gas chromatography -ion mobility spectrometry (gc-ims ... · gas chromatography -ion mobility...
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Gas Chromatography - Ion Mobility Spectrometry (GC-IMS)
-
Trace Gas Analysis of Volatiles in various Applications
by
G.A.S. Gesellschaft für analytische Sensorsysteme mbH
Dortmund - Webinar2.4.2019
Company:
▪ Founded in 1997 as spin-off of the ISAS –Leibniz-Institute for Analytical Sciences e.V.
▪ R&D and manufacturing facilities atTechnologyCentre Dortmund
▪ Interdisciplinary team (17 employees)consisting of chemists, physicists, machin-ery/electrical and computer engineers
▪ Development, production and distribution ofanalytical instruments based on GasChromatography coupled to Ion MobilitySpectrometry customized to application and customer requirements
▪ More than 200 installed instrumentsat global market leaders in food &flavours, process industry, researchinstitutes
▪ since 09/2018 VAR of Agilent Technologies
G.A.S. – Gesellschaft für analytische Sensorsysteme mbH
G.A.S. – What we do…?
GC-IMS BreathSpec® FlavourSpec®
Detection of VOCs in gases
Detection of traces of VOCs
in exhaled human breath
Detection of traces of VOCs in the
headspace of solid, liquid samples in food
Applications
Siloxanes in biogasFilter breakthrough
Odorants in Natural GasesBad smell from Industry
Applications
Marker compounds in human breath
MAC-Monitoring
Applications
QC of raw material, semi-finished and end-products
(Off-) Flavour analysisShelf life…
Trace gas Analysis in dedicated civilian Application
Driftgas inlet
Ionisation region
Drift region
Faraday plate
Outlet
Sample Inlet
Electrical field
Shutter
+
++
++
++
+
+
IMS Drift Tube
Working Principle of IMS – Formation of Charged Analytes
Tritium Source
- Ionization of water molecules from operation gas by ß-radiation - Analytes are ionised due to collisions with positively charged proton clusters, which form a positively charged analyte-water-cluster-complex
Driftgas inlet
Ionisation region
Drift region
Faraday plate
Outlet
Sample Inlet
Electrical field
Shutter
+
++
++
++
+
+
IMS Drift Tube
Working Principle of IMS – Formation of Charged Analytes
Tritium Source
Sample neutral Reactant ion Cluster ionProduct ionProtonated monomer Water
Driftgas inlet
Ionisation region
Drift region
Faraday plate
Outlet
Sample Inlet
Electrical field
Shutter
IMS Drift Tube
Working Principle of IMS – Separation of Analytes
Tritium Source +
+++
+
+
+
+
+
+
+
+
- Analytes are kept (ion-trap) in ion chamber and pushed into the drift tube - driftgas molecules enter the drift tube from opposite site- Collisions between analyte and drift gas molecules
Driftgas inlet
Ionisation region
Drift region
Faraday plate
Outlet
Sample Inlet
Electrical field
Shutter
IMS Drift Tube
Tritium Source +
++
+
++
+
+
+
Sig
nal
Drift time / ms
+
+
+
+
Working Principle of IMS – Separation of Analytes
- Analytes are separated in a lowelectrical field based on theirphysical parameters (µ, CCS)
- Determined value: Drift time, tD
Driftgas inlet
Ionisation region
Drift region
Faraday plate
Outlet
Sample Inlet
Electrical field
Shutter
IMS Drift Tube
Tritium Source
+
+
+
Sig
nal
Drift time / ms
+ + +
- Analytes are separated in a lowelectrical field based on theirphysical parameters (µ, CCS)
- Determined value: Drift time, tD
Working Principle of IMS – Separation of Analytes
Driftgas inlet
