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Thermal Desorption: A Practical Applications Guide
I. Environmental Air Monitoring andOccupational Health & Safety w
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Introduction to MarkesInternational Ltd.
Formed in 1997, Markes International Ltd. is one ofthe world’s leading suppliers of thermal desorption(TD) equipment for monitoring trace toxic andodorous chemicals in air, gas and materials. Servingfast growing markets from environmental health andsafety to materials testing and from food / flavour /fragrance to defence / forensic, Markes’ globalcustomer base includes major industry, governmentagencies, academia and the service laboratory sector.
Markes has introduced several highly successfulbrands of TD instruments to the market including:UNITY™ – a universal TD platform for single tubes,the 100-tube ULTRA™ TD autosampler, theAir Server™ interface for canisters and on-linesampling, the µ-CTE™ Micro-Chamber / ThermalExtractor for materials testing, the TT24-7™ forcontinuous on-line monitoring and the TC-20™ multi-tube conditioner.
Markes also supplies a wide range of samplingaccessories and consumables for all TD applicationareas.
What is TD?
Since the early 1980s, thermal desorption hasprovided the ultimate versatile sampleintroduction technology for GC / GC-MS. Itcombines selective concentration enhancementwith direct extraction into the carrier gas andefficient transfer / injection all in one fullyautomated and labour-saving package.
Markes International Ltd. UK headquarters
ApplicationsThermal desorption is now recognised as thetechnique of choice for environmental air monitoringand occupational health & safety. Relevant standardmethods include: ISO/EN 16017, EN 14662 (parts 1& 4), ASTM D6196, US EPA TO-17 and NIOSH 2549.Related applications include monitoring chemicalwarfare agents (CWA) in demilitarisation / destructionfacilities & civilian locations (counter-terrorism).
TD is also routinely used for monitoring volatile andsemi-volatile organic compounds (S)VOCs in productsand materials. Examples include residual solvents inpackaging & pharmaceuticals, materials emissionstesting and food / flavour / fragrance profiling.
This publication presents several real worldapplications in environmental air monitoring andoccupational health & safety. Accompanyingpublications cover the application areas of:
• Food, flavour, fragrance & odour profiling
• Defence & forensic
• Emissions from products and materials
Environmental air monitoring• Atmospheric research
• Ambient / urban air monitoring
• Industrial (stack) emissions
• Odour components
• Indoor air quality
Occupational health & safety• Personal exposure monitoring (inhalation)
• Biological exposure assessment (breathtesting)
Markes International Ltd.T: +44 (0)1443 230935 F: +44 (0)1443 231531E: [email protected] W: www.markes.com
Typical analytes of interest:• Freons
• Volatile aromatics such as benzene
• C2 - C10 hydrocarbons
• Nitrates
Concentrations: ppt levels
Atmospheric research Background:Thermal desorption is used extensively inatmospheric research for monitoring trace organicvapours. For example:
• Global migration of pollution
• Research into stratospheric chemistry
• Marine research – studying the oceans as apotential ‘sink’ or reservoir for air pollutants
• Historical pollution data – e.g. levels of freonsin air bubbles trapped in polar ice
Std. methods: EN ISO 16017-1, ASTM D 6196, USEPA TO-17, (tubes) or US EPA TO-15 (canisters)
Typical TD-GC conditions:Sampling: Pumped multi-sorbent tube or canister
TD: ULTRA-UNITY or UNITY-Air Server (+dryer)
Dry purge if no dryer used during sampling
Splitless desorption
Trap: Air Toxics / water m’gement: -15 to 320ºC
Analysis by GC-MS using SIM or NCI
Reference: TDTS17 UNITY detection limits,TDTS31 UNITY system performance
30 ml of air from bubbles in the ice core collected incanisters. Analysis by TD-GC-MS in NCI mode. Unit ppt
detection limits
Ions: 3579127
Typical analytes:• Freons & other halogenated hydrocarbons
• Volatile aromatics
• Oxygenates
Concentrations: ppt levels
Background:SafeLok samplers have the same capacity asstandard tubes but incorporate Markes’ patented*
diffusion-locking (DiffLok™) technology at bothends of the tube to prevent artifact ingress.
With the same external dimensions as standardTD tubes, SafeLok tubes are ideal for monitoringultra-low concentration environments – forexample at the North Pole or in mid-Pacific.Samples are protected from contaminationduring storage / transport and duringsubsequent TD-GC-MS analysis in a conventionallaboratory.
