A New State of the Art in Thermal Desorption Thermal Desorption - - PowerPoint PPT Presentation

A New State of the Art in Thermal Desorption Thermal Desorption

Presented by: Stephen Wesson P d t & S l M Products & Sales Manager CDS Analytical – Oxford, PA

S i l Th k t D Mi h l S i l Th k t D Mi h l Ell Ell (ECBC) (ECBC)

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Special Thanks to : Dr. Michael Special Thanks to : Dr. Michael Ellzy Ellzy (ECBC), (ECBC), and and Hernan Hernan Diaz (Agilent Technologies) Diaz (Agilent Technologies)

Thermal Desorption Thermal Desorption

• Generally accepted as,“ A technique by which a

known volume of air or gaseous sample is drawn through a tube packed with solid sorbent to collect through a tube packed with solid sorbent to collect volatile organics. The tube is then thermally desorbed, by rapid heating and sweeping of the volatiles with an inert gas into a GC or other volatiles with an inert gas into a GC or other analyzer.”

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Multi-Bed Sorbent tube

Standard TD Techniques Standard TD Techniques

AIR M i i

• AIR Monitoring

–Chemical Agents – Dynatherm’s g y Beginning –TO Methods – EPA Ambient Air TO Methods EPA Ambient Air montioring Industrial Hygiene/Worker Safety –Industrial Hygiene/Worker Safety

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• Product Emissions

Advantages of Thermal Desorption Advantages of Thermal Desorption

I d i i i

• Increased sensitivity
• Very Cost Effective
• Very Cost Effective

– Elimination of solvents – Minimal sample preparation – No Cryogens or extra gases needed (with the y g g ( right system)

• Flexibility!

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• Flexibility!

Problems with Traditional Thermal Desorption Systems Thermal Desorption Systems

• Collection and Analysis

f i i i

• Analysis of Volatile Gases

i i i i

• f High Boiling Analytes

– Classical sampling done at ambient temperatures

require Peltier or Liquid cryogen.

Peltiers are problematic ambient temperatures. – Systems limited to 200º C valves or ovens – Peltiers are problematic – Liquid Cryogens can be expensive & difficult to use. p Goal: Develop a system that can answer Goal: Develop a system that can answer

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Goal: Develop a system that can answer Goal: Develop a system that can answer both problems and then some! both problems and then some!

Problem # 1

• The U.S. Army has been trying to develop air

monitoring methods for VX (Boiling point 298ºC) and higher boiling compounds that will not require sample derivitazation, allowing for continuous monitoring in a near real time scenario Altho gh monitoring in a near-real time scenario. Although, several systems are commercially available to provide a portion of their requirement no system provide a portion of their requirement, no system was capable of meeting all of their needs

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Items of Concern

• Need for elevated collection and system

temperatures (up to 375º C) p ( p )

• Need for Higher sampling flow rates (up to

1 5 L/min) 1.5 L/min)

• Need for quicker cycle times (Heat-up/cool

down) down)

• Flexibility and ease of use are critical

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The Solution

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Agilent 5975T with CDS 9350 Agilent 5975T with CDS 9350

Key elements of the solution Key elements of the solution

New CDS 9350 with New CDS 9350 with S i i S i i Heated Sampling Line Heated Sampling Line

Fast Flow Tubes Fast Flow Tubes

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• Calibration Curve by liquid injection approach

VX Analysis with System VX Analysis with System

Calibration Curve by liquid injection approach. Process performed with injection through Sample line (TL) and CDS injection port.

• Calibration results illustrates instability of analyte

(VX) Th h th TL 25 i th l i t Th h (VX). Through the TL 25ng is the low point. Through injection port 12.5ng is the low point.

• Improvements are underway to improve the analyte
• transmittance. For non-reactive analyte VX di-sulfide

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y 0.1 ng is detected.

VX Analysis with System VX Analysis with System

VX Liquid Calibration Curve

2500000 y = 10572x R2 = 0.9917 1500000 2000000 2500000 detector) 500000 1000000 Area(MS d VX Cal Pt VX cal 50 100 150 200 250 Concentration (ng)

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VX Composition VX Composition

S-2-(diisopropylamino)ethyl O-ethyl methylphosphonothioate Chemical Formula: C11H26NO2PS Exact Mass: 267 14219

P O N

Exact Mass: 267.14219 Molecular Weight: 267.3684 m/z: 267.14 (100.0%), 268.15 (12.3%), 269.14 (4.7%), 268.14 (1.2%), 269.15 (1.1%) Elemental Analysis: C, 49.41; H, 9.80; N, 5.24; O, 11.97; P, 11.58; S, 11.99

