Development of a Portable Monitor for Detection of Toxic Organic Compounds

摘要

A dual beam prototype instrument was designed, constructed, tested, and delivered to the Environmental Monitoring Systems Laboratory, Research Triangle Park, North Carolina, in December 1983. It was designed for monitoring benzene with the Hg 253.7 nm line using the TALMS (tunable atomic line molecular spectrometer) technique. The instrument consisted of three units: the optical unit (weight: 52 lbs), the electronics unit (weight: 16 lbs), and a power supply (weight: 14 lbs). Tests of the performance of the benzene monitor showed linear response from the detection limit of approximately 40 to 3000 ppm-v. The magnetically contained lamps used with the TALMS technique were improved so that they are more stable, intense and have longer service lives. Searches for locations of potential TALMS signals in o-, m-, p-xylenes, bromobenzene, benzene and aniline were carried out. TALMS signals were found for p-xylene with Si, Co, and Sb lines at 252.9 nm. No signals were found at this wavelength for o- or m-xylenes. TALMS signals were also found for bromobenzene at 270.2 nm (Pt) and 266.5 nm (Fe) and aniline at 293.8 nm (Bi). It is recommended that further searches be carried out to extend the potential of the TALMS technique to other organic compounds and to decrease its detection limit for benzene. The use of a new related technique, Atomic Line Molecular Spectroscopy (ALMS), is also recommended.