Series 2
Air Server
Thermal Desorption
Options
Automated canister and on-line air/gas analysis
Series 2
Air Server
A range of accessories for series 2
UNITY thermal desorbers offering
automated canister analysis and
on-line air/gas monitoring
1. Patent# GB 2395785 (Automated re-collection using a single TD autosampler), 2. Patent# US 6,446,515 B2, 3. Patent# GB 2337513 US 6,564656 B1
4. Patent# GB 2336649
Thermal desorption technology
Thermal desorption (TD) is a highly versatile, sensitive
and labour-saving sample preparation technique for the
measurement of volatile and semi-volatile organic
compounds (VOC and SVOC) in air and materials. It is
applicable to GC-compatible organics ranging in
volatility from acetylene to n-C40and a few inorganic
gases; including nitrous oxide, SF6, CS2and H2S. Key
applications include:
• Environmental and workplace air monitoring
• Civil defence and forensic analysis
• Materials and materials emissions testing
• Food, flavour and fragrance profiling
Many material samples such as drugs, foods, textiles,
polymers, paints etc. can be directly thermally
desorbed by weighing them into empty TD sample
tubes.
Alternatively, vapours in gas or air can be concentrated
on- or off-line onto sorbent traps/tubes before TDGC(MS) analysis.
Innovation and excellence in
thermal desorption
Since 1997 Markes International has re-engineered
analytical thermal desorption for the 21st century.
Harnessing unparalleled technical expertise, the
company has developed a suite of “universal” TD
systems and unique sampling accessories incorporating
key proprietary innovations such as:
• SecureTD-Q™ and automated sample recollection using a single TD autosampler
1
• RFID tube tagging (TubeTAG™)
2
• Diffusion-locking for effective tube sealing and
robust automation
3
• Innovative low volume valving specifically
designed for TD
4
Many of these innovations now set the standard for TD
instrumentation worldwide.
Introducing the series 2 Air
Server range
Series 2 Air Server modules add to any series 2
(ULTRA-)UNITY system to allow a controlled flow of
whole-air or gas to be introduced directly into the
electrically-cooled focusing trap of the desorber. The
combined systems operate cryogen-free (to minimise
running costs/maintenance) and offer optimum
analytical performance/sensitivity.
With 3- (Air Server) or 8-channel (Canister Interface
Accessory - CIA 8) options available, method-compliant
series 2 (U
LTRA-)UNITY-Air Server systems are suitable
for both automated analysis of canister/bag samples
and round-the-clock unattended monitoring of on-line
air/gas streams.
Key applications include:
• Continuous monitoring of ozone precursors (C
2
to C10hydrocarbons) in ambient air and/or
vehicle emissions
• On- or off-line odour monitoring e.g. measuring
reduced sulphur species such as H
2
S, mercaptans
and sulphides in canister, bags or on-line air
streams at sub- to low-ppb levels
• “Air Toxics” in ambient air e.g. US EPA Method
TO-(14)15
• Industrial process control of gas purity and
odour
• Atmospheric research e.g. global background
pollution levels, pollution transport and kinetic
studies, such as monitoring diurnal changes in
urban air pollution or biogenic emission profiles
Series 2 (U
LTRA-)UNITY-Air Server systems connect to
any Agilent or other brand of GC(MS)
Air Server 2 Main Features
• Adds automated canister and on-line air/gas stream analytical capability to any series 2 (ULTRA-)UNITY
thermal desorption (TD) system.
• Cryogen-free operation and low consumption of gas supplies for lower running costs and higher uptime.
• 3 or 8 channel operation for sequencing between sample, zero and standard air/gas streams during
unattended on-line monitoring or automated canister/bag analysis
• Quantitative retention of ultra-volatiles such as acetylene from increased sample volumes (up to 1.5 L)
combined with peerless high-resolution capillary chromatographic performance (even under splitless conditions)
ensure optimum sensitivity. Parts per trillion (ppt) levels are readily detected.
