Simple and efficient method to detach intact PM10 from field filters. Elements recovery assessment

Toxicity of the soluble fraction of particulate matter (PM) has been extensively evaluated, but it has also been demonstrated that insoluble aerosol species can considerably contribute to toxicological potential of PM. However, most of the procedures regarding the assessment of toxicological effects of the whole PM (soluble and insoluble species) requires targeted treatments of the sampled filters, such as the employment of organic solvents, or the application of ultrasounds. Both methods can introduce a bias in the toxicological assessment, altering PM oxidative potential and biological outcomes. In this study, we applied a non-invasive, simple and efficient method for the detachment of intact PM10 from field filters by using an electrical toothbrush, which allows obtaining a PM10 water-suspension to be used for PM toxicity assessment. The efficiency of this method was evaluated by comparing the elemental content (As, Ba, Bi, Ca, Co, Cs, Cu, Fe, Ga, K, Li, Mg, Mn, Mo, Ni, Pb, Rb, Sb, Se, Sn, Sr, Ti, Tl, U and W) obtained by brushing the filters to that measured by applying a conventional procedure to PM samples (n. 20 pairs of equivalent PM10 filters). Soluble and insoluble fractions were separately analyzed, in order to discriminate the recovery due to partial solubilization of sample from that due to detachment of insoluble particles. The high recovery percentage of elements, the very-high linear correlation coefficients and the low relative percentage differences with respect to a conventional procedure for elemental analysis of PM10 confirmed the efficiency of the toothbrush method.