Ionisation region
Drift region
Faraday plate
Outlet
Sample Inlet
Electrical field
Shutter
IMS Drift Tube
Tritium Source
+
+
+
Theoretical Principle of the IMS – Ion Mobility K
µ = reduced mass of ion / drift gas molecule
k = Boltzmann constantT = Temperature of drift gasQ = Ion chargen = drift gas number densityσ = Collision cross section of the ion
RIP(H2O)nH+
HexanoneMonomer
MH+
HexanoneDimerM2H+
5 ppb
16 ppb
49 ppb
Quantitative information
frompeak intensity
Qualitative information
frompeak position
IMS Resolution: ~ 100
Calibration for 2-Hexanone
Peak Analysis (Height, Volume) for Quantification
+ Water (NH3, NO) +H2O
Ionisation driftgas
Creation of reaction ions
(H2O)xH+, (H2O)yNO+, (H2O)zNH4+ + e-
− − + −+ → + +N N e2 2
'
(Nitrogen)
positve negative
Positive analyt ions
• Proton transfer(H2O)xH++ A → AH+ + xH2O
• Charge transfer(H2O)yNO+ + A → A+ + NO + yH2O
• Nucleophilic attachment(H2O)yNO+ + A → ANO+ + yH2O
Negative analyt ions
• Associative electron captureAB + e- → AB-
• Dissociative electron captureAB + e- → A + B-
• Proton abstractionABH + (H2O)nO2
- → AB- + nH2O + HO2
Ionisation Mechanism
Soft-Ionization and Ambient pressure – reasons for outstanding Sensitivity!
Aromatic Amines 930.0 KJ/mol Pyridine
Amines 899.0 KJ/mol Methyl Amine
Phosphorous Compounds 890.6 KJ/mol Trimethylphosphate
Sulfoxides 884.4 KJ/mol Dimethyl Sulfoxide
853.6 KJ/mol Ammonia
Ketones 832.7 KJ/mol 2-Pentanone
Esters 821.6 KJ/mol Methyl Acetate
Alkenes 805.2 KJ/mol 1-Hexene
Alcohols 789.2 KJ/mol Butanol
Aromatics 750.4 KJ/mol Benzene
691.0 KJ/mol WaterAlkanes 543.5 KJ/mol Methane
Source: Gary Eiceman & Zeev Karpas, Ion Mobility Spectrometry, CRC Press, 2005, ISBN 0-8493-2247-2
Protone affinities of various VOCs can be found at the NIST chemistry webbookhttp://webbook.nist.gov/chemistry/
Pro
ton
e A
ffin
itie
s
Proton Affinities of VOCs
fast GCpre-separation
(typically 1 to 15 min)
IMS separation (30 ms)
IMS separation
Synergy of Selectivity through GC separation matched with Sensitivity of IMS!
Application in complex Matrices require a GC-separation
pseudo-colour representationIMS chromatogram
3DIMS chromatogram
SingleIMS spectraIM
S s
igna
l
IMS drift time
2-Dimensional separation by GC and IMS
Full GC-IMS headspace analysis
Analytical evaluation
VOCal - GC-IMS Data Analysis -
• Visualisation
• Organisation of measurement data
• List of experimental conditions
• Data analysis:
• compound calibration → quantification
• compound identification → comp. Libary
• Data export (csv, excel, rapid miner, etc….)
• Reporting
Customized Software
e.g. BeerAnalyzer
• reduced/application
based functionalities
• easy and reliable
operation at-line:
• data acquisition
• calibration
• reporting
Inhouse Software secures maximum Output and Flexibility
PlugIn Modules
Conditions: Room temperature, no-salt-added, 10min sampling
Geosmin: Total-Ion-Current Chromatograms 0-50ppt
5 ppt
50 ppt
Geosmin was pre-concentrated using a thermodesorber unit
Specific Compounds can be extracted for Data Analysis
→ Mark compounds/signals of interest
→ Signals are “extracted” and plotted
Single Compounds in Measurements are tracked/followed
▪ Gallery Plot enables easy and fast comparison of different
samples▪ Differences in concentrations
or presence/absence of marker signals can be easily
seen
NIST-based GC-RI indices plus IMS drift times allow high Certainty!
