A New State of the Art in Thermal Desorption Thermal Desorption Presented by: Stephen Wesson P Products & Sales Manager d t & S l M CDS Analytical – Oxford, PA S S Special Thanks to : Dr. Michael Ellzy Special Thanks to : Dr. Michael i l Th i l Th k t k t D D Mi h Mi h l l Ell Ell Ellzy (ECBC), (ECBC), (ECBC) (ECBC) and Hernan and Hernan Diaz (Agilent Technologies) Diaz (Agilent Technologies) NEMC: 08/2011 1
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.” Multi-Bed Sorbent tube NEMC: 08/2011 2
Standard TD Techniques Standard TD Techniques • AIR Monitoring AIR M i i – 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 • Product Emissions NEMC: 08/2011 3
Advantages of Thermal Desorption Advantages of Thermal Desorption • Increased sensitivity I d i i i • 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! • Flexibility! NEMC: 08/2011 4
Problems with Traditional Thermal Desorption Systems Thermal Desorption Systems • Collection and Analysis • Analysis of Volatile Gases of High Boiling Analytes f i i i require Peltier or Liquid i i i i cryogen. – Classical sampling done at ambient temperatures ambient temperatures. – Peltiers are problematic Peltiers are problematic – Systems limited to 200 º C – Liquid Cryogens can be valves or ovens expensive & difficult to use. p Goal: Develop a system that can answer Goal: Develop a system that can answer Goal: Develop a system that can answer Goal: Develop a system that can answer both problems and then some! both problems and then some! NEMC: 08/2011 5
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 NEMC: 08/2011 6
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 NEMC: 08/2011 7
The Solution Agilent 5975T with CDS 9350 Agilent 5975T with CDS 9350 NEMC: 08/2011 8
Key elements of the solution Key elements of the solution New CDS 9350 with New CDS 9350 with Heated Sampling Line Heated Sampling Line S S i i i i Fast Flow Tubes Fast Flow Tubes NEMC: 08/2011 9
VX Analysis with System VX Analysis with System • Calibration Curve by liquid injection approach 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). Through the TL 25ng is the low point. Through (VX) Th h th TL 25 i th l i t Th h injection port 12.5ng is the low point. • Improvements are underway to improve the analyte transmittance. For non-reactive analyte VX di-sulfide y 0.1 ng is detected. NEMC: 08/2011 10
VX Analysis with System VX Analysis with System VX Liquid Calibration Curve 2500000 2500000 detector) y = 10572x 2000000 R 2 = 0.9917 1500000 Area(MS d VX Cal Pt 1000000 VX cal 500000 0 0 50 100 150 200 250 Concentration (ng) NEMC: 08/2011 11
VX Composition VX Composition S -2-(diisopropylamino)ethyl O -ethyl methylphosphonothioate Chemical Formula: C 11 H 26 NO 2 PS Exact Mass: 267.14219 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 O P N S O decompositioon products Analytes typical Analytes typical O O O observed in synthesized observed in synthesized O P S P VX VX S P SH O O O O -ethyl S -hydrogen methylphosphonothioate VX-Disulfide VX-Thiol O S P P O S O O diethyl methylphosphonate di h l h l h h O , S -diethyl methylphosphonodithioate di h l h l h h di hi (O,S-DEMPS) (DEMP) Impurities and/or reaaction products NEMC: 08/2011 12
VX Composition with LTM Chromatographic Separation VX Composition with LTM Chromatographic Separation KEY POINTS: KEY POINTS: DEMP DEMP GB at 3.000 min GB at 3.000 min GB GB VX VX DEMP at 5.222 min DEMP at 5.222 min HD HD HD at 6.25 min HD at 6.25 min Scan window Scan window VX at 8.82 min VX at 8.82 min All within in ten minutes. All All within in ten minutes. All ithi ithi i i t t i i t t SIM window SIM window Note some co Note some co elution producing more Note some co Note some co-elution producing more elution producing more elution producing more 79 m/z than expected 79 m/z than expected VX Fragmentation VX Fragmentation LTM = Low Thermal Mass chromatographic oven LTM = Low Thermal Mass chromatographic oven CASARM =Chemical Agent Standard Analytical Reference Material CASARM =Chemical Agent Standard Analytical Reference Material designed for Fast designed for Fast- -GC GC NEMC: 08/2011 13
Thermal Desorption of Di Thermal Desorption of Di- -Pinacolyl Pinacolyl Methyl Phosphonate and Ton Container VX Methyl Phosphonate and Ton Container VX Abundance TIC: DPMP030.D\data.ms 1.25e+07 8.322 7.484 Vapor Vapor 1.2e+07 DPMP DPMP DPMP DPMP RSH RSH 1.15e+07 1.1e+07 Generator 1.05e+07 1e+07 9500000 9000000 8500000 DEMPO DEMPO VX VX- -Pyro Pyro VX VX 7.087 7.533 8.102 8000000 8.732 Thiazol Thiazol 7500000 7000000 6500000 6000000 6000000 RSSR RSSR RSSR RSSR 5500000 9.644 DEMPS DEMPS 5000000 7.276 4500000 4000000 7.949 3500000 7.657 7.657 3000000 2500000 7.421 2000000 8.503 1500000 7.879 8.028 8.381 1000000 7.743 9.004 6.262 500000 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 NEMC: 08/2011 14
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 114 100 RT= 8.732 O S VX VX P N 50 O 72 30 127 79 139 167 43 98 107 56 252 0 0 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 (replib) VX Illustrates difference in VX composition coming from Ton Container versus CASARM Preparation Illustrates difference in VX composition coming from Ton Container versus CASARM Preparation NEMC: 08/2011 15
VX Problem Demonstrated Fixes VX Problem Demonstrated Fixes • CDS 9350 with Agilent 5975T MSD provides • 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 analog. l • 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 simple and does not require sampling tube changes, i l d d t i li t b h • Operates with continuous sampling providing sampling turnover every 20 min for VX at 25ng in 24L sampling turnover every 20 min for VX at 25ng in 24L of vapor at a 1.5L/min sampling rate. NEMC: 08/2011 16
VX Problem Demonstrated Fixes VX Problem Demonstrated Fixes • System reproducibility illustrated for GB and HD • System reproducibility illustrated for GB and HD . 30min challenger HD Vapor 45000 GB STEL Concentration GB 30 Min Collection Time 1200000 40000 1000000 35000 30000 800000 25000 600000 600000 20000 15000 400000 10000 200000 5000 000 0 0 1 6 11 16 21 26 31 36 41 46 51 56 61 66 71 76 81 86 91 96 1 4 7 10 13 16 19 22 25 28 31 34 37 40 43 46 49 GB and HD Vapor collected at same time starting as soon as generator is connected to CDS-9350 thermal desorber. Data points for alternating properly match tubes. NEMC: 08/2011 17
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. NEMC: 08/2011 18
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