Direct solids atomic emission spectrometric analysis of metal samples by "laser-Induced argon spark ablation" coupled to ICP-OES

A new type of laser ablation system (laser-induced argon spark atomizer) co mbined with inductively coupled plasma optical emission spectrometry (ICP-O ES) was used for the direct analysis of compact metallic samples. The mater ial is ablated with the aid of a Nd:YAG laser (lambda = 1064 nm, 300 mJ/pul se, v = 4-20 Hz) and entered with a carrier-gas into a commercial ICP-OES s ystem (Plasma 2000, Perkin-Elmer) with two monochromators. The influence of the laser parameters (pulse frequency and power) on the ablation rate and the particle size of the ablated material were investigated, and they were found to range from 1.0 to 16.7 mug/s and below 100 nm, respectively. In th e case of brass samples, selective evaporation of the matrix elements Cu an d Zn was found to occur. Laser parameters such as frequency, power, and abl ation time were found not to influence the selective evaporation of Cu and Zn significantly. The detection limits for Ni, Cr, Mo, Mn, and Si in low-al loyed steel; Fe, Ni, Sn, and Pb in brass; and Fe, Cu, and Si in aluminum we re found to be at the 20-100 mug/g level, independent of the sample matrix. The long-term stability of the emission signal was found to be better than 5% for ablation times of up to 10 min, and relative standard deviations us ually are between 1 and 5%. For Mo, Mn, Si, Ni, and Cr in the BAS SS 435 sa mple, good agreement of the analytical results at the 0.01-0.5% level with certified values could be obtained when calibrating with other BAS standard reference samples.