‚GCxIMS Library Search‘ for Compound Identification
Gas Chromatograhy-Ion Mobility Spectrometer (GC-IMS)
Trace analysis of volatiles in Food and Flavourby
G.A.S. Gesellschaft für analytische Sensorsysteme mbH
Product Quality Control in Food & Flavour Industry
Specific compounds Authentication
Quality Control Differentiation
Classification
- static headspace analysis
- automated sample handling- solid / liquid / gaseous samples (HS)- no sample pretreatment necessary
FEATURES
R&D / Product Quality Control: FlavourSpec®
2005: UCO – G.A.S. start Cooperation in Food/Agro Field
Improvements on G.A.S.’ systems lead to success of GC-IMS in new Applications
Niche for GC-IMS in different Applications of QC
Hedonistic EvaluationHigh-end Mass Spec GC-IMS
- ‘golden standard‘
- approved technology
- R&D
- available data base
- well known
- most decissive Criteria
- availability critical
- subjectivity problematic
- easy-to-use
- reliabe (phys. principle)
- QC related
- fingerprint and data base
- attractive value for money
- flexible/portable use
Workflow of the FlavourSpec® headspace Analysis
Fill vialGenerate headspace
Sampling
FlavourSpec®
Injection Data Analyis
Headspace sampling
Long runtimes for complex mixtures
Well developed technology
Limited sensitivity
Detectortime
Gas Chromatography – Conventional Detector
Second physical separation
Outstanding sensitivity
High GC mapping by fast spectrometry
time
IMS
Gas Chromatography – Ion Mobility Spectrometry
Process Control in Brewing: Analysis of vicinal Diketones
Quantification of Diacetyl/Pentanedione in the headspace determines end of Brewing
Diacetyle
Pentanedione
Ethanol
IMS signal
IMS drift time / ms
Diacetyl/Pentandione are known markers related to brewing (butterscotch flavour).
Their measurement lies in the range of 0 and 250 µg/L.
Determination is a worldwide standard in larger breweries.
Conventional GC systems use ECD as detector (radioactive source).
Process Control in Brewing: Analysis of vicinal Diketones
FlavourSpec plus customized BeerAnalyzer software is a very attractive Alternative
Gallery plot of selected evaluation areas
Significant rise of peak intensities of e.g. various Aldehydes with exposure times!
0days
7days
14days
21days
Increasin
g A
ge
UHT Milk: Storage Time effects on VOC Composition
Substance Identification
Ageing of Wine: Monitored by effects on VOC Composition
2018 (6 months old)
2017(18 months old)
2016(30 months old)
2014(54 months old)
Compounds in NZ Sauvignon Blanc
increasing with age (34)
Compounds in NZ Sauvignon Blanc
decreasing with age (31)
FlavourSpec - Monitoring Increase and Decrease of flavor inducing Volatiles !
Outgasing from Packaging Material
Packaging Type is differentiated by outgasing Marker Compounds/Volatiles !
37
Criteria GC-MS FlavourSpec1.
An
alyt
ical
asp
ects
Selectivity Excellent selectivity for broad range of analytical tasks
High level of selectivity due to 2-dimensional separation (GC and IMS). By that availability of a true orthogonality (like GCxGC) with
regard to separation capacity to separate even co-eluting compounds
Sensitivity Good, but -depending on application - might need to pre-concentrate to reach
low ppb-range. Besides CI configuration and operation in single ion mode needed
Outstanding sensitivity (low ppb) without pre-concentration -sampling 'as is'
Sample pre-treatment
Needed for several applications to reach level of odour thresholds
Not needed
Data base Available, related to NIST data baseFully established state-of-the-art technology -
analytical benchmark
GC-retention indices of NIST plus IMS drift times for approx. 150 compounds available (editable).Customized libraries possible.