• Method compliant tube desorption capability included with every system. Can be automated.
• Thermostatted flow path and internal standard addition options for compliance with standard canister
methods.
• Negligible sample carryover plus versatile sampling flows & flexible splitting options allow analysis of both
high and low concentration samples.
• Small footprint: Especially useful for installation in mobile labs.
• Versatile water management options for analysis of both dry and humid air/gas samples.
Overview of Air Server operation
Series 2 Air Servers connect to any series 2 UNITY or
ULTRA-UNITY TD system. They contain 3, or 8 inert
sample/stream selection valves uniquely configured to
eliminate dead volumes and prevent carryover. Each
whole air/gas sample (pressurised or at
(sub-)atmospheric pressure) is introduced directly into
the electrically-cooled, sorbent-packed, focusing trap of
the UNITY 2 thermal desorber for a user-specified
sampling time. Conventional sorbent sampling tubes
are not used in this process.
The sampling flow is regulated by an electronic mass
flow controller (MFC) and optional pump located
downstream of the trap to eliminate risk of
contamination. Focusing trap sorbent and trapping
temperatures are selected for quantitative retention of
the compounds of interest and for selective purging of
potential interferences such as CO
2
and water. No
liquid cryogen is required and only inert, non-emitting
components come into contact with the sample. All
sampling parameters are monitored by system
software as an integral part of the analytical method.
At the end of sample introduction, the flow path is
purged with carrier gas to prevent carryover and
eliminate oxygen from the focusing trap. The trap then
heats rapidly in a reverse stream of carrier gas to
inject/transfer retained compounds into the
measurement system and trigger the analysis. This
transfer/injection may be performed splitless for
maximum sensitivity. (See UNITY 2 brochure for
more details.)
Once the focusing trap has desorbed, it cools and reequilibrates at the trapping temperature. Focusing of
the next air/gas sample in the sequence may begin
while analysis of the previous sample is ongoing to
optimise throughput.
Series 2 Air Server range
The table below highlights the differences between the
Air Server 3 and CIA 8.
Note: Air Server 3 is integrated with UNITY 2 prior to
shipment or during field installation to minimize bench space in
confined locations such as mobile labs or remote monitoring
stations. The CIA 8 is a separate module.
Air Server 3
Canister Interface
Accessory (CIA 8)
Number of channels 3 8
Thermostatted flow path
Internal standard addition
Schematic of Air Server 3 operation
Sample
selection
valves
Series 2
Air Server
UNITY 2 GC(MS)
Cold
trap
Optional
split
Desorption
flow
Sampling
flow
Intuitive user interface
Control of series 2 (ULTRA-)UNITY-Air Server systems
(Air Server 3 or CIA 8) is intuitive and integrated with
the UNITY 2 TD software to provide one comprehensive
and easy to understand user interface (UI).
The UI offers a specific mode for on-line/canister
operation (see figure opposite) and, once selected,
users are prompted to enter the relevant sampling
parameters such as sampling time, flow rate and purge
times.
Sequence building
Automated sequences for on-line monitoring and/or
automated canister/bag analysis are easily constructed
via the sequence builder. Samples may be assigned
individual desorption methods. Each sample is
classified as sample, calibrant or blank and all
sequences may be stored and recalled for future
reference or repeat use.
Graphical sequence viewer
The sequence viewer presents a clear graphical display
of current sequence status.
Sequence reporting
Information associated with each analysis, such as the
time, date and any deviations, are all recorded in the
sequence reporter. Any sample sequence failure
triggers the GC(MS) system to start a blank run to
keep the analyser in step with the autosampler.
Up to 8-channels for
optimum throughput
Control method screen (top) of user interface.
Complete user interface screen (bottom)
Round-the-clock,
cryogen-free monitoring
On-line operation
On-line monitoring systems typically comprise a
series 2 UNITY with integrated 3-channel Air Server
module. The combined system is programmed to
repeatedly introduce air/gas from the sample
stream(s) and to automatically sequence calibration
gas and zero air/gas at user-defined frequencies,
typically once every 24 hours. Sequences may be
recycled indefinitely to minimise system programming.
