UV and IRlaser ablation study of natural organic powdered materials—an example: ICP-OES with laser ablation of spiked infant formula cast pellets

Abstract

Laser ablation (LA) sample introduction into inductively coupled plasma optical emission spectrometry (ICP-OES) was used for powdered infant food formula being representative of samples with an organic matrix. Milk samples enriched with eight naturally occurring elements were presented for LA-ICP-OES experiments as cast epoxy resin disks. For Ca, Cu, Fe, Mg and Zn, a performance of IR (1064 nm) and UV (266 nm) ablation was compared in a fixed spot mode (UV) and in a scanning mode (both UV and IR). Signal vs. content dependences proved to be linear both with and w/o the internal standard Ca (IS). Using the IS the linear regression parameters for the scanning mode were improved for both UV and IR ablation. The UV fixed spot ablation provided the closest correlation and so, except for Cu (low content), repeatability for all elements of interest did not exceed 10% RSD. Lowest determinable quantities were 0.06% Ca, 0.008% Mg, 0.0005% Cu, 0.001% Fe and 0.0008% Zn. Condensation of Zn on ejected particles was observed at the UV ablation.