Information Structure information with average benifit as EI spectra often not clearly interpretable.
Chemometric fingerprinting limited often due to strong interference of analyte signals and
background.
Identification of unknown compounds through NIST retention index and IMS drift times
Identification confirmed by pure compounds (permeation tubes) if requested
Quick decissions based on VOC-pattern ('fingerprint') and/or intensities of single compounds
Run times - Sample throughput
Rather laborous and time consuming (depending on user's experience) - run times
significantly beyond 15 minutes
High sample throughput depending on selected GC column.Run times of 10-20 minutes inject-to-inject allowing to test for >100
samples per dayData analysis Automated data analysis available for most systems After development of analytical method: Automated data processing and
result interpretationBenifits from
systemData base can be fed with user's spectra Learning system - regular use will improve results and ease operation
New compounds can be added to libraryIntervalls Depending on use, rather maintenance intensive -
besides source cleaning approx. every 200 - 500measurements, depending on sample complexity.
Regular maintenance of vacuum pump needed
Routine check-ups every 24 month. Besides only minor maintenance (septum change, syringe
change, automated backing out)
2. Economicaspects
Investment costs Depending on configuration approx. 75-150 K€ 60 K€
Consumables Helium (approx. 50 €/month) Lab supply or nitrogen from cylinder 40-60 €/month
Use of nitrogen/air generator possible - available at G.A.S.Maintenance and
other costs4,000-5,000 €/year
Vacuum pump 10,000 € every 5 years
2,000 € every 24 month (1,000/year)
3. Other aspects
Vacuum pump Noisy for lab personnel No pump
Portability Pure lab instruments Semi-portable, can operate within lab or at production line and be easily moved to other location
Readiness/warm-up time <1 hours
Benchmark of GC-MS vs. FlavourSpec
FlavourSpec Application Summary in Categories
• Process control:
1. Beer: Precise quantification (range:10-50µg/L) of VDK (diactyl & pentanedione) during brewing
2. Washing agents: Replace sensory panels regarding Off-smell of semi-finished products
3. Bottling lines: Purity of soft drink manufacturing hoses
• Product authentication
1. Quality determination of olive oil (L, V, EV)
2. High priced destillates from frauds
3. Cigarette counterfeit detection
• Impartial proof of flavours/Flavour documentation
1. Support of sensory panels regarding critical samples via VOC-fingerprint/marker compounds
2. Support of sensory panels during blending
• Quality control
1. Raw material sourcing with regard to flavour quality
2. Overcome limited access of sensory panels/achieve 100% finished product QC procedures
3. Shelf life and storage conditions of foodstuff same as of beverages
4. Sensitive off-flavour detection from packaging on foodstuff (cap liner, ink, etc)
5. Replacement of bisphenol A on flavour compounds of beverages
• ... List of applications/feasibility study separately provided
Innovative Flavour Measurement using GC-IMS
• GC-IMS (Gas chromatograph coupled to Ion Mobility Spectrometer)
– Separation by GC
– Separation/Detection via IMS at very low (ppb) level
• Characteristics:
– Appropriate for the routines in a QC-laboratory or “at line”
– No sample pre-treatment
– Automatic data analysis
– “Portable”, no helium required
– Fast cycle times (inject-to-inject: <15 minutes)
– Low operational costs (< 75 €/month)
39
breath DSafter smoking
breath DS
Intoxication: Smoking
One minute after smoking a significant number of volatile compounds (VOC) can be detected.Source of VOCs is mainly pyrolysis, e.g. acroleins, ketones, aldehydes etc.)
GC
Run
time
/ sec
IMS Drift Time / RIPrel.
