Implementation of laser-induced breakdown spectroscopy as a continuous emissions monitor for toxic metals

Laser-induced breakdown spectroscopy (LIBS) has been considered for some time as a potential CEM method for toxic metals. Recently, improvements in sampling methodology and signal processing have allowed LIBS to achieve detection limits below the proposed MACT limits for 5 out of 6 of the RCRA metals. This paper discusses performance improved by nearly 2 orders of magnitude of this in situ monitoring technique following implementation of conditional analysis. Results from trial burns at two incinerators and at a DoD contained burn facility are highlighted. At the incinerators, implementation of conditional analysis yielded much lower detection limits than previously reported using the LIBS technique. At the contained burn facility, reproducible, transient Pb measurements were recorded in real-time for concentration values that varied by more than two orders of magnitude. Method detection limits of between 2 and 100 μg/dscm are reported for toxic metals Be, Cd, Cr, Hg, and Pb.