Thermal Desorption Systems & Units
Markes innovative range of thermal desorption instruments includes:

UNITY 2 is a flexible, method-compliant TD platform which incorporates every technical innovation of the last 10 years and is compatible with any make of GC(MS).
Key features include:
- Compatible with electronically-tagged or untagged tubes in 3.5-inch (standard) or 4.5-inch (DAAMS*) lengths.
- Provides a single platform for all TD applications - labile species, semi-volatiles (up to n-C40), ultra- volatiles (including C2H2 and freons), trace levels (ppt) and high concentrations (ppm/%).
- Repeat analysis via SecureTD-Q: Overcomes the one shot limitation of other TD systems.
- Cryogen-free operation: Electrically-cooled, sorbent trapping to -30°C eliminates ice plug formation and reduces running costs.
- Retention time stablity: Enhanced using optional electronic carrier gas control (ECC) through the entire TD-GC(MS) system. Available with leading brands of GC. ECC complemented by optional intengrated MFC's for electronic control of split and desorb flows.
- Fully upgradeable to multi-tube, multi-canister and/or on-line automation. Can also be coupled with headspace for even greater sample flexibility.
* DAAMS: Depot Area Air Monitoring System as used in some chemical agent destruction facilities
Series 2 U
LTRA automated the peerless analytical performance of any series 1 or 2 UNITY TD.
With capacity for up to 100 tubes U
LTRA 2 offers the following key advantages:
- Round-the-clock automation optimising TD-GC(MS) productivity.
- TubeTAG™: Reading/writing of RFID tags on sorbent tubes is now fully integrated with automated TD operation. This revolutionizes tube and sample traceability.
- Compatibility with various tube sizes: Two versions of ULTRA 2 are available; one for standard (3.5-inch) tubes and the other for 4.5-inch long (DAAMS) tubes. Both versions are compatible with tagged or untagged tubes.
- Stringent sample sealing. Patented DiffLok™ caps preserve sample and blank tube integrity more effectively than other caps and ensure compliance with standard methods.
- Quantitative sample re-collection (SecureTD-Q) is offered as standard on every series 2 ULTRA-UNITY system for repeat analysis of critical samples and/or method validation. Automation of SecureTD-Q is available using single or double ULTRA configurations.
- ULTRA-reliability: Field-proven, mechanically-simple automation ensures robust operation.
- Method compliance: Incorporates the ambient temperature/no-flow leak test of UNITY 2 as a guarantee of data integrity. Option of internal standard addition to blank or sampled tubes.
- Optional dry-purging of sorbent tubes as part of the automated sequence.
Incorporates all the main features of series 2 U
LTRA plus:
- Quantitative & automatic re-collection of the trap desorption (outlet) split flow for up to 50 (or 100) samples.
- Automatic dry purge of every tube, in the sampling direction, prior to desorption.
- Colour-coded trays clearly identify sample and re-collection tubes.
- Adds to any series 1 or 2 UNITY.
AutoSecure TD™ system
- The AutoSecureTD system comprises a series 2 UNITY TD and two series 2 ULTRA autosamplers
- Offers desorption of up to 100 tubes with quantitative and automatic re-collection of both trap and tube (inlet and outlet) split flow onto clean tubes located in the second ULTRA 2.
- AutoSecureTD system offers optimum versatility and productivity, particularly for high throughput laboratories. If demand for tube desorption increases, addition of a second UNITY 2 allows an AutoSecureTD system to be transformed into two series 2 ULTRA-UNITY systems to help cope with the volume of samples.

Series 2 Air Server options include 3- or 8-channel Air Server modules for on-line air/gas monitoring and the CIA 8 for automated, method-compliant canister analysis. All these options add to UNITY 2 and allow a controlled flow of whole-air or gas to be introduced directly into the electrically-cooled focusing trap of the desorber.
Key features include:
- Cryogen-free operation and low consumption of gas supplies for lower running costs and higher uptime.
- Minimum 3 channels for sequencing between sample, zero and standard air/gas streams during unattended online monitoring.