Continuous monitoring of ozone precursors (C2–
C10hydrocarbons) in urban air, as required by both
European and US regulations
1,2
, is a key application for
series 2 UNITY-Air Server systems.
Key advantages of Markes series 2 UNITY-Air Server
systems for ozone precursor monitoring include:
• Unattended operation for extended periods:
Cryogen-free operation and low consumption of
gases simplifies installation in mobile labs and
offers extended periods of unattended operation
in remote field monitoring stations. Markes
cryogen-free series 2 UNITY-Air Server systems
consume only 40 ml/min dry gas/air when
configured without a Nafion dryer and less than
200 ml/min when a dryer is configured. This is
between 3 and 10 times less than other cryogenfree ozone precursor monitoring systems and
allows extended operation without cylinder
replacement
• Sensitivity: Quantitative retention of ultravolatiles such as acetylene from up to 1.5 L air
sample volumes combined with efficient splitless
desorption at low (<2 ml/min) flows ensures best
possible detection limits (typically 1-50 ppt
levels)
1. Council Directive 96/62/EC: On ambient air quality assessment and
management, and the daughter directive - 2002/3/EC relating to ozone in
ambient air
2. 1990 US Clean Air Act Ammendment
Splitless desorption of 56-compound US EPA mix of ozone precursors using series 2 UNITY-Air
Server 3 with dual column/dual FID GC with Dean’s switch
Compound
Det limit
(ppb)
450 ml
sample
Column
%RSD
(n=12) R
t
450 ml
sample
% RSD
(n=12)
peak area
450 ml
sample
Ethane 0.026 Al PLOT 0.07 0.3
Butane 0.010 Al PLOT 0.01 0.4
Hexane 0.019 DB1 0.01 0.5
Octane 0.017 DB1 0.01 1.0
Data courtesy of Ecole des Mines de
Douai, France
Field-proven, robust on-line monitoring of H2S and other reduced sulphur compounds down
to sub-ppb levels in ambient air
On-line odour monitoring - Another key application for series 2 UNITY with integrated Air Server 3 option
y = 0.2953x + 5.2249
R
2
= 0.9999
Sample Volume (mL)
Acetylene Peak Area
H
2
S
CH
3
SH
DMS
DMDS
H
2
S
CH
3
SH
DMS
DMDS
10 ppb
20 ppb
Compound
Minimum
Detection
Limit (ppb)
%RSD
(n=10,
20ppb)
Hydrogen sulphide
(H2S)
0.15
4.1
Methyl mercaptan
(CH3SH)
0.15 1.8
Dimethyl sulphide
(C2H6S)
0.15 0.8
Dimethyl disulphide
(C2H6S2)
0.10
0.8
Data courtesy of Ecole des Mines de
Douai, France
Data courtesy of ITC, South Korea
Cryogen-free trapping of ultra-volatile compounds
including acetylene (ethyne) from up to 1.5 L of air
• Reliably excellent chromatographic
performance: Great resolution, stable retention
times and repeatable concentration data minimise
measurement uncertainty and simplify data
interpretation/validation
• Small footprint: The Series 2 UNITY with
integrated 3-channel Air Server is only 22 cm
(9-inches) wide
Timed start
Series 2 UNITY-Air Server systems allow the start of a
monitoring sequence to be programmed for a specific
date and time (e.g. noon on Monday May 1st) and for
the period between each sampling cycle to be fixed.
The sampling cycle used for ozone precursor
monitoring for example, is typically 1 hour. In this case
air is usually sampled into the UNITY 2 focusing trap
for 40 minutes of every hour starting on the hour.
Automated off-line analysis of
Cryogen-free operation saves
thousands of dollars a month...