Std methods: EN ISO 16017-1, US EPA TO-17,ASTM D 6196
Typical TD-GC conditions:Sampling: Pumped multi-sorbent SafeLok tube
TD: ULTRA-UNITY
Dry purge
Splitless desorption
Trap: Air Toxics / water m’gment: -15 to 320ºC
Analysis by GC-MS using SIM or NCI
Reference: TDTS61 on diffusion lockingtechnology, Markes SafeLok tubes leaflet
SafeLok™ – Specialist sampletubes for trace detection
Threaded DiffLokinserts protect bothends of the sorbenttube
SafeLok samplers incorporate Markes’ patented*DiffLok technology to prevent artifact ingress. This
aids trace level monitoring
* GB 2337513US 6,564,656 B1
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Typical analytes:• Volatile aromatics
• 1,3-butadiene
Concentrations: Sub to low ppb levels
Criteria pollutants in ambientair by diffusive sampling
Background:Accurate mapping of pollution levels across amajor urban centre requires hundreds of samplingpoints. Diffusive samplers, combined withautomated TD-GC(-MS) analysis, provide anaffordable and easily deployed monitoring option.
Std. methods: EN 14662-4, EN ISO 16017-2,ASTM D 6196
Typical TD-GC analytical conditions:Sampling: Diffusive (passive)
Sorbent: Carbograph 1TD™ (benzene),
Sorbent: Carbopack X™ (1,3-butadiene)
Monitoring time: 7-14 days (axial), 4-6 hours(radial)
Desorption: 5-10 minutes at 320ºC
Trap: C’graph 1TD / Carb X from +30 to 320ºC
Split: ~20:1 during trap desorption only
Analysis by GC-FID or GC-MS
Reference: TDTS10 on diffusive monitoring ofambient air, TDTS01 on uptake rates, TDTS42on radial diffusion for TD
Rouen (Northern France)Interpolated benzene isoconcentration plot
Measurements performed from 19-23/01/98
Typical analytes:Hydrocarbons, halogenated hydrocarbons, CS2,volatile aromatics, ketones, esters & other odorous /toxic VOCs ranging in volatility from freons tohexachlorobutadiene
Concentrations: Sub to low ppb levels
TO-17 ‘Air Toxics’ in urban airusing pumped sorbent tubes
Background:US Clean Air Act regulations have identifiedspecific ‘Hazardous Air Pollutants’ (HAPs) alsoknown as ‘Air Toxics’. These analytes cover a widerange of polarities & volatilities and are mosteffectively monitored using pumped sampling ontomulti-sorbent tubes / traps with automatedTD-GC-MS(SCAN) analysis.
Std. method: US EPA Method TO-17
Typical TD-GC analytical conditions:Sampling: Pumped sorbent tube
Sorbent: Dual-sorbent – e.g. ‘Air Toxics’ tube
TD system: ULTRA-UNITY
On- or off-line dry purge before desorption
Desorption: 10 mins at 320ºC
Trap: Air Toxics trap: +30 to 330ºC
Split: Low split during trap desorption only
Analysis: GC-MS(SCAN)
Reference: Markes Technical SupportDocument for TO-17, TDTS27 on samplingmethods for VOCs in air
Active sampling of volatiles in ambient air usingsorbent tubes / traps
Markes International Ltd.T: +44 (0)1443 230935 F: +44 (0)1443 231531E: [email protected] W: www.markes.com
CO
S
HC
C2H
2F 4
CH
3Cl
HCC
HClF
2CCL 2
F 2
CH
3Br
SO
2
CS
2
Freo
n 1
13
Met
hyl
ene
Chlo
ride
HC
Oxy
gen
ated
HC
CCl 3
F
Ben
zene
1,1
,1-t
rich
loro
ethan
e
Tric
hlo
roet
hyl
ene
CCl 4
C2Cl 4
Tolu
ene
Dim
ethyl
Sulp
hid
e
Background:While sorbent tubes provide the most cost-effective and versatile sampling solution for VOCAir Toxics, passivated and evacuated canisters canalso be used for ‘grab’ sampling ambient air.Subsequent analysis is by TD-GC-MS(SCAN). Veryvolatile apolar VOCs are quantitatively recoveredfrom the canisters, however, polar and less volatilecompounds may be lost due to condensation oninner surfaces.
