Master TD 4750 Thermal Desorber: High Sensitivity Analysis of VOCs in Air

OI Analytical’s new Master TD 4750 Thermal Desorber processes air samples collected in sorbent tubes for high sensitivity GC/GC-MS analysis of volatile organic compounds (VOCs) and semi-volatile compounds (up to C44). Concentrating a large volume sample in a sorbent tube followed by thermal desorption onto a GC column allows for monitoring of pollutants at parts per billion (ppb) or parts per trillion (ppt) levels.

The Master TD 4750 is designed to help laboratories handle testing of environmental air, industrial emission, and workplace air samples in an efficient, cost-effective manner. A built-in 50-position autosampler supports unattended operation with industry standard (.25-inch O.D. x 3.5-inch long) stainless steel and glass sorbent tubes, and Radiello® air sampling cartridges. An optional Air Sampler module connects to the Master TD 4750 for direct sampling of air, or to automate sampling from SUMMA® canisters and Tedlar® bags. The Master TD 4750 employs a two-stage thermal desorption process. In operation a sorbent tube in the autosampler is lifted into a heating device and sealed at each end for an automatic cold pressurised-gas leak

test. Primary desorption of VOCs from the sorbent tube occurs as the temperature increases to a programmed set point of 40° to 400°C. Carrier gas flow transfers VOCs to a sorbent

trap.

The trap is a quartz tube containing application-specific sorbents to focus analytes before the second thermal desorption step is performed. The trap is surrounded by a patented shuttle mechanism that rapidly positions a Peltier cooling device or electric heating element for instantaneous cooling and heating. Peltier cooling (to – 40 °C) focuses even extremely volatile

compounds (e.g.; chlorofluorocarbons - CFCs) onto the trap. Instantaneous heating of the trap desorbs the VOCs in a narrow band and introduces them into the GC column via a heated transfer line to preserve chromatographic resolution and accuracy.

The Master TD 4750 is compatible with current models of GC/GC-MS instruments manufactured by Agilent, Shimadzu, Thermo-Fisher, and others.