DETECTION OF METALS IN THE ENVIRONMENT USING A PORTABLE LASER-INDUCEDBREAKDOWN SPECTROSCOPY INSTRUMENT

A portable instrument, based on laser-induced breakdown spectroscopy ( LIES), has been developed for the detection of metal contaminants on s urfaces. The instrument has a weight of 14.6 kg, fits completely into a small suitcase (46 x 33 x 24 cm), and operates from 115 V ac. The in strument consists of a sampling probe connected to the main analysis u nit by electrical and optical cabling. The hand-held probe contains a small laser to generate laser sparks on a surface and a fiber-optic ca ble to collect the spark light. The collected light is spectrally reso lved and detected with the use of a compact spectrograph/CCD detector system. The instrument has been evaluated for the analysis of metals i n the environment: Ba, Be, Pb, and Sr in soils; Pb in paint; and Be an d Pb particles collected on filters. Detection limits in ppm for metal s in soils were 265 (Ba), 9.3 (Be), 298 (Pb), and 42 (Sr). The detecti on limit for Pb in paint was 0.8% (8000 ppm), corresponding to 0.052 m g/cm(2). The higher limit obtained for Pb in paint is attributed to th e use of the 220.35-nm Pb(II) line instead of the stronger 405.78-nm P b(I) line used for soils. Spectral interferences prevented use of the 405.78-nm line to determine Pb in paint. The surface detection limit f or Be particles on filters was dependent on particle size and ranged f rom 21 to 63 ng/cm(2). The detection limit for Pb particles on filters was 5.6 mu g/cm(2).