Std. method: US EPA Method TO-15 (formerlyTO-14)
Typical TD-GC analytical conditions:Sampling: Evacuated canister
TD system: UNITY-Air Server (no dryer)
Trap: Air Toxics trap: +30 to 330ºC
Dry purge of cold trap before desorption
Split: Low split during trap desorption only
Analysis: GC-MS(SCAN)
Reference: TDTS27 on sampling methods forVOCs in air
TO-15 ‘Air Toxics’ in urban airusing canisters
Typical analytes:Hydrocarbons, halogenated hydrocarbons, CS2,volatile aromatics, esters & other odorous / toxicVOCs ranging in volatility from freons tohexachlorobutadiene
Concentrations: Sub to low ppb levels
Repeat analysis of TO-14 / 15 canister standard usingUNITY-Air Server (up to 8 channels)
Typical analytes:Hydrocarbons ranging in volatility from ethane,ethene and ethyne (acetylene) to trimethyl benzene
Concentrations: Sub to low ppb levels
‘Ozone precursors’ (C2 to C10hydrocarbons) in ambient air
Background:C2 to C10 hydrocarbons, primarily from carexhausts, have been identified as precursors tothe formation of street level ozone and urbansmog. US, European and other regulators requireround-the-clock monitoring of these compounds inmajor urban centres during the summer months.UNITY-Air Server allows continuous, unattendedand cryogen-free monitoring at low to sub ppblevels. Chromatographic data, from multiplestations, are accessed via telemetry and processed/ validated at remote network control centres.
Official guidance: US EPA Tech. Assist. Documentfor sampling and analysis of ozone precursors
Typical TD-GC analytical conditions:Sampling: On-line from manifold at 10-15 ml/min
Sampling volume: ~400 ml
TD system: UNITY-Air Server (with dryer)
Trap: Ozone Precusor trap: -15 to 320ºC
Splitless desorption
Analysis: GC, dual column, dual FID & Deans switch
Reference: TDTS16 On-line monitoring ofozone precursors in ambient air
Splitless desorption of 56-compound US EPA mix ofozone precursors using UNITY-Air Server with dual
column / dual FID GC with Deans switch
PLOT column
BP1 column
Markes International Ltd.T: +44 (0)1443 230935 F: +44 (0)1443 231531E: [email protected] W: www.markes.com
Background:Polyaromatic hydrocarbons (PAH) are toxic semi-volatile organic compounds present in ambient airin both particulate and vapour form. Fast(~500 ml/min) pumped sampling of the vapourfraction onto tubes packed with a combination ofquartz wool and carbon sorbents followed by TD-GC-MS analysis allows measurement of PAH at lowppt levels.
Typical TD-GC analytical conditions:Sampling: Pumped sorbent tube
Sorbent: Quartz wool with 1 or 2 carbon blacks
Sample volume: ~100 L at 500 ml/min
TD system: ULTRA-UNITY
Desorption: 15 mins at 350ºC
Trap: High boilers trap: -10 to 350ºC
Split: Typically 30:3 during trap desorption only
Analysis: GC-MS(SIM)
Reference: M. Caputi, ‘Monitoring of VOCsand PAHs in the atmosphere’, PhD thesis2004, TDTS53 on quantitative recovery ofsemi-volatiles with Markes (ULTRA-)UNITY TDsystems
Vapour-phase PAH by TD
Analytes shown:1: naphthalene 9: benz(a)anthracene2: acenaphthylene 10: chrysene3: acenaphthene 11: benzo(b)fluoranthene4: fluorene 12: benzo(k)fluoranthene5: phenanthrene 13: benzo(a)pyrene6: anthracene 14: dibenz(a,h)anthracene7: fluoranthene 15: benzo(g,h,i)perylene8: pyrene 16: indeno(1,2,3-cd)pyrene
Semi-volatile PAHs are quantitatively recovered usinga Markes ULTRA-UNITY TD system
1
16
15
14
13
12
11
10
987
654
32
Typical analytes:Isoprene, monoterpenes (α-pinene, limonene, etc.),sulphur compounds, ketones
Concentrations: 0.1 to 100 ppb
Biogenic emissions - VOCsfrom moulds, plants, etc.
Background:Plants, moulds, animals and other life forms emitVOCs and contribute to the ‘cocktail’ of organicvapours in ambient air. Monoterpenes, for example,are emitted by pine trees on sunny days, possiblyas a defence against potential photochemicaldamage. These reactive hydrocarbons aremonitored using pumped sampling onto inert,Tenax tubes followed by TD-GC-MS analysis.Mould emissions of methyl benzoate are monitoredin indoor air using a similar method.
Std. methods: EN ISO 16017-1, ASTM D 6196
Typical TD-GC analytical conditions:Sampling: Pumped sorbent tube
Sorbent: Tenax TA™ in stainless / Silcosteel™ tube
TD system: ULTRA-UNITY
Desorption: 5 mins at 220ºC
Trap: Tenax trap: -10 to 250ºC
Split: Low split during trap desorption only
Analysis: GC-MS(SCAN)
Reference: J. Kristensson et al., ‘Sampling &analysis of atmospheric monoterpenes’, Deptof Meteology, Stockholm University, 1991
Terpenes from leaf litter
Monoterpenes & terpenoids
Sesquiterpenes
Terpenoids
Markes International Ltd.T: +44 (0)1443 230935 F: +44 (0)1443 231531E: [email protected] W: www.markes.com
Industrial (stack) emissions -solvents
Background:Stack gases are aggressive matrices requiring asampling train to remove particles, acids etc. Theresultant air is either pulled through a TD tube usinga gas syringe (grab sampling) or pumped onto atube at low flow rates (time weighted average).Analysis by TD-GC(-MS) using a high (double) splitratio, allows fast, solvent-free quantification of highVOC concentrations. Mi SecureTD-Q (re-collectionfor repeat analysis) validates quantitative data.