Schematic of series 2 UNITY - CIA 8 operation
Versatile sample splitting options offer compatibility
with vapour concentrations ranging from ppt to ppm
CIA 8
Stream
selection
Internal
standard
addition
Samples
Internal
standard
Sampling
flow
Desorption
flow
UNITY
GCMS
Optional split
canister/bag samples
Key issues associated with automated canister analysis
include throughput, running costs, sensitivity, water
management and method compliance. A typical Air
Server system configuration in this case would include:
The series 2 (ULTRA-)UNITY with a Canister Interface
Accessory (CIA 8) for 8 channels.
Series 2 UNITY with CIA 8 features a thermostatted
sample flow path and internal standard (IS)
addition to the focusing trap. The system is fully
compliant with relevant standard methods such as
US EPA Method TO-15 for “Air Toxics”.
Air toxics monitoring
Key advantages of Markes series 2 (ULTRA-)UNITY-
CIA 8 technology for Air Toxics monitoring and for
canister air analysis generally include:
• Productivity: Markes systems offer 8-channels
for automated operation over extended periods.
Confirmatory repeat analysis of each canister
may be included in the automation sequence
• Cost reduction. Cryogen-free operation
minimises:
• Capital costs (no liquid nitrogen dewar
required)
unning costs (cryo-cooled systems require
• R
fresh supplies of liquid coolant as often as
every 2 or 3 days)
• Manpower (changing/refilling of liquid
coolant dewars takes time and effort)
• Downtime (replenishing liquid cryogen often
interrupts an automated sequence)
TO-15 standard chromatogram (1ppb in 1 L) (main) and real air sample (insert)
Canisters, bags and sorbent tubes
1
2
3
4
5
6
7
8
9
10
11
12
13
14
16
15
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
1 Dichlorodifluoromethane
2 1,2–Dichlorotetrafluoroethane
3 1,3–Butadiene
4 Trichlorofluoromethane
5 1,1,2–Trichlorotrifluoroethane
(Freon 113)
6 Isopropyl alcohol
7 Carbon disulfide
8 Methylene chloride
9 Tert-butyl methyl ether
10 n-Hexane
11 1,1-Dichloroethane
12 Ethyl acetate, methyl ethyl ketone
13 Tetrahydrofuran
14 Cyclohexane
15 Benzene
16 n-Heptane
17 Trichloroethylene
18 1,2–Dichloropropane
19 Bromodichloromethane
20 Trans-1,3-dichloropropene
21 Methyl isobutyl ketone
22 Toluene
23 Cis-1,3-Dichloropropene
24 Tetrachloroethylene
25 Methyl n-butyl ketone
26 Dibromochloromethane
27 1,2–Dibromoethane
28 Chlorobenzene
29 Ethylbenzene
30 Xylene
31 Styrene
32 Tribromomethane
33 1,1,2,2-Tetrachloroethane
34 1,2,4-Trimethylbenzene
35 1,3,5-Trimethylbenzene
36 1,2-Dichlorobenzene
37 1,3-Dichlorobenzene
38 Chloromethylbenzene (alpha)
39 1,4–Dichlorobenzene
40 1,2,4–Trichlorobenzene
41 Hexachloro-1,3-butadiene
Isopropyl alcohol
DCM
Hexane
Methyl cyclopentane
Cyclohexane
1-Methyloxy-2-propanol
Toluene
2-Methyl butane
Benzene
2,4-Dimethyl pentane
0.1 ppb level
Time (mins)
• Analytical excellence: Super-efficient trap
desorption and reliably excellent chromatographic
performance, even under splitless conditions and
without on-column focusing (see Series 2 UNITY
brochure), optimise sensitivity and simplify
identification of target air toxic analytes even in
complex backgrounds.