- Quantitative retention of ultra-volatiles such as acetylene from increased sample volumes (up to 1.5 L of air) 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 & internal standard addition available on the CIA 8 for compliance with standard canister methods.
- Negligible carryover, versatile sampling flows and flexible splitting options allow analysis of both high and low concentration samples.
- Versatile water management options for analysis of both dry and humid air/gas samples.
- Single analytical instrument for all TD applications - VOC, SVOC, thermally labile & reactive compounds, trace levels (ppt) and high concentration (ppm/%) in a single sequence. Simultaneous analysis of VOC and SVOC
- Cryogen (liquid nitrogen) free operation - electrically cooled sorbent trapping to eliminate ice plug formation and reduce running costs
- Quantitative sample re-collection (SecureTD-Q™) for repeat analysis - overcomes the one-shot limitation of other analytical thermal desorption systems
- Automation for up to 100 thermal desorption tubes
- RFID sorbent tube and sample tracking (TubeTAG™) for recording tube and sample history as standard; TD-100 can also accomodate untagged thermal desorption tubes
- Fully method compliant including stringent leak testing
- TD-100 adds to any commercial GC or GC/MS and is designed for easy maintenance
- Time saving overlap mode allows desorption of a subsequent sample to begin while GC analysis of a previous sample continues
- Patented DiffLok™ caps provide a uniquely effective tube seal pre- and post-desorption – preserving the integrity of sample and blank tubes
For continuous air/gas monitoring applications, where no down-time can be tolerated (civil defence, kinetic studies, process control,
etc.), TT24-7 provides a robust, cryogen-free and high-performance solution
- Two electrically-cooled cold traps operate in tandem for continuous monitoring with no ‘blind’ spots
- 100% sampling efficiency
- Sub-ppb concentrations of organic vapours can be monitored with minimal cycle times
- Robust transportable unit suitable for lab or field operation
- Tube desorption accessory allows introduction of standards to either focusing trap
- Ideal for unattended on-plant operation
- Compatible with a wide range of bench top GC, GC/MS, MS and alternative analysers
Flexible Upgrade Path
UNITY 2 provides a full upgradeable platform with systems available at prices to suit every budget. Upgrade options include:
- Manual and automated headspace-trap operation with leading brands of headspace samplers
- Online/canister sequencing
- ULTRA 2 automation for up to 100 standard or DAAMS tubes with optional TubeTAG read/write
- ULTRA 50:50 or AutoSecureTD for automation of both tube desorption and re-collection
Accessories for instrumentation
- Calibration Solution Loading Rig: For introduction of gas or liquid calibration standards to sorbent tubes.
- Flowmeter: A digital flowmeter, to provide accurate real-time measurements for gas streams.
- Helium Gas Leak Detector: An essential piece of equipment for locating leaks in analytical systems that use helium as a carrier gas.
TD Innovation
For over a decade, Markes International has pioneered and commercialised enhancements to analytical TD instrumentation and associated sampling apparatus. The following examples of key technical advances have all been introduced by Markes since 1997 and now set the standard for TD instrumentation:
- SecureTD-Q™ (quantitative re-collection of ALL split flows for repeat analysis), which overcomes the historical one-shot limitation of TD methods and simplifies method/data validation
- Electronic tube tagging (TubeTAG™): RFID tube tags available for industry standard sorbent tubes and 4.5-inch (DAAMS) tubes
- Diffusion locking (DiffLok™) for enhanced sample integrity and robust automation
- Patented inert valving for compatibility with every TD application on a single analytical platform: Ultra-volatiles, semi-volatiles (up to n-C40) plus reactive species (mercaptans, CS gas, etc.) all on one TD system
- Automated internal standard introduction onto blank as well as sampled tubes
- Electronic Carrier gas Control (ECC) through the entire TD-GC(MS) system with leading brands of GC
- Electrically-cooled sorbent trapping with uniquely fast trap heating rates for splitless capillary GC operation and optimum sensitivity without risk of ice formation.
- Offline conditioning for multiple tubes without the need to blank-off unused tube connections
- Online desorbers with twin, electrically-cooled, reciprocally-operated focusing traps for truly continuous air monitoring (TT24-7™)
- Specialist sorbent tubes: Certified reference standards, SafeLok™ tubes, Silcosteel® tubes.
- A range of unique sampling tools, several of them patented, for measuring volatile and semi-volatile organics in challenging matrices: liquids/solids/emulsions, breath, in situ soil, polymers, natural products, construction products, etc.

For part numbers and pricing please contact your local Markes distributor.
Relevant technical support publications from Markes International can be automatically downloaded from this web site (registration required). Examples include: