accelerant Sampling with MiniCans

Quickly sample vapor phase chemicals by sweeping inlet nozzle over locations most likely to revel accelerants.

Use the Solvent Enhancement Enclosure (SEE) to concentrate vapors where concentrations are expected to be low due to intense heat or gusty winds.

slide74
Emergency Response

Monitoring of Chemical Releases

RGS

RGS

Chemical Release

RGS

RGS

Facility

4 Hr PS

4 Hr PS

4 Hr PS

Community

RGS - Restricted Grab Sample (5-15 minutes)

conclusion
Analysis of Trace VOCs can be performed in a variety of matrices using a static sample introduction technique.

For natural products, maintaining the sample in an unaltered state allows the analysis of “normally occurring” volatile compounds.

Inert flow paths and reduced temperature trapping increases the range of analytes that can be recovered, including oxygen, nitrogen, and sulfur containing compounds.

Sampling devices are available for collecting and storing gas-phase volatile chemicals opening up a host of new applications and possibilities.

Conclusion
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