Multi-element analysis of size-segregated fine and ultrafine particulate via Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry

In this study a novel and reliable Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICPMS)
measurement protocol for the elemental characterization of size-segregated particulate was
developed. Special efforts were made to improve and optimize sample pre-treatment steps and LA
operating conditions to avoid some critical drawbacks encountered during analysis and to make the
particulate samples suitable for an accurate and reproducible LA-ICP-MS analysis, regardless of the mass
loading on each filter. For example, a new approach for dust-fixation on the sample-carrier was developed
using a glycerol coverage, which allowed to overcome problematic sample losses during the
ablation process. Under the optimum conditions, dust samples, blank filters and standards for calibration
were analyzed by multiple rastering of defined spot areas. Quantitative analysis was accomplished with
dried micro-droplets of aqueous standard solutions. Derived method detection limits varied between
0.001 and 0.1 ngm3 and allowed even for the smallest particle fraction quantitative measurements. The
accuracy of LA-ICP-MS results was verified by comparison with conventional ICP-MS analysis of selected
PM samples after sample mineralization. The proposed LA treatment procedure benefits from a simple
and fast sample preparation, thus overcoming the laborious pre-treatment steps required for wet
chemical digestion. Moreover, the better sensitivity of the LA-ICP-MS approach provided more complete
information about the mass concentration and size-distribution of the investigated elements, thus allowing to deeper investigate the composition of the most dangerous PM fractions in terms of health concern.