BreathSpec® - Application Summary
• Intoxication:
1. Alcoholic poisoning methanol/ethanol (Horizon2020 project)
2. Working place related exposure control of TICs
• Medical Research
1. Marker compounds as indicators for diseases (acetone, amonia)
2. Oxidative stress of astronautes after sky walks (project with airbus DS)
• Monitoring of anaesthetic gases
1. Dosing of ketamine in intensive care (G.A.S. project application)
• Pharmacokinetics
1. Drug efficiency/dosing
... List of applications/feasibility study separately provided
Source: www.ciggyfree.com
GC-IMS in Various other Applications
Quality Control of Solvents (DME)
Siloxanes in Digestion Gas/Biogas
Outgasing from sample bags
Detection of TICs forWorking Place
Monitoring
Portable Quantification of Odorants in natural gas
On-line Monitoring of Odorants in natural gas
Power Supply
GC-IMS Set-Up at-site
GC-IMSMeasurement System
Gas Generator
Sampling via internal pump of the device
Data transfer via:LAN cable, current loop, Modbus, USB
Control room
Results, Quantifcation
at-site
Petro-Chemical / Environmental Applications:BTX – Quantification - Calibration
0 ppb25 ppb
60 ppb
150 ppb
Measurements of Benzene, Toluene and o-Xylene in the range of 0 → 500 ppb
LOD (o-Xylene) = ~10 ppb
LOD (Toluene, Benzene) = ~25 ppb
o-Xylene
Toluene
Benzene
49
5 ppb DMS
IMS spectra of DMS (5 to 140 ppb).
• Methylating agent in pharma industry• Toxic, cancerogenic
➢ Online monitoring of chemical facilities (working places) needed
➢ Detection limit of DMS: ~200 ppt
Chemical Industry: Detection of Dimethyl Sulfate DMS
Instrument screen while measuring.
GC-IMS: Monitoring of DMS in Chemical Facilities
Integrated into a process measuring and control system
of Bilfinger Maintenance GmbH, Frankfurt a.M.
57ppb
12ppb
1ppm
H2S COS
• Measurements of Hydrogen sulfide and Carbonyl sulfide• Concentration range 12ppb – 1ppm
• LOD (H2S) <10 ppb• LOD (COS) ~10 ppb
Petrochemistry, Hydrodesulfurization / Chemical Industry:Hydrogen sulfide H2S / Carbonyl sulfide COS
25 ppb
0ppb10 ppb
25 ppb50 ppb
100 ppb
1000 ppb
Continuous at-site measurements every 90 sec
→ no hysteresis
Petrochemistry, Environmental:Nitric Oxide (NO) in Ethene
GC-IMS Data Analyis
GC-IMS for Dimethylsulfate and Isocyanate Monitoring
Control Room
Different sources forgaseous samples…
Gases
Gas nets
Working Places
Emissions
Data/Result transfer
Continuous MonitoringSample bags
Sampling
Self Check and Fault Detection for Industrial Applications
Industrial application: Filter load/efficiency/breakthrough
Out Out Out
Time
In In In
1. Beginning offilling
Diagram:Concen-tration inair
2. Absorption process ofcarbon filter
3. Filter Breakthrough
CarbonFilter
GC-IMS on-site: Filter Load/Efficiency/Breakthrough Testing
GC-IMS
Sensitive, rugged and easy to use on-site Tool !
HVC, Alkmaar, NL
Circular Gas Flow Unit (CGFU) – from 10/2015 onwards
GC-IMS
City of Madrid: Off-smell from waste plants due to saturated Filters!
Odournet S.L.-project: Madrid
…enables further on-site Applications!