• Versatile water management: Markes TD
systems offer selective purging of water,
sophisticated sample splitting and the option of
in-line dryers for effective water management
under any air monitoring conditions.
ppm...ppb...ppt
Versatility
The application range of series 2 Air
Server technology
Series 2 (ULTRA-)UNITY–Air Server systems (Air Server
3 or CIA 8) offer quantitative and cryogen-free
retention, even of ultra-volatile species such as freons
and C2hydrocarbons, together with complete recovery
across the air toxics boiling range. Labile, odorous
analytes, such as H2S and mercaptans may also be
measured at sub-ppb concentrations. Markes systems
are compatible with the highest boiling compounds that
can be recovered from canisters or ambient
temperature air/gas streams.
New improved stream selection valves and an inert,
thermostatted flow path eliminate sample carryover
even when monitoring over a wide concentration range
(ppt to ppm). This allows ambient air samples to be
calibrated with small volumes of relatively concentrated
standard gas. It also allows automated sequencing of
samples varying widely in concentration without fear of
contamination.
Compatibility with samples over a wide concentration
range is further enhanced by sophisticated,
electronically-controlled sample splitting during trap
desorption (and during tube desorption, if applicable).
On-line monitoring, canisters/bags
AND tube desorption
Whether they are used for on-line monitoring or offline canister/bag analysis, all systems incorporating
series 2 Air Server technology, offer complementary
tube desorption.
Every series 2 Air Server is connected to a Markes
(U
LTRA-)UNITY 2 system. The UNITY 2 TD platform
offers method-compliant desorption of single tubes and
the addition of a series 2 ULTRA allows automatic
analysis of up to 100 sorbent tubes. Series 2 (ULTRA-)
UNITY systems are described in detail in the associated
brochures and their performance is not compromised in
any way by the addition of an Air Server module.
In summary, key advantages of series 2 (U
systems for tube desorption include:
• Application versatility. Series 2 (U
systems are compatible with every TD application
on one analytical platform; ultra-volatiles (e.g. C
hydrocarbons), semi-volatiles (up to n-C40) and
reactive compounds. Samples for tube desorption
either comprise sorbent tubes used to collect
organic vapours or material samples (solid or
liquid) weighed directly into empty TD sample
tubes for direct desorption. Splitless, single or
double split options allow analysis of samples
ranging in concentration from ppt to percent
without overloading the analytical system
LTRA-)UNITY
LTRA-)UNITY
2
• Method compliance. Markes’ tube desorption
technology complies with all key standard
methods; US EPA Method TO-17 (ambient and
indoor air), ISO 16017 (workplace, ambient and
indoor air), EN ISO 16000 (materials emission
testing), NIOSH 2549 (workplace indoor air), etc.
Important features for method compliance include
effective tube sealing during automation,
stringent (ambient-temperature/no-flow) leak
testing, cryogen-free cooling and the option of IS
addition
Detection of trace level analytes aids atmospheric
research
Real time monitoring -
real time detection
30 ml of air from bubbles in the ice core
collected in canisters. Analysis by TD-GCMS in NCI mode. Unit ppt detection limits
Toluene
Subsequent blank run
Contaminated air sample
Negligible carryover with series 2 UNITY-Air Server
• Repeat analysis. The proprietary SecureTD-Q
facility is supplied as standard with every series 2
(ULTR
A-)UNITY system. It offers quantitative recollection of any split flow (during tube or trap
desorption) facilitating repeat analysis and
simplifying method/data validation.
SecureTD-Q
overcomes the one-shot limitation of other
thermal desorbers
• High throughput. 100-tube capacity and
overlap mode (the ability to begin desorption of a
subsequent sample while analysis of a previous
sample is ongoing) optimise productivity/revenue
generation
• Compatibility with RFID tagged tubes
(TubeTAG) for enhanced tube/sample
traceability
Trademarks
SecureTD-Q™ and TubeTAG™ are trademarks of
Markes International Ltd.
Markes International Ltd.
Gwaun Elai Medi Science Campus
Llantrisant
RCT
CF72 8XL
United Kingdom
T: +44 (0)1443 230935 F: +44 (0)1443 231531
E: enquiries@markes.com W: www.markes.com
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