Neue Möglichkeiten zur Überwachung der Umgebungsluft mit Thermodesorption und GC/MS

Transcription

1 Neue Möglichkeiten zur Überwachung der Umgebungsluft mit Thermodesorption und GC/MS Moritz Hebestreit, PhD Applications Chemist Agilent Technologies Europe, Middle East, Africa and India

2 Monitoring Ambient Air by TD and GC/MS

3 What is Thermal Desorption? Sorbent Material Sample Matrix e.g. Chamber or micro-chamber air

4 What is Thermal Desorption? Sample passes onto the sorbent Compounds of interest are adsorbed on the sorbent surface

5 What is Thermal Desorption? Lighter gases such as nitrogen pass through the sorbent

6 What is Thermal Desorption? Sorbent is now heated in a reversed flow of clean carrier gas (back flushed)

7 What is Thermal Desorption? Compounds are released from the sorbent into the flow of carrier gas It is a simple extension of the technique of Gas Chromatography and is a sample introduction technology for difficult or real-world samples

8 2 Stage Thermal Desorption PROBLEM: Compounds are released SLOWLY from the sorbent tube Would lead to very wide chromatographic peaks and low sensitivity

9 2 Stage Thermal Desorption SOLUTION: Use a narrow secondary trap STAGE 1 Transfer compounds from tube to secondary trap Electrically cooled narrow bore cold trap

10 2 Stage Thermal Desorption STAGE 2 Rapid transfer of compounds from cold trap to GC Cold trap heated rapidly (100 C/sec) for sharp chromatographic peaks Backflush of cold trap for greater volatility range

11 Cold Trap Flow during trap desorption Flow during focusing / sampling onto trap Restricted narrow bore inlet / outlet end of trap Narrow design allows splitless injection Use sorbent(s) to suit specific application 15 standard traps + custom packed traps available from Markes

12 Key Component - Heated Valve The sample flow path through the valve assembly is uniformlyheated, short (< 10 cm total) and narrow to eliminate condensation Fused silica of column or transfer line inserted here Split filter or SecureTD-Q tube attaches here Sample tube connects here Inlet / outlet end of focusing trap connects here

13 Intensity Patented TD valve: All applications & sample re-collection Stage 1: Primary (tube) desorption with optional (inlet) split Heated valve To GC Time Patented heated valve is inert and low volume: Allows quantitative recovery of high & low volatility and reactive compounds The heated valve isolates the TD system allowing method compliance: leak testing, backflush trap desorption, purge to vent, overlap mode, etc.

14 Intensity Patented TD valve: All applications & sample re-collection Stage 2: Secondary (trap) desorption with optional (outlet) split Heated valve To GC Time Repeat analysis of re-collected samples makes it easy to validate analyte recovery through the TD flow path A change to the overall VOC profile indicates any bias

15 Using Re-collection (SecureTD-Q ) Validation of routine methods Demonstrating quantitative recovery of high boilers Repeat desorption of a mixed phthalate std di-ethyl- to di-n-decylphthalate Repeat analysis shows quantitative recovery without bias, across the analyte range Repeat 2 µl phthalate solution in methanol with 21:1 single split 20 re-collection, repeat analyses Good match between expected decay (lines) and observed decay (points) Demonstrates quantitative recovery Original DEHP DDP NB: ASTM Method D6196 references quantitative re-collection for validation

16 ULTRA 2 DiffLok TM caps Inert or Stainless steel outer body (shown transparent) Sample tube pushes into cap here Coned end for Auto-alignment with tube nozzle on ULTRA (the TD autosampler) O-ring for sealing tube into cap Threaded diffusion-locking insert in plain, cylindrical body. Schematic of DiffLok Cap as used to seal tubes on ULTRA Patented DiffLok caps provide a very effective seal for tubes on ULTRA 2 preventing artifact ingress and loss of analytes DiffLok caps allow gas to flow when pressure is applied & can stay on the tubes throughout TD operation This makes automatic TD simple and mechanically robust

17 Unique SafeLok sorbent tubes SafeLok tubes reduce risk of artefact ingress and loss of sampled analytes Threaded DiffLok inserts protect both ends of the sorbent tube They make it easier to handle tubes in the field (e.g. capping/uncapping) without risk of contamination They also facilitate collection and analysis of air samples from ultra-clean atmospheres. They allow pumped sampling at low flow rates over extended periods (< 1 ml/min) Same mass of sorbent and same external dimensions as standard tubes * Patent Numbers: GB , US 6, B1

18 TubeTAG : Tracking Air monitoring samples in transit A patented unique tool for tracking TD tubes in transit during field monitoring Consists of RFID tag assemblies for attaching onto sorbent tubes (various types and sizes), a read/write device (TAG SCRIBE ) and software Tags are re-usable indefinitely Patent # US 6.446,515 B2. Priority: 2002

19 The TubeTAG advantage for air monitoring Tube Information Sorbent packing # thermal cycles Impedance Leak test info Sample Information TubeTAG is a genuine breakthrough in TD technology. It allows the user to immediately identify the sorbent in each tube, when it needs repacking and whether or not it has a history of leak test failures, back-pressure anomalies, etc.

20 What can TD-GC/MS do? Any volatile or semi-volatile organic compounds which meet the following criteria: < n-c 40, bpt <525 C Can be easily gas chromatographed The sorbent or matrix containing the compounds is compatible with the high temperatures required Unsuitable compounds Inorganic compounds Most permanent gases exceptions include N 2 O, SF 6 & CS 2 Compounds with volatility > n-c 40 Compounds which don t work well with GC (including formaldehyde) Methane

21 Thermal Desorption systems UNITY 2 A universal platform for single tube thermal desorption TD-100 Automated TD system for up to 100 RFID-tagged or untagged tubes

22 Standard methods See TDTS 3: National and International Standard Methods Relating to Speciated Monitoring of Vapour-phase Organic Chemicals in Air

23 Online air monitoring applications CF 4 C 2 F 6 Extracted ion 69 C 2 F 6 SF 6 N 2 O Extracted ion 119 Extracted ion 127 Extracted ion 30 Acetylene up to 2L of sample taken without breakthrough Key: Blue (3 am) Red (12 noon) Green (5.30 pm) Green house gas analysis Diurnal profiling of ozone precursors

24 Canister analysis methods (e.g. US EPA TO-15) Method summary Grab sampling using canisters is easy, TWA monitoring is not Samples may be stored for up to 30 days A small volume of air from the canister (typically ~500 ml) can be introduced straight to the focusing trap of the desorber Trapping conditions are set such that water is selectively eliminated during the trapping process. Analysis by GC/MS CIA 8 UNITY 2 GC/MS Ambient Air

25 Air toxics in canisters: US EPA Method TO-15 1 L of a 1 ppb air toxics mix analysed splitless and cryogen-free using UNITY-CIA 8 Source: TDTS 81

26 Use canisters: Air monitoring: Canisters or tubes? 1. For non-polar compounds 2. Preferably at trace levels for ultravolatiles 3. When you have to Canister limitations 1. Expense ( each) 2. Poor recovery of anything higher boiling than Xylene 3. Cleaning needs expensive vacuum equipment, at least 3 cleaning cycles and verification with GC/MS

27 Canisters or tubes? Tubes Canisters Perception World-wide acceptance Gold standard for US ambient air market Applications Handling Ambient air, indoor air, vapor intrusion, industrial hygiene Material emissions Food & flavor Chemical weapons Light weight for personal monitoring and general ease of use Ambient air, indoor air, vapor intrusion, emergency response Larger and heavier; more costly to ship Sampling C 3 - C 40 Concentration range ppt to % C 2 -C 10 Concentration range ppt to low ppm Cleaning Analytical process automatically cleans tube for re-use Cost $50 $130 each $200 - $700 each Canister cleaning requires separate equipment as additional step prior to background certification and sampling. Profiles of soil gas contaminated with kerosene obtained using: a) canister sampling with TO-15 analysis (blue) b) sorbent tube sampling with TO-17 analysis (red)

28 Active (pumped) sampling TO-17 summary: Pre-screen area using 2 tubes in parallel (50 ml/min, 1 & 4 L) to identify type/level of VOCs. Confirm sorbent selection. Sample air Store capped tubes up to 30 days (below 4⁰C if multi-sorbent) TD-GC/MS analysis steps: Leak test then add gas phase IS and/or dry purge in sampling direction Sampling direction Weak Medium Strong Prepurge then desorb tube with carrier gas flowing in reverse direction Refocus analytes in electrically-cooled trap and desorb rapidly in backflush direction Analyse by GC/MS Pump Sampling Analysis Result

29 Air toxics on sorbent tubes: US EPA Method TO-17 10:1 Split desorption of Air Toxics tube loaded with 1 L of 1 ppb std Source: TDTS 86

30 Easy-VOC Pumped tube sampling made easy Grab sampling for sorbent tubes: Reliable sampling of 50 or 100 ml volumes (or multiples of same) Kit includes: hand pump, Safelok tubes and caps. Main features Ease of use Humidity effects Negligible Breakthrough? Minimised Use of SafeLok tubes and push on caps simplifies operation and prevents over tightening of storage caps no need for calibrated pumps Easy-VOC - For soil gas, workplace air & stack gas.

31 Comparisons of Easy-VOC with standard pumped sampling Comparison with FLEC constant flow pump (Black) and Hand pump (Red & Blue) equal performance

32 Extending the volatility range Smaller volume less chance of breakthrough, so lighter compounds can be retained. Isobutane Propane 2-butene

33 TD isn t just for trace levels: High-concentration industrial emission samples Pumped sampling of 1 L stack gas with TD-GC/MS analysis Sample splitting during both primary (tube) and secondary (trap) desorption. Total split ratio: 3000:1 Quantitative re-collection of both splits allows repeat analysis for confirmation

34 Passive (diffusive) sampling for workplace and environmental air monitoring Vapours migrate across the air gap at a constant uptake rate Diffusive sampling is a slow process, typically sample for complete shift (workplace/personal exposure) or days/weeks (environmental air monitoring) Brass cap Diffusion cap (fitted to sampling end of tube) Ambient conc. of vapours in the environment Zero conc. of vapours at the sorbent surface Note: Diffusive (passive) sampling won t work with glass or SafeLok tubes. Use standard stainless steel or Silcosteel tubes Air gap

35 Typical applications for air monitoring in industry Workplace air monitoring (Occupational hygiene) Industrial perimeter monitoring Stack and fugitive emissions Monitoring guidelines (sorbents, uptake rates, sampling volumes, etc.) available from standard methods (and from Markes)

36 Breath sampling for occupational hygiene (Bio-VOC ) Breath sampling is another application for TD-GC/MS It allows assessment of the total exposure inhalation, skin absorption, ingestion Key applications include: People working with chemicals absorbed by the skin People wearing protective equipment (How effective is it) Chronic exposure causing build up of chemicals in the body Environmental exposure studies Solvents in the breath of shoe workers

37 Specialist applications for air monitoring in industry Soil gas and vapour intrusion assessments Mapping criteria pollutants in ambient air, diurnal changes Atmospheric Research In situ monitoring of underground contamination

38 Specialist applications for air monitoring in industry Landfill gas monitoring Odorous industrial emissions Indoor air quality and tracer gases used for ventilation studies Biogenic emissions

39 Online monitoring of odorous sulphur compounds in ambient & industrial air (UNITY-Air Server ) Target compounds: H 2 S (hydrogen sulphide) CH 3 SH (methanethiol/me.mercaptan) C 2 H 6 S (dimethyl sulphide) C 2 H 6 S 2 (dimethyl disulphide) 3 channels with H 2 S focusing trap at - 15 C to -30ºC and flow path at 80ºC. GC-PFPD Performance in field operation: Detection limits: 0.15 ppb Retention time stability: <0.1% RSD across all compounds Gas standards at 20 ppb and 10 ppb levels Standard reproducibility: 0.5-5% RSD Recovery: >87% for all analytes

40 Input from Agilent? Sampling Thermal desorption GC/MS Data analysis Soil Gas samples MTS-32 no need for calibrated pumps Breath Samples Canisters and Bags Cryogen-free Method compliant 100 tubes Universal: C 2 to C 40 + reactive compounds Repeat analysis CFT (e.g. Backflush, Splitter, 2D-GC) Synchronous SIM/Scan 5 th generation of EPC EM Saver ChemStation, MassHunter RTL + DRS Libraries Sorbent Tubes Water management TubeTAG Normalized gain

41 Different Columns, Same GC Retention times vary from column-tocolumn by as much as 0.5 min... GC Column 1 Column 2 Column 3 Column 4

42 Retention Time Locking Retention times match from column-tocolumn AND instrument-to-instrument to min or better... GC1 Column 1 GC2 Column 2 GC3 Column 3 GC4 Column 4

43 Results for 5 Retention Time Locking Runs on GC/MS RTLOCK1.D -20 % pressure RTLOCK2.D -10 % pressure RTLOCK3.D nominal pressure RTLOCK4.D +10 % pressure RTLOCK5.D +20 % pressure

44 DRS - TICs of surface water extracts How many pesticides are in these samples?

45 Seventeen (17) surface water samples Targets Found (not counting ISTD) False Positives Processing Time CDFA* 37 1 ~8 hrs (ChemStation Only) Agilent DRS with 927 Compound Database Same more 0 34 min *CDFA is the California Department of Food and Agriculture Data files courtesy of Dr. Mark Lee and Steve Siegel

46 DRS = MSD + AMDIS + NIST Search MSD Chemstation RTLock and ID targets based on r.t. and 4 ions and quantitate AMDIS ID targets based on deconvoluted full spectra and qualify targets based on r.t. NIST Search search targets using deconvoluted full spectra from AMDIS against 191,000+ compounds Automate the above and produce an easy to read Report

47 What is AMDIS? Automatic Mass spectral Deconvolution and Identification Software Developed to automatically detect chemicals in violation of Chemical Weapons Convention Identify target compounds at low concentration levels in complex matrices Developed by National Institute of Standards and Technology Retention Time can be used as a qualifier, so RTL is a big advantage

