We describe a new instrument (μDirac) capable
of measuring halocarbons in the atmosphere. Portability,
power efficiency and autonomy were critical design requirements
and the resulting instrument can be readily deployed
unattended on a range of platforms: long duration balloon,
aircraft, ship and ground-based stations. The instrument is
a temperature programmed gas chromatograph with electron
capture detector (GC-ECD). The design requirements
led to μDirac being built in-house with several novel features.
It currently measures a range of halocarbons (including
short-lived tracers having biogenic and anthropogenic
sources) with measurement precision relative standard deviations
ranging from±1% (CCl4) to±9% (CH3I). The prototype
instrument was first tested in 2005 and the instrument
has been proved in the field on technically challenging aircraft
and ground-based campaigns. Results from an aircraft
and a ground-based deployment are described.