Official guidance: UK Env Agency docs M2, S4.01, S4.02
Typical TD-GC analytical conditions:Sample volume: 100-1500 ml
Sampling: Pull through tube (gas syringe / lowflow pump)
Sorbent: Tenax / carbon or carbon / carbon
TD system: ULTRA-UNITY
Desorption: 5 mins at 330ºC or 280ºC (if Tenax)
Trap: Tenax / carbon or 2 carbons 30 to 300ºC
Split: 3,000:1 double split with SecureTD-Q
Analysis: GC-MS(SCAN) or GC-FID
Reference: TDTS77 on stack emissionsmonitoring
Quantitative stack analysis confirmed by SecureTD-Q
Analyte Mass in µg for 3 repeats
MEK 580 583 580Benzene 0.14 0.18 0.18Toluene 94 91 93
Ethyl benzene 30 30 29PGMEA 43 43 43Xylene 274 275 271DMS 28 28 28
Trimethylbenzene 43 44 42
Second re-collectedsample
First re-collectedsample
Original sample
Vapour-phase semi-volatiles byThermal Desorption
Background:Thermal desorption is usually associated withanalysis of volatile organic chemicals. However,the short, inert, heated flow path of Markes TDsystems also ensures quantitative recovery ofsemi-volatiles up to n-C40.
Typical TD-GC analytical conditions:Sampling: Pumped sorbent tube
Sorbent: Quartz wool with 1 or 2 carbon blacks
Sample volume: ~100 L at 500 ml/min
TD system: ULTRA-UNITY
Desorption: 15 mins at 350ºC
Trap: High boilers trap: -10 to 350ºC
Split: Typically 50:2.5 during trap desorption only
Analysis: GC-MS(SCAN)
Reference: TDTS53 on quantitative recoveryof semi-volatiles with Markes (ULTRA-)UNITYTD systems
Typical analytes:• Polychlorinated biphenyls (PCBs)
• Polyaromatic hydrocarbons (PAHs)
• Plasticisers such as phthalates
• Hydrocarbons from diesel emissions
Complete recovery of n-C40 through Markes UNITY TD
Markes International Ltd.T: +44 (0)1443 230935 F: +44 (0)1443 231531E: [email protected] W: www.markes.com
C18
C20
C24
C26
C32
C36
C40
Typical analytes:• CS2
• H2S (NB: requires special focusing trap)
• Mercaptans (thiols)
• Sulphides
Concentrations: Sub to low ppb
Odorous industrial emissions Background:Highly odorous sulphur compounds in industrial orlandfill emissions must be controlled to sub or low-ppb levels. These very volatile and highly reactivecompounds are usually sampled on-line or incanisters / bags and analysed using TD-GC-FPD.
Std. method: Korean Government GuidanceMethod - Standard Method for Off-Odour Analysis(2005)
Typical TD-GC analytical conditions:Sample volume: 100-500 ml
TD system: UNITY-Air Server (+ dryer)
TD flowpath: 80ºC
Trap: Sulphur trap or H2S trap -15 to 250ºC
Split: 5:1
Analysis: GC-FPD
Reference: TDTS32 onanalysis of sulphurcompounds
Reduced sulphur compounds via UNITY-Air Server
H2S
Met
hyl
mer
capta
n
Eth
yl m
erca
pta
nD
imet
hyl
sulp
hid
e
CS
2
Dim
ethyl
dis
ulp
hid
e
Typical analytes:Freons such as CF4, C2F6 and C3F8
Concentrations: Low mg/m3
Stack emissions of freons Background:Highly volatile freons are emitted by aluminiumsmelting and industrial halogenation processes.Freons are known to damage the protective ozonelayer in the higher atmosphere and their emissionsare rigorously controlled. With a bpt. of -169ºC,CF4 is extremely difficult to trap, but sampling intobags / cans combined with TD-GC-MS or ECDanalysis of small volumes of the gas allowscryogen free monitoring at low levels.