China: Analytical Assignment Car Application
Detection & quantification of compounds in below standing concentration/limits:
Compound Requested Limit / ppb
Benzene 19
Toluene 27
o-, m-, p-Xylene 231
Ethylbenzene 231
Styrene 61
Formaldehyde 82
Acetaldehyde 111
Acrolein 22
Aromatic hydrocarbons
Aldehydes
5
1
43
21 Thermodesorber
2 TENAX TA Tube slot
3 Heated Sample Line
4 Heated Transfer Line
5 GC-IMS with internal loop and touch-screen
6 Interlink (Trigger)
6
G.A.S.-Solution: Setup and Working Principle
• Thermodesorber
•manages all sampling (and self-cleaning) steps
•handles measurements cycles (‘master’ mode)
•periodical measurements possible
• GC-IMS
•acts in ‘slave’ mode
•Trigger initiates measurement program
•suction of enriched sample gas
•injection to gas chromatographic column
Analyzer set-up works stand-alone, no PC is required for routine analysis!
Gallery Plot of the VOCs of ‘Chinese Car Industry‘
No CompoundLimit / ppb
Suggested Detection Set-Up
1 Acetaldehyde 111 GC-IMS
2 Acrolein 22 GC-IMS or µTD-GC-IMS
3 Benzene 19 µTD-GC-IMS
4 Toluene 27 µTD-GC-IMS
5 Ethylbenzene 231 GC-IMS or µTD-GC-IMS
6,7,8 p-, m-, o-Xylene 231GC-IMS or µTD-GC-IMS
9 Styrene 61 GC-IMS or µTD-GC-IMS
0ppb10ppb50ppb
100ppb200ppb312ppb
0ppb5ppb
20ppb50ppb
100ppb
GC
-IM
SµT
D-G
C-I
MS
Using GC-IMS technology alone and in combination with the µTD enables detection of
all desired compounds in the desired concentration range (s. table) except Formaldehyde
GC-IMS: Application Summary
• Process control:
1. Filter load/efficiency/breakthrough in biogas plants
2. Quality control of landfill gas w.r.t. concentrations of siloxanes/total silica
3. Clean room/FAP monitoring during wafer production
4. VOC-Emissions in car indoors
• Personal care
1. Flavour development from cosmetic products
2. Perfume twins/dupes
• Environment
1. Bad smell from industrial plants via fingerprint/marker compounds
2. Working Place control/MAC monitoring
• Natural gas
1. Odorants Gasodor-S-Free/THT/TBM in natural gas
2. Traces (<1ppm) of H2S, COS and light mercaptanes – under investigation
... List of applications/feasibility study separately provided
2018: Ion Mobility Spectrometer for Benchtop GCs
*Coupling available for Agilent GCs 6890/7890B and Shimadzu GC-2010 Plus
ADVANTAGES
• Sensitive: Detection limits in the low ppbv
(µg/m3) range for VOCs with heteroatomslike ketones, aldehyds, alcohols, amines orhalogenated and sulphurous compounds
• Selective due to specific analyte ion drifttimes (2 dimensional separation, fullorthogonality)
• Flexible: Positive and negative iongeneration
• High GC sampling frequency
• No licence for 3H source requiredaccording to EU directive 96/29 EURATOM
• High reproducibility
• Operation with nitrogen or synthetic air
• Atmospheric Pressure Ionisation (API)
• Stand alone data aquisition software andsoftware suite for 3D GC-IMS data analysis
• No need for a radiation protection officer
2019: Integration of IMS into µGC490 of Agilent
Gas Chromatograph - Thermo Conductivity Detector - Ion Mobility Spectrometer
Unique Solution for industrial Applications in one Instrument!
ADVANTAGES
• Sensitive: Detection limits in the low ppbv
(µg/m3) range for VOCs with heteroatomslike ketones, aldehyds, alcohols, amines orhalogenated and sulphurous compounds
• Flexible: Positive and negative iongeneration
• High GC sampling frequency
• No licence for 3H source requiredaccording to EU directive 96/29 EURATOM
• High reproducibility
• Operation with nitrogen or synthetic air
• Atmospheric Pressure Ionisation (API)
• No need for a radiation protection officer
Thank you for your attention!
For further questions please
contact
G.A.S. mbH Gesellschaft für analytische Sensorsysteme mbHOtto-Hahn Str. 1544227 Dortmund
+49 231 [email protected]