This can vary from monitoring the atmosphere within a factory to analysing atmospheric emissions. Various models are available dependent upon the requirements such as a single inlet mobile system through to a multi-inlet fixed station. At the heart of all these is the well-proven DQC2000 computer controlled quadrupole mass spectrometer, with a comprehensive software package. 

The main advantage of the TGA1 system is that it is the only system that can provide fast on-line analysis down to ppb levels. Low level alarm facilities. Automatic self calibration, and automatic data storage.

The hardware consists of 3 distinct sections - the quadrupole, the vacuum system and the inlet system.

DQC2000 is available with mass ranges from one to 100, 200 or 300 amu dependent upon the masses of the species to be detected. It consists of an analyser head, rf generator, MS supplies unit and IBM compatible PC with colour monitor and keyboard. The specification and software description are listed in a separate datasheet.

The standard vacuum system consists of a turbomolecular pump backed by a trapped 2-stage rotary pump with oil mist filter. Penning and Pirani gauges are standard. The analyser is mounted onto the vacuum system and a background level in the region of 3 x 10-9mbar can be reached. 

The heart of the inlet is the membrane sampler that enriches volatile organic materials in atmospheric samples. The characteristics of the membrane are such that organic materials pass through more easily than the normal air gases. This enrichment factor can be up to 500 enabling detection down to sub ppb levels to be achieved. As the membrane material has varying sensitivities to the organic species, a calibration facility is provided. The system is calibrated with the prepared/reference sample and it is then ready to monitor the environment. The inlet stability is maintained by either enclosing it in a temperature-controlled environment. Or the automatic self-calibration facility provided by the software.

For many applications, it will be required to monitor several locations. A multiple inlet is available for this providing 8, 16, 24 or 32 sampling points. The control software allows setting of variable delay times and inlet sequencing.

Some detection limits achieved are:- 

Development is continuing on new membrane probes and channel averaging software. Detection levels lower than the figures quoted above are expected in the near future.