Total reflection X-ray fluorescence analysis of laser-deposited solid sample material

Abstract

Laser ablation (LA) was applied as a sampling technique for the analysis of solids by total reflection X-ray fluorescence (TXRF). The sample material ablated by a pulsed Nd∶YAG laser was collected directly on a quartz glass or Plexiglas® disc commonly used as a sample carrier for TXRF. The analytical capabilities of the combined method were investigated using an improved arrangement of solid sample and TXRF carrier. The technique was applied to the analysis of metallic samples, i.e. Fe–Cr binaries and high-alloy steel, and non-metallic samples, i.e. Al–Ti ceramics, native mineral rocks and gallstones. The nanogram amounts of material deposited on the carrier were always sufficient for TXRF analysis. Quantification was performed by addition of an internal standard. Absolute detection limits for Fe and Cr in binary samples were 50–60 pg, corresponding to a mass fraction of 5–6 mg g−1 assuming a 10 ng deposit. Sampling from preselected spots of mineral rocks made possible the identification of different components in granite by means of their major and minor constituents. The combined method of LA and TXRF can be used for the rapid characterization of solids on the 10 µm scale without laborious steps of sample preparation.