Rapid Determination of Metal Particles on Air Sampling Filters Using Laser-Induced Breakdown Spectroscopy

Abstract

A preliminary investigation of an alternative method of analysis for metal particles is presented. The mass of thallium (TI) particles on filters was determined in less than 1 minute using the technique of laser-induced breakdown spectroscopy (LIBS).Thallium was collected by passing contaminated air through a filter or by wiping a TI-contaminated surface with a filter. The particles (<20 µm diameter) were in the form of thallic oxide used in the manufacture of superconducting metals. Thallium was detected by forming a series of laser sparks across the filter surface. The sparks vaporized the particles and excited the resulting atoms. Thallium was detected by temporally and spectrally resolving the spark light. The detection limit for TI was 40 ng/cm2 on a filter surface. The useful dynamic range extends from 0.2 to 40 µg/filter using the strong 535.05 nm neutral TI emission line. The LIBS method of detection is intended to supplement (rather than replace) conventional analytical methods such as atomic absorption spectroscopy. Based on the investigation reported, LIBS has the potential to provide a method for rapidly ansalyzing multiple samples on-site at a low cost.