Direct Solids Atomic Emission Spectrometric Analysis of Metal Samples by “Laser-Induced Argon Spark Ablation” Coupled to ICP-OES

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Abstract
A new type of laser ablation system (laser-induced argon spark atomizer) combined with inductively coupled plasma optical emission spectrometry (ICP-OES) was used for the direct analysis of compact metallic samples. The material is ablated with the aid of a Nd:YAG laser (λ = 1064 nm, 300 mJ/pulse, ν = 4–20 Hz) and entered with a carrier-gas into a commercial ICP-OES system (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 μg/s and below 100 nm, respectively. In the case of brass samples, selective evaporation of the matrix elements Cu and Zn was found to occur. Laser parameters such as frequency, power, and ablation 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-alloyed steel; Fe, Ni, Sn, and Pb in brass; and Fe, Cu, and Si in aluminum were found to be at the 20–100 μg/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 usually are between 1 and 5%. For Mo, Mn, Si, Ni, and Cr in the BAS SS 435 sample, 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.