MARKES Air 2 Server User Manual

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