VX

S O O O

decompositioon products

Analytes typical Analytes typical

P S O P O SH O P O S O

O-ethyl S-hydrogen methylphosphonothioate VX-Thiol VX-Disulfide

• bserved in synthesized
• bserved in synthesized

VX VX

P O O O

di h l h l h h

P S S O

di h l h l h h di hi

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diethyl methylphosphonate (DEMP) O,S-diethyl methylphosphonodithioate (O,S-DEMPS) Impurities and/or reaaction products

VX Composition with LTM Chromatographic Separation VX Composition with LTM Chromatographic Separation

KEY POINTS: KEY POINTS:

GB at 3.000 min GB at 3.000 min GB GB DEMP DEMP VX VX DEMP at 5.222 min DEMP at 5.222 min HD at 6.25 min HD at 6.25 min VX at 8.82 min VX at 8.82 min All ithi i t i t All ithi i t i t

Scan window Scan window

HD HD All within in ten minutes. All within in ten minutes.

Note some co Note some co elution producing more elution producing more SIM window SIM window Note some co Note some co-elution producing more elution producing more 79 m/z than expected 79 m/z than expected VX Fragmentation VX Fragmentation

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LTM = Low Thermal Mass chromatographic oven LTM = Low Thermal Mass chromatographic oven designed for Fast designed for Fast-

• GC

GC

CASARM =Chemical Agent Standard Analytical Reference Material CASARM =Chemical Agent Standard Analytical Reference Material

1.2e+07 1.25e+07 Abundance TIC: DPMP030.D\data.ms 7.484 8.322

Thermal Desorption of Di Thermal Desorption of Di-

• Pinacolyl

Pinacolyl Methyl Phosphonate and Ton Container VX Methyl Phosphonate and Ton Container VX

DPMP DPMP

Vapor

9000000 9500000 1e+07 1.05e+07 1.1e+07 1.15e+07

DPMP DPMP RSH RSH

Vapor Generator

6000000 6500000 7000000 7500000 8000000 8500000 7.087 7.533 8.102 8.732

RSSR RSSR VX VX VX VX-

• Pyro

Pyro Thiazol Thiazol DEMPO DEMPO

3500000 4000000 4500000 5000000 5500000 6000000 7.276 7.657 7.949 9.644

RSSR RSSR DEMPS DEMPS

500000 1000000 1500000 2000000 2500000 3000000 6.262 7.421 7.657 7.743 7.879 8.028 8.381 8.503 9.004

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6.50 7.00 7.50 8.00 8.50 9.00 9.50 Time-->

Illustrates difference in VX composition coming from Ton Container versus CASARM Preparation Illustrates difference in VX composition coming from Ton Container versus CASARM Preparation

Thermal Desorption of Di Thermal Desorption of Di-

• Pinacolyl

Pinacolyl Methyl Phosphonate and Ton Container VX Methyl Phosphonate and Ton Container VX

RT= 9.644

RSSR RSSR

100 114 S O

RT= 8.732

VX VX

50 30 43 56 72 79 98 107 127 139 167 252 N P O

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(replib) VX 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 260 270 280 290

Illustrates difference in VX composition coming from Ton Container versus CASARM Preparation Illustrates difference in VX composition coming from Ton Container versus CASARM Preparation

• CDS 9350 with Agilent 5975T MSD provides

VX Problem Demonstrated Fixes VX Problem Demonstrated Fixes

• CDS-9350 with Agilent 5975T MSD provides

repeatable transport of VX without carry over between sampling or silver fluoride pad conversion of VX to G l analog.

• Collects and detects 25ng on column VX from vapor

stream passing through 15 foot heated sampling line stream passing through 15 foot heated sampling line (flow rate of sampling 1.5L).

• CDS-9350 Injection port makes liquid calibration

i l d d t i li t b h simple and does not require sampling tube changes,

• Operates with continuous sampling providing

sampling turnover every 20 min for VX at 25ng in 24L

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sampling turnover every 20 min for VX at 25ng in 24L

• f vapor at a 1.5L/min sampling rate.

• System reproducibility illustrated for GB and HD

VX Problem Demonstrated Fixes VX Problem Demonstrated Fixes

• System reproducibility illustrated for GB and HD .

1200000 30min challenger HD Vapor 40000 45000 GB STEL Concentration GB 30 Min Collection Time 600000 800000 1000000 25000 30000 35000 200000 400000 600000 000 10000 15000 20000 1 6 11 16 21 26 31 36 41 46 51 56 61 66 71 76 81 86 91 96 5000 1 4 7 10 13 16 19 22 25 28 31 34 37 40 43 46 49

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• desorber. Data points for alternating properly match tubes.

Problem # 2

• A commercial environmental laboratory

wants to set-up a mobile lab with the p capability of doing volatile organics in air water and soil, and PAHs in soil, but lacks , , the funds to do solvent extraction and purchase both a Thermal Desorption System p p y and a Purge & Trap System.

