Measurements of atmospheric concentrations of volatile organic compounds are currently required in both urban and rural environments, where their presence can be directly detrimental to health. The DVLS Automatic Air Monitoring Analyser (A2MA) Provides in situ Analysis of VOCs in Urban Air.
The A2MA instrument has been developed for the automated in situ determination of airborne volatile organic compounds (VOCs) using programmed temperature vaporisation injection from a sorbent tube trap. A sorbent tube placed as an injection port liner can be repeatedly used to collect samples of air, with the trapped analytes being subsequently desorbed onto a capillary gas chromatography (GC) column without use of intermediate cryogenic refocussing.
The automation of sample collection and the elimination of the intermediate refocussing step, reduces much of the necessary on-site maintenance required for continuous monitoring, and allows in situ analysis in locations where previously this was not possible.
Using a multi positioning valve, the system can select between standards from, e.g., a tedlar bag or taking sample directly from the outside via, e.g., a probe on the roof of a mobile lab.
Via a smart flow system, sample is pumped through the injector port liner containing a suitable trapping material in reverse flow from bottom to top trapping the analytes, while the carrier gas is re-routed to the GC capillary column by-passing the injector port. Sampling is during a fixed time with a constant flow controlled with a mass flow controller, without the use of additional coolant as LN2 or CO2.
Once the sampling period has finished, the carrier gas via the injector port is re-established. Following, the injection port is heated to desorb the analytes from the injection port liner for transfer to the GC capillary column. In parallel to start heating the injection port liner, the GC–MS analysis has started.