Typical TD-GC analytical conditions:Sampling: On-line or whole air / gas containers
TD system: UNITY-Air Server
Trap: Carbon molecular sieve -15 to 320ºC
Low split during both tube and trap desorption
Analysis: GC-MS or GC-ECD
Note that TD-GC-MS (SCAN)was used in the exampleshown
30 ml volumes of freon standard showing quantitativetrapping of CF4 without liquid cryogen
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80 mg/m3
mixed std
300 mg/m3 std ofCF4 & C2F6 only
Typical analytes:• Benzene
• 1,3-butadiene
• Mixed solvents and hydrocarbons
Concentrations: ppb to ppm
Industrial fence-line monitoring Background:Is your industry a good neighbour? Unobtrusivediffusive (passive) samplers may be placed arounda factory fence-line for extended time periods –e.g. 3 to 14 days. When combined withsubsequent automated TD-GC(-MS) analysis, thisprovides a low cost and reliable method formonitoring perimeter concentrations at ppb-ppmlevels.
Std. methods: EN 14662-4, EN ISO 16017-2,ASTM D 6196
Typical TD-GC analytical conditions:Sampling: Diffusive (passive) tubes
Sorbent: Carbograph 1TD, Carbopack X or other
TD system: ULTRA-UNITY
Desorption: 5 mins at 320ºC
Trap: Dual carbon black -10 to 320ºC
Split: Low split during trap desorption only
Analysis: GC-MS(SCAN) or GC-FID
Reference: TDTS49 on fence-line monitoring
2-week diffusive sampling around a refinery perimeter.VOCs detected include benzene, toluene & xylene
Xyl
ene
Tolu
ene
Hep
tane
Met
hyl
cycl
ohex
ane
Ben
zeneHex
ane
Penta
ne
Typical analytes:• Hydrocarbons from fossil fuels
• Halogenated solvents
Concentrations: 1 to 100 ppm
In-situ monitoring ofunderground fuel leaks
Background:Underground fuel or chemical leaks present agrave environmental risk. Soil probes containingstandard diffusive tube samplers allow cost-effective, in-situ screening of large areas of landincluding active production sites. They can also beplaced along the length of fuel pipelines to provideearly warning of a leak. Diffusive tubes inside thesoil probes monitor the soil gases for ~24 hours.Automated TD-GC analysis allows rapididentification of the nature, source and spread ofground contamination.
Typical TD-GC analytical conditions:Sampling: Diffusive tubes inside soil probes
Sorbent: Tenax TA
TD system: ULTRA-UNITY
Desorption: 5 mins at 280ºC
Trap: Tenax TA or dual bed -10 to 300ºC
Split: Double split
Analysis: GC-MS(SCAN) or GC-FID
Reference: TDTS29 on monitoring soilpollution using soil probes
VOC-Mole™ Soil Probes arranged in a grid patternaround an industrial site allow low-cost mapping of
contaminated ground
Markes International Ltd.T: +44 (0)1443 230935 F: +44 (0)1443 231531E: [email protected] W: www.markes.com
Target compounds include:Chloroethane, VCM, benzene, 2-butoxy ethanol,1,1-dichloroethane, trichloroethene, tetrachloromethane,1,1-dichloroethene, 1,2-dichloroethene, CS2, methanethiol,butyric acid, ethyl butyrate, 1-propanethiol, dimethyldisulphide, ethanethiol, 1-pentene, 1-butanethiol, dimethylsulphide, 1,3-butadiene, furan
Concentrations: 10 to 100 ppb
Odours and toxics in landfill gas Background:New EU regulations require monitoring of tracetoxic and odorous compounds in landfill gas. 100-200 ml samples are drawn through a specialsorbent tube using a gas syringe. Subsequentgentle desorption on an inert ULTRA-UNITY TD setat low (<100ºC) flow path temperatures allowsmeasurement of trace target analytes includingthiols.
Official guidance: UK Env. Agency publication‘Monitoring trace components in landfill gas.’
Typical TD-GC analytical conditions:Sample volume: 100-500 ml
Silcosteel tube with Tenax TA / UniCarb™
TD system: ULTRA-UNITY
TD flowpath: 120ºC
Trap: Sulphur trap -15 to 220ºC (40º/min)
Split: From 10:1 to 50:1
Analysis: GC-MS(SCAN)
Reference: TDTS47 andTDTS74 on analysis oflandfill gas
100 ml landfill gas with trace target analytes andmany major components identified
Redesorption blank
Vin
yl c
hlo
ride
Chlo
roet
han
e
1-p
ente
ne
1,1
,1-t
rich
loro
ethan
e
1,1
- &
1,2
-dic
hlo
roet
hen
eButa
n-2
-ol
1,1
-dic
hlo
roet
han
e
Car
bon d
isulp
hid
eD
imet
hyl
sulp
hid
eFu
ran
Dim
ethyl
dis
ulp
hid
e
Tric
hlo
roet
hen
e
Ben
zene
Buta
n-1
-ol
Buta
noic
aci
d e
thyl
est
er
Xyl
ene
Tolu
ene
Nonan
e
Lim
onen
e
Dec
ane
α-p
inen
e
Typical analytes:Almost any VOC or (S)VOC
Concentrations: Sub to low ppb levels[Note that in this example detection limits are in theorder of 10-50 ppt.]
Profiling indoor air quality Background:TD is used extensively for monitoring indoor airquality and for related applications such asevaluating emissions from building materials. Inthis example, pumped tube samplers were usedwith subsequent TD-GC-MS analysis for profiling ofppt-ppb level VOCs.
Std. methods: US EPA Method TO-17, EN ISO16017-1, ASTM D 6196
Typical TD-GC analytical conditions:Sampling: Pumped sampling: 2-20 L
Sorbent: Typically multi-sorbent
TD system: ULTRA-UNITY
Desorption: 5 mins at 280ºC (depends on sorbent)
Trap: Tenax TA or dual bed -10 to 300ºC
Split: During trap desorption only ~15:1
Analysis: GC-MS(SCAN)
Reference: TDTS28 on monitoring indoor air
Thermal Desorption: A Practical ApplicationsGuide. II. Residual Volatiles & MaterialsEmissions Testing
Clean indoor air pumped onto multi-sorbent tube andanalysed by TD-GC-MS
Markes International Ltd.T: +44 (0)1443 230935 F: +44 (0)1443 231531E: [email protected] W: www.markes.com
1,1
-diflu
oro
ethan
e
Eth
anol
Isopen
tane
1,1
-diflu
oro
-1-c
hlo
roet
han
eD
ichlo
rodiflu
oro
met
han
e
1,1
,1,2
-tet
rafluoro
ethan
e
Hex
ane
Ace
tone
Freo
n 1
13
Propan
ol
Tric
hlo
rofluoro
met
han
e
Dic
hlo
rom
ethan
e
Met
hyl
cycl
ohex
ane
Ben
zene
Tetr
achlo
rom
ethan
e
Eth
yl a
ceta
te
Hex
anal
Tolu
ene
Eth
yl b
enze
ne
Eth
ylcy
clohex
ane
o/p
xyl
ene
Tetr
achlo
roet
han
e
α-p
inen
e
Trim
ethyl
ben
zene
Dec
ane
Sty
rene
Lim
onen
e Undec
ane
Ben
zyl al
cohol
Nonan
alD
odec
ane
Trid
ecan
e
Tetr
adec
ane
Monitoring car cabin air Background:Car cabins are small confined spaces. Vapour-phase (S)VOC levels can build up – especially inparked cars on a hot day. Car manufacturers andtheir suppliers are currently focused on improvingthe quality of cabin air and reducing emissionsfrom vehicle trim components. This will reducethe exposure of drivers and passengers. Pumpedsampling onto sorbent tubes with TD-GC-MSanalysis is the method of choice for profiling carcabin air.
Std. methods: EN ISO 16017-1, ISO 16000-6,ASTM D6196
TD-GC analytical conditions:Sampling: Pumped sampling of 2 L volume
Sorbent: Tenax TA or multi-sorbent
TD system: ULTRA-UNITY
Desorption: 6 mins at 280ºC
Trap: Tenax or dual bed -10 to 300ºC
Split: 75:1
Analysis: GC-MS(SCAN)
Reference: TDTS33 on profiling car cabin air
Air from the cabin of a small saloon car showing acomplex range of VOCs and high total-VOC levels
Saloon car cabin air 23°CTVOC 3.7 ppm
Saloon car cabin air 40°CTVOC 9.7 ppm
MEKn-H
exan
eBen
zene
Cyc
lohex
ane
Eth
yl b
enze
ne
n-O
ctan
e
Isooct
ane
NN
DM
FTo
luen
e
Met
hyl
cycl
ohex
ane
Hep
tane
Eth
yl t
olu
ene
n-N
onan
eo-X
ylen
eSty
rene
m-/
p-x
ylen
e
Trim
ethyl
ben
zene
n-D
ecan
eD
imet
hyl
ben
ylam
ine
C11
C11/1
2C
12
C13
Cubeb
ene
/ Copae
ne
n-C
13
Sily
l es
ter
2-(
2-b
uto
xy-e
thox
y)et
han
ol
o-x
ylen
eSty
rene
m-/
p-x
ylen
eEth
yl b
enze
ne
Tolu
ene
NN
DM
F
Met
hyl
cycl
ohex
ane
n-d
ecan
eTr
imet
hyl
ben
zene
n-n
onan
e
Dim
ethyl
ben
zyla
min
eC
11
C11/1
2C
12
C13
2-(
2-b
uto
xy-e
thox
y)et
han
ol
Copae
ne
n-C
13
Sily
l es
ter
Dodec
ane n-C
14
Typical analytes:• Benzene
• 1,3-butadiene
• General VOCs
Concentrations: Sub to low ppb
Personal exposure indoors Background:TD is used for several applications relating to ‘SickBuilding Syndrome’. Here, diffusive tube samplerswere used with subsequent TD-GC-MS analysis forindoor & outdoor air sampling & simultaneouspersonal monitoring. Diffusive (passive) samplers areunobtrusive, low cost (no pumps) & simple to deployfacilitating personal exposure assessment & largescale studies of indoor air quality & human exposure.
Std. methods: EN 14662-4, EN ISO 16017-2,ASTM D6196
Typical TD-GC analytical conditions:Sampling: Diffusive sampling
Sorbent: Carbograph 1TD, Carbopack X or Tenaxdepending on target analyte range
TD system: ULTRA-UNITY
Desorption: 5 mins at 320ºC
Trap: Dual carbon -10 to 320ºC
Split: ~10:1 during trap desorb only
Analysis: GC-MS(SCAN)
Reference: TDTS10 on diffusive sampling inindoor air, TDTS01 on uptake rates, TDTS54on personal exposure to 1,3-butadiene.
Poor indoor air quality and high personal exposure inthis home were linked to a diesel car parked in a
garage under the living space
Markes International Ltd.T: +44 (0)1443 230935 F: +44 (0)1443 231531E: [email protected] W: www.markes.com
Outdoor
Personal
Indoor
Typical tracer gases:• PDCB – perfluorodimethylcyclobutane
• PMCP – perfluoromethylcyclopentane
• PMCH – perfluoromethylcyclohexane
Concentrations: ppt to low ppb
Building ventilation tests withtracer gases
Background:To test building ventilation, sources of individualperfluorocarbon tracer gases are placed indifferent rooms. They are sampled, diffusively orwith pumps, onto sorbent tubes. Use of diffusionreduces monitoring costs. After sample collectiontubes are analysed via TD-GC-MS/ECD. The riseand subsequent decay in tracer gas concentrationsallows the building ventilation (rate of air exchange)to be monitored.
Typical TD-GC analytical conditions:Sampling: Diffusive or pumped
Sorbent: Carbograph 1TD (40-60 mesh)
TD system: ULTRA-UNITY
Desorption: 5 mins at 320ºC
Trap: Carbograph 1TD -10 to 300ºC
Split: ~10:1
Analysis: GC-MS or ECD
Reference: H. Bloemen et al.,‘Ventilation rate andexchange of air indwellings’, RIVM,Netherlands, 1992
FirstFloor
GroundFloor
PMCH
PMCP
PDCB
PDCB
PMCP
PMCH
Typical analytes:• Solvents
• Hydrocarbons and haloforms
• Ketones, esters, glycol ethers
• Amines and nitriles
Concentrations: ppb to low ppm
Occupational hygiene -monitoring inhalation exposure
Background:Health and safety at work legislation requirespersonal exposure assessment of workerspotentially exposed to toxic chemicals. Pumped ordiffusive sampling onto sorbent tubes followed byTD-GC(-MS) analysis provides a solvent-free, safeanalytical option with ~1000 x more sensitivitythan conventional charcoal tube / CS2 extractionmethods. TD tubes are also reusable indefinitely.
Std. methods: UK MDHS series, EN ISO 16017,ASTM D 6196, NIOSH 2549
Typical TD-GC analytical conditions:Sampling: Diffusive or pumped
Typical sorbent: Tenax or Chromosorb™ 106
TD system: ULTRA-UNITY
Desorption: 5 mins at 300ºC or 200ºC (for C106)
Trap: Tenax or Tenax/Carb 1TD from -10 to 300ºC
Split: 50:1 to 500:1
Analysis: GC-MS(SCAN) or ECD
Reference: TDTS37 on industrial airmonitoring, TDTS38 on occupationalexposure limit levels, TDTS50 on workplacemonitoring
Reactive amines inworkplace air
Personal exposure tosolvents at work
PNCB
FAN
1PP
D
4N
4A
Markes International Ltd.T: +44 (0)1443 230935 F: +44 (0)1443 231531E: [email protected] W: www.markes.com
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Typical analytes:• Solvents
• Hydrocarbons and haloforms
• Ketones, esters, glycol ethers
• Amines and nitriles
Concentrations: ppb to low ppm
Diffusive (passive) sampling inthe workplace
Background:Unobtrusive, low-cost diffusive samplers facilitatepersonal exposure monitoring because they can beworn close to the breathing zone withoutimpacting worker behaviour. Analysis by thermaldesorption means tubes are re-usable indefinitely.The enhanced sensitivity of TD, relative to solventextraction, also allows compliance with new lowerthreshold limit values.
Std. methods: UK MDHS series, EN ISO 16017,ASTM D 6196, NIOSH 2549
Typical TD-GC analytical conditions:Sorbent: Tenax, carbon or porous polymer
TD system: ULTRA-UNITY
Desorption: 5-10 mins. Temp depends on sorbent
Trap: Dual sorbent -10 to 300ºC
Split: Between 50:1 and 500:1
Analysis: GC(-MS)
Reference: TDTS01 on uptake rates, TDTS08on principles of diffusive sampling, TDTS38on limit levels, TDTS50 on workplacemonitoring
Standard sorbent tube fitted with adiffusion cap at the sampling
(grooved) end
Analytes:Dichlorvos DiazinonChlorpyrifos MethacrifosEtrimfos PhosfamidonChlorpyrifos-methyl Pyrimifos-methylFenitrothion Malathion
Concentrations: ppb
Monitoring inhalation exposureto pesticides
Background:Agricultural workers involved in pesticideapplication must be monitored to ensure that theirexposure to these highly toxic chemicals does notexceed safe levels. Pumped monitoring using inert(glass or Silcosteel) tubes together with TD-GC-MSanalysis provides a reliable and highly sensitivemonitoring method.
Std. methods: UK MDHS series, EN ISO 16017-1,ASTM D 6196, NIOSH 2549
Typical TD-GC analytical conditions:Sampling: Pumped
Sorbent: Tenax in glass or Silcosteel tubes
TD system: ULTRA-UNITY
Desorption: 10 mins at 280ºC
Trap: Tenax -10 to 300ºC
Split: ~10:1 during trap desorption only
Analysis: GC-MS
Reference: TDTS39 on using TD withSecureTD-Q to monitor vapour phasepesticides
Primary and repeat analysis of pesticides for personalexposure monitoring
Markes International Ltd.T: +44 (0)1443 230935 F: +44 (0)1443 231531E: [email protected] W: www.markes.com
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Fenitro
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Met
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Phosp
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Typical analytes include:• Halogenated solvents
• Styrene
• Ketones
• Aromatics
Biological monitoring viaalveolar breath
Background:Biological exposure monitoring allows assessmentof the whole body burden of chemicals via allroutes of exposure – skin absorption, ingestionand inhalation. Alveolar breath sampling using thedisposable Bio-VOC allows large-scale, non-invasivebiological monitoring of workers using PPE orhandling skin-absorbed chemicals. After breathcollection, the sample is discharged into a Tenaxtube and analysed by TD-GC-MS.
Official guidance: Suite of breath samplingguidance notes available from UK HSL.
Typical TD-GC analytical conditions:Sorbent: Tenax TA (35-60 mesh)
TD system: ULTRA-UNITY
Desorption: 5 mins at 250ºC
Trap: Tenax TA -10 to 280ºC
Split: ~10:1
Analysis: GC-MS(SCAN)
Reference: TDTS13 Evaluation of theBio-VOC, TDTS48 Overview of breathsampling
Skin-absorbed solvents in the breath of shoe workerscollected using the Bio-VOC™
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The Markes International advantage
• Markes leads the market in TD
• Unparalleled reputation for product quality andreliability
• Excellence in technical and applications support
• For further information on Markescomprehensive range of instruments, samplingaccessories and consumables please use one ofthe contact numbers / email address below orbrowse the web site
Trademarks
UNITY™, ULTRA™, Air Server™, µ-CTE™, SafeLok™, DiffLok™, VOC-Mole™,Bio-VOC™, TT24-7™, TC-20™, UniCarb™ and SecureTD-Q™ are trademarks ofMarkes International Ltd., UK
Tenax TA™ is a trademark of Buchem B.V., Netherlands
Carbograph 1TD™ is a trademark of LARA s.r.l., Italy
Carbopack X™ is a trademark of Supelco Inc., USA
Silcosteel™ is a trademark of Restek Inc., USA
Chromosorb 106™ is a trademark of Manville Corp., USA
The Markes International team
Markes International Ltd.T: +44 (0)1443 230935 F: +44 (0)1443 231531E: [email protected] W: www.markes.com
Markes International Ltd.
Gwaun Elai Medi Science CampusLlantrisant
RCTCF72 8XL
United Kingdom
T: +44 (0)1443 230935 F: +44 (0)1443 231531E: [email protected] W: www.markes.com
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