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Mobile Lab Needs

• Be able to analyze Air Tubes,

Canisters, Water and Soil samples. Canisters, Water and Soil samples.

• Limited space and funds to outfit lab.

C ’ i i i

• Can’t use Peltier or Liquid cryogen
• Flexibility and ease of use are critical

y

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Environmental Analyses Environmental Analyses

• General VOC’s in ambient air or Soil gas

– EPA methods TO-17, TO-14/15, TO-1/2; EPA methods TO 17, TO 14/15, TO 1/2; Trace Volatile Compound Collection Methods in Air.

• Water & Soil Samples for VOC – SW-846

methods or EPA wastewater methods.

• Semivolatile screening for Pesticides/PCBs

and PAHs.

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The Solution

CDS 9350 with Purge & Trap CDS 9350 with Purge & Trap

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CDS 9350 with Purge & Trap CDS 9350 with Purge & Trap accessory on your favorite GC accessory on your favorite GC

Ambient air monitoring (TO Ambient air monitoring (TO-

• 17)

17)

65 component mixture

Sorbent Tubes Sorbent Tubes

65 component mixture

• 1. Propylene
• 2. Dichlorodifluoro

methane

• 2. Chloromethane
• 3. Vinyl chloride

. . . . 64 1 2 4 T i hl

• 64. 1,2,4-Trichloro

Benzene

• 65. Hexachlorobutadiene

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Column: CP Column: CP-

• Select 624

Select 624

T k R l P j T k R l P j Tank Removal Project Tank Removal Project

Canister sampling Canister sampling

Column: RTx Column: RTx-

• 5

5

Gasoline standard Gasoline standard Soil gas sample: Soil gas sample: Gas & Lighter Fluid Gas & Lighter Fluid

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g

But do we have PAHs in the soil as well? But do we have PAHs in the soil as well?

• 0.5 grams of soil thermally

0.5 grams of soil thermally

extracted at 325º C

– Empty TD tube Pre dry sample or Dry Tube

Thermal Extraction Thermal Extraction

– Pre-dry sample or Dry Tube – 1 ppm standard (~ 0.5 ug)

• LOD 1 – 5 ng, but is that

really achievable in the field?

Phenanthene Phenanthene Fluoranthene & Pyrene Fluoranthene & Pyrene Benzanthracene & Chrysene Benzanthracene & Chrysene

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Benzo (a) Pyrene Benzo (a) Pyrene

Client has a water sample they need analyzed!! Client has a water sample they need analyzed!!

Purge & Trap Purge & Trap

Remember this is on Remember this is on a RTx a RTx-

• 5 column!

5 column!

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Pesticides in Soils and waters Pesticides in Soils and waters

• Extract at 325o C
• Glass/Tenax Focus

trap

• Dry focus trap to

remove moisture remove moisture

• Desorb FT at 300o C
• GC/MS
• DB-5 column

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DB 5 column

10 ng standard by Thermal Desorption

PCBs PCBs

• Extract at 325o C
• Glass/Tenax Focus

trap

• Desorb FT at 300o C
• GC/MS

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p

• Dry focus trap
• DB-5 column

Larger Vessel Headspace Larger Vessel Headspace

• Plastics, molded

parts etc. can be too large for Direct large for Direct thermal desorption.

• Large vessel

Dynamic Headspace, f ll d b th l followed by thermal desorption is a good alternative

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alternative

Simplified view of sorbents

Boiling point

• 50

50 100 150 200 250 300 350 400 Boiling point 50 50 100 150 200 250 300 350 400 Molecular Sieve 200 300 400 Carboxen 200 300 400 Carbotrap 100 200 300 Tenax-TA 100 200 300 Glass Beads 100 150 200 Glass Beads 100 150 200 100 300 Temperature required to 200 400 Desorb analytes off sorbent

Many applications require the use of multi-bed tubes

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Direction of Flow

Glass Frit Tenax Carboxen Carbosieve SIII Collect on to tube Tenax/Carboxen/carbosieve Desorb off of tube Carbosieve/Carboxen/Tenax Tubes always go into Autosampler Frit Down, and into 9300 Frit

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towards the valve oven (Back)

Sampling Techniques

• Passive badges (Typically charcoal),

transferred to an empty “sorbent tube” tube”

• Personal Sampling
• Personal Sampling

pump, like this SKC pump, with adjustable

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pump, with adjustable low flow holder.

D l Ch l S l Dual Channel Sampler

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Tedlar Bag Fast Flow Tube Vacuum Time set control

Q i Q i Questions Questions

Purge & Trap Thermal Desorption Dynamic Headspace Thermal Extraction

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Thanks Again to : Dr. Michael Thanks Again to : Dr. Michael Ellzy Ellzy (ECBC), and (ECBC), and Hernan Hernan Diaz (Agilent Technologies) Diaz (Agilent Technologies)