48 A Single Chromatographic Peak May Contain Multiple Components TIC TIC & Spectrum Components and Mixed Spectra TIC Component 1 Component 2 Component 3

49 Components and Mixed Spectra AMDIS Deconvolution Deconvoluted components and spectra TIC matrix Component 1 Component 2 Component 3 interference Deconvolution target

50 DRS User Benefits Ease of use no need to learn deconvolution software Automation part of a method or part of a sequence, analyst can be doing other things Quality program results are not subject to changes in mood/attention of analyst Sensitivity AMDIS will find answers that an analyst might miss Confidence DRS will report the fewest false positive / negatives in the shortest time

51 DRS App Notes Available Comprehensive Pesticide Screening by GC/MSD using Deconvolution Reporting Software pub # New Tools for Rapid Pesticide Analysis in High Matrix Samples pub # A Blind Study of Pesticide Residues in Spiked and Unspiked Fruit Extracts Using Deconvolution Reporting Software pub # Building and Editing RTL Screener/Quant Databases and Libraries pub # Building Agilent GC/MSD Deconvolution Reporting Libraries for Any Application pub # (32 pages, so, use the videos!!!) Replacing Multiple 50-Minute FPD/ELCD/SIM Analyses with One 15-Minute Full-Scan Analysis for 10x Productivity Gain

52 DRS App Notes Available Screening for Hazardous Chemicals in Homeland Security and Environmental Samples Using GC/MS/ECD/FPD with a 731 Compound DRS Database pub # Improved Forensic Toxicology Screening Using A GC/MS/NPD System with a 725-Compound DRS Database pub # Semivolatiles Retention Time Locked (RTL) Deconvolution Databases for Agilent GC/MSD Systems pub # Screening for Pesticides in Food Using the Japanese Positive List Pesticide Method: Benefits of Using GC/MS with Deconvolution Reporting Software and a Retention Time Locked Mass Spectral Database pub # Can "Deconvolution" Improve GC/MS Detectability?

53 Commercial and RTL Databases

54 Free RTL Databases at RTL GC/MS Databases for Organotin Derivatives VOC MS Library and RTL Databases for GC and MS PCB Congener GC/MSD RTL Databases Forensic Toxicology GC/MSD RTL Databases Fatty Acid Methyl Ester GC and GC/MSD RTL Databases Flavors RTL Databases for GC/FID and GC/MS Allergens DRS Database for GC/MS Includes methyl, ethyl, and pentyl derivatives Includes the GC RT-locked database, the MS screener database, and full-spectra library of 65 volatile organic compounds Includes two RT-locked screener databases and MS library for 209 PCB congeners. Includes an RT-locked screener database and MS library for 277 drugs and other substances Includes RT-locked GC retention time databases and GC/MSD spectral libraries and screener databases for 37 common FAMEs Includes RT-locked GC/FID and GC/MS retention time databases and mass spectral library containing 409 compounds. Includes RT-locked GC/MS method, retention time databases and mass spectral library containing 24 regulated allergens and their isomers (total 32 target compounds and 1 internal standard), installation guide and related application note.

55 Who are monitoring Air Toxics? Contract laboratories Research laboratories and universities Government agencies in charge of environmental monitoring regulations Industry/manufacturing monitoring personal exposure Agencies involved in land remediation Health trusts interested in breath analysis for disease marker recognition

56 Summary Whichever vapour-phase organic chemicals are of interest Whatever your air monitoring application Whether it s VOCs in whale breath or the most polluted air on the planet Photograph courtesy of: Dr. Rei Rasmussen, Oregon Graduate Institute, USA

57 Further information Markes website Thermal Desorption Application notes Brochures Environmental applications guide

58 TDTS 16 Analysis of ozone precursors TDTS 80 Evaluation of a Soil Gas sorbent tube for improving the measurement of volatile and semi-volatile fuel vapors in soil contaminated land TDTS 81 EPA TO-15 canister analysis TDTS 86 EPA TO-17 tube analysis Further information TDTS 87 Analysis of Ultra volatile GHGs TDTS 78 Low level odorants in drinking water TDTS 29 VOC air monitoring technology and its application to contaminated land TDTS 47 The analysis of landfill gas compounds using thermal desorption GC/MS and a RTL Database TDTS 49 Fence-line and ambient monitoring of benzene and other hydrocarbons using diffusive sampling and thermal desorption analysis TDTS 37 Industrial air monitoring using pumped sampling onto sorbent tubes and the UNITY thermal desorber TDTS 77 Using thermal desorption for industrial (stack) emission testing

59 Thank